I don't think I have enough info for an app to estimate an overall hp/torque increase for my rebuilt 350 so thought I'd throw my specs out here to see if anyone else running similar build who might have already done this homework and can offer some idea.


'72 350 with 7a heads - fully rebuilt all new albeit essentially stock valve train parts, no porting. Negligible surfacing (block/heads combined approx. .010). Block bored .030, new speed pro L2320F flat tops - 72cc chambers. Crank (nodular) was cut .010 and polished. Compression is estimated at 9.5 . Milodon water pump, Cloyes 2x roller t-chain, Mellings standard vol oil pump. Carter mech fuel pump. TH350 also rebuilt and will use Hughes BPO25-HD converter (up to 2500 stall), in addition to ATI flexplate.


Will be running stock exhaust manifolds through dual 2.25 exhaust with Flowmaster 40s, MSD 8.5mm plug wires and stock-ish heat range plugs.


Cam.lifters = Howards CL510011-12
Duration Exhaust: 269

<li class="wsm_product_details_tags2"> Duration Intake: 259 <li class="wsm_product_details_tags2"> Duration at 050 Exhaust: 215 <li class="wsm_product_details_tags2"> Duration at 050 Intake: 205 <li class="wsm_product_details_tags2"> Engine: 260-455 <li class="wsm_product_details_tags2"> Firing Order: 1-8-4-3-6-5-7-2 <li class="wsm_product_details_tags2"> Intake Centerline: 108 <li class="wsm_product_details_tags2"> Lobe Separation: 112 <li class="wsm_product_details_tags2"> Engine Manufacturer: Oldsmobile <li class="wsm_product_details_tags2"> RPM Range: 800 to 4800 <li class="wsm_product_details_tags2"> Valve Lift Exhaust: .475

Edelbrock 2711 intake, fully rebuilt/ethanol friendly Qjet 750 w/electric choke (from '76 Olds 350), Pertronix Flamethrower III HEI with MSD coil. Rear will be 3.08 Posi. Running 245-60-15 rubber all around. Will be topped off with 14x3 open air cleaner assembly.


Radiator is aluminum 2-core with 1-1/8 tubes, 180 t-stat, 5-blade stock-type fan with thermal fan clutch.


thanks!

 

Did the heads CC at 72cc? That is on the high side, those pistons sit around .025" in the hole, similar to stock, not the best quench if you used Felpro head gaskets. I say maybe 300 HP and a bit more torque. I would of added 10 degrees more duration on the intake and at least 5 more on the exhaust. You will have very high cylinder pressure with that small cam. Meaning you can run very little vacuum advance, a slower timing curve and 91 octane minimum. I have 9.5 to 1 with Performer cam, very similar except has 2 degrees wider LSA. I had pinging issues and shitty running on 91 octane. I went with very cold NGK 5670-8 plugs, slowed the timing curve, limited the vacuum advance to 11 degrees and removed the choke plate on my custom Qjet to get to run right. I ran mid 14's with a 2300 stall 2004R and 3.42 open with slicks, nothing impressive. I am going with a bigger custom from Cutlassefi before the 350 goes in my 70 S.

 

300-320 or so is what I guessed based on experience with my prior Skylark 350, which was a factory 10.25 comp rated motor - I am using the Felpro gaskets and it was 72cc that my engine advised as to the heads - he knew I didn't want to exceed 9.5 comp where possible since my ragtop will primarily be a street cruiser - power brakes, a/c, etc.


Really hoping everything will dial in ok - I had planned to run 91 gas or greater anyway where possible (that was the factory spec recommendation even back in '72).


My goal was to maintain stock valve train geometry and good vacuum but boost the usable low-to-mid range power for better street performance. To that end I also tried to leave myself enough room from the .500 lift level cams for those not to be an issue.


Most of the cams I inquired about were somewhat similar in design to the Howards I ultimately selected so it ultimately came down to what I thought might be the best potential combo for the motor. The Howards set was also matched to its lifters and springs.