why clutch head screws

[Werner R.]

just for curiosity: does anyone know why holley uses clutch head screws to attach the secondary metering block on certain 4160 carburettors [3310-3; 1850-2]? would not a simple phillips head screw do the job?

[Gerry Proctor]

Re: Don't SCREW with it.

Most of the time when these oddball (clutch or butterfly head screws) are used it's an anti-tampering issue or a torque issue. But anti-tampering doesn't seem to make sense since I think there is a natural tendancy with a Holley to take the thing apart and twiddle with it. So I'd have to conclude that it is a screw torque issue. These things are on kind of tight and I'd hate to have to either install or remove them with a phillips.

[Werner R.]

Re: Don't SCREW with it.

i have done a couple of these with good results, using a dremel grinding wheel to cut a screwdriver to make it kind of "clutch head". that part is ok. i jave had no sign of a fuel leak internally etc.
i was just wondering why clutch head. i suppose it is a torque issue, but then why not use clutch head on the fuel bowl screws, where it is suggestred to use about 50 ft lbs of torque [i think that is way too much]. i know what you are saying: probably clutch head to allow lots of torque; but there are other screws on the carb that need torque, and they are all filister head. i still have no idea why the clutch head.

[Clem Z.]

DO NOT use 50# ft

believe me the bowl screws are NOT 50#feet of torque. they are 25/30 INCH #s. i have see more warped metering bodies and float bowls since holley went to 5/16" hex head float bolt screws and people use a ratchet on them.

[Werner R.]

Re: DO NOT use 50# ft

i completely agree with that. 50 is way, way too much. i have never had a leak with good gaskets and gentle turning.

[Chuck G.]

Why Not Buy Clutch Head Screwdrivers?

Solid axle guys know all about these They're available. I have a set of just about every size clutch head encountered in 53-62 Corvettes. Chuck

[John H.]

Re: Why Not Buy Clutch Head Screwdrivers?

I do too, and have clutch bit sockets to match (from Apex) - can't live without 'em if you have a C1