North of 40

Just installed a rebuilt 4160 3367 Holley on my 1966 327/350 horse vert. Stock engine, Points in distributor.

I need your help with a little trouble shooting

When driving(car at operating Temp or not), as I accelerate and then let off the gas, push in the clutch, the idle stays at approx. 2500 - 3000 RPM. and will not drop down to idle. If I stab the gas pedal the idle drops down to approx. 1,000 RPM. This is consistent and does not change no matter what I try. The choke is the original Bimetal type unit. All parts are new.

This is not a safe way to drive.

Any suggestions would be appreciated.

Working on bringing her slowly back to original.

Thanks in advance

62Jeff

Howdy,
This likely won't be your problem but I still feel compelled to pass it on...

I had what sounds like this exact problem on my 65 327/350 with Holley. My power brake vacuum hose was routed under my throttle linkage, and the linkage would pinch down on top of the hose, keeping the throttle from closing all of the way and thus keeping the idle high. If I blipped the throttle the faster action would allow the throttle linkage to push past the pinch point on the vacuum hose.

I really suspect you've got something else going on, but you can't ignore the obscure solutions sometimes.

Good luck.

Jeff

North of 40

Thanks Jeff,

I will check my throttle linkage for obstruction once again, but don't think that is the issue. My car is a manual Brake car.

Appreciate you taking the time to answer.

vark_wso

North of,

There's a nylon cam on the choke side of the carburetor. In the photo below, it is kind of a cream colored piece near the carb base behind the lever where the divorced choke rod goes.



There are several 'steps' on this cam. They set the fast idle speed depending on the position (amount) of choke. The extreme fast 'step' position (choke closed) will typically give you over 2000 rpm.

The bimetal spring coil in the choke stove pocket moves the choke and thus determines which step is engaged. Holding the throttle partially open with one hand, move the choke stove rod up and down to simulate the coil heating/cooling. Observe the cam & see if anything's binding in that area.

Added: Another place to check is back at the throttle lever -- insure that the braided copper ground strap between the throttle lever & the LH aft intake manifold bolt is positioned and "trained" properly so that it does not bind the linkage rod anywhere throughout the entire range of motion from idle to wide open & back.

PAmotorman

make sure the advance weights in the distributor are not stuck in the advance position as this will cause the problem.

JohnZ

The photos below show how the choke/fast idle system works on the 3367. You’ll notice in the left photo that the plastic fast idle cam is pivoted all the way down (normal warm idle position), with the tang on the throttle lever above the top of the disengaged cam. In this mode, idle rpm is controlled by the idle speed screw in the primary throttle lever on the other side of the carburetor.

At cold start, when you press the accelerator to set the choke, the rod from the thermostatic coil (not shown in the photo) pushes up on the lever in the foreground, which pivots the plastic cam up (and closes the choke butterfly), and when your foot comes off the accelerator, the tang (with the slot in it) on the primary throttle lever comes to rest on one of the raised steps on the fast idle cam as shown in the center photo. The amount the plastic cam is raised (and thus, the height of each fast idle step on the cam the tang comes to rest on) is determined by the temperature of the choke thermostatic coil.

There is no fast idle adjustment screw on the R-3367; to adjust it, insert a flat-bladed screwdriver through the slot in the tang that contacts the steps on the cam (right photo) and bend it slightly clockwise (as viewed from the top) to increase rpm at any given step on the cam, or bend it slightly counter-clockwise to reduce rpm.

Assuming your choke unloader and choke vacuum break are adjusted properly as outlined in the Chassis Overhaul Manual and the choke thermostat coil operating rod length is adjusted as outlined in the Chassis Service Manual, the automatic choke is pretty trouble-free, and the fast idle rpm adjustment is quite simple, as outlined above.

You can't just "bolt the carb on and go"; you need to adjust the choke first and verify its operation.

65 vette dude

Check an make sure the little throttle shaft spring,next to the idle adjustment screw,has tension and its leg is still in the slot. Also,make sure the throttle plates are centered, and are closing all the way, and are not binding on the throttle body.

62Jeff

Geez, I've been so wrapped up in my 65 project, that I had completely forgotten about the exciting full-throttle run I made on a dead end street heading towards a bayou in 1983, when my carburetor stuck open on my 62 for that very same reason.

yes yes yes do verify the throttle plates are centered in the bores and not getting stuck when they go over-center.