Cam Recommendation

[ditzr]

I have watched a couple of videos explaining cam specifications, but i am still not sure what the numbers all mean... there are so many options that it all becomes a blurr after looking at the different cams..I would like your opinion on what Camshaft specifications would best suit my engine and driving style..

I have a sbc 350 4-bolt that i bought sometime ago and i have been acquiring parts slowly for it...it is bored 30 over, i have an edlbrock performer intake manifold, MSD HEI ignition, double-hump heads with 64cc chamber 2.02 intake and 1.60 exhaust, long tube headers. I want to bolt it to a 700R4 trans. I don't know my gear ratio yet.

this is going into a 1975 GMC half-ton, 2wd.

i would like something better than stock with more torque and hp. I have no intentions of racing it in any way, but would like good throttle response and be a fun driver..

my intended fuel system will be a self-learning EFI setup like a Holley Sniper or FiTech system.

if i have left out any information needed to make a recommendation, please let me know and i will try to get that as quickly as i can.

thanks in advance for your suggestions.

also, are there markings on the cams themselves, like a part number that would tell me what i already have??

rod

 

[4WDKC]

if you call a cam manufacturer you will need vehicle weight, gear ratio, stall convertor, tire size I think, compression, and exhaust. It sounds like youre looking more for a truck cam so something like a H258-H264 high energy cam is what you might like but , thats just a guess until you get all the other details of the engine figured out.

 

[ditzr]

thanks, appreciate the input.

 

[75gmck25]

Your cam choice should be matched to the flow of your heads and the compression ratio. Camel humps are better than stock smog heads, but still not that great compared to a Vortec or other modern designs. Your compression ratio is probably about 9.2 if you have stock pistons in a crate engine, and 64 cc heads. Based on those factors, I would use a cam duration with a max of about 214/218 @ .050, and try to find one with an LSA of 112. This should give you a good torque curve that comes in a fairly low RPM.

Set base timing at 12 degrees BTDC, and set the distributor for 20 degrees of mechanical advance by about 2200-2500 RPM (32 degrees total).

Then you need to consider what you want to do about rear end ratio and transmission. If you are using stock height tires (29-31"), then something around 3.42 would probably work fine, but 3.73 is better. If you are running larger tires, then 4.10 or even 4.56 would work better. Since you want to use a 700R4, you can have a fairly low ratio and still keep decent highway gas mileage. Another possibility is to install a 2500 RPM stall torque converter, which will let the automatic transmission get farther up in the RPM range (and power band) during take-off.

Bruce

 

[ditzr]

thank you Bruce...

 

[gpmorgan]

I ran the same combo you are describing for 15yrs. Ported camel hump heads with a comp 294s cam and valve train. 10 to 1 compression. I ran a 750 mechanical secondary carb and a 410 gear with a 700r4. If you are going to use a fi throttle body, read up on it and pay attention to what lobe seperation they recommend. I am currently running a fitech 1200hp unit on a 632 bbc and I've been very pleased with it.

 

[shiftpro]

I am currently running a fitech 1200hp unit on a 632 bbc and I've been very pleased with it.

Wow rough life...

 

[bucket]

Wow rough life...

We were just discussing our humble builds, until Mr Big Stick walked in

I only joke because I'm jealous

 

[ditzr]

gpmorgan, thank you for your comments.. I initially liked the FiTech system, but i am hearing mixed thoughts on it.. mostly with the entry level 400hp version.. but before i decide, I will do a lot of reading on it..

thanks again

 

[trukman1]

if you call a cam manufacturer you will need vehicle weight, gear ratio, stall convertor, tire size I think, compression, and exhaust. It sounds like youre looking more for a truck cam so something like a H258-H264 high energy cam is what you might like but , thats just a guess until you get all the other details of the engine figured out.

I second what 4WDKC says. Call Comp Cams. They are great people to work with and will have all the information to help you make the right selection. I purchased a Hi-Energy camshaft (I thought it was called a H268 but was for a BBC.) They walked me through all the things I needed to consider and recommended a camshaft I was very pleased with.

 

[ditzr]

thanks again