I need some help

[crebo]

First of all Happy Holidays

I need alittle help finding the cam, head and intake spec's for the 65 396 vette. Just trying to figure out what I need to do to get that type of hp or better.

This is what I have:
10.5-1 compression
mild cam
true duals- headers
850 street demon double pumper

Within a week I plan to buy:
Comp extreme 292 Cam
edelbrock performer rpm intake
heads are http://www.paceparts.com/product.asp?0=243&1=246&3=509

Please let me know your ideas. What would work better.
Crebo

 

[Scott81]

I have no idea but you might ask on the NCRS Board . I have the Comp Cams Extreme 284 in my 383, I can only imagine what the 292 is like :eek

 

[crebo]

Hey Scott,
The 284 is pretty mean?
I'm hoping to produce the #'s that you already have. I'm hopefully close to the tq.
Crebo

 

[Tom Bryant]

Crebo,

I think you are already there if not more. You have a far better combo for a street driven engine. The rectangular port heads were dead on low end torque due to the large volumn of the intake runners, as was the camshaft that was used with them. Lots of overlap and didn't begin to pull til around 3500-4000 rpm or so. This stuff was meant for the track where the rpms were kept up in the torque peak all of the time.

Tom

 

[crebo]

Tom,
So you think my future set-up will be too much for the street? It runs pretty good now. I guess I just want alittle more. I was thinking of changing to 3.70 instead of my 3.08. I kinda like the highway gears. So I thought I'd give it more power maybe the 3.08 would be okay for awhile.
What do you think?
I'm also running a 700r4

 

[JohnZ]

Every performance mod presents a compromise of some sort to what you're used to, so it just depends what you want to live with for regular driving. The most frequent mistake people make is to over-cam their engines, which results in poor low- and mid-range performance (which is where you spend 99% of your time in normal driving), unstable idle, poor throttle response, and lousy fuel economy, plus noise, poor reliability of some of the "hot-rod" pieces, and not enough vacuum for the power brakes. If you install "race" parts, expect some disappointments in normal operation.

 

[crebo]

JohnZ

I know I'm being alittle general. Do you think think I'm over caming the car with the set-up I want. I want to have about 400 hp on the ground. I do want it to be well rounded though.
Do you have any suggestions?
Any info would be much appreciated.
Crebo

 

[Tom Bryant]

The 3.70 gears are an excellent choice with the .7 overdrive in the 700R4. With the very low 1st gear in the trans that your cam will like, you will have ungodly stomp off the line and very reasonable highway cruise rpm in overdrive.

Tom

 

[JohnZ]

To get 400hp at the wheels, you'll need close to 500hp at the flywheel, which will require LOTS of "race" parts; the original 396/425hp Corvette was rated under the old "gross" horsepower system, and under today's "net" rating method only made about 350hp at the flywheel instead of 425. What's important in a street engine is TORQUE, not high-rpm horsepower; torque is what plants you back in the seat, and you want it at the rpm's where you drive the car most of the time to have "fun" with the car. A street engine built for low- and mid-range torque is a LOT more "fun" than an engine full of high-rpm power parts, and it's a lot easier to live with from day to day - how often will you be at 6000+ rpm at wide-open throttle around town? Cam it for mid-range torque, not high-rpm power, and you'll enjoy it a lot more.

 

[crebo]

JohnZ

I understand what you're saying. Which cam and heads do you suggest? I'm looking at making a move on some parts very soon. Trying to find the right set-up.

Crebo

 

[vettefinderjim]

Don't out engineer the engineers

John Z is so correct. So many "hot rod" Corvettes are brought back to factory specs after theowner discovers it runs lousey. Believe it or not, the General wasn't totally stupid.

I like a mid range cam that comes on at 2200 RPM, makes power at 4000 and is maxed at 6500. It just lasts longer and gives much better driveability.

Road racers use cams that have torque at 2000-3000 RPM as first man off a corner is OUT IN FRONT. Then the rest have to catch them.

All of the cam shaft companies have good tech people that can help, especially here in California.

And don't forget the carb. 850DP is a LOT of GAS. I have seen many good motors set up with everything correct and then a garden hose carb that FLOODS the engine is put on top. And the owner wonders why it bogs off the line.

Don't forget there is no substitete for cubic inches. The new 502 may be your answer.
Jim

 

[crebo]

vettefinderjim

Not trying to be hardheaded. I'm far from a engine man. I'm comfortable with my big block. I just want alittle more. That's why I'm running through head and cam combos. I want something powerful and streetable. More power. I drive it about 4 times a week. Roughly 30 miles a week on the high side.

I just it's safe to assume the parts I planned on buying were geared more towards high rpm and top end.

I plan to buy:
Comp extreme 292 Cam
edelbrock performer rpm intake
heads are http://www.paceparts.com/product.asp?0=243&1=246&3=509

How about the heads with a different cam?
Please offer me some head options....as far as I know I'm running 427 heads now. I'll check casting #'s this weekend.

Thanks for all the info

 

[Tom Bryant]

With that cam you need low gears (high numerically) or a very loose converter and low gears. About a 3000 rpm stall on the converter will make it a pain to drive on the street. You will have to rev the snot out of it to make the car move. But it would be a bear at wide open throttle. The rest of the time you will be looking at the rear bumper of Hondas.

Tom

p.s. Hot Rod Magazine loves those heads. You just need to match a cam for how you will really be driving the car. I would suggest calling Comp Cams helpline (1-800-999-0853) and talking to the pros. Then you can be assured of getting the best combo from the people that designed these cams and know exactly what they will do with various components. All that most of us here could do in cam selection is read the catalog and guess.

 

[crebo]

Tom

Okay!! Anyway that makes sense. Right now I have a auto700r4. My rear end is a highway setup. Stock 3.08. Plan to go to 3.70 maybe 3.90.

Well now have a pretty good start. Most people seem to like the heads. Now I have to figure out a cam. Trying to match up an intake. I have a modified stock hood. I have a L-88 cowl glassed in. I just want to make sure that I have enough room under the hood.
I plan to do it all at the same time...cam-heads-intake. I'll pick up a fan shroud too.

Which heads do you recommend?

 

[vettefinderjim]

Go slow to go fast

Crebo,

Double check that rear end. If your car is a factory 77, that came with an automatic, it is probably a 3:36 rear ratio and not a 3:08. The 3:36 rear end with a 700R4 is a great street combo.

If you are using the factory GM new alluminum heads as you showed, I would go with the GM performance cam and intake. Edlebrock has done lots of work with GM Performance and their intakes are very good as well. I like their Vic Jr. unit.

You will find, that you need to talk to experts who need your complete driveline specifications to accurately give advice.

The cam you have picked is very high on horsepower, but low on torque at low RPM. Great for a 7500RPM blast down a 1/4 mile dragstrip, but terrible for around town.

Again, you need to get the numbers off the rear end and trans so you know what your gear ratios are.Think of the modifications you want to do as a whole package

Then you need to determine if you want your finished car to be a canyon runner, drag racer, or Silver state 200MPH road car.

Racers always learn that you" have to go slow to go fast". There is a lot to the whole package, and rushing out and spending money too fast on the wrong parts always leads to a compromise that you really never considered.
Regards,
Jim Gessner

PS: You live in California. What about the bi-annual smog checks? What ever you are doing that problem should be addressed or you finished car is worthless.

 

[crebo]

vettefinderjim,

Thank you and everyone else for their patience with me. You guys are helping me a great deal. As for my rear end. I'm going to look under their again. Almost positive that my code is OA with by my book says 3.08.

Getting ready to get on the horn with pace and GM to check out some of the cam and intake combos. You can believe that I want to make the right decision. I just don't want to be disappointed. I understand that there will be sacrifices either way. I guess I have to figure out which I want more.

If you guys want to know I'll let you know what I go with and how it works.

As for the smog thing. I'll be outta Cali within a year. I'm in the military and due for a transfer. Just waiting for my wife to finish her nursing degree.

Thank you so much and I'll tell you what the cam people say.

Chris