Thread: 350 chev streetable engine build

Tweet

Originally Posted by techinspector1

I'm cheap, but not so cheap that I would begin a build with the heads or intake manifold you have on hand. Begin the hunt for L31 Vortec heads, casting number 12558062 or 10239906. They were used on '96-'99 Chevy trucks with the L31 5700 Vortec motor and are the best flowing production heads that Chevy ever produced. The 062's and some of the 906's had induction hardened seats, while some of the 906's used in heavy duty trucks got pressed in exhaust seats. Pin the studs, install new seals, put a 5-angle valve job on 'em and use CompCams drop-in beehive valve springs and retainers matched to the cam of choice. These heads use rail rockers, so if you find a set in a boneyard, get the rockers and valve covers with 'em. I have found 'em on craigslist and ebay. Don't be hoodwinked into buying some fosdick heads that somebody says are "vortec" heads, look for genuine GM heads with either of the casting numbers I listed.

Also, begin your search for an Edelbrock Performer RPM Vortec #7116 or Performer RPM Air Gap Vortec #7516 intake manifold. Either of these manifolds will make more power and torque from idle to 6000 than any other manifold you could bolt on the motor, even with your 600 carb. Both are Vortec-specific. Nothing wrong with a used manifold if you can find one. Again, check craigslist and ebay. Sell that weak-suck Performer Air Gap to someone who doesn't know any better.

Use this piston with the Vortec 64cc heads for a static compression ratio of 9.6:1....
http://kb-silvolite.com/performance....tails&P_id=155
KB's use an offset dish in a D-cup configuration that allows a generous flat pad on the crown to mate up with the underside of the head to make a good squish.

Cut the block decks to 9.001" for a zero piston deck height and use a 0.039" or 0.040" compressed head gasket for the correct squish to prevent detonation on pump gas.

1 5/8" long tube, equal length headers.

CompCams hydraulic flat tappet cam.....
http://www.compcams.com/Cam_Specs/Ca...x?csid=87&sb=0

Makes 427 hp @ 5500 and 444 ft/lbs @ 4000.

That sounds like a nicely balanced combo. The only thing I would change would be primary tube size on the headers. I am a fan of bigger pipes. I'd go 1 3/4"

Originally Posted by Flipper_1938

That sounds like a nicely balanced combo. The only thing I would change would be primary tube size on the headers. I am a fan of bigger pipes. I'd go 1 3/4"

You wouldn't if you had seen the torque loss I saw with bigger pipes.

Originally Posted by techinspector1

You wouldn't if you had seen the torque loss I saw with bigger pipes.

I run a 3500 stall converter. I guess low end torque never figures in. It jumps when I gas it at whatever speed that may be.

I have 1 3/4 primaries, feeding into 3 1/2 collectors, into 3 1/2 pipes, and run flowmaster world of outlaw spec mufflers.

It breathes nicely and sounds GOOOOOD!