I just picked up a '55 Thunderbird that was restored a few years back, but has been sitting for the last year or so. Once I got it started, there was a pretty healthy gasoline leak from the pump, no doubt caused by the upstream electric pump. With the electric fuel pump disconnected and a new stock pump in place, it's running again, but it doesn't idle well. New plugs to replace the fouled ones didn't help a lot. I connected a vacuum gauge and it is between 10 and 11 inches hg, which seems awfully low. The timing seems to be advanced well beyond the 6 or 8 degrees that it should be, but retarding it makes it worse. When you rev it, it seems smooth and as powerful as you would expect, with vacuum in the 22-24 range.

The previous owner kept receipts of all the work that had been done, and it looks like a couple shops have tried to resolve similar issues with it. There has been a valve job with the heads resurfaced, new intake gaskets, carb overhaul, Pertronix ignition, etc. Compression is a little low, but consistent at 105 psi or so. The valves were set a little loose, so I reset them at .020 but that seemed to make the vacuum drop an inch or so. There is zero blow-by and no evidence of oil on the plugs, so I think that the rings are good.

Finally, sometimes it will idle as long as you like at 7-800 RPMs and is almost acceptable. Other times, one of the secondary barrels fills with fuel, eventually killing it by flooding. It has the original Holley 4000 teapot carb, which I have no experience with.

Anyway, it strikes me as having a vacuum problem that no one has been able to find as well as a carburetor issue. This is my first Y block, but I wouldn't think that it would be much different than diagnosing any other engine. That said, it's kicking my butt and I'm having to reach out to the experts.

Any help is appreciated.

Thanks,
Bobby