Quote:
Originally Posted by Scott Stoneburg
I am and have always used stock rubber mounts, the 2 bolt mounts due to year of the car. I have always had some sort of limited tied to the front of the head. Currently i have a 1" CM tube with hiem ( hope i spelled that right ) joints from the head to a tab I welded to the frame. ( see pic ) What would the advantage be to switching to a motor plate. Front only or front and mid plate. And would the front plate be more sturdy than having the ears from each head to the frame.
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On my 69 GP dirt track car I had a 69 428 HO block and of course used the 2 hole mounts, as there wasn't any other mounts available to use on that particular block, and chassis. Engine was roughly 450 HP, which at the time was good for cast iron D port heads.
A set of brand new mounts (late 70s time frame) at that time were a lot more robust than the Korean mounts of today, made with silly putty. They still would break in 2-3 weeks. The steel interlock would twist and break, then the rubber would delaminate. I then incorporated 2 turnbuckles tying the left and right cylinder heads directly to the frame (right side was to counteract abruptly braking when entering turns), and decelerating at the same time. I never broke another mount for 2 years after adding the turnbuckles to the cylinder heads, until the car was retired.
The twist load was transferred to the cylinder heads with no adverse effects in 2 years of circle track racing. That's a bunch more than running a quarter mile at a time in a straight line. Roughly 13 miles around a 1/3 mile dirt oval every week. I still have the engine assembled, just as I pulled it out of the car back in 1980. The motor mounts are pristine.
I even did a few smokey burnouts on the driveway in front of the gas station I ran at the time:
During that time frame no one was using motor plates except in tube chassis super late model cars. Using a stock frame car, the turnbuckles worked just fine for keeping the engine from twisting in the chassis and breaking mounts. It also transferred the stress from the bottom edge of the block to the cylinder head area. Primitive by today's standards, but it worked just fine at the time.