Thread: 700 hp 565 cid Bowtie

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Originally Posted by arock

I recycled this motor from my Hot Boat. Freshened it with some new parts and installed it in my 1973 Vega with built powerglide, 9" Ford spooled rear end and 8.5 certified cage.
I am running AFR heads, solid roller cam, girdles, dual 600 cfm carbs and MSD. Line lock and transbrake. I only run 10.5 to 1 compression so I can drive it on the street with pump gas. I have about 700 hp, which is more than enough in a 2000 lb car.
My question is: When I first fired it up, the headers turned cherry red in a matter of seconds. The cam was installed straight up. I retarded the cam 4 degrees and getted the hell out of the carbs. It now runs at 180 degrees in the garage for 30 minutes. That is where the cam was set while in the boat.
Does retarding the cam lower the compression? Cranking compression is 100 psi.

Compression in the cylinder does not begin until the intake valve closes, as the piston is coming back up the bore on the compression stroke. So, if the intake valve were closing at, for instance, 50 degrees after bottom dead center @0.050" tappet lift.........and you advanced the cam to close the intake valve at, for instance, 46 degrees after bottom dead center @0.050" tappet lift, then the cranking cylinder pressure should theoretically increase because less of the air fuel mixture that has just been forced into the cylinder by atmospheric pressure is being blown back out the "still open" intake valve by the ascending piston.

A cranking pressure of 100 psi would indicate to me that either the rings and/or valves are due for overhaul/replacement or the cam is much too large for the static compression ratio.......or both, making the motor a dog on the street. Crane Cams recommends a maximum 165 psi cranking pressure for use with pump gas and that's a long way from 100. I might expect 100 psi from a bone-stock flathead Ford, for instance.
http://www.vanpeltsales.com/FH_web/f...48_221-239.htm
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