Don Terrill’s Speed-Talk

Over balance and under balance are arrived at by modifying/changing the bob-weights. Changing the bob-weight balance factor from 50% to 51% (over-balance) which will (or might) allow the engine to maintain high RPM levels better. Changing the bob-weight balance factor from 50% to 49% (under-balance...

Over balance and under balance are arrived at by modifying/changing the bob-weights. Changing the bob-weight balance factor from 50% to 51% (over-balance) which will (or might) allow the engine to maintain high RPM levels better. Changing the bob-weight balance factor from 50% to 49% (under-balance)...

Most balance shops/engine builders use a specific balance speed, usually about 500 RPM, for all of the engines they balance. If the engine is in balance at 500 RPM, it will still be within balance specs at 3000, 5000, 7000, 9000 RPM, etc.

The old Holley bowls with lever-operated vent, vented the gasoline vapor directly into the atmosphere, no charcoal filters nor emissions concerns. The vent was closed when the engine wasn't running, to keep dirt and other contaminents out of the fuel bowl. In later designs the bowls are vented via v...

Don Hardy was probably one of the first, if not THE first manufacturer who built cars specifically for the "new" Pro Stock class back in the early 70's. He produced excellent quality cars at his shop in North Central Texas. He will be missed . . . . . . . .

I think the Holley bowls with spring loaded lever plug are very old applications, long before emissions were a concern. Bowl vents are necessary for the fuel to move efficiently from the bowls to the venturi boosters as the engine is running. Current Holley bowls are vented via a round tubing vent t...

The amount of increase due to small journal crank pins depends on many variables in the engine combination/design. The torque/horsepower attributed to small diameter rod journals does not just show up via magic. The small rod journal has a significantly smaller surface area, which will reduce intern...

Mike Lewis is a very qualified engine builder. However, if you are in Southern California, check out Jeff Ginter Racing Engines in Artesia. Phone 562.972.9763. Jeff has been in the high performance industry for several years.

Combustion heat is transferred through the piston top to the piston ring, then through the ring to the cylinder wall, to the coolant jacket. Real-world testing has shown that ring gap is not critical in developing torque/horsepower - AS LONG AS MINUMUM GAP SPECS ARE RECOGNIZED AND FOLLOWED. In other...

[/quote] If that’s true, why not leave the ring out altogether? The. It won’t butt for sure. [/quote] A well-known crew chief once told me that he was pretty sure that a Top Fuel engine would run much better without any rings. The only problem was getting the engine to start without rings . . . . . ...

.0045" to .0050" per inch of cylinder diameter is safe and will work very well. i.e. 4.000" bore will be fitted with a top ring with gap of .018" to .020". This would be considered the absolute minimum for top ring gap, unless piston manufacturer recommends otherwise (such a...

Yes, the oil ring support rail should have the locating tang in order to keep the support rail gap away from the void over the wrist pin. Most of the support rails in the industry are supplied by Perfect Circle/MAHLE and Hastings and I believe that both of them are still utilizing the locating tang....

AmericanPie, Welcome to the forum. Of the three cams you have listed, I would go with the Isky cam. The cam is not going to make a huge difference performance-wise in a big car with mostly stock engine and powerglide. I would highly recommend that you install new lifters, springs and valve locks whe...

Valve guide to valve stem clearance of .0024" to .0026" is fine. As long as the stem clearance is within factory specs, all is well. Tightening the clearances is not a good idea, especially if you are running positive valve stem seals. Too little clearance here will cause the valve stems t...

Make sure that the valve stem to guide clearance is within specs. Go with the high side of the specs if you are using positive valve seals.