Modifing the L88 - Chevelle Tech
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post #1 of 9 (permalink) Old Dec 2nd, 19, 4:38 PM Thread Starter
Tom
 
Join Date: Dec 2019
Location: Upstate NY
Posts: 19
Modifing the L88

I have an L88 that I put together from parts 38 years ago. The Car(68 Camaro 396) was damaged badly in an accident and so the engine was never installed and just stashed in the corner of the garage. Since the restro parts are easy to find now,I am putting the car back together. The original L78 is loog gone having sold it around 1982. Since gas quality is a concern ,I decided to make some changes to the L88.
I decided to stroke it to 4.250 and change the pistons to 10-1 Icon's.
I went with a comp cams 11-219-4 FT solid. [email protected] and .595 lift. I love solid cams.Old school I know.
This will be 100% street. Just a toy that will likely only get 200 miles a year on it.
Opinions needed.
What would be the expected power range and what would be the redline on this?
Do you think it will run fine on pump gas? Is the cam too much? Its not too late to exchange it if needed.
Specs
4 bolt block,Forged steel crank,pro stock rods(7/16") 6.385,Forged Full Float pistons.
Open chamber heads(074) with round exh port,rect intakes,GM fuel injection valve springs. Heads had the ports cleaned up a touch,polished chambers and cc'd to 114. Voodoo roller rockers.
Holley strip dominator with 950 Brawler carb.
2" headers,34"primary's/3.5 collector with Pypes 2.5 X-pipe system with race mufflers.
MSD Mech adv dist,MSD 6AL Box
Car has M21 trans with 3.73 axle.
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post #2 of 9 (permalink) Old Dec 2nd, 19, 5:09 PM
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Gary
 
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Location: Kansas City,Mo.
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Re: Modifing the L88

The round exhaust ports really hurt those heads. It seems like somebody made a sheet metal insert for those things but filling the floor fixes them.
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post #3 of 9 (permalink) Old Dec 3rd, 19, 9:44 AM
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Lew
 
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Re: Modifing the L88

I think the question also on the heads - are they unleaded gas valve seats - if not that can be an issue? You can always run the lead additive but that is getting harder to find and expensive. Plus with mileage you are doing that may not be an issue. Are they 1967-1969 L88 heads or later GM heads (over the counter heads sold in the 1970s) that might have the hardened seats. Pump gas should be fine at 10 to 1 with that cam. Nice size cam for that motor especially with that extra stroke. One question is are you set on using those heads or maybe selling them and getting a more modern head like an AFR 305 that will make more power, run on unleaded gas and be made of better quality aluminum which has a variety of benefits.
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post #4 of 9 (permalink) Old Dec 3rd, 19, 8:10 PM Thread Starter
Tom
 
Join Date: Dec 2019
Location: Upstate NY
Posts: 19
Re: Modifing the L88

Quote:
Originally Posted by gnicholson View Post
The round exhaust ports really hurt those heads. It seems like somebody made a sheet metal insert for those things but filling the floor fixes them.
Do you know if Devcon liquid steel or An epoxy would work? Anyone here ever done a build up on an exhaust port?

Last edited by 68RS/SS; Dec 3rd, 19 at 8:25 PM. Reason: spelin
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post #5 of 9 (permalink) Old Dec 3rd, 19, 8:24 PM Thread Starter
Tom
 
Join Date: Dec 2019
Location: Upstate NY
Posts: 19
Re: Modifing the L88

Quote:
Originally Posted by Lew540 View Post
I think the question also on the heads - are they unleaded gas valve seats - if not that can be an issue? You can always run the lead additive but that is getting harder to find and expensive. Plus with mileage you are doing that may not be an issue. Are they 1967-1969 L88 heads or later GM heads (over the counter heads sold in the 1970s) that might have the hardened seats. Pump gas should be fine at 10 to 1 with that cam. Nice size cam for that motor especially with that extra stroke. One question is are you set on using those heads or maybe selling them and getting a more modern head like an AFR 305 that will make more power, run on unleaded gas and be made of better quality aluminum which has a variety of benefits.

The heads are dated 1970. A buddy back in those days (late 70's)run the heads on a oval track car.
I'm pretty well set on using them heads, as my budget for engine mods is about used up.
I was hoping that cam I purchased would be okay for the long stroke and the 482 cu in.
I still need to balance the lower,but that comes after I check clearances such as rod/block and piston/valve. I'm also getting a new balancer.
The car was darn fast with the 375/ 396 in it. Should be more so with the 482.
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post #6 of 9 (permalink) Old Dec 10th, 19, 1:42 PM
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mark
 
Join Date: Mar 2009
Location: Gilbert, AZ
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Re: Modifing the L88

"GM fuel injection valve springs"

Are these springs matched to the cam? Or are they take offs from a more modern fuel injected 454?

I would check what springs CompCams recommended with that cam, and test the springs you have to make sure you are in the ball park.
Steve R likes this.

1969 Chevelle
412 small block
M-20 4spd
4:11 12 bolt

1957 Thundarbird Gasser
Aluminum Shafiroff 582
Richmond 5spd
4:33 59 Olds rear
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post #7 of 9 (permalink) Old Dec 10th, 19, 4:19 PM
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kevin
 
Join Date: Sep 2008
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Re: Modifing the L88

looks like a winner to me...
think you will be in the upper 500 to mid 600 HP range -
redline - sure it would go higher but figure 6500 to be safe.

fwiw - I run a 10.7:1 - 496 in my Chevelle. The cam is a comp XS-290-S solid flat tappet 598 lift I think. It rocks! and revs like a small block. Makes 627 ft/lb @ 3500.
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post #8 of 9 (permalink) Old Dec 11th, 19, 9:50 PM Thread Starter
Tom
 
Join Date: Dec 2019
Location: Upstate NY
Posts: 19
Re: Modifing the L88

Quote:
Originally Posted by marks412 View Post
"GM fuel injection valve springs"

Are these springs matched to the cam? Or are they take offs from a more modern fuel injected 454?

I would check what springs CompCams recommended with that cam, and test the springs you have to make sure you are in the ball park.
I have a new set of GM 3989354 springs that was intended for the Fuel injection cam 3994094 for the BB. That cam had an advertised duration of 364 degrees and .600 lift. It should approximate the Comp cam spring.
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post #9 of 9 (permalink) Old Dec 11th, 19, 10:26 PM Thread Starter
Tom
 
Join Date: Dec 2019
Location: Upstate NY
Posts: 19
Re: Modifing the L88

Quote:
Originally Posted by the heckler View Post
looks like a winner to me...
think you will be in the upper 500 to mid 600 HP range -
redline - sure it would go higher but figure 6500 to be safe.

fwiw - I run a 10.7:1 - 496 in my Chevelle. The cam is a comp XS-290-S solid flat tappet 598 lift I think. It rocks! and revs like a small block. Makes 627 ft/lb @ 3500.
Sounds like where I would like to be with power. I was thinking along the same lines for a redline.
Looks like you have a real runner with your 496. Thanks for the post.
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