Dart head install
Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
Dart head install
I got new heads for my 76 now the fun part. The tech sheet has the part no. for the intake gasket and ex. (felpro 1205 and 1404) But none for head gasket. For proper quench a .015 shim would work however with aluminum heads some say yes some say no. The rocker studs are open into the intake port. do i use a thread sealer or lock tight ? Intake bolts, sealer or anti seize? Spark plugs, 3/4 inch reach with gasket. any idea or what heat range i should start with? I know its alot of questions for a Friday but i don t want to do this twice. Thanks guys
Burning Brakes
Joined: Mar 2010
Posts: 943
Likes: 15
From: Valdosta Georgia
Use anti seize on the plugs for sure, I was recommended Champion RC12YC plugs. I'm using an .020 copper head gasket. I'm waiting for answers on the rocker studs and intake bolts, too. I would think threadlocker blue would seal the threads as well, but someone will chime in with the answer soon.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
For proper quench a .015 shim would work however with aluminum heads some say yes some say no.
The rocker studs are open into the intake port. do i use a thread sealer or lock tight
http://www.summitracing.com/parts/arp-100-9904
Intake bolts, sealer or anti seize?
Spark plugs, 3/4 inch reach with gasket. any idea or what heat range i should start with?
Heat range on a plug is variable depending on CR, use, and ping resistance that the engine has. If it has low ping resistance then you may need a cooler plug. Racing, cooler plug.
Street use hotter plug. High altitude, hotter plug.
Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
Thank guys Im always a little squeamish about steel bolts into aluminum without anti seize. Tuff to get out sometimes, or they break off. Then I flip out and start throwing things.
Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I did not deck my block either. Just check to see that it's flat with a straight edge and feeler gauges. It doesn't have to be perfect to work.
Mine has .004" variance from one side to the other giving me a squish of .037 to .041 IIRC.
Le Mans Master
Joined: Oct 2007
Posts: 7,445
Likes: 971
From: Tennessee/Rhode Island
I say yes. I have aluminum heads with 015 shim gasket and no issues. I used copper coat to insure the seal to the block and head.
thread sealer. ARP is what I used. No leaks.
http://www.summitracing.com/parts/arp-100-9904
Same sealer.
Assuming this is a street dirven car I would start with a 5 or 6 heat range in an NGK plug. I'm using 6 heat range. I'm at a high altitude so I run the plugs a little hotter to keep then clean. NGK is a high quality plug and easiest to read for jetting. Also is short enough for most header applications.
Heat range on a plug is variable depending on CR, use, and ping resistance that the engine has. If it has low ping resistance then you may need a cooler plug. Racing, cooler plug.
Street use hotter plug. High altitude, hotter plug.
thread sealer. ARP is what I used. No leaks.
http://www.summitracing.com/parts/arp-100-9904
Same sealer.
Assuming this is a street dirven car I would start with a 5 or 6 heat range in an NGK plug. I'm using 6 heat range. I'm at a high altitude so I run the plugs a little hotter to keep then clean. NGK is a high quality plug and easiest to read for jetting. Also is short enough for most header applications.
Heat range on a plug is variable depending on CR, use, and ping resistance that the engine has. If it has low ping resistance then you may need a cooler plug. Racing, cooler plug.
Street use hotter plug. High altitude, hotter plug.
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Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
Lots of good info! Heres my dilemma, with an ICl of 55 and a .040 quench, my dcr is 8.64Kind of high you think? With a .026 gasket ,dcr is 8.35 and qu. is .051 I can't have it both ways. What's the less of 2 evils? (sometimes I over analyze things)
Le Mans Master
Joined: Sep 2003
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From: eastern NC
Good luck... GUSTO
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
It is also possible to install the cam retarded which would delay your intake closing.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
9.1 would be fine for static but he's talking dynamic. 8.35 dcr is a little high.
Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
350 .020 over / TH 400 trans. / 3:36 rear / tq. converter is stock
(2000 ? ) / flat tops W 4 valve reliefs / cam = XE256 ........ changing cam timing did cross my mind. the cams kind of mild I know but i've read 1000 times DON'T OVER CAM. Before I found this site I have never even heard of this stuff DCR vs. SCR cam timing geeeze! I'm feelin kind a dumb!
It runs fine the way it is just want a little more. Speed is addictive.
I'll know more when I get the heads off, deck clearance / piston cc .
This will be a winter time project, just want to get all my ducks in a row. Thanks to all lots of great info. here
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
That cam may be a disappointment .
What dart heads are you using ?
And quench being 40 as a must I disagree with. You have room on that measurement don't get stuck thinking it makes or breaks the build. If you can get it with out any problems shot for it , but if you think 53 is going to hurt you with what your putting together I cant see it.
I would bet anyone most motors built , crate or rebuilds are not hitting 40 quench. A standard head gasket for a GM small block is .039 ..
So don't make that your main focus , get close but worry about what cam will provide the best power and street manners for the heads and compression ratio you have.
I would go with the straub .028 .. And ask Straub what cam to use.
What dart heads are you using ?
And quench being 40 as a must I disagree with. You have room on that measurement don't get stuck thinking it makes or breaks the build. If you can get it with out any problems shot for it , but if you think 53 is going to hurt you with what your putting together I cant see it.
I would bet anyone most motors built , crate or rebuilds are not hitting 40 quench. A standard head gasket for a GM small block is .039 ..
So don't make that your main focus , get close but worry about what cam will provide the best power and street manners for the heads and compression ratio you have.
I would go with the straub .028 .. And ask Straub what cam to use.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Whether you need .040" squish or not is dependent on how fine of a line you want to walk on your DCR, the fuel you intend to use, weight of the vehicle your gearing, etc.
Detonation has many causes. There is no reason to introduce one only to find out after you put the engine together that you have a detonation problem and now have to try to work around it.
I know from personal experience that squish is of significant importance. Disregard it at your own risk.
You might get by, you might not.
My stock engine on the 77, only 7.66:1 CR detonated badly under high load on a hot day. So high SCR or DCR are not the necessarily the primary cause. Poor combustion turbulence caused by poor piston top design as in the stock L-48 can also be a contributing factor.
The stock L-48 has no real squish area due to the piston design.
If you haven't purchased a cam yet, you might want to look at different cams for that build. Lots of options that will put you in the 8.2 to 8.5 range.
Call Straub. He could give you a good recommendation.
Detonation has many causes. There is no reason to introduce one only to find out after you put the engine together that you have a detonation problem and now have to try to work around it.
I know from personal experience that squish is of significant importance. Disregard it at your own risk.
You might get by, you might not.
My stock engine on the 77, only 7.66:1 CR detonated badly under high load on a hot day. So high SCR or DCR are not the necessarily the primary cause. Poor combustion turbulence caused by poor piston top design as in the stock L-48 can also be a contributing factor.
The stock L-48 has no real squish area due to the piston design.
If you haven't purchased a cam yet, you might want to look at different cams for that build. Lots of options that will put you in the 8.2 to 8.5 range.
Call Straub. He could give you a good recommendation.
Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
OK I crudely C/C one combustion chamber today and came up with 65 C/Cs
With .040 qu. i'm at 8.55 DCR. With a.021 gasket qu. at.046 and DCR of 8.43 .
I'm using one of the online calculators so who knows how close it really is. Either way i'll need hi test. If this stuff was easy,it wouldn't be fun. Thank you gentlemen
With .040 qu. i'm at 8.55 DCR. With a.021 gasket qu. at.046 and DCR of 8.43 .
I'm using one of the online calculators so who knows how close it really is. Either way i'll need hi test. If this stuff was easy,it wouldn't be fun. Thank you gentlemen
Thread Starter
Instructor
Joined: Jun 2014
Posts: 185
Likes: 10
From: S W pa. pa
OK I crudely C/C one combustion chamber today and came up with 65 C/Cs
With .040 qu. i'm at 8.55 DCR. With a.021 gasket qu. at.046 and DCR of 8.43 .
I'm using one of the online calculators so who knows how close it really is. Either way i'll need hi test. If this stuff was easy,it wouldn't be fun. Thank you gentlemen
With .040 qu. i'm at 8.55 DCR. With a.021 gasket qu. at.046 and DCR of 8.43 .
I'm using one of the online calculators so who knows how close it really is. Either way i'll need hi test. If this stuff was easy,it wouldn't be fun. Thank you gentlemen
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
8.41 would be on that fine line given it's taking altitude into consideration to arrive at it.
If you want to do it that's up to you.
I ran your numbers and your at 10:1 DCR.
You could comfortably run a greater duration and get more power since you'll be able to extend the top end a bit more.
I built mine to accept lower octane fuel in consideration of the possible future of pump fuel.
Doesn't seem like it's going to get better, but who really knows. I just like to hedge my bet a little and anticipate fuel quality getting worse. This way I'm not pushing the limit too hard. I want to keep it simple and still use future potentially lower octane pump fuel without having to make CR or cam changes.
I have 9.9:1 SCR at 4000 ft with a 270* roller cam, 219*@ .050. This with a TH350 and a 3.08 Rear end. I put in a 2600 stall torque converter to help with launches with the poor gearing for such things.
The biggest grunt for my combo is the shift from 2nd to third. That's where the old combo would detonate.
This combo allows 6000 RPM shifts reducing the acceleration effort after the shift to third.