My '54 Merc 256 has a leaking vacuum advance canister. It works a bit, but won't hold vacuum. I have a N.O.S. '55 Ford distributor with a N.O.S vacuum canister (smaller diameter than the '54) and was wondering if the '55 unit (distributor and vac. canister) would be compatable with the '54 Merc's Holley 4V carb. Do the larger diameter '54 vacuum canisters have different ratings than the smaller '55-'56 canisters? I found a N.O.S. '54 canister at Hershey but the vendor wanted $100.00 for it which I felt to be a little much.  Thanks : Bruce

I switched my ’56 Town Sedan (292 Teapot 4V) with its original L-O-M distributor from a dual chamber vacuum pod to a single chamber vacuum pod simply due to the double chamber pods no longer being readily available.  The engine drives the same with no discernible differences.  And from a standing start, the car still smokes the tires to the point you have to back out of the throttle.  So performance doesn't suffer either.  Where the dual pod was using a direct vacuum source for one side of the pod, I blocked the direct vacuum source at the rear of the carb when I switched to the single chamber pod.  The vacuum source for the single pod chamber is still coming from the venturi/timed port at the front of the Teapot carb.  I'm not familiar with the '54 Merc distributor but I would suspect the '55 vacuum chamber will be okay as long as it physically bolts on the distributor.  You can consider changing out the springs and shims in the two pods if there's any doubt about the advance curve.

Lorena, Texas (South of Waco)

Bruce, just my 2 cents if it were mine. I would replace with a 57 or later dist, if you do a search on here, you will find a lot of discussion on the problems with the early dist. Not sure but I think you will have too change the gear and pump drive, but in my opinion it would be worth it. Some of the guys with more experience with the early engines (pre 56) will jump on here later, but for the time being search the forum and I think you will find some good info. I told you so, while I was typing one of the experts jumped in ahead of me.

Glen Henderson



Freedom is not Free

Letohatchee, AL

X2 on the 57 up dist.

Ron.

Thanks for the input guys. I'm becoming very aware that the '57 up Y block distributor is the way to go now, but was curious as to how to fix what I already have, or to put it another way, how would one have solved this problem in 1956. The '54 Merc vacuum pot is about 3/4" bigger in diameter than the '55-'56 unit, so does it react to a specific amount of vacuum quicker and advance the spark easier than the smaller unit?? Thanks : Bruce

Since engine vacuum would be about the same, I would guess that the '55 chamber is smaller for some reason, maybe cost savings, with springs to match.  Using the '55 springs with the '55 chamber would probably not affect the advance rate much.  If it weren't for the need to change the oil pump and drive rod, you could just use the whole '55 distributor.

John - "The Hoosier Hurricane"