missing or stumbling on acceleration

Well blew out both carbs and they were clean. Changed plugs-more autolites, hooked everything up and she fired up on the second round. Let’s hope it was just the plugs fouling.

Mike
 
1930artdeco said:
Well blew out both carbs and they were clean. Changed plugs-more autolites, hooked everything up and she fired up on the second round. Let’s hope it was just the plugs fouling.

Mike
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Did you road test it yet? I don't recall you mentioning any problems with start or idle in your OP. Can't beat the 3X plugs with a stick. Hope you got it fixed.

John
 
Thanks, me too. I haven’t had a chance to road test her yet. I will have to do that tomorrow when I get home from the base.

Mike
 
1930artdeco said:
Thanks, me too. I haven’t had a chance to road test her yet. I will have to do that tomorrow when I get home from the base.

Mike
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Just curious as to what Auto lite plug you are using and does it have the same reach? Those 3X's are pretty steep price wise.

John
 
1930artdeco said:
Well blew out both carbs and they were clean. Changed plugs-more autolites, hooked everything up and she fired up on the second round. Let’s hope it was just the plugs fouling.

Mike
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Both carbs !? That's the problem, one too many carbs! LOL Enjoy your test drive to day Model A Day!!
 
Gene F said:
Really? The 3X plugs are that great?
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In my experience the 3X's have been the best, I can't speak for every one. I have always been a believer in that you get what you pay for. I never had a problem with a 3X and have had problems with modern (maybe made in China) Champion and Autolites.

John
 
Well went for a test drive and no hiccups. Although she started to pop in decel and ran a bit rough. So I will change out the condenser and ask her idle and I should be good to go!

Thanks everyone,

Mike
 
1930artdeco said:
Well went for a test drive and no hiccups. Although she started to pop in decel and ran a bit rough. So I will change out the condenser and ask her idle and I should be good to go!

Thanks everyone,

Mike
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Good idea, easiest way to test is to disconnect existing condenser and connect new one to + coil terminal, alligator clip other side to engine. Crappy Chinese condensers causing a lot of problems. Hard to believe they fail but they do.
 
It can be easy to damage a sparkler and not realize it. The porcelain can crack pretty easy and cause an intermittent misfire.
 
1930artdeco said:
Well went for a test drive and no hiccups. Although she started to pop in decel and ran a bit rough. So I will change out the condenser and ask her idle and I should be good to go!

Thanks everyone,

Mike
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In decel. if it was rapid you may be back in the idle circuit. Turn Idle mixture adjusting needle in 1/4 turn at a time. Same goes if you start from idle and try to accelerate. For the aircraft people remember that in is to enrichen and out to lean on a Model A, bass ackwards from an airplane.

John
 
1930artdeco said:
Hi Folks,

This one has me baffled-not that that is hard to do sometimes. Here are the symptoms. Upon acceleration in 1stgear she is fine, move to second she is fine 90% of the time, third gear and she stumbles, misses and stumbles an coughs but she still accelerates. Then when she hits about 40-45 all is well and she cruise just fine.

What I have done: I opened up the GAV-no change, Altered the spark-no change, cleaned the plugs, changed the carb-all no change. No I am running the 3X plugs and #1 just started leaking oil out of the gasket area between the base and small part of the plug-not sure what to call it. Some sooting of the base but the ceramic was clean albeit dark grey/black. The dist. body had all of the electrical arcing evidence on the bottom half of the steel studs. Here temp is around 180 at the top and 170 at the bottom of the radiator.

Theories: coil going bad when under a load? maybe the condenser-I did change that awhile back and no real difference. I am going to change plugs this week to see what happens.

Thanks,

Mike
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I know this is from several years ago, but did you figure out the problem? I’m working on getting my father’s 31 coupe back up and running and I have the exact same symptoms. It’s not the carburetor. I’ve cleaned all the jets and passage ways and used flow tested jets and also original gets that I cleaned, in addition to multiple space carburetors that he had. It starts and idles fine, it cruises down the road fine but anything but light acceleration and low rpm it stumbles. I also think I eliminated any vacuum leaks. The points seem to be in good shape. Maybe try replacing the condenser next?
 
Check the cam timing by observing the valves at TDC on #4 cyclinder with the distributor rotor pointing to #1 cyclinder. (Or visa versa.) Both valves should be up a small amount. And the piston should be at the very top. You can check that the piston is at the top by rocking the engine a small amount back and forth and observing the piston. It should not move or move very little.
 
Good Afternoon...I have had similar problems from time to time and more than once I found a cracked distributor body! Best to check just as it is getting dark or in the garage with the door up. Just my own experience...Ernie in Arizona
 
Verify that your carburetor (Zenith or Tilitson) fuel level is 5/8" below the gasket. Shim the shut off valve to adjust the level - donot bend the float. It sounds as though the fuel flow is marginal due to float level setting. Opening the GAV will not solve this problem.
 
Thanks guys. I’ll verify the timing, even though I’m not sure how it would suddenly come out of time, the fuel bowl level (I just went with the eyeballing level method) and the condition of the distributor. I appreciate the suggestions! It ran beautifully till a few months ago.

Also, I can’t respond to private messages until I have ten posts. I appreciate the PM advice too.
 
I miss understood. If this is a change from running well then, yes, very unlikely the valve timing changed.
 
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