Thread: sluggish down low! help!

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Originally Posted by glennsexton

If it were mine, I’d pull the heads and measure the deck clearance to determine if I could get the C/R down below 10:1 with a thicker head gasket.

Glenn, before learning differently, that may have been my suggestion as well. But reading through the Keith Black Piston catalog, I noted that John Erb, Chief Engineer for KB has stated that using a thicker head gasket to lower static compression ratio will increase the squish measurement and may allow the motor to detonate worse than it would have with the tighter squish, thinner gasket and higher static compression ratio.

Piston crown configuration and combustion chamber volume are ways to change static compression ratio. Piston deck height and gasket thickness are ways to change squish.

The fact is, this combination is not going to be street friendly because the OP has chosen the wrong parts.
1. Static compression ratio is too high for iron heads. 9.5:1 max for today's fuels. 10.5:1 max for aluminum heads.
2. Heads are steaming piles of dog poo. Much better heads are available for less money than re-furbishing these old relics.
3. Wrong intake manifold. Use a single-plane if you need to make power over 6500. At low rpm's, there is too much volume in a single-plane intake to generate good vacuum to fill the cylinders. Use a dual-plane, high-rise such as the Edelbrock 7101 Performer RPM, Holley 300-36 or Weiand 8016 Stealth if you want to make good street power from idle to 6500. Holley and Weiand part numbers are out of production, but these manifolds can be found in good used condition on ebay, craigslist, racing junk, etc.
4. Combination needs a 10", 3500 stall converter and a minimum 3.73 rear gear. More gear than that would be OK too, but 3.73 minimum. Use a vacuum-operated secondaries carburetor with a stock converter. Use a double-pumper with a looser aftermarket converter or manual trans.
5. Not enough ignition timing. Disable centrifugal weights and lock timing out at 36 degrees at the crank. Install momentary push-button (normally closed) with 12-15 amp capacity. Cut the power wire to the coil and install the switch on the dash or some other easy-to-get-to place in the driver's compartment. When starting the motor, push the momentary-off switch with your left hand to interrupt power to the coil so that the motor will turn over easily with the starter switch that you are operating with your other hand. Once the motor has spun up, release both switches and she will be idling, no muss, no fuss.

Use this tutorial to find true top dead center so that you can intelligently set the ignition timing with a light.......
http://www.crankshaftcoalition.com/w...op_dead_center


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