Don Terrill’s Speed-Talk

Yes throw those old intakes away , you have two choices left. Even though a Quadrajet is a great carb , I would use a Holley carb for the bigger primaries throttle response. You should list your engine specs. LOL A QJet with the right tuneup, and specifically the correct modification to the seconda...

I would rather have an original GM tall cast iron 65-66 325/360HP 396 or 66 390HP 427 QJet intake than any of those.

If the pushrod guide slots are not worn and the installation was done on a cylinder head machine or milling machine so the threads are tapped accurately, such that the studs are in line with each other and on the blueprint spec for the angle it should be no problem. How long have they been running t...

Not familiar with those but I wouldn't use anything but Holley® blue gaskets

What do you mean by center them in the bores? I have the rear idle at 1/8 of a turn. Barely cracked. Center all butterflies by removing the base from the body, back the idle speed screws all the way to no contact so the throttle plates are closed to touching the bore walls and look at the light lea...

Might It be a good idea to plate a layer of tin on the homemade bearings ?? I recall the good old school Delco Moraine bearings had a 'Tin overlay for conformability' and it was disappointing when they became no longer available.

You don't want any T-slot showing on the secondary and in fact if the bottom of the slot is near the butterfly edge, when manifold vacuum is high it can cause high enough velocity past the butterfly edge it the resulting low pressure will cause fuel discharge and undesired richness. When curb idle o...

I have tried .020 T-slot, but then I have to richen up the mixture screws and Im back in the same boat. You are right Steve. It acts like fancy carbs I had in the past with 5 emulsion holes. I got tired of screwing with them, so I switched to this basic metering block style. That’s why I think ther...

I would use 10-32 for T-slot jet. You may need a larger orifice than a 8-32 can provide. If you use 8-32 you can always go to 10-32 later. Calculate T-slot L x W = Area and start with about 10% less in the jet than the slot. Example: if slot is .025" x .200 = .00500" Area equivalent to nea...

I hadn't thought of that. I think it's difficult to get that information, it's bought from China. Can it be protected with a diode? Yes, you can limit the flyback voltage in the primary with a zener diode, but shunting the primary to ground at some arbitrary voltage limits the output of the coil by...

Does the DCO have progression holes at the throttle blade, the DCOE has them under a brass cap, but a DCO pic has nothing there? Blocking the last progression hole with a wood toothpick cured a too rich low end transition problem that a lotta new jets plus many with number drills & solder didn'...

If you can check with the manufacturer, find out if it can tolerate the high voltage flyback from the ignition coil, which can be as high as 400 V, depending on turns ratio of the coil and maximum voltage rating which can be reached if a plug wire is not connected when the spark fires.

The smaller jet requirement is because in this 1-3/8" venturi carb the annular booster occupies a greater percentage of venturi area, in comparison to larger venturi carbs, so the flow through the main venturi around the outside of the booster is somewhat restricted and flow through the booster...

30-35 years ago this was brought to my attention by a pal who is a deep thinker, always looking for the last little detail to make things better on his race car. We measured a bunch of NGK and Autolite racing plugs and found the same thing you have. New plugs measure some small resistance or open, a...

Not sure about the idle circuit calibration, but the out of the box main jet sizes are 4 to 6 sizes too large. Best get a wide band O2 and tune it.