The Stovebolt Site Forums The Shop Area Engine Shop Carter YF problem

This is the story

I bought a Carter YF 4480s carb rebuilt it ,I work part time at CJC auto parts where I got the rebuilding kit.

I installed it this last weekend ,started right up and ran, but the engine was not right, you know what I mean,You can tell.

Today I put the timming light on and the timming was not even near the ball ,so I took my vac gauge and took some readings at the wiper line I'm getting 21 inches than I put it on the line going to the dist. and I'm getting 21 inchs it should read 0 so take the carb off and the vac. hole is below the plate ,so I'm getting full vac on the dist.

I've got 3 "B"s and 2 W1 carters and all of them the vac hole is above the plate.

So did anyone else run into this? And is there a way to fix it? Or is this the wrong carb and thats it.


Pete

Carb King ,maybe some help here,please.

Pete

Pete - I don't have a 4480s to look at, but suspect you are correct.

The 965s (up to 1956 engines) has ported vaccuum, as do the W-1's.

The 3211s (for 1957 and newer engines) has manifold vaccuum.

Carter specified the 4480s for use on Chevrolet engines 1963~1967.

I don't have a 1957 or newer Rochester B to look at.

At this point in time, you need a "distributor guy", not a "carburetor guy".

I cannot advise you on the advantages/disadvantages of ported vs manifold vaccuum.

Maybe I can add a little to the discussion here- - - - - -Most of the stovebolt engines work best with ported vacuum to the distributor, as the pointer & ball setup on the flywheel is designed to allow the engine to be timed with the vacuum advance out of the picture. This is done by drilling the port for the distributor fitting so it enters the bore above the throttle plate, choking off the vacuum source while idling. As soon as the throttle is opened slightly, the vacuum comes in gradually to work the advance unit. The distributor will be calibrated to take into account the position of the timing port when advancing the spark. The vacuum advance is mostly used to provide better gas mileage under light-throttle cruise conditions, with the majority of the spark timing advance provided by the centrifugal advance weights which respond to engine speed. The final 10 degrees or so of advance is available under light-throttle cruise conditions by allowing vacuum to be applied to the advance unit when there's little or no heavy pulling going on. As soon as a driver steps on the gas to pass, pull a hill, etc., the vacuum drops off, and the ignition timing is retarded several degrees to prevent detonation while accelerating or pulling a hill under load. As soon as the load goes away, the timing can be advanced again for best fuel mileage.

If vacuum is available at idle, the timing gets advanced 8-10 degrees or so as soon as the vacuum line is connected. This raises the idle speed, and requires that the idle speed screw and mixture adjustments must be made with incorrect initial timing. The added initial timing also affects the engine's response to load-pulling and cruising fuel economy. I don't know of a way to correct the problem, other than to find a carburetor with the right passageways drilled to provide ported vacuum rather than manifold vacuum at idle.
Jerry

Thanks carbking and Jerry ,

Carbking does the carter YF2100s have the port above or below the plate?Should that be the carb I'm looking for?Anyone out there have a 2100s to look at?Thanks again.

A carb with the vac. below the plate gives me full advance at idle ,and it will not run right the timming should be at the ball at idle,so what YF s should I be looking for?

Pete

Not Jon or Jerry, but I just happen to have a 2100S carb handy. The port is just barely below the plate.

Thanks,Bill I guess I'll have to start looking for one.

Long day ,I should of said it will give me the same problem I'll start looking for a 965s.


Pete