Model A starting issue

U

Upstate gearhead

Junior Member
I'm trying to rebuild a '28 that has been sitting a long time. I rebuilt the Tillotson square bowl carburetor. I had to take .030 off the top float flange to get it flat. I adjusted the float so that I just got gas pouring out, then lowered it 1/32. The only way I can get the engine to fire is to advance the gas rod 13 notches. Timing is 2 degrees past TDC. Choke is 2 turns out. Idle screw 2 turns out. What do I need to adjust to get this to run right?
Thanks for your help.
 
If you have a carburetor from another engine you know is good, try that. When timing the engine, set the spark lever to full retard, all the way up, and turn the engine over until your timing pin slips into the hole in the timing gear. Set points to just open at that position, taking the slack out of the distributer drive gears. Rotor should be in the 4 o'clock position looking at it from the passenger side of car.
 
Why!

Get a new carburetor. I know there are owners who are going to really disagree, but why bother with an after market product that was a cheap replacement to start with. I would get a new or rebuilt Zenith, end of story, move on to other issues.

If they were better carburetors, someone would be reproducing them.

Enjoy.
 
OK reset the timing per Mike. I reset the idle screw to 1 turn and was able to get it to fire occasionally with the gas rod up all the way, so some progress. If I put my hand over the carburetor air intake, it will fire which makes me think there is an air leak. I know this is dangerous to say, but I'm confident that the intake to block and carb to intake manifold connections are not leaking. Where else might there be an air leak and how would I test for it? Need to let the battery recharge.
 
Pull choke and turn GAV. The Tillotson is basic and most need some warpage work due to the soft characteristics of the zinc die casting. If you have to choke it down for it to fire then it is too lean. You may have a port that is blocked in the carb. The idle port circuit & GAV port circuit have to be open to pass gas.

Renners Corner has a neat idea for adjusting floats. He make level gauges for most model A type units.
 
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Good info above.

1.Inside of carburetor [ all passages] must be clean.
2.GAV/choke turned out from lightly seated 1 turn
3.Idle fuel mixture screw out 1.5 turns from lightly seated. Screw adjusts air, not fuel.
4.Idle speed screw, remove linkage, adjust screw until it makes contact and shaft
starts to open a bit. Attach linkage
5. To start. left lever/spark up. Right lever/throttle down several clicks
6. Key on. press starter button while pulling out on choke/GAV rod for 1 or 2 revolutions.
 
The idle circuit in the top portion of the body may need to have carb cleaner sprayed through to make sure that the throttle plate bleeds are passing mixture. Some kits come with the little welsh plug that seals the drillings for the bleeds into the throat. I would only pull it out if fluid won't pass through the bleeds but that's the only way to clean them in some cases. If a person takes a good bit of metal off the sealing surface of the top, the float level may be lowered further into the bowl. Adjusting the float level can be done with one of the fluid check gauges that attaches to the bottom of the carb. I haven't had to use one yet but sometimes it needs to be done. I only mention this because I'm not sure how you adjusted the float level. The bowl level has to be even with the emulsion tube level for proper atomization. It doesn't sound like it's running rich but first you have to get it to idle and run correctly to see how everything works through the whole range and in turns.
 
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WHN said:
Why!

Get a new carburetor. I know there are owners who are going to really disagree, but why bother with an after market product that was a cheap replacement to start with. I would get a new or rebuilt Zenith, end of story, move on to other issues.

If they were better carburetors, someone would be reproducing them.

Enjoy.
Click to expand...

Agree.
 
I bought a professionally rebuilt Tillotson for my car and it worked great straight out of the box. The rebuilder tested it on his car before sending it to me. It was already adjusted correctly.
 
Properly set up/rebuilt carburetors really make a difference. I din't want to ' un-warp ' the only Tilly I had laying around so I bought a ' professionally ' rebuilt one. It was a lurcher so I took it off and threw it in the corner and stuck on a good old Zenith. I needed something to do so I found that Tilly and took it apart and put it back together after playing with it. No more lurching. These are very simple carburetors but they still have to set up correctly.
 
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