Thread: 6 inch rod 357CID SBC

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o.k., here's a helpful hint. If you want to run high compression on pump gas, there are three areas of concern.

1. Squish. Piston crown to cylinder head clearance of 0.035" to 0.040" will optimize your combination to reduce the tendency toward detonation by jetting the fuel mixture across the combustion chamber to maximize mixing and also to eliminate a dead combustion space above the piston where cooling water will keep that space cooler than the rest of the chamber/head. I've seen some fellows run as tight as 0.018" squish by angle milling the piston crown so that as the piston cocks in the bore, it will still clear the head at TDC.

2. Camshaft. Altering the intake closing point will alter the amount of fuel/air charge that is trapped in the cylinder on the compression stroke. Using short timing on the cam with a high static c.r. will result in very high cylinder pressures which won't work with pump gas. Conversely, long timing on the cam with a low static c.r. will result in very low cylinder pressures and a motor that won't pull the hat off your head.

3. Aluminum heads. Generally speaking, you can run about a full point more static c.r. with aluminum over iron due to the heat rejection capabilities of aluminum.

Furthermore, you'll notice that I didn't say a word about those silly-ass 305 heads you're using. I'm really trying to be a nice guy.

I sometimes add links to my answers because you're not the only one reading these posts. There are over 3,000 members on this forum and maybe some of the newbies will be educated better if I include links to expand further on what I'm talking about.