Lq4 shortblock need help with head selection
Lq4 shortblock need help with head selection Hey guys, I wanna do a carbed ls swap in my 71 4door impala. I wanna go carbed top end but I have questions on the head selection. I have a set of 317 heads that probably need a valve job, in any event they need to be tested. Rather than pay 300 for a valve job I found a set of LS3 Heads that are refurbished and ready to run. What all will it take to run them and how will the lq4 perform with these heads? Is it worth paying 800 for some ready to run LS3 Heads or should I just use the 317 heads? Are there any dangers to running LS3 Heads? Please let me know any experiences you guys have. This is a cruiser, so performance is not the main priority. Thanks in advance guys!
TECH Senior Member
Joined: Jun 2016
Posts: 22,288
Likes: 3,615
From: Central Cal.
Those 63 are likely like me. Cool stuff, but I'm not the one to answer this. Gotta give some of us credit! WE don't wanna BS you! lol Someone more qualified than us will be along soon enough....
I know you guys are right. I think this carb and kit would work. I can have the harness swapped since my motor is 24 reluctor.
https://www.skspeed.com/ls3-l92-l76-...-msd-6014-box/
https://www.skspeed.com/ls3-l92-l76-...-msd-6014-box/
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TECH Addict
Joined: Oct 2016
Posts: 2,513
Likes: 480
From: PDX-OR-USA
https://www.hotrod.com/articles/ls3-...take-shootout/
Rectangle port ,, there are a few choices for manifolds
Your also really only asking a small percentage of the LS engine population,
the number of carb vs efi engines is way towards the EFI side. (Just talking percentages,, don't care which one you run)
Especially on pure street cars, so the number of guys that play is small.
I just helped build a old school Model T roadster with a 327 and a Holley, we switched to a
Edelbrock to get it to handle E10 standard fuel. Just could not get the Holley to run tight at low
RPM's and this car will see a lot of cruise nights and parades so low speed had to be dialed.
And it had to fit under the stock hood. After all the dinking around a self contained unit would
have cost less and we would still have the carb look.
Good luck and keep us updated its always good to see stuff that isnt a track queen..
Rectangle port ,, there are a few choices for manifolds
Your also really only asking a small percentage of the LS engine population,
the number of carb vs efi engines is way towards the EFI side. (Just talking percentages,, don't care which one you run)
Especially on pure street cars, so the number of guys that play is small.
I just helped build a old school Model T roadster with a 327 and a Holley, we switched to a
Edelbrock to get it to handle E10 standard fuel. Just could not get the Holley to run tight at low
RPM's and this car will see a lot of cruise nights and parades so low speed had to be dialed.
And it had to fit under the stock hood. After all the dinking around a self contained unit would
have cost less and we would still have the carb look.
Good luck and keep us updated its always good to see stuff that isnt a track queen..
https://www.hotrod.com/articles/ls3-...take-shootout/
Rectangle port ,, there are a few choices for manifolds
Your also really only asking a small percentage of the LS engine population,
the number of carb vs efi engines is way towards the EFI side. (Just talking percentages,, don't care which one you run)
Especially on pure street cars, so the number of guys that play is small.
I just helped build a old school Model T roadster with a 327 and a Holley, we switched to a
Edelbrock to get it to handle E10 standard fuel. Just could not get the Holley to run tight at low
RPM's and this car will see a lot of cruise nights and parades so low speed had to be dialed.
And it had to fit under the stock hood. After all the dinking around a self contained unit would
have cost less and we would still have the carb look.
Good luck and keep us updated its always good to see stuff that isnt a track queen..
Rectangle port ,, there are a few choices for manifolds
Your also really only asking a small percentage of the LS engine population,
the number of carb vs efi engines is way towards the EFI side. (Just talking percentages,, don't care which one you run)
Especially on pure street cars, so the number of guys that play is small.
I just helped build a old school Model T roadster with a 327 and a Holley, we switched to a
Edelbrock to get it to handle E10 standard fuel. Just could not get the Holley to run tight at low
RPM's and this car will see a lot of cruise nights and parades so low speed had to be dialed.
And it had to fit under the stock hood. After all the dinking around a self contained unit would
have cost less and we would still have the carb look.
Good luck and keep us updated its always good to see stuff that isnt a track queen..
i looked looked at the article, I guess my question is more related to should I use LS3 Heads or 317s and if I run the LS3 Heads is it as simple as a bolt on. That’s really what I wanna know. Not what intake, I’m goin carbed intake regardless.
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Joined: Oct 2016
Posts: 2,513
Likes: 480
From: PDX-OR-USA
There is no such thing as bolt on.. Delete it from your vocabulary.. <joke>
I didn't see where you said what block and cam your using and that has
as much to do with your choice as anything..
There are tons of head discussions on here,, and I'd guess you need to
do some more searching to match the question
to the performance your actually expecting..
Your going to have to do some deep
research on the head questions,You will need to check every measurement
in the top end, there is no simple head X will fit with no issues answer.
To tell if LS3 heads are the right move you'll need the spec on , Block,
crank, pistons, cam, pushrods, valves, rockers, springs, retainers.
Then the operating spec, Auto/Stick, if auto what converter, what RPM
you want to peak out at. You mentioned not needing performance but I
doubt you want to spend the money and not get at lest the best decent
bang for the buck$... If the performance is not that big a deal,
why bother with LS3 heads? its 300 tops vs 800 to start..
So I'm lost a bit on the decision your struggling with there..
I didn't see where you said what block and cam your using and that has
as much to do with your choice as anything..
There are tons of head discussions on here,, and I'd guess you need to
do some more searching to match the question
to the performance your actually expecting..
Your going to have to do some deep
research on the head questions,You will need to check every measurement
in the top end, there is no simple head X will fit with no issues answer.
To tell if LS3 heads are the right move you'll need the spec on , Block,
crank, pistons, cam, pushrods, valves, rockers, springs, retainers.
Then the operating spec, Auto/Stick, if auto what converter, what RPM
you want to peak out at. You mentioned not needing performance but I
doubt you want to spend the money and not get at lest the best decent
bang for the buck$... If the performance is not that big a deal,
why bother with LS3 heads? its 300 tops vs 800 to start..
So I'm lost a bit on the decision your struggling with there..
Use either head. a 6.0 it won't really make alot of difference save for the smaller chamber on rect port heads. The small bore will work for either head BUT wont shroud the 317 heads as much.
Most people still like the cathedral port for sub 4.065 bore.
We have the perfect cam that will fit either with a carb intake on our high lift asa cam.
Most people still like the cathedral port for sub 4.065 bore.
We have the perfect cam that will fit either with a carb intake on our high lift asa cam.
Teching In
Joined: Dec 2013
Posts: 40
Likes: 4
From: Central Ohio
The kit you show has a basic operating range starting at 3500 rpm, heads are more $, intake is more $. We know 317 heads work on block, kit range starts at 1500 rpm, is $200 less, and heads are $500 less. For me, I would do 317 and have $700 for other goodies. Good luck with build.
So I ended up going with 253 heads and an ls3 stick cam in it. Should I go with a bigger cam in the lq4 or would this set up I have work?? I’m thinking about getting an ls6 intake and probably be going fuel injected now.
i just have a set of 253 stock heads that have had a valve job. I really just want around 400 hp. And the best possible gas mileage possible and have it be reliable. Those are my goals. I was told that with those heads on an lq4 would bump up the conpression and get more power. Let me know what you guys think.