Ok, 11 to 1 327. Its in a midyear vette.
4 speed, 2.56 1st gear muncie with 3.70 rears.

stock fuelly heads, with the HP rams horn manifolds and 2.5 chambered exhaust all the way out the back. dual plane aluminum intake with a holley dbl pumper.

i'd like to get it to turn a 12.90 if possible.

i know the manifolds will probably be the killer, but i'm not willing to sacrifice the OE look.

I was considereing the 30-30 cam, or the LT-1 cam or perhaps somthing a littel more modern.

I had the LT-1 in the car, but at that point it had the 2.20 1st gear, and slightly lower compression.. still ran good but probably a low 14 second car never had it on the track, but my 04GTO had better off the line performance and that runs 13.5s

Drivebility is a big concern for me, as i'm cruising with the car all the time, but i don't have AC or powerbrakes, so vaccum isn't that much of an issue. just as long as I don't have too much overlap becasue the manifolds will be a big problem i suspect.

any suggestions???

thanks for your help.

Because of the cast-iron exhaust manifolds, you can't go very large in camshafts. I would use the Lunati 401A3LUN, which is my replacement for the LT1 cam. It makes a good little bit more power, though. The specs are: 272/282 at .020, 238/248 at .050, .485"/.503" valve lift--you can run the lash at .018"/.018" for .470"/.485" net lift, and 112 LSA. This cam is quite a bit more responsive than the LT1 cam, and more torque and BHP everywhere. It should be able to get you in the high 12s if you can hook it up.....

UDHarold

Harold,
I was wondering if you were gonna chime in.. :)
Thanks,


do you think your 30-30 replacement is too big for manifolds?

Thanks

Aaron

Aaron,

Is this the same Vette that you recently installed the Isky roller cam or is this a different car?

same car,

something is wrong though...

either the heads flow too much with that cam for the combination with the manifolds,

not enough compression,

or whoever did the porting, killed the heads (i never had them checked... becasue they looked great, but i really don't know what i'm looking at) he did say that he had over 50 hours into them, and wasn't a pro

or possibly a combination of everything. LOL

i was thinking of having my stock heads fitted with screwin studs, and bigger springs to see if it was the heads, but i hate to cut into my numbers matching heads.

i was thinking of just getting a smaller roller cam, but realistically, the Roller I have now is actually smaller in duration than the LT-1 cam that I was running, much more lift, and much faster ramps obviously. I did drop the compression though so that might be part of the problem, but ISKY said that 9.5 to one shoudl be fine. I'm getting abotu 140 lbs of cylendar pressure, which to me is a bit low, but Ron at Isky said it didn't surprise him. so....

any thoughts?

i'm a perfect case for ... don't do too many things at once. LOL

I don't think that Isky roller is too big for your 327, but 140 psi does sound a little low.

I would double check where you have your cam installed and and make sure it was ground to what you ordered. Did you degree it in?

Also, I would pull the heads off and have them flowed to see what you have. They may look good, but maybe your head ported "messed something up" on your heads.

That Isky roller should run rings around the oem GM cam that you were using. I am also running a custom ground Isky roller very close to yours in my 454: (290/290,248/252,.638"/.646",110 lsa, 1.8/1.7 rocker ratio). I know I have some displacement on you but at a measured scr of 10:1, my cranking compression is 190psi. Starts pulling real good at about 2500 rpm and keeps going thru 6500.

I would also strongly consider you installing a good set of headers.

Aaron,
You have mail,,,

If the cam is out send it to me & I will check it. As was stated, something is not right.
As I told you when you first started, I would have opted for less cam but the one you have is not too big if you actually have the compression you think you have,, bigger than what I would have liked but it should be a killer from about 3800-4000 on,,
The 140 cranking tells me either the compression is down or the cam is installed retarded or it is possible it is ground wrong,,,, it happens :(

Mike,
once the cam is out, i'll get it to you...

the car runs ok under part throttle and midrange is good from about 2500-4500 (although still not better than it was with the LT-1 cam)

when you nail it, its almost like something is holding it back...

but the carb is opening all the way (alreaddy checked that)

Thanks

Aaorn

Imho, you need at least a true 11 to 1 CR.

pdq67