350 performance upgrade

[bigbug6900]

Hello I have a Early 90s 350 & I've purchased a set of stock vortec heads with the 61cc combustion Chambers in the upgraded valve springs it's supposed to be a stop at 921 motor from the factory I'm looking for the right cam to put in there that's not too over-aggressive but just enough to get the power in low and hold at mid-range just a stop light to stop light deal it's going into a 1977 Chevy stepside with a 373 rear gear it's going to have a 750 vacuum secondary carburator it has a true 2 and 1/2 inch dual exhaust flowmaster exhaust mufflers any suggestions on cam just looking for a real good tire spinner till I get through with my 427 build.

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[bigbug6900]

My bad 9 to 1 compression already pretty decent but it's got them throttle body heads on it which don't flow after 3000 RPM


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[75gmck25]

Stock vortec’s should be 64 cc heads, which will raise your compression a little over the TBI heads - this is good. I assume you have a TH350.

- 3.73 is a good rear end, and use stock height tires to keep a good ratio
- I would probably keep cam duration to about 218 @ .050 or less if you want a strong low end to move a heavy truck off the line. Most will be dual pattern cams (like 214/218, etc.). Check the cam lift specs carefully to make sure it works with stock vortec springs.
If you go with higher duration cams (e.g., 225, 228) most of the power gain will be at higher rpm. You may get that rump, rump idle, but less low end power to spin tires.
- swapping to a higher stall torque converter would help a lot off the line. Just make sure you get one from a reputable vendor.
- set base timing to about 16, and try to bring in full mechanical of 20 degrees by about 2000 rpm.

Bruce