Carter, thanks for the detailed explanation, it sincerely is appreciated and helps a guy like me who is learning his way around here. My follow up question is that in looking at other Truck and CJ engine bays with the L134 I don't notice it being there. Is it just related to the type of distributor that is in my truck? Here is my Auto Lite. Thanks.
* Important Note* The distributor vacuum line connects to a port on the carburetor that is slightly above the throttle blade when it is in the closed position... Virtually zero vacuum until the throttle is increased to above an idle....So, at idle no vacuum advance...As you open the throttle the supplied vacuum is manifold vacuum and that depends on throttle position and engine speed..
Mickey, I don't know the answer to your question, but in the 1970s I bought a new distributor, and my obsolete Jeep parts dealer felt that I would be better off with a distributor that did not have vaccum advance. I went ahead and got one with vaccum advance, because the tune-up books I'd been reading said vaccum advance was important. I've never really been able to get the vaccum advance to move. On other cars, I can suck on the vaccum line and the inside of the distributor moves considerably. I may have bought a distributor with a broken vaccum advance.
Sorry for the late response. I’m not familiar with the 4-cylinder engines, I’ve only worked on the Super Hurricane, so I don’t know.
The distributor on my 1953 CJ3B with F134 uses centrifugal weights inside to advance the timing. The faster you go the more the weights move out and advance the timing.
