More Power!

[72VETTE454]

Hello all, I'm looking for suggestions. I've got a '72 LS5 4-SPD. This came stock with 8.5:1 compression, rated at 270HP. I'm sure the cam was nothing to right home about either. The car itself is not perfect, it is a driver, so I'm not interested in keeping it stock or numbers matching. I am looking to add more power for my street enjoyment . Here are my thoughts: increase compression to 10:1, install a matching cam/intake/carb package. I'm talking from off idle to 5,000 range, nothing crazy. My biggest concern is the heads, I don't know if the 72 heads will flow well enough :confused . Please share your thoughts.

 

[titan81]

I'd look into some trikflow al heads
and some better pistons.
An extreme cam.
I think your carb and intake are fine, maybe a different intake
but the heads, pistons, and cam are a must on most small block c3

 

[mike weyman]

whats the casting number on the heads you have .??mike

 

[Checklst]

You are right the cam is junk and the heads are not to much better. It would take a lot of time or money to get the old heads to flow good, and 10.1 on iron heads, while not imposable would take a vary good machine shop achieve(not to many of those left)



My advice would be to store the old heads and put on (just about any ones) Aluminum heads, with a cam. This set up should put you over 400hp with out breaking a sweat. I personally have a 71 454 am looking at a similar project as well. I still can’t decide whether to keep it around 400 to 425hp or go for 500 and above which would require more bottom end work.



The LS5 has good rods and a good crank(5500rpm and under) and would only require some good ARP rod bolts, and the crank to be shot peened to stay on that lower hp side, BUT THAT LITTLE DEVIL ON MY SHOLDER keep saying come over to the dark side and go for 500 to 600 hp. Hopefully common sense will win out, and my wallet will be a lot happier. The dollars for a 600 hp engine are not all that bad, it’s the Tranny,drive shaft, ujoints and every thing else that will be screaming replace me if the devil wins.

Good Luck

 

[72VETTE454]

Casting number 3999241. Thanks for the input.

 

[72VETTE454]

I feel your pain, Checklst, I've already decided to keep it on the lower HP end. Much more streetable and less breakage.

 

[SG4206]

Hello all, I'm looking for suggestions. I've got a '72 LS5 4-SPD. This came stock with 8.5:1 compression, rated at 270HP. I'm sure the cam was nothing to right home about either. The car itself is not perfect, it is a driver, so I'm not interested in keeping it stock or numbers matching. I am looking to add more power for my street enjoyment . Here are my thoughts: increase compression to 10:1, install a matching cam/intake/carb package. I'm talking from off idle to 5,000 range, nothing crazy. My biggest concern is the heads, I don't know if the 72 heads will flow well enough :confused . Please share your thoughts.

I am in partnership on a LS-5 '71 Vette NHRA stocker. We made 440 hp/460 tq on the dyno with the stock specs. The only trick part is the Hyd. 258 degree @ .050 cam . It has the stock lift of .460 /.480 . We have to use all the stock induction and factory bottom end ; therefore you have a good founation .
A high rise dual plane intake , cam of 230 degrees@.050 and a good 3 angle valve job will net you 100 hp on your factory parts.

 

[74bigblock]

From what I understand, no one makes a dual plane intake that fits under the stock hood of a c3. Is this correct?

 

[Blue82]

I'm running an Edlebrock Performer RPM with a 1" TBI adapter plate and a 454 TBI on my 82. I just had to remove the rubber seal that connected to the top of the Crossfire air cleaners.

I would think you could fit a carb in less space than a adapter plate and 454 TBI unit.

 

[74bigblock]

Blue,

Any chance you have or could take a picture of your setup? I have a Performer RPM sitting on my workbench, but just looking at fitting it in makes me say "Can't be done". The main issue is that the carb is to tall.

Thanks.
Dave

 

[Blue82]

Dave, check your PM. I'll have to email you the pictures because I don't have a site to host them.

 

[windrider50]

When I bought my 72 LS-5 in '88, it had a Edelbrock Torker manifold, which is for upper range applications. When I asked Edelbrock about their Performer / Performer RPM manifolds, they told me they wouldn't fit under a stock BB hood.

I too am in the process in mod'ing my engine for some more lower end power. I looking to add a cam around.500 lift, Crane aluminum roller rockers, and either a high rise dual plane manifold for my 600 cfm Holley, or going with the Edelbrock EFI setup.

I found a L-88 hood on Ebay which will allow me to use either. Plus, the L-88 hood just looks good, at least to me.

I seem to remember reading a couple of articles a while ago that stated for the street, the oval port BBC heads were the way to go. About the only mods they recommended was to match the intake to the heads, clean up any casting marks / flash in intake runners, and a fresh valve job. I'm looking to do this on the stock heads, although Edelbrocks Performer Alum. heads look good from a performance and weight perspective.

What the hell all it takes is $$, and we can't take it with us!!


NJ BB Ken

 

[Evolution1980]

Hello all, I'm looking for suggestions. I've got a '72 LS5 4-SPD. This came stock with 8.5:1 compression, rated at 270HP. I'm sure the cam was nothing to right home about either. The car itself is not perfect, it is a driver, so I'm not interested in keeping it stock or numbers matching.

Ken,

Given that the LS5, although severly lacking any real balls, should still be worth a pretty penny to a collector, you may want to just pull the engine, put it up on eBay, and then put that money towards a brand new engine. Of the people I've talked to that have taken old engines and rebuilt them, a majority of the time they end up spending about the same amount as they would've if they had just bought a new crate engine (which comes with warranty). Those same people also said at first, "Well, I'm just gonna do <top end/bottom end>", and then end up doing the rest because "...why do only half?" So they essentially took a worn block and filled it with new pieces. It's still not as solid as a comparably new crate engine... Just something to ponder...

 

[mike weyman]

241 casting is concidered a "good" flowing head. with the right cam and some porting on those heads, you should be able to get 500 h.p. with them.they do have a small chamber though.mike

 

[72VETTE454]

Thanks a bunch for all of the great suggestions!