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Old 12-06-2019, 09:16 AM
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79Poncho 79Poncho is offline
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Join Date: Mar 2006
Location: Brighton, MI
Posts: 11
Default Ported vs. Stock Heads for a Mild 455

Hello all,

I'm in the planning phase of my 455 build and I'd like to see what people's thoughts are on the value of porting work for my build.

I've got a '74 4-bolt main 455, std bore.

I'm planning to run forged pistons (Sealed Power L-2359NF - Speed-Pro Forged Pistons) with stock rods on a stock crank

I'm considering the SD performance hydraulic roller "Stump Puller" grind

I have a set of 6x-8 heads that came off a 400 that I wiped the crank on. They've been milled to reach 93cc chambers and have 2.11 and 1.77 valves. I think it's about 9.57:1 compression.

I've thought about porting these heads at home using Jim Hand's book, but am hesitating to get started due to repeatability concerns from port to port. I'm considering if it's worth to do the work myself, pay to ship the heads to SD Performance for CNC work, or just bolt them on as-is and see how it runs.

I'm not looking for anything crazy, any form of 455 is a bump up from the Oldsmobile 350 small block I'm running now.

Thoughts? I'd really like to hear from guys building and running mild 455 combos to see what the impact of 20-40 cfm really is.

Thanks,
Geoff

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1979 Pontiac Trans Am
'75 Olds 350, Muncie M21, 3.23 Posi