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Author Topic:   Compression for a small block Chevrolet
Dirt Forum Champ
Total posts: 569
posted April 19, 2005 09:17 AM  
How much compression is too much?

I'm looking at a Classic Series Jr Motorsports 406 (hypertech pistons, Scat crank and "race prepped" stock 5.7 rods) with 13:1. My last motor was the same motor with 11:1 and I liked it but wonder if I'd be happier with more compression. I had a 360 a few years ago with 12:1 (from another builder) that was not too good - little power, tough to start and just generally a dog. I always attributed this to too much compression, but maybe I was wrong.

Here are some particulars - the heads are Dart iron eagles (64 cc chambers and 215 cc runners), 3000 lb car and 750 dbl pump Holley running on Sunoco racing fuel (110 octane I believe). Also, the rpm range is 4500 to around 7000.

Is 13:1 a sensible ratio?

Dirt Maniac

Total posts: 148
posted April 19, 2005 11:26 AM  
I think you'll be ok. go a little easy on the timing, watch the plugs carefully.
If you race at someplace that is above 1000 ft Elevation you're even better off.
Tighter you squeeze it the more it pops.

Some People Race For A Living; I Live To Race


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