if you were to build a new 427/454 from scratch would you consider using a set of prepared L-88 heads or look at another supplier? Price for the heads is $800.
I am not looking for an engine from hell, 500 Hp max and streetable.
Thanks,

 

I can't imagine L-88 heads only being worth $800.00 I would probably by them just for the investment. I am not an expert on this subject, but come on 800 bucks for L-88 heads. As for using them on a 500 HP street engine they are marinal. L-88 heads would probaly be a little better suited for a motor a little more than 500 hp, maybe 550-600. There are good oval ports that would be a little better in the bottom end. Saying that if you step up the compression and cam a bit you can make 550-600 hp pretty easy and have it very streetable. My 454 makes in the neighborhood of 580-590 hp, and is very streetable. :chevy

 

open or closed chambers?open chamber L-88s were rated at 430 HP but they made 560HP so 500 HP should not be a problem. if you want to run pump gas you will need the 454 ci because the L-88s were 12.5:1 comp.


[Modified by clem zahrobsky, 1:31 AM 1/30/2002]

 

Was there a difference in a L88 head and a LS6 head? Weren't they both just recangular port heads with 2.19 and 1.88 valves? Sure some were open and some closed heads but the pistons made the 12.5 compression for the L88 and not the heads?
Don't know just asking.

 

the open chamber heads make about 40 more HP with the same compression ratio.

 

I know about the open vs the closed chamber and can show where an independant test took 4 sets of heads with a big block and compared all 4 sets in dyno runs. Guess who won? The closed chamber rectangular port.

 

69,
I am assuming from your response that you feel the heads would be worth $800. I really don't want them for my vette, just am having thoughts about something to play with at the strip.
The heads have been on a shelf under the guys garage for at least 25 years.
He and his brother raced dirt track cars for awhile in eastern PA.
I assume that they were an extra set left when they stopped. I just assumed that theywere not that desirable if he still had them after all these years. I talked to him about 4 years ago and he had them and a 427 bare block, which he wanted $600 for.
I declined his offer and elected to built my 76 L-82 instead. I may have made a mistake! The cost to do the 427 from bare block seemed very expense, well after the money spent on the 350 redoing things over, it would have been a bargain! I think now that for 6k I could of had a decent BB, even a dog would be better than the 350 I now have.
Thanks for your help,
Bud

 

Well, considering that I just ordered a set of AFR BBC heads today, I guess you know my answer :lol: :lol: :lol:

 

if that is true chevy wasted a lot of money developing the OC heads. i was used to test the open chamber heads before the were released to the public. i was sent a pair of sand cast heads to use on our race car and even with CC pistons which lowered the compression ratio to 11:1, the engines make more power than the same short block with CC heads.

 

For $6500, you can have an aluminum head, roller cammed 502/502 H.P., 565 ft/lbs. torque, with a GM warranty!

 

Several things.

First the L-88 heads came in first and second design versions. Open and closed chamber. The open chambers will almost always make more power. They unshroud the intake valve greatly. Plus I believe Gm actually shrunk the port size of the 2nd design heads to the 290-300cc range to add a little midrange back into the equation.

If I'm not mistaken, that 4 head swap test was run on a very mild 402" engine. it was just dying for anything that made more compression. The test engine was very poorly suited for that kind of test. To make rectangular port heads really work on a 396/402 you must twist it very hard and that requires a cam to go with them.

If you buy those heads, you need to look at them REAL close. I have had a good deal of experience with them and they aren't known for being the strongest pieces out there. Typically you see rocker studs/bosses have been broken out of the head and rewelded, valve seats fall out and chambers have been repaired etc. Very few are in good shape today and even then I would question their reliability on something you were going to play with.

They can make pretty good power but they are very dated. The round ex. ports don't flow all that well as compared to new stuff. If i was doing a cruising resto deal, I'd run them. If I wanted to actually go out and play with them and be able to hit 6500+ rpm (which you will need to do to get it to run) I'd spend my money on something else.

500 hp isn't going to require monster heads. 427's START to really come alive with rectangular ports about 5500+. That means you need a cam and valvetrain that makes power in the 6500+ range. If you put in a weenie little cam with huge heads it will do nothing well. Low end or top.


Jim

 

The combination that worked extremely well for me in the good old days was:
- started with stock L71
- closed-chamber rectangular-port iron heads
- I used 2.19" intake and 1.88" exhaust valves
- port and polish
- Edelbrock Torker Tarantula intake (ports done to match heads)
- Holley 850 dbl-pumper
- #3959180 ZL-1 cam (rumpity, rumpity, rumpity) and valve springs to match
- Kustom Headers side-mount (the original brand with Chevrolet part numbers - before Hooker)

Street driveability was definitely less than you'd want in a daily driver. Low rpm pulling away from stop lights was always interesting...(would it bog down or would I burn rubber just trying not to stall? Also, very low manifold vacuum). But.....oh the interesting sounds coming out from under the hood!!!!!

On the track, in flat out mode.....gargantuan acceleration! L-88s, with no headers, didn't stand a chance.

 

On the street, the Edlebrock O port heads will work better and make at least 550 HP. I have a set of the L88 heads that I don't need if anyone is interested. they work really well above 4000 RPM but the ports are really a bit big for a 427 or a 396. I decided at the last minute to but brand new heads for my 427 build up since I went with a hyd cam. the L88 heads really need to rev to make a difference over the "baby" square port Edelbrock RPM heads which also have a better exh port design. the L88 ports are HUGE!!! Contact me if interested Ron_Kreigh@hotmail.com