Don Terrill’s Speed-Talk

FWIW:, I have an antique L.S. Starrett Co., No. 122, 6" inside and outside calipers with a vernier scale that I use to VERIFY every measurement that was taken with a battery or geared dial in the measurement chain. When you work in a real shop, the least piece of dirt under the gear works of th...

Quote: I make up a crude testing rig from a battery, ignition condenser, jumper wires, coil and spark plug..I keep opening the gap until the spark fails..But this doesn't tell me much about what's going on in a running engine..Unquote The problem with this testing method relates to an induction coil...

MANY years ago, I was part of a similar discussion with Racer Brown. He was of the opinion 1 ounce per gallon of acetone added to gas acted as a detergent to gas, breaking up the surface tension, and giving SLIGHTLY better performance/mixture consistence. I’m no chemist, but R.B. was a pretty smart ...

Jerry Bramlett has a great accumulation of Rochester FI knowledge. I can only add little with my experience. Of my original Bill Thomas unit, I can say this: The air meters have the choke blades removed and are bored straight through to clean out the metal left in the venturis so they could use a st...

Paul, I used to run my 097 cam at .006" and .009". Sounded like a hydraulic and I thought it ran slightly better. FWIW, the FI cams idled nicely with the Rochester FI. My observation is most of the loping came from poor mixture distribution of the 2 and 4 bbl intake manifolds, especially w...

Sorry for all the typos. That's what I get for hurrying earlier.

Measure the radius of the pivot ball with a radius gage. Whatever that is, that is the radius of the circle the rocker is pivoting around. If you use a radius from a standard machinist radius set, like a Starrett or Lufkin set, you can lay the half ball in the gage and measure to the bottom/top of t...

Dave, the setting for accurate measurement of impact air has a formula, but I do not have it handy. If you have an original air cleaner holder you can copy that. It is approximately 3/4 of the length of the radius with the short measurement closest to the OD of the tube. I'll bet someone on this sit...

I have replaced the cranking signal valves with the equivalent to the 1973 transmission spark control solenoid. Those can be bought from various surplus supply houses for less than $5.00. Ebay prices for original solenoids are over $100.00. Total rip offs. Solenoids are triggered by starter and vent...

The Rochester F.I. hides its complexity with of simplicity. Think of the Rochester system as a Hilborn with an adjustable pill operated by a pitot tube, because that's what it is. They will give excellent fuel curves which follow torque curves and will adjust for different air density's and temps. E...

Paul, if you have a lathe, a tool post grinder, and centers in the end of the tap, you can grind a pilot on the tap about 1/2"-3/4" long and 3/8" in diameter. Use a taper tap and don't grind the pilot so long that you run out of taper on the tap. Done properly, this will work well for...

Your Lunati roller cam calls for a .030" hot lash setting. Set it TIGHTER than this for extended life and street life. Try setting it cold at .018.020" COLD and then check to when hot. Look for around .022 .024 ish HOT. loose valve lash is hard on ANY roller lifter. To expand a little on ...

You're not alone, MadBill!

The Chevelle website has some good timing articles along with a bunch of vacuum canister numbers for standard and HEI distributors. I've seen cruise speed advance numbers as high as 60 degrees. If you don't add extra timing at cruise speed, your engine may overheat, because the mixture is burning fa...

My personal opinion is it takes power to make noise. Get rid of the whine and you should go faster. A good "Silent Chain" drive makes excellent power, absorbs shock/harmonics, and runs without slack. Roller chains do not work as well as Morse silent chains. The only reason I can see that T...