L98 into 68' vette
02-16-2015, 02:26 PM
#1
L98 into 68' vette
Hi,
I have just pulled my L98 engine from my 1987 vette (it's getting a 383).
As my original 327 in my 1968 vette needs a rebuild I'm planning to use the L98 longblock in the '68 until I finish the rebuild.
Which leads to my questions, which flexplate should I buy for the L98 for use with the TH400 transmission and the original starter?
Is this converter a good match with the L98 + edelbrock performer intake and the qjet? (quality and stall)
http://summitracing.com/parts/sum-g2699
I can understand from the archive, that the D-port from the ZZ4 does not fit well with the stock exhaust manifolds, but will that be a problem with the earliere 112 heads that I have?
I have just pulled my L98 engine from my 1987 vette (it's getting a 383).
As my original 327 in my 1968 vette needs a rebuild I'm planning to use the L98 longblock in the '68 until I finish the rebuild.
Which leads to my questions, which flexplate should I buy for the L98 for use with the TH400 transmission and the original starter?
Is this converter a good match with the L98 + edelbrock performer intake and the qjet? (quality and stall)
http://summitracing.com/parts/sum-g2699
I can understand from the archive, that the D-port from the ZZ4 does not fit well with the stock exhaust manifolds, but will that be a problem with the earliere 112 heads that I have?
02-16-2015, 04:22 PM
#2
Race Director
I'm assuming you you're the L98 cam? If so, that tq converter should be a pretty decent match.
I believe you'll need a 168T flexplate for a 1pc rear main seal. The starter would have staggered bolt holes, if so. That is, one of them will be slightly closer to the front of the block than the other. If that's what you've got, you should be G2G. Good thread on starters here (see the first 2 images):http://www.chevytalk.org/fusionbb/sh...hp?tid/171683/
I believe the L98 requires an external balance flexplate as well, but not 100% sure on that.
I believe you'll need a 168T flexplate for a 1pc rear main seal. The starter would have staggered bolt holes, if so. That is, one of them will be slightly closer to the front of the block than the other. If that's what you've got, you should be G2G. Good thread on starters here (see the first 2 images):http://www.chevytalk.org/fusionbb/sh...hp?tid/171683/
I believe the L98 requires an external balance flexplate as well, but not 100% sure on that.
02-16-2015, 07:47 PM
#3
D-port
Hi,
I have just pulled my L98 engine from my 1987 vette (it's getting a 383).
As my original 327 in my 1968 vette needs a rebuild I'm planning to use the L98 longblock in the '68 until I finish the rebuild.
Which leads to my questions, which flexplate should I buy for the L98 for use with the TH400 transmission and the original starter?
Is this converter a good match with the L98 + edelbrock performer intake and the qjet? (quality and stall)
http://summitracing.com/parts/sum-g2699
I can understand from the archive, that the D-port from the ZZ4 does not fit well with the stock exhaust manifolds, but will that be a problem with the earliere 112 heads that I have?
I have just pulled my L98 engine from my 1987 vette (it's getting a 383).
As my original 327 in my 1968 vette needs a rebuild I'm planning to use the L98 longblock in the '68 until I finish the rebuild.
Which leads to my questions, which flexplate should I buy for the L98 for use with the TH400 transmission and the original starter?
Is this converter a good match with the L98 + edelbrock performer intake and the qjet? (quality and stall)
http://summitracing.com/parts/sum-g2699
I can understand from the archive, that the D-port from the ZZ4 does not fit well with the stock exhaust manifolds, but will that be a problem with the earliere 112 heads that I have?
02-17-2015, 07:23 AM
#4
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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What size flexplate? With a TH400 i assume a 14" 168 tooth flexplate. For the L98 u need a 1 piece seal flexplate that is "externally balanced".
U need to measure the torque converter bolt pattern to choose the correct size flexplate to match. Some flexplates are drilled for 2 different bolt patterns.
GM flexplate #14088767 is a 14", 168 tooth, 1 piece seal, external balance fo '89 and later 350 HO thats heavy duty.
#10128413 is 168 tooth, 1 piece, ext bal, extra thick heavy duty for '86 & later.
#14088761 is 14", 168 tooth, 1 piece, ext bal for '89 & later 350 HO.
#10128414 is 168 tooth, 1 piece, ext bal for '86-'96.
U also need to use the correct bolts with star washers as there are 2 different sizes of bolts.
As to converters there are so many options it would make me dizzy shopping - good luck.
I dont understand what u are asking/saying about the D port heads? Are u using the ZZ4/L98 D-port heads or the 112 heads?
If using the D-port heads nothing is wrong with connecting a round port header to a D-port head. Misconception is that the D shape needs to continue into the header manifold/pipe. My understanding is the mismatch provides some amount of anti-reversion which is a good thing. The D-port shape helps the exhaust gas turn out of the head - and thats all.
Hope this helps.
U need to measure the torque converter bolt pattern to choose the correct size flexplate to match. Some flexplates are drilled for 2 different bolt patterns.
GM flexplate #14088767 is a 14", 168 tooth, 1 piece seal, external balance fo '89 and later 350 HO thats heavy duty.
#10128413 is 168 tooth, 1 piece, ext bal, extra thick heavy duty for '86 & later.
#14088761 is 14", 168 tooth, 1 piece, ext bal for '89 & later 350 HO.
#10128414 is 168 tooth, 1 piece, ext bal for '86-'96.
U also need to use the correct bolts with star washers as there are 2 different sizes of bolts.
As to converters there are so many options it would make me dizzy shopping - good luck.
I dont understand what u are asking/saying about the D port heads? Are u using the ZZ4/L98 D-port heads or the 112 heads?
If using the D-port heads nothing is wrong with connecting a round port header to a D-port head. Misconception is that the D shape needs to continue into the header manifold/pipe. My understanding is the mismatch provides some amount of anti-reversion which is a good thing. The D-port shape helps the exhaust gas turn out of the head - and thats all.
Hope this helps.
02-17-2015, 05:29 PM
#5
Drifting
The L98 should be the same basic motor as the ZZ4 which I installed in my 1980 vette.
You'll need a new flexplate that is externally balanced for the ZZ4. manifolds should swap close enough. Dip stick will be on other side but not a problem. You may need a new harmonic balancer if the L98 is too big to clear the cross member.
You'll need a new flexplate that is externally balanced for the ZZ4. manifolds should swap close enough. Dip stick will be on other side but not a problem. You may need a new harmonic balancer if the L98 is too big to clear the cross member.
02-22-2015, 03:56 PM
#6
Thanks for the help 
The means that it would probably not be a good idea to reuse my original l98 external balance flexplate with my new internal balanced 383
If I understand you correct, would it then possible to use my L98 flexplate in the '68 instead if I also use my original l98 starter and get a th400 converter that fits the l98 flexplate.
I measured my l98 flexplate and it has a 10.75 inch bolt pattern (diameter) which would mean that I only need to buy this converter and then reuse my l98 flexplate, right?
http://www.summitracing.com/int/parts/sum-g2699/
The means that it would probably not be a good idea to reuse my original l98 external balance flexplate with my new internal balanced 383
If I understand you correct, would it then possible to use my L98 flexplate in the '68 instead if I also use my original l98 starter and get a th400 converter that fits the l98 flexplate.
I measured my l98 flexplate and it has a 10.75 inch bolt pattern (diameter) which would mean that I only need to buy this converter and then reuse my l98 flexplate, right?
http://www.summitracing.com/int/parts/sum-g2699/
