L-98 valvetrain questions
10-23-2010, 05:54 PM
#1
Le Mans Master
Thread Starter
L-98 valvetrain questions
Looks like I found a good deal on a 28K mile 90 L-98 for my 84. As a result, I have a few questions about the valvetrain.
AFAIK, all my accessories should swap over to the L-98. I'll get the oil pan and re-use my flywheel. I don't want to change converters at this point as if I do anything with the trans I'll get a later model one with the HD parts and 30 spline input instead of my current 27 spline trans. Apparently the trans has already gotten a shift kit and trans cooler, so it may have been upgraded previously. When the day comes that I do the engine swap I'll pop off the converter and count the input shaft splines to see what I have there.
Yes, I know that if I get guide plates I need hardend pushrods.
So, anything I'm forgetting?
- What is the max lift you can run with stock springs - and not run a piston into a valve?
- Are the stock screw-in studs long enough on the head side to accept guide plates?
- If not in #2, are self-aligning rockers required?
- Since I already have Crane 1.5 aluminum roller rockers, will they fit on the centerbolt heads and with the stock valve covers? Yes, I know I'd have to snap off the drip tabs inside.
AFAIK, all my accessories should swap over to the L-98. I'll get the oil pan and re-use my flywheel. I don't want to change converters at this point as if I do anything with the trans I'll get a later model one with the HD parts and 30 spline input instead of my current 27 spline trans. Apparently the trans has already gotten a shift kit and trans cooler, so it may have been upgraded previously. When the day comes that I do the engine swap I'll pop off the converter and count the input shaft splines to see what I have there.
Yes, I know that if I get guide plates I need hardend pushrods.
So, anything I'm forgetting?
10-23-2010, 07:00 PM
#2
Burning Brakes
Member Since: Feb 2010
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My understanding with center bolt heads you need to run the narrow type rocker arms.
Try this link it has alot of info about the stock motor what cam in wich years ect.
http://temp.corvetteforum.net/c4/vader86/
The eary 700r4 have the 27 spline the web site I posted tells all this stuf.
I would think you can run a little higher lift and longer duration with the stock valve springs with out having any issues.
Try this link it has alot of info about the stock motor what cam in wich years ect.
http://temp.corvetteforum.net/c4/vader86/
The eary 700r4 have the 27 spline the web site I posted tells all this stuf.
I would think you can run a little higher lift and longer duration with the stock valve springs with out having any issues.
Looks like I found a good deal on a 28K mile 90 L-98 for my 84. As a result, I have a few questions about the valvetrain.
AFAIK, all my accessories should swap over to the L-98. I'll get the oil pan and re-use my flywheel. I don't want to change converters at this point as if I do anything with the trans I'll get a later model one with the HD parts and 30 spline input instead of my current 27 spline trans. Apparently the trans has already gotten a shift kit and trans cooler, so it may have been upgraded previously. When the day comes that I do the engine swap I'll pop off the converter and count the input shaft splines to see what I have there.
Yes, I know that if I get guide plates I need hardend pushrods.
So, anything I'm forgetting?
- What is the max lift you can run with stock springs - and not run a piston into a valve?
- Are the stock screw-in studs long enough on the head side to accept guide plates?
- If not in #2, are self-aligning rockers required?
- Since I already have Crane 1.5 aluminum roller rockers, will they fit on the centerbolt heads and with the stock valve covers? Yes, I know I'd have to snap off the drip tabs inside.
AFAIK, all my accessories should swap over to the L-98. I'll get the oil pan and re-use my flywheel. I don't want to change converters at this point as if I do anything with the trans I'll get a later model one with the HD parts and 30 spline input instead of my current 27 spline trans. Apparently the trans has already gotten a shift kit and trans cooler, so it may have been upgraded previously. When the day comes that I do the engine swap I'll pop off the converter and count the input shaft splines to see what I have there.
Yes, I know that if I get guide plates I need hardend pushrods.
So, anything I'm forgetting?
10-23-2010, 07:52 PM
#4
Le Mans Master
Thread Starter
Not toast, but this seems to be the most effective way to get a fresh and better performing engine into it. It also allows me to easily run the 95 LT-1 cam I have.
Since installing the Renegade it's painfully obvious that the stock cam is too small. There are too many things that I want to "correct" on the old engine and this gives me "one stop shopping". I get much better heads that are easy to port a little before they go into the car, I can easily drop in the HR cam, I can solve all the oil leaks at once, I can replace the water pump while I'm swapping everything over, and I should be in the 275-300 hp range when I'm done which is where I wanted to be.
Since installing the Renegade it's painfully obvious that the stock cam is too small. There are too many things that I want to "correct" on the old engine and this gives me "one stop shopping". I get much better heads that are easy to port a little before they go into the car, I can easily drop in the HR cam, I can solve all the oil leaks at once, I can replace the water pump while I'm swapping everything over, and I should be in the 275-300 hp range when I'm done which is where I wanted to be.
10-23-2010, 08:14 PM
#5
Le Mans Master
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Old springs are prob worn so spend $40 and put a set of GMPP LT4/ZZ4 springs in ; good for .525 lift
No you won't.
'90 is 1 pce seal crank; early 2 pce seal crank FW won't bolt up.
Different bolt pattern on crank flange
10-23-2010, 10:14 PM
#6
Corvette Junkie
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2023 C7 of the Year Finalist - Unmodified
Sounds like the renegade isnt any better than stock if you are changing the bottom end to get it to work right.
Seems like you could have bought a C5 for the money you have already spent on your car.
Seems like you could have bought a C5 for the money you have already spent on your car.
Last edited by CorvetteMike2024; 10-23-2010 at 10:16 PM.
10-24-2010, 12:58 AM
#8
Le Mans Master
Thread Starter
The centerbolt heads ( with SA rockers ) have assembly plates under the rocker studs.True guide plates are a straight swap if changing to NSA rockers
Old springs are prob worn so spend $40 and put a set of GMPP LT4/ZZ4 springs in ; good for .525 lift
No you won't.
'90 is 1 pce seal crank; early 2 pce seal crank FW won't bolt up.
Different bolt pattern on crank flange
Old springs are prob worn so spend $40 and put a set of GMPP LT4/ZZ4 springs in ; good for .525 lift
No you won't.
'90 is 1 pce seal crank; early 2 pce seal crank FW won't bolt up.
Different bolt pattern on crank flange
10-24-2010, 01:04 AM
#9
Le Mans Master
Thread Starter
Right now I still need to fix the code 44 I have, so the car only runs "right" at full throttle. Aside form that I can tell you that the Renegade TROUNCES the stock intake in every way! No loss anywhere in response, low end torque, etc. but when you nail it, it will pull to 5K now (where it used to STRAIN to hit 4) and when you shift out of first at 5K and drop to 3600 it PULLS. If I'm on the freeway and punch it, it kicks down and MOVES whereas before it would make some noise and eventually start accelerating.
Sure, it's no 2010 Z06, but it's WAY better than it was before!
And for the record, even if I had all the cash I've put into my 84 at once and could buy a C5, I still wouldn't. I haven't spent enough on it to buy a C5 anyways, even at the prices they are at locally. My only other choices would have been a 96 LT-4 car or a ZR-1. A 90 would have been the third choice except for the TPI dilema.
10-24-2010, 02:23 AM
#10
Melting Slicks
One thing you won't have to worry when you switch over the induction is the 90
TPIs don't have a MAF. They have the MAP like the 84s have.
TPIs don't have a MAF. They have the MAP like the 84s have.
10-24-2010, 05:52 AM
#11
Team Owner
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St. Jude Donor '05
Def. No worries on piston to valve thats a tiny cam
Get new springs as stated above
Get new springs as stated above
10-24-2010, 08:08 AM
#15
Drifting
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St. Jude Donor '10
Interesting that the 84 stock lift is higher than the 87 roller cam!
Last edited by Lemme; 10-24-2010 at 08:14 AM.
10-24-2010, 09:32 AM
#16
Safety Car
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What about California emmissions?
Does the Renegade have a CARB #? Just wondering since you're replacing the Cam, Rockers and Heads and I read that your Vette is your daily driver.
Why don't you just rebuild the current engine? I think you're going to create a lot of new problems.
Does the Renegade have a CARB #? Just wondering since you're replacing the Cam, Rockers and Heads and I read that your Vette is your daily driver.
Why don't you just rebuild the current engine? I think you're going to create a lot of new problems.
10-24-2010, 10:27 AM
#17
Le Mans Master
Thread Starter
What about California emmissions?
Does the Renegade have a CARB #? Just wondering since you're replacing the Cam, Rockers and Heads and I read that your Vette is your daily driver.
Why don't you just rebuild the current engine? I think you're going to create a lot of new problems.
Does the Renegade have a CARB #? Just wondering since you're replacing the Cam, Rockers and Heads and I read that your Vette is your daily driver.
Why don't you just rebuild the current engine? I think you're going to create a lot of new problems.
No CARB EO# for the Renegade, but unless they pull the air cleaner assembly, they'd never know it's there. The LT-1 cam is still mild enough to easily pass smog. The only possible red flag for smog would be the EGR tube comming up off the exhuast manifold, but that's why I want to keep it OE looking.
10-24-2010, 10:52 AM
#18
Le Mans Master
If the Renegade has an EO number, then it's a legal swap. Since your original manifold took advantage of the heat risers built into the old heads, there is no EGR external feed tube. Since the L98 has no heat risers in the heads, the manifold would require an external source, but that would be an argument to keep it in compliance.
Just some thoughts here.
1. if you plan on running an 11 inch clutch, you need a larger diameter flywheel (168 tooth) since you have to buy a flywheel anyway.
2. if you use the bigger flywheel, you need a starter compatible with that flywheel. I would use a mini starter since your starter if original and never rebuilt would soon require a rebuld. Mini starters come dual pattern for either flywheel, and since most later small blocks were drilled for both starter patterns, it should work even if yours isn't drilled and tapped for both.
3. you might have interference in the bellhousing with the larger flywheel;. I think Jegs or Summit sell one that will fit.
4. The 90 L98 has flat top pistons. The 89, 88, 87, late 86 have dished pistons. The heads are still 58cc for all those years and the 90-91.
You are going to run into a detonation problem with your computer. My advice to you is since your engine has flat top pistons anyway, save yourself some grief, and just go buy a retro roller cam and lifters for your current shortblock. Switching to a roller cam block is one thing, but if you buy the 90 L98, you need to switch heads from 58cc to 64cc or open up the engine and install dished pistons to get a pump gas compatibility with your early computer.
You need to buy a set of patriot heads to complete your engine build. They are decent heads for around $850-$900. and come in a 180 that won't slow down the Renegade's performance.
5. I would suggest running the stock 90 rockers till you get it running and all the bugs worked out, then swap in the rockers. Sometimes there are other modifications to do to the covers, and starting up a freshly modded engine with scraping and rubbing sounds is unnerving. Since that is most likely where errant noises are going to emanate from, and they are simple to install, I would hold off on the rockers right away. Concentrate on the basic rebuild before adding the extras.
Just some thoughts here.
1. if you plan on running an 11 inch clutch, you need a larger diameter flywheel (168 tooth) since you have to buy a flywheel anyway.
2. if you use the bigger flywheel, you need a starter compatible with that flywheel. I would use a mini starter since your starter if original and never rebuilt would soon require a rebuld. Mini starters come dual pattern for either flywheel, and since most later small blocks were drilled for both starter patterns, it should work even if yours isn't drilled and tapped for both.
3. you might have interference in the bellhousing with the larger flywheel;. I think Jegs or Summit sell one that will fit.
4. The 90 L98 has flat top pistons. The 89, 88, 87, late 86 have dished pistons. The heads are still 58cc for all those years and the 90-91.
You are going to run into a detonation problem with your computer. My advice to you is since your engine has flat top pistons anyway, save yourself some grief, and just go buy a retro roller cam and lifters for your current shortblock. Switching to a roller cam block is one thing, but if you buy the 90 L98, you need to switch heads from 58cc to 64cc or open up the engine and install dished pistons to get a pump gas compatibility with your early computer.
You need to buy a set of patriot heads to complete your engine build. They are decent heads for around $850-$900. and come in a 180 that won't slow down the Renegade's performance.
5. I would suggest running the stock 90 rockers till you get it running and all the bugs worked out, then swap in the rockers. Sometimes there are other modifications to do to the covers, and starting up a freshly modded engine with scraping and rubbing sounds is unnerving. Since that is most likely where errant noises are going to emanate from, and they are simple to install, I would hold off on the rockers right away. Concentrate on the basic rebuild before adding the extras.
Last edited by coupeguy2001; 10-24-2010 at 10:57 AM.
10-24-2010, 10:58 AM
#19
Le Mans Master
Thread Starter
If the Renegade has an EO number, then it's a legal swap. Since your original manifold took advantage of the heat risers built into the old heads, there is no EGR external feed tube. Since the L98 has no heat risers in the heads, the manifold would require an external source, but that would be an argument to keep it in compliance.
Just some thoughts here.
1. if you plan on running an 11 inch clutch, you need a larger diameter flywheel (168 tooth) since you have to buy a flywheel anyway.
2. if you use the bigger flywheel, you need a starter compatible with that flywheel. I would use a mini starter since your starter if original and never rebuilt would soon require a rebuld. Mini starters come dual pattern for either flywheel, and since most later small blocks were drilled for both starter patterns, it should work even if yours isn't drilled and tapped for both.
3. you might have interference in the bellhousing with the larger flywhee;. I think Jegs or Summit sell one that will fit.
4. The 90 L98 has flat top pistons. THe 89, 88, 87, late 86 have dished pistons. The heads are still 58cc for all those years and the 90-91.
You are going to run into a detonation problem with your computer. My advice to you is since your engine has flat top pistons anyway, save yourself some grief, and just go buy a retro cam and lifters for your current shortblock. Switching to a roller cam block is one thing, but if you buy the 90 L98, you need to switch heads from 58cc to 64cc or open up the engine and install dished pistons to get a pump gas compatibility with your early computer.
You need to buy a set of patriot heads to complete your engine build. They are decent heads for around $850-$900. and come in a 180 that won't slow down the Renegade's performance.
5. I would suggest running the stock 90 rockers till you get it running and all the bugs worked out, then swap in the rockers. Sometimes there are other modifications to do to the covers, and starting up a freshly modded engeine with scraping and rubbing sounds is unnerving. Since that is most likely where errant noises are going to emanate from, and they are simple to install, I would hold off on the rockers right away. Concentrate on the basic rebuild before adding the extras.
Just some thoughts here.
1. if you plan on running an 11 inch clutch, you need a larger diameter flywheel (168 tooth) since you have to buy a flywheel anyway.
2. if you use the bigger flywheel, you need a starter compatible with that flywheel. I would use a mini starter since your starter if original and never rebuilt would soon require a rebuld. Mini starters come dual pattern for either flywheel, and since most later small blocks were drilled for both starter patterns, it should work even if yours isn't drilled and tapped for both.
3. you might have interference in the bellhousing with the larger flywhee;. I think Jegs or Summit sell one that will fit.
4. The 90 L98 has flat top pistons. THe 89, 88, 87, late 86 have dished pistons. The heads are still 58cc for all those years and the 90-91.
You are going to run into a detonation problem with your computer. My advice to you is since your engine has flat top pistons anyway, save yourself some grief, and just go buy a retro cam and lifters for your current shortblock. Switching to a roller cam block is one thing, but if you buy the 90 L98, you need to switch heads from 58cc to 64cc or open up the engine and install dished pistons to get a pump gas compatibility with your early computer.
You need to buy a set of patriot heads to complete your engine build. They are decent heads for around $850-$900. and come in a 180 that won't slow down the Renegade's performance.
5. I would suggest running the stock 90 rockers till you get it running and all the bugs worked out, then swap in the rockers. Sometimes there are other modifications to do to the covers, and starting up a freshly modded engeine with scraping and rubbing sounds is unnerving. Since that is most likely where errant noises are going to emanate from, and they are simple to install, I would hold off on the rockers right away. Concentrate on the basic rebuild before adding the extras.
Mine is an automatic, so no concerns about clutches, etc. I'll have the heads off so when I re-assemble I can run slightly thicker head gaskets to drop the CR a little, plus I'll be running the larger cam which should help to bleed off a little compression as well.
My plan was to run the stock rockers initially, then change to the rollers later down the road.
10-24-2010, 11:09 AM
#20
Mine is an automatic, so no concerns about clutches, etc. I'll have the heads off so when I re-assemble I can run slightly thicker head gaskets to drop the CR a little, plus I'll be running the larger cam which should help to bleed off a little compression as well.
My plan was to run the stock rockers initially, then change to the rollers later down the road.
My plan was to run the stock rockers initially, then change to the rollers later down the road.
Why are you trying to drop compression? Compression (to a point) is all good. Good for power, and good for emissions. If it were mine, I would put as thinner head gasket, if anything. This raises compression, and improves quench, all in a positive, efficient way.
