Thread: 350 engine unknown cam not running well

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The main problem here is that the cylinder pressure is too high for pump gas. I don't expect you to believe me, take a look at what the CraneCams engineers have to say here.....
Crane Cams |

Trust me, fuel octane boosters are not the answer. Read the bottle/can that junk comes in. When it says it raises the octane rating of your fuel by 2 points, it actually means 2/10ths of a point, like from 91.0 to 91.2. Utter foolishness. Makes you want to grab the makers by the throat.

There is nothing you can do for this motor except disassemble it and re-engineer it for use with pump gas (9.5:1 max static compression ratio with iron heads, 10.5:1 max with aluminum heads). I suspect that whomever built it used pop-up pistons and that the static compression ratio is 11.0:1 or higher. I further suspect that you have one or more cam lobes goin' south due to improper installation and break-in by the builder. Here's a tutorial on flat tappet cams that you may find interesting......
http://www.crankshaftcoalition.com/w...ips_and_tricks

Experience will show that a 350 will make max power with a 750 carb. If max power is not what you are looking for, then use a smaller carb for better driveability (smaller primary throttle bores contribute to faster air which contributes to a better signal at the venturi which contributes to better mixing which contributes to a more complete burn). My personal favorite is the 750/800 Rochester Quadrajet on a spread-bore RPM intake manifold. Tiny little primary bores for best driveability and mileage, huge secondary bores for best power.

Let us know when you have the motor down to a bare block and we can instruct you how to proceed.
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