26’ running sweet again

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Model T Ford Forum: Forum 2012: 26’ running sweet again
Top of pagePrevious messageNext messageBottom of page Link to this message  By Jason Given - St. Paul, MN on Wednesday, July 25, 2012 - 10:37 pm:

To make a long story short. For the past month my roadster has been running poorly. This past weekend I went through and cleaned and checked over the various systems. For the past few years she required 1 ½ turns on the fuel air mixture, no more, no less, no matter what kind of weather. When I was all done I found that she wants to run at 1 full open turn on the fuel air mixture and absolutely nothing more, a little less seams ok. Anyone have any ideas why the all of a sudden change in air fuel mix? It has been a hotter and more humid summer is the only thing I can think of. I would guess there is about 5K miles since the engine was rebuilt. During the first 100 or so miles I needed about 2 - 2 ½ turns, otherwise she has been stable at 1 ½ turns.

Thanks for any feed back.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Halpin on Thursday, July 26, 2012 - 06:05 am:

Air/fuel mixture is so subjective and varies so much from car to car and climate conditions, I don't think I'd get too concerned with it. If you were having to open it up more than usual, I'd be looking for a vacuum leak.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Danial - Veneta OR US Earth Solar System on Thursday, July 26, 2012 - 06:13 am:

When I was trying to get my 27 T vaporizer tuned, it had been suggested that I start with about 1-1/4-1-1/2 turns. This summer, after having driven it on multiple outings, I have learned that just shy of one full turn seems to be the optimum setting.

ANd interestingly enough, Jason, this was after I had gone through and cleaned and regapped the plugs, cleaned the contacts in the distributor and generally gave every contact under the hood a once-over.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, July 26, 2012 - 11:19 am:

A sudden change could happen after filling the gas tank. A different formula gas could make a difference. It is also dependant on the weather. If there is a great difference, then you could suspect maybe need a carburetor rebuild, or have a vacuum leak. With my cars, I just get it running and then turn the adjustment to find the "sweet spot". After it has warmed up, I re adjust for the "sweet spot". It will change with the temperature of the engine. If it runs smoothly, at all speeds, don't worry about it.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jason Given - St. Paul, MN on Thursday, July 26, 2012 - 02:09 pm:

I always buy my fuel from the same station (non oxygenated). It still could be the fuel. I did have a really good back fire about a month or so ago also, so a vacuum leak could also be in play.

Weather never seems to matter. Hot, cold, humid, dry, summer or winter ALWAYS 1 ½ turns.

She runs nice at 1 turn. However, I left the fuel on while I picked up the kid today. When I came back I noticed fuel dripping out of the hot air pipe (I drilled a small drain hole at the carb inlet to drain any extra fuel). So something is not right. Tomorrow the carb will come off again for a check over. I bumped the float hard when I pulled the bowl off. Maybe the float needs a tweek.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, July 26, 2012 - 02:54 pm:

It should not drip when parked even with the fuel valve on. Sounds like you have a float or float valve problem. Maybe too high float level, but more likely dirt in needle valve or a worn out needle and valve. It could also be caused by the float rubbing on the bowl if the hinge is bent to cause the float to go to one side. I think it is also related to the mixture needle. Too high float level will cause a problem with the mixture.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jason Given - St. Paul, MN on Thursday, July 26, 2012 - 04:24 pm:

I’m thinking the float is out of adjustment, the carb was rebuilt about 5K miles ago. When I had it apart I checked the needle and valve and they physically looked in good shape. It looked like there was dirt in the valve, so I cleaned it all

Too bad as she runs like a dream.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jason Given - St. Paul, MN on Monday, July 30, 2012 - 09:18 am:

I pulled the carb off, and went through it again. I found a bit of debris in with the needle valve. Who knows how it got there, after the initial cleaning. I adjusted the float a little from that hard knock it took when I pulled the bowl off the first time. No leaks!

Took her for a test drive; the kid and I went to downtown Minneapolis and drove around down there for a while. She drove really nicely. Still only 1 turn on the fuel air mix, acceleration is excellent, very smooth shifting, surprisingly extremely quite.

I am very happy, even had to drive her to work today, which I have not done in a month.


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