1990 Engine Swap
12-30-2014, 10:47 PM
#41
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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I looked up the casting marks a while back and I actually think they're the 190s. I'm frequently wrong though. Did you see something on them to show that they're 227s?
Thanks for the heads-up on that gasket. I'll look into it.
Ok, i read u posted 68cc chambers in post #17 and thats all that comes up on a AFR search - #1121NP which has 68cc chambers (dont know what the NP means). Yes 190cc intk runners would be awesome for your combo - good for u. And your c.r. is a little higher for a 65cc chamber then. But lets measure the chamber before any more calcs.
As for quench your engine will run very well even without quench. Your priority should be a good composite gasket for alumin heads so your engine will live. Quench is more for detonation prevention and your compression ratio will be far from being close to that margin - i expect. We will know more once u measure the head chambers. Good quench would add just a few ponies if any and a thick composite gasket would be soo much more reliable than any steel shim gasket under alum heads. Just think of nearly all the new cars that roll off the assembly line that dont have cyl quench. Nice but not required. I have seen owners with small coolant leaks after a head swap and they were not having fun trying to stop the gas bubbles in the radiator.
Hope this helps more than it hurts.
Thanks for the heads-up on that gasket. I'll look into it.
Ok, i read u posted 68cc chambers in post #17 and thats all that comes up on a AFR search - #1121NP which has 68cc chambers (dont know what the NP means). Yes 190cc intk runners would be awesome for your combo - good for u. And your c.r. is a little higher for a 65cc chamber then. But lets measure the chamber before any more calcs.
As for quench your engine will run very well even without quench. Your priority should be a good composite gasket for alumin heads so your engine will live. Quench is more for detonation prevention and your compression ratio will be far from being close to that margin - i expect. We will know more once u measure the head chambers. Good quench would add just a few ponies if any and a thick composite gasket would be soo much more reliable than any steel shim gasket under alum heads. Just think of nearly all the new cars that roll off the assembly line that dont have cyl quench. Nice but not required. I have seen owners with small coolant leaks after a head swap and they were not having fun trying to stop the gas bubbles in the radiator.
Hope this helps more than it hurts.
12-31-2014, 02:14 AM
#42
Drifting
Thread Starter
Here's a quick and dirty shortcut.
I take modelling clay, fill whatever I'm trying to measure, and in the case of a piston in a cylinder, or a combustion chamber in a head, take a straight edge and smooth the clay even with the surface, then remove the clay and drop it in a graduated cylinder / tube partially filled with water and see how much it displaces. It's fast, easy and can measure (almost) any cavity in any position. example: 58 cc (nominal) Chevy heads measured out at 57.6 cc's.
If you use craft type modelling clay that hardens, and mark the volume on it, you can keep a permanent record of whatever you measured.
I take modelling clay, fill whatever I'm trying to measure, and in the case of a piston in a cylinder, or a combustion chamber in a head, take a straight edge and smooth the clay even with the surface, then remove the clay and drop it in a graduated cylinder / tube partially filled with water and see how much it displaces. It's fast, easy and can measure (almost) any cavity in any position. example: 58 cc (nominal) Chevy heads measured out at 57.6 cc's.
If you use craft type modelling clay that hardens, and mark the volume on it, you can keep a permanent record of whatever you measured.
that damper should work just fine; but before the heads go on, but with the timing chain, timing chain cover, and damper installed, set the number one piston at TDC and confirm that 0 on the damper lines up with the pointer on the timing chain cover; adjust as necessary...
I looked up the casting marks a while back and I actually think they're the 190s. I'm frequently wrong though. Did you see something on them to show that they're 227s?
Thanks for the heads-up on that gasket. I'll look into it.
Ok, i read u posted 68cc chambers in post #17 and thats all that comes up on a AFR search - #1121NP which has 68cc chambers (dont know what the NP means). Yes 190cc intk runners would be awesome for your combo - good for u. And your c.r. is a little higher for a 65cc chamber then. But lets measure the chamber before any more calcs.
As for quench your engine will run very well even without quench. Your priority should be a good composite gasket for alumin heads so your engine will live. Quench is more for detonation prevention and your compression ratio will be far from being close to that margin - i expect. We will know more once u measure the head chambers. Good quench would add just a few ponies if any and a thick composite gasket would be soo much more reliable than any steel shim gasket under alum heads. Just think of nearly all the new cars that roll off the assembly line that dont have cyl quench. Nice but not required. I have seen owners with small coolant leaks after a head swap and they were not having fun trying to stop the gas bubbles in the radiator.
Hope this helps more than it hurts.
Thanks for the heads-up on that gasket. I'll look into it.
Ok, i read u posted 68cc chambers in post #17 and thats all that comes up on a AFR search - #1121NP which has 68cc chambers (dont know what the NP means). Yes 190cc intk runners would be awesome for your combo - good for u. And your c.r. is a little higher for a 65cc chamber then. But lets measure the chamber before any more calcs.
As for quench your engine will run very well even without quench. Your priority should be a good composite gasket for alumin heads so your engine will live. Quench is more for detonation prevention and your compression ratio will be far from being close to that margin - i expect. We will know more once u measure the head chambers. Good quench would add just a few ponies if any and a thick composite gasket would be soo much more reliable than any steel shim gasket under alum heads. Just think of nearly all the new cars that roll off the assembly line that dont have cyl quench. Nice but not required. I have seen owners with small coolant leaks after a head swap and they were not having fun trying to stop the gas bubbles in the radiator.
Hope this helps more than it hurts.
I know I don't need quench, but I'd like to have it so that I can either run lower-octane gas or advance the timing a bit extra.
What have you found to be the problem with steel shim gaskets? I've been researching the use of steel shim gaskets with aluminum heads, and the one problem I see is that they don't seal if the block or heads is significantly warped. Since my engine was recently prepped by an engine shop, I wouldn't think this would be the case.
I don't mean to disagree with you, I just like to make my own decisions based on the facts.
My gaskets arrived a couple days ago and I'm running out of time so I don't want to have to mail back these gaskets and get new ones if I don't have to.
I appreciate all of your advice.
EDIT:
As much as I hate to say it, I'm leaning toward going with a different gasket. Although plenty of people say they've used steel shim gaskets using aluminum heads with no problems, some people report damage. Those against the use of a steel shim gasket with aluminum heads argue (as you mentioned) that the differential rates of thermal expansion and contraction of iron and aluminum causes wear on the heads unless the gasket is designed for such usage. The other prevailing argument is that the steel in a steel shim gasket, being harder than aluminum, causes brinelling (indentation) on aluminum heads. My heads may not be new, but they're still worth a pretty penny so I'm not sure risking damaging them is worth maybe 5 horsepower. On the other hand, it sounds like brinelling from steel shims is insignificant enough that a fairly light milling of the heads will remove it.
Does anyone have recommendations for head gaskets? I'd like to keep compressed thickness under .030" and price under $40/each. I was thinking the Clevite 5746 or the GM 14096405? To be clear, I haven't decided I want to change gaskets, but I want to have a plan in case I do.
Last edited by C4ProjectCar; 12-31-2014 at 03:05 AM.
12-31-2014, 08:26 AM
#43
Melting Slicks
Member Since: Sep 2008
Location: Cherokee National Forest TN
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I use a glass burette to cc heads. Inexpensive plastic unit here:
http://www.ebay.com/itm/100mL-Acrylic-Plastic-Burette-with-PTFE-Stopock-100-mL-Geissler-Buret-/331195429593?pt=LH_DefaultDomain_0&hash=item4d1cc932d9
Racers trick when using steel shim gaskets with aluminum heads:
Spray each side of each gasket with 4 coats of rattle can aluminum paint.
After 1 (one) heat cycle torque the head bolts again when the engine is cold.
http://www.ebay.com/itm/100mL-Acrylic-Plastic-Burette-with-PTFE-Stopock-100-mL-Geissler-Buret-/331195429593?pt=LH_DefaultDomain_0&hash=item4d1cc932d9
Racers trick when using steel shim gaskets with aluminum heads:
Spray each side of each gasket with 4 coats of rattle can aluminum paint.
After 1 (one) heat cycle torque the head bolts again when the engine is cold.
12-31-2014, 02:30 PM
#44
Drifting
Thread Starter
I use a glass burette to cc heads. Inexpensive plastic unit here:
100ml Acrylic Plastic Burette with PTFE Stopock 100 ml Geissler Buret | eBay
Racers trick when using steel shim gaskets with aluminum heads:
Spray each side of each gasket with 4 coats of rattle can aluminum paint.
After 1 (one) heat cycle torque the head bolts again when the engine is cold.
100ml Acrylic Plastic Burette with PTFE Stopock 100 ml Geissler Buret | eBay
Racers trick when using steel shim gaskets with aluminum heads:
Spray each side of each gasket with 4 coats of rattle can aluminum paint.
After 1 (one) heat cycle torque the head bolts again when the engine is cold.
I heard to install coated headgaskets bare so the coating can seal with each surface?
What are your thoughts on my head gasket situation? I'm guessing since you know that trick then you've used steel shims with aluminum heads before?
Here are what I see to be the pros and cons of each side.
Steel shim:
- Won't seal if both surfaces aren't smooth (newly prepped engine, shouldn't be an issue)
- Can brinell heads (will only be a problem when I remove the heads, which will hopefully be many years from now)
- If they don't seal, not only will I have to replace the head gaskets but I may have to have my heads milled to remove the brinelling (don't know how much this costs, or how much it would hurt value/performance of the heads)
- Thicker, giving less compression and less quench (realistically only a few horsepower, but it could allow me to run normal gas and save a little money)
- More expensive, especially with shipping to return current gaskets and buy new ones
- Postpones reassembly of my new engine for a week, which is after break ends (not sure how much time I'll have after break; this could postpone my swap until spring break)
12-31-2014, 06:50 PM
#45
Melting Slicks
[QUOTE
EDIT:
As much as I hate to say it, I'm leaning toward going with a different gasket. Although plenty of people say they've used steel shim gaskets using aluminum heads with no problems, some people report damage. Those against the use of a steel shim gasket with aluminum heads argue (as you mentioned) that the differential rates of thermal expansion and contraction of iron and aluminum causes wear on the heads unless the gasket is designed for such usage. The other prevailing argument is that the steel in a steel shim gasket, being harder than aluminum, causes brinelling (indentation) on aluminum heads. My heads may not be new, but they're still worth a pretty penny so I'm not sure risking damaging them is worth maybe 5 horsepower. On the other hand, it sounds like brinelling from steel shims is insignificant enough that a fairly light milling of the heads will remove it.
[/QUOTE]
Call me a dinosaur but I still think, from an absolute reliability standpoint , that the best combination is a cast iron head on a cast iron block with a steel shim gasket; absent some corrosion issue, that combo will take abuse and not fail.
Aluminum heads on a cast iron block, another story.
All my research says that because of the difference in expansion rates between aluminum and cast iron, the gasket MUST accommodate relative movement between the head and the block. At a minimum, this means an extra smooth surface on the head and block and a TEFLON coated gasket. Don't even think of using anything else. This is one place I would have to trust the factory; get whatever gasket that the factory installed on the LT4 engines, (the highest performance and the last aluminum head, cast iron block small block chevy engine produced).
EDIT:
As much as I hate to say it, I'm leaning toward going with a different gasket. Although plenty of people say they've used steel shim gaskets using aluminum heads with no problems, some people report damage. Those against the use of a steel shim gasket with aluminum heads argue (as you mentioned) that the differential rates of thermal expansion and contraction of iron and aluminum causes wear on the heads unless the gasket is designed for such usage. The other prevailing argument is that the steel in a steel shim gasket, being harder than aluminum, causes brinelling (indentation) on aluminum heads. My heads may not be new, but they're still worth a pretty penny so I'm not sure risking damaging them is worth maybe 5 horsepower. On the other hand, it sounds like brinelling from steel shims is insignificant enough that a fairly light milling of the heads will remove it.
[/QUOTE]
Call me a dinosaur but I still think, from an absolute reliability standpoint , that the best combination is a cast iron head on a cast iron block with a steel shim gasket; absent some corrosion issue, that combo will take abuse and not fail.
Aluminum heads on a cast iron block, another story.
All my research says that because of the difference in expansion rates between aluminum and cast iron, the gasket MUST accommodate relative movement between the head and the block. At a minimum, this means an extra smooth surface on the head and block and a TEFLON coated gasket. Don't even think of using anything else. This is one place I would have to trust the factory; get whatever gasket that the factory installed on the LT4 engines, (the highest performance and the last aluminum head, cast iron block small block chevy engine produced).
12-31-2014, 07:02 PM
#46
Drifting
Thread Starter
Call me a dinosaur but I still think, from an absolute reliability standpoint , that the best combination is a cast iron head on a cast iron block with a steel shim gasket; absent some corrosion issue, that combo will take abuse and not fail.
Aluminum heads on a cast iron block, another story.
All my research says that because of the difference in expansion rates between aluminum and cast iron, the gasket MUST accommodate relative movement between the head and the block. At a minimum, this means an extra smooth surface on the head and block and a TEFLON coated gasket. Don't even think of using anything else. This is one place I would have to trust the factory; get whatever gasket that the factory installed on the LT4 engines, (the highest performance and the last aluminum head, cast iron block small block chevy engine produced).
Aluminum heads on a cast iron block, another story.
All my research says that because of the difference in expansion rates between aluminum and cast iron, the gasket MUST accommodate relative movement between the head and the block. At a minimum, this means an extra smooth surface on the head and block and a TEFLON coated gasket. Don't even think of using anything else. This is one place I would have to trust the factory; get whatever gasket that the factory installed on the LT4 engines, (the highest performance and the last aluminum head, cast iron block small block chevy engine produced).
Have you personally had problems using a steel shim with aluminum heads?
I ask because I researched it quite a bit and I saw people saying that they've used steel shims with aluminum heads and an iron block without any problems, and people saying that a steel shim won't work, but I have yet to find anyone saying they used a steel shim and it didn't work. Although I love theory and science, in the end real world data is what I believe matters.
12-31-2014, 09:35 PM
#47
Melting Slicks
Cast iron head and block combo's are another story.
good luck
01-02-2015, 02:59 PM
#48
Drifting
Thread Starter
I decided that the possible disadvantages of using the wrong head gaskets warrant buying replacements. I've narrowed the replacement gaskets down to four options:
EDIT: I finally got around to measuring the head combustion chamber volume.
Knowing that they should have a volume of 70mL or so, I realized that using a 5mL syringe 14 times would introduce a significant margin for error. I decided to use a 10mL graduated cylinder instead, which was by itself more precise than a syringe but also cut the number of measurements I had to make in half.
However, I realized that my measurements would be thrown off due to the substantial amount of oil that would stick to the walls of the graduated cylinder, so I decided to use denatured alcohol instead.
Before beginning, I removed a spark plug from my car and installed it in the combustion chamber I was measuring so that the alcohol wouldn't pour straight out through the spark plug hole. I put white lithium grease on the threads for a better seal.
I poured the alcohol straight from the cylinder to the combustion chamber until it was nearly full, and then used a pipette to fill up the remainder. I used the same acrylic disk that I used to measure the cylinder volume. Before putting the disk over the combustion chamber, I smeared white lithium grease around the edges so alcohol could't leak out.
To my surprise, I measured the combustion chamber to be 61.6cc, instead of the 68cc or 74cc that I expected. Apparently the heads have been milled a bit.
I realized that my earlier measurements of the cylinder volume were not entirely accurate, so I remeasured using the same procedure as to measure the combustion chambers. This time I measured cylinder #1 to be 15.8cc, a measurement I know is more accurate than my least measurement of 17.2cc.
With these two new measurements, my calculated compression is about 10.5:1 with a .026" head gasket. Perfect!
- Clevite 5746 http://www.summitracing.com/parts/cl...make/chevrolet
- Chevrolet Performance 10105117 http://www.summitracing.com/parts/na...make/chevrolet
- Chevrolet Performance 14096405 http://www.summitracing.com/parts/na...make/chevrolet
- Mr. Gasket 1134G http://www.summitracing.com/parts/mr...make/chevrolet
EDIT: I finally got around to measuring the head combustion chamber volume.
Knowing that they should have a volume of 70mL or so, I realized that using a 5mL syringe 14 times would introduce a significant margin for error. I decided to use a 10mL graduated cylinder instead, which was by itself more precise than a syringe but also cut the number of measurements I had to make in half.
However, I realized that my measurements would be thrown off due to the substantial amount of oil that would stick to the walls of the graduated cylinder, so I decided to use denatured alcohol instead.
Before beginning, I removed a spark plug from my car and installed it in the combustion chamber I was measuring so that the alcohol wouldn't pour straight out through the spark plug hole. I put white lithium grease on the threads for a better seal.
I poured the alcohol straight from the cylinder to the combustion chamber until it was nearly full, and then used a pipette to fill up the remainder. I used the same acrylic disk that I used to measure the cylinder volume. Before putting the disk over the combustion chamber, I smeared white lithium grease around the edges so alcohol could't leak out.
To my surprise, I measured the combustion chamber to be 61.6cc, instead of the 68cc or 74cc that I expected. Apparently the heads have been milled a bit.
I realized that my earlier measurements of the cylinder volume were not entirely accurate, so I remeasured using the same procedure as to measure the combustion chambers. This time I measured cylinder #1 to be 15.8cc, a measurement I know is more accurate than my least measurement of 17.2cc.
With these two new measurements, my calculated compression is about 10.5:1 with a .026" head gasket. Perfect!
Last edited by C4ProjectCar; 01-02-2015 at 05:49 PM.
01-02-2015, 07:15 PM
#49
Intermediate
Member Since: Feb 2014
Location: Latrobe PA
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45 years ago I worked in a custom shop specializing in foreign cars. Even in the sixties Alfa, Jaguar, Jenson, and others used aluminum heads mated to iron blocks. Most gaskets back then were composit/lubricitous. We also didn't have the aftermarket parts available back then like we have now. In the early seventies stamped steel gaskets started to be used.
Whenever we replaced head gaskets mating aluminum heads to iron blocks we always coated both sides of the gasket with a thin layer of axle grease to both sides. Apply using your fingertips to spread the grease evenly as possible. Place the gasket and head in place and torque down. Run the engine until warm, let cool, torque down again.
These were high compression engines back then before emission controls and we never had a car come back with a bad head gasket.
Whenever we replaced head gaskets mating aluminum heads to iron blocks we always coated both sides of the gasket with a thin layer of axle grease to both sides. Apply using your fingertips to spread the grease evenly as possible. Place the gasket and head in place and torque down. Run the engine until warm, let cool, torque down again.
These were high compression engines back then before emission controls and we never had a car come back with a bad head gasket.
01-03-2015, 04:17 AM
#50
Melting Slicks
Whenever we replaced head gaskets mating aluminum heads to iron blocks we always coated both sides of the gasket with a thin layer of axle grease to both sides. Apply using your fingertips to spread the grease evenly as possible. Place the gasket and head in place and torque down. Run the engine until warm, let cool, torque down again.
These were high compression engines back then before emission controls and we never had a car come back with a bad head gasket.
01-03-2015, 01:17 PM
#51
Drifting
Thread Starter
45 years ago I worked in a custom shop specializing in foreign cars. Even in the sixties Alfa, Jaguar, Jenson, and others used aluminum heads mated to iron blocks. Most gaskets back then were composit/lubricitous. We also didn't have the aftermarket parts available back then like we have now. In the early seventies stamped steel gaskets started to be used.
Whenever we replaced head gaskets mating aluminum heads to iron blocks we always coated both sides of the gasket with a thin layer of axle grease to both sides. Apply using your fingertips to spread the grease evenly as possible. Place the gasket and head in place and torque down. Run the engine until warm, let cool, torque down again.
These were high compression engines back then before emission controls and we never had a car come back with a bad head gasket.
Whenever we replaced head gaskets mating aluminum heads to iron blocks we always coated both sides of the gasket with a thin layer of axle grease to both sides. Apply using your fingertips to spread the grease evenly as possible. Place the gasket and head in place and torque down. Run the engine until warm, let cool, torque down again.
These were high compression engines back then before emission controls and we never had a car come back with a bad head gasket.
01-03-2015, 04:06 PM
#52
Melting Slicks
Member Since: Sep 2008
Location: Cherokee National Forest TN
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Pic of the block is a bit fuzzy, deck looks to be freshly machined. If were not machined the deck height would be .030
Check for block & head straightness with a good straight edge. Set it on edge & shine a light behind it.
If you are going to use coated steel gaskets suggest Victor Reinz MLS (multi layer steel).
Heads have probably been milled which could cause intake manifold fit issues. Set intake gaskets in place, set base manifold on. Check intake to head port alignment the manifold may sit high. If so have the intake machined.
Check for block & head straightness with a good straight edge. Set it on edge & shine a light behind it.
If you are going to use coated steel gaskets suggest Victor Reinz MLS (multi layer steel).
Heads have probably been milled which could cause intake manifold fit issues. Set intake gaskets in place, set base manifold on. Check intake to head port alignment the manifold may sit high. If so have the intake machined.
01-03-2015, 05:14 PM
#53
Drifting
Thread Starter
Pic of the block is a bit fuzzy, deck looks to be freshly machined. If were not machined the deck height would be .030
Check for block & head straightness with a good straight edge. Set it on edge & shine a light behind it.
If you are going to use coated steel gaskets suggest Victor Reinz MLS (multi layer steel).
Heads have probably been milled which could cause intake manifold fit issues. Set intake gaskets in place, set base manifold on. Check intake to head port alignment the manifold may sit high. If so have the intake machined.
Check for block & head straightness with a good straight edge. Set it on edge & shine a light behind it.
If you are going to use coated steel gaskets suggest Victor Reinz MLS (multi layer steel).
Heads have probably been milled which could cause intake manifold fit issues. Set intake gaskets in place, set base manifold on. Check intake to head port alignment the manifold may sit high. If so have the intake machined.
Thanks for the gasket suggestion. I'll look into those if my deck isn't flat.
Assuming the deck is flat, do you think I'll be fine with a steel shim and the axle grease tip?
I'm not worrying about the brinelling anymore since I saw the heads already have indentations around the combustion chambers, I'm guessing from the fire rings of the gaskets the shop put on.
I hadn't even thought of an alignment issue. Since it was put together by a machine shop, I'm hoping they made sure everything lined up, but I'll be sure to check.
Last edited by C4ProjectCar; 01-03-2015 at 05:17 PM.
01-04-2015, 12:33 AM
#54
Melting Slicks
Member Since: Sep 2008
Location: Cherokee National Forest TN
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Heads can be checked with a straight edge.
Never used grease with single layer shim gaskets, as stated in a previous post I spray painted them. There is a spray copper coat available now that may work better than paint. IDK never tried it.
Reinz MLS gaskets come coated no sealant/lube necessary. The multi layer composition eliminates thermal expansion issues encountered using a single steel shim gasket with aluminum heads on an iron block. Victor Reinz gasket part # 1178SSB should work on your build. .020 compressed, 4.100 bore. Details here:
http://www.rockauto.com/catalog/more...623&cc=1041242
Never used grease with single layer shim gaskets, as stated in a previous post I spray painted them. There is a spray copper coat available now that may work better than paint. IDK never tried it.
Reinz MLS gaskets come coated no sealant/lube necessary. The multi layer composition eliminates thermal expansion issues encountered using a single steel shim gasket with aluminum heads on an iron block. Victor Reinz gasket part # 1178SSB should work on your build. .020 compressed, 4.100 bore. Details here:
http://www.rockauto.com/catalog/more...623&cc=1041242
Last edited by Churchkey; 01-04-2015 at 12:39 AM.
01-04-2015, 12:30 PM
#55
Drifting
Thread Starter
Heads can be checked with a straight edge.
Never used grease with single layer shim gaskets, as stated in a previous post I spray painted them. There is a spray copper coat available now that may work better than paint. IDK never tried it.
Reinz MLS gaskets come coated no sealant/lube necessary. The multi layer composition eliminates thermal expansion issues encountered using a single steel shim gasket with aluminum heads on an iron block. Victor Reinz gasket part # 1178SSB should work on your build. .020 compressed, 4.100 bore. Details here:
http://www.rockauto.com/catalog/more...623&cc=1041242
Never used grease with single layer shim gaskets, as stated in a previous post I spray painted them. There is a spray copper coat available now that may work better than paint. IDK never tried it.
Reinz MLS gaskets come coated no sealant/lube necessary. The multi layer composition eliminates thermal expansion issues encountered using a single steel shim gasket with aluminum heads on an iron block. Victor Reinz gasket part # 1178SSB should work on your build. .020 compressed, 4.100 bore. Details here:
http://www.rockauto.com/catalog/more...623&cc=1041242
EDIT: Just to be sure, 10.6:1 (8.84:1 dynamic) with .040" quench and aluminum heads should be fine with a max of 91 octane, right? I'd like a decent safety margin in case one of my volume measurements was off.
Actually, the cam card has different specs than I read elsewhere. It states the intake closes 31.5 ABDC, not 59, and that advertised duration is 263/271, not 262/270. A closing point of 31.5 would give me a DCR of over 10:1, which can't be right. Right?
The grind number is that of the cam I ordered, but the part number is different. I'm confused. Here's a picture of the cam card:
Well... pulled my old camshaft and found that the holes on my new cam don't line up with the holes on the timing gear. I thought it was entirely standard! Do I need a new gear, or what?
...
Turns out the Lunati Voodoo series of cams are retro-fit rollers, meaning among other things that the nose of the cam isn't stepped to accommodate the retainer plate. Great. Now I guess I'll have to call Lunati and see if they'll take returns or do an exchange.
Last edited by C4ProjectCar; 01-04-2015 at 09:18 PM.
01-04-2015, 09:12 PM
#56
Melting Slicks
Member Since: Sep 2008
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Non roller cam blocks use a cam timing gear that that rides on the block. The flat tappet cam lobes are ground at a slight angle which does 2 things. The lifter spins in the bore + the cam is forced to the rear of the block causing contact of the cam timing gear with the block. The cam gear bolt spacing for a flat tappet cam is larger in diameter than the cam gear designed for a roller cam block. If installing a roller cam in a non roller block a thrust button is installed in the cam gear, it is held in place by the timing cover. The thrust button keeps the cam from moving for/aft in the block.
Roller cam blocks use a thrust plate bolted to the front of the block to locate the cam. Timing gears are specific to a roller cam block.
If the bolt spacing diameter on your new cam is larger than the bolt spacing diameter of the removed parts your new cam is designed for a early non roller tappet block.
You need a cam for a roller block.
Don't have time to figure the DCR now.
Roller cam blocks use a thrust plate bolted to the front of the block to locate the cam. Timing gears are specific to a roller cam block.
If the bolt spacing diameter on your new cam is larger than the bolt spacing diameter of the removed parts your new cam is designed for a early non roller tappet block.
You need a cam for a roller block.
Don't have time to figure the DCR now.
01-04-2015, 09:23 PM
#57
Drifting
Thread Starter
Non roller cam blocks use a cam timing gear that that rides on the block. The flat tappet cam lobes are ground at a slight angle which does 2 things. The lifter spins in the bore + the cam is forced to the rear of the block causing contact of the cam timing gear with the block. The cam gear bolt spacing for a flat tappet cam is larger in diameter than the cam gear designed for a roller cam block. If installing a roller cam in a non roller block a thrust button is installed in the cam gear, it is held in place by the timing cover. The thrust button keeps the cam from moving for/aft in the block.
Roller cam blocks use a thrust plate bolted to the front of the block to locate the cam. Timing gears are specific to a roller cam block.
If the bolt spacing diameter on your new cam is larger than the bolt spacing diameter of the removed parts your new cam is designed for a early non roller tappet block.
You need a cam for a roller block.
Don't have time to figure the DCR now.
Roller cam blocks use a thrust plate bolted to the front of the block to locate the cam. Timing gears are specific to a roller cam block.
If the bolt spacing diameter on your new cam is larger than the bolt spacing diameter of the removed parts your new cam is designed for a early non roller tappet block.
You need a cam for a roller block.
Don't have time to figure the DCR now.
What would you suggest I do? It doesn't look like Lunati makes any non-retrofit roller cams for first gen SBC, and I have a feeling they will only accept an exchange, not a return. This cam (http://www.lunatipower.com/Product.aspx?id=2010&gid=289) seems to be identical except with the stepped nose, but it's for the LT1 and I see that the pin on the nose is too long.
01-05-2015, 01:19 AM
#58
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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C4 congrats, u are really getting the know for this compression measuring fast. I like your denatured alcohol choice. I i think now u can see how important finding your c.r. accurately is. I got lazy and could have worded my advice for priorities better - as this is really all your show here and your the one paying for it. But i tried to make u see the issue.
But now im worried your compression may be a little too high. Good quench is becoming more important than before. With your new numbers and a 0.020"x4.100" gasket i get c.r. = 10.57:1. 10.5 is usually considered the limit for pump gas and a short cam.
So it reads like your cam is a mismatch as is. As for pre '88 block (2 piece rear main seal) retro roller cams they usually use the cam button which butts against the timing cover to steady the cam. Some water pumps will have a adjustable stop to backup/support thin timing chain covers. U should be able to use the "retro cam" using a cam button but u will need a cam timing gear (set) for a retor roller cam - i believe the stock roller lifters with the spider and dogs bones will work - u have a stock spider web lifter set and dog bones dont u? Waite, is that new block 1 piece rear main seal or 2? What is your block casting number in the back on the drivers side?
The problem is u may want a larger cam to lower your D.C.R. for safe use of 91 octane pump gas.
U are so close to the edge here i really dont know what to say as u could just slap it together and it may work well enough. Not trying to preach here but i think u can see a performance engine assembly is not something that can be slapped together in hurry. Definitely not on the first try. Im sorry if this is busting your bubble but IMHO u need to spend time (and maybe the money) to get a good thin head gasket - Cometic gaskets make custom gaskets for this but ya know they are 0.027" and are still MLS like that Victor Reinz so the decision is all yours.
http://www.cometic.com/automotive-gaskets.aspx
http://www.shopengineparts.com/parts...00+%28Gen+I%29
U need to get the correct cam for the correct DCR and that may take days just in crunching the numbers and shopping for cams. Right now i dont know what block u have and dont know if u need and entire different cam and lifters or just a timing set.
Retarding ignition timing it is no fun to reduce timing to prevent detonation and really not a fix. Best to get your parts right before assembly.
And another issue is that since the heads were milled reduce the chamber your intake will not fit without milling. Using some numbers i have found is for each 1.4cc removed from the head it takes 0.010" of flat milling the head. So your 68cc heads lost 7.2cc which looks like over 0.050" removed. That plus assuming another cut on the block deck would require some deep cuts on the intake - off the chart i have for intake milling. Thats not all, when u mill down the intake the distributor is left hanging above the intake and will need shimming - not a big deal but something to understand.
Just trying to help and sorry if i bring the bad news too.
But now im worried your compression may be a little too high. Good quench is becoming more important than before. With your new numbers and a 0.020"x4.100" gasket i get c.r. = 10.57:1. 10.5 is usually considered the limit for pump gas and a short cam.
So it reads like your cam is a mismatch as is. As for pre '88 block (2 piece rear main seal) retro roller cams they usually use the cam button which butts against the timing cover to steady the cam. Some water pumps will have a adjustable stop to backup/support thin timing chain covers. U should be able to use the "retro cam" using a cam button but u will need a cam timing gear (set) for a retor roller cam - i believe the stock roller lifters with the spider and dogs bones will work - u have a stock spider web lifter set and dog bones dont u? Waite, is that new block 1 piece rear main seal or 2? What is your block casting number in the back on the drivers side?
The problem is u may want a larger cam to lower your D.C.R. for safe use of 91 octane pump gas.
U are so close to the edge here i really dont know what to say as u could just slap it together and it may work well enough. Not trying to preach here but i think u can see a performance engine assembly is not something that can be slapped together in hurry. Definitely not on the first try. Im sorry if this is busting your bubble but IMHO u need to spend time (and maybe the money) to get a good thin head gasket - Cometic gaskets make custom gaskets for this but ya know they are 0.027" and are still MLS like that Victor Reinz so the decision is all yours.
http://www.cometic.com/automotive-gaskets.aspx
http://www.shopengineparts.com/parts...00+%28Gen+I%29
U need to get the correct cam for the correct DCR and that may take days just in crunching the numbers and shopping for cams. Right now i dont know what block u have and dont know if u need and entire different cam and lifters or just a timing set.
Retarding ignition timing it is no fun to reduce timing to prevent detonation and really not a fix. Best to get your parts right before assembly.
And another issue is that since the heads were milled reduce the chamber your intake will not fit without milling. Using some numbers i have found is for each 1.4cc removed from the head it takes 0.010" of flat milling the head. So your 68cc heads lost 7.2cc which looks like over 0.050" removed. That plus assuming another cut on the block deck would require some deep cuts on the intake - off the chart i have for intake milling. Thats not all, when u mill down the intake the distributor is left hanging above the intake and will need shimming - not a big deal but something to understand.
Just trying to help and sorry if i bring the bad news too.
01-05-2015, 04:00 PM
#59
Drifting
Thread Starter
Yeah, I hadn't even considered the possibility that the heads had been milled. Live and learn.
I have to pass smog and want to emphasize low-end power, especially since I have the stock TPI intake, so getting a bigger cam is out of the question. I also have a fairly nice double roller timing set so I'd rather keep it as is. I called Lunati and they'll exchange the cam I have for the equivalent LT1 version, which is meant for a roller block.
I have a 1 piece block, casting # 638.
No, I definitely understand that it requires a lot of careful thought. I was just hoping I would avoid most of the problems since all I'm doing is swapping the cam and head gaskets. Live and learn.
I think I'll just get thicker head gaskets. I'll be losing quench, but I don't see an alternative. If I go this route, how thick of a gasket do you think I'd need? The engine came with Fel-Pro 1044 gaskets which would put me at 8.26:1 dynamic compression, and that way I would save 70 to 80 bucks.
When I got the engine, the intake was already installed and permatexed on. I'm hoping the engine shop would have dealt with any sort of problems before returning the engine to the person I bought it from, but we'll see.
I didn't know about shimming the distributor though. Thanks for the heads-up.
I have to pass smog and want to emphasize low-end power, especially since I have the stock TPI intake, so getting a bigger cam is out of the question. I also have a fairly nice double roller timing set so I'd rather keep it as is. I called Lunati and they'll exchange the cam I have for the equivalent LT1 version, which is meant for a roller block.
I have a 1 piece block, casting # 638.
No, I definitely understand that it requires a lot of careful thought. I was just hoping I would avoid most of the problems since all I'm doing is swapping the cam and head gaskets. Live and learn.
I think I'll just get thicker head gaskets. I'll be losing quench, but I don't see an alternative. If I go this route, how thick of a gasket do you think I'd need? The engine came with Fel-Pro 1044 gaskets which would put me at 8.26:1 dynamic compression, and that way I would save 70 to 80 bucks.
When I got the engine, the intake was already installed and permatexed on. I'm hoping the engine shop would have dealt with any sort of problems before returning the engine to the person I bought it from, but we'll see.
I didn't know about shimming the distributor though. Thanks for the heads-up.
Last edited by C4ProjectCar; 01-05-2015 at 04:16 PM.
01-05-2015, 04:20 PM
#60
Melting Slicks
You can mix and match valve train components, but sometimes there's unanticipated issues. My suggestion? Keep your GM car all GM; chevy makes a whole series of hydraulic roller cams suitable for your application, all the way from plain jane vanilla grocery getter to wilder than you'd ever want (yeah better check for coil bind and valve stem seal interference with some of the more radical ones)
