The motor in my '27 was recently redone and runs strong but idles poorly. I am running a Vaporizer and other than hard starting it seems to be OK. When I short out #1 at low idle it makes no difference in engine speed but at higher RPM's shorting out #1 has the same effect as shorting out any of the other cylinders. The plugs are new, coils are new rebuilds and the coil box is fine. I moved plugs, wires and coils around with no change and installed a new Anderson timer. Does anyone have any suggestions? I am inclined to think it is the carburetor and, if so, is there a way to make these Vaporizers work better short of replacing them with something else?
you dont have to replace it. most likely the vaporizer isnt working properly
kinda reminds me of when i had vaccuum leak between manifold and the block.
sombody told me that there is a flapper in there that gets stuck. its supposed to richen the idle mix and make it idle smoother, im sure theres some vaproizer experts around here that have a better idea. i know ive run them before and they start and idle well.
Val - Have you done a compression test recently? One of my T's has a compression leak on #1 and as a result it acts just like yours. It misses on #1 when idling, but when you rev it up a bit or when driving, #1 fires normally.
Keith
Val that's a shame as a vaporizer is known for a smooth idle. Also check the sheetmetal hot plate in the manifold for cond. They don't always seem to last forever.
You have a vacuum leak at the forward ring / gland on the intake manifold I think. Try spraying some WD40 around it with the engine idling. If it gets sucked in it will increase idle speed.
I think Royce is on track, you cannot have any vacuum leaks on a vaporizer set up. KB
I will check for a vacuum leak but didn't think that was the problem because I just assumed it would affect # 2 as well. Compression is 50 plus all around so it can't be that and the hot plate is brand new. Hope Royce is right, I was not able to use the rings for the middle exhaust ports as the manifold is warped but I was able use them on the outside exhaust ports and intake manifold. Instead of the glands I then used the two piece manifold gaskets and thought that I had the problem solved as I don't have a detectible exhaust leak. Thanks for all the suggestions!
Exhaust gasses would not be of concern, it's only the intake side that you need to worry about if there's a vacuum leak. Make sure your primary air tube is sealed also.
Our Labor Day weekend guests finally left so I was able to do the WD40 test and the idle speed increased when I sprayed it around the front intake port so I took the intake manifold off and re-installed it with new rings and glands. It definitely made a difference. I'm still puzzled as to why the leak didn't affect #2 as well but at least the problem is solved. Thanks to everyone for the help!
vaccuum leaks will make engines do weird things, when i had one it would miss only on one cylinder.
Val......I'm doing the same thing with my '27 Tudor.
At some point the GOOD manifold gaskets were replaced with those sheet things....... .......and it was poofing exhaust on #1.
Today the set of rings and copper gaskets arrived so I removed the manifolds and found a leaking intake section too.....which explained a low rpm miss on #4.
Unfortunately the exhaust manifold had shrunk and is in the junk while I wait for a new one.
Grrrrrrrrrrrrrrrrrrrrrrrrrrrrrr
Craig, don't pitch that exhaust manifold if it is just warped. If it has good threads and gland seats, it can be straightened. Dave
I am in the process of building a jig to straighten exhaust manifolds now that I found an I beam to work with. I must have a dozen warped exhaust manifolds on the shelf waiting to be straightened and since I have three cars with slight exhaust leaks I think it's time!
Craig, Give this a look.
http://mtfctulsa.com/Tech/manifold.htm