Starting Difficulty

[sport coupe newbie]

Hi there. I am completely new to Model A's and need some help. We have just finished restoring a 30 Sport Coupe, including motor rebuild and new replacement Zenith Repro Carb. When it was first started, the motor started right up and idled very smoothly. Ran for about 20 minutes. Shut off and immediately restarted fine. A short while later, the car struggled starting. Would start to fire and struggle running over a few seconds. When finally got it started close to 10 minutes later, it ran super rough (not firing on all cylinders). With throttle applied, back fired numerous times through carb. After a few minutes it completely smoothed out and idled perfect again. I let it sit for two days and tried to restart. Pulled choke and it immediatly fired, but stumbled again like previous day. When finally got it running it ran super rough again, backfiring and appeared to drip some excess gas out of carb. 5 minues later it smoothed out completely like a flip of a switch. Acts like I am flooding out a cyliner or two. What am I missing that must be obvious? I just have zero experience but want to learn.

[SeaSlugs]

you HAVE re-torqued the head bolts now its had a hot cold cycle right?

[old ford fan]

When starting, did you turn the GAV counterclockwise 1/2 to 1 turn and close it back to about 1/4 turn open when started? Try that first. It also sounds like there might be a sticky intake valve. Perhaps one of the engine guys can chime in and shed more light. You said you just finished restoring....so the car has probably been sitting some time without fresh fuel in the tank. Is it possible you might have debris/rust coming from the gas tank?

[Tom Wesenberg]

Take the new carb apart and blow out all passages. Something may have been left from machining or something may have gotten in from the tank and lines.

[Chuck Sea/Tac]

Moisture in the distributor? Are you in a high humidity area? as mentioned sticky valves, use mmo. Head gasket leaking water into the cylinder, or crack. ( usually water will end up in the oil with this problem).

[sport coupe newbie]

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Great replies. I will review each one. I have re torqued head bolts. Put in new gas and filter looks clean. I did have seepage around head gasket but did not see anything in oil. Re torqued and put some premium stop leak in and seepage is gone. Thx for any ideas.

[jg61hawk]

I'm less than a year into having an A so far be it from me to suggest anything too substantial but from my own experience are you remembering to set the timing handle up each time you start it even when warm?

[Sparky]

No one has suggested checking the ignition points yet. They may have closed up and that could cause some of your symptoms. The standard gap is .020"

[sport coupe newbie]

I am starting with the timing full upward. The first time couple of times I started it it ran excellent and idled fine. AS month later and it would barely fire and was not getting any gas in the carb bowl. It was a no-name replacement carb so I put a new zenith on it. It started right up cold that time and idled great for 15 minutes. I shut it down and restarted it fine. The next few times it acted like 1-2 cylinders were loading up and ran very rough with popping in the carb and exhaust. It eventually goes away and idles fine and sounds great. Last time it did that cold and took 3-5 minutes, dripped some gas out of the carb and then the sound completely changed and ideled great. Seems like points would not get better, Could it be as simple as idle mixture is way off? It is a new cap and rotor. Car is in cool basement/garage in upstate ny.

[1931 flamingo]

"new Zenith" Are we talking a fork lift carb or a new zenith?? Where did you get the carb?? Have you tried adj it?? Do you have good fuel flow at the carb??
Paul in CT

[Mitch//pa]

you have alot going on since the car is a new rebuild with many changed parts...
i would hook up a spark tester to make sure your not having an issue on the electrical side.... i look for a steady intensity and rythmetic flash. if the spark flutters or dims when the problem occurs you need to refocus on this area

[Tom Wesenberg]

Could you be running the engine for too short a time and loading the plugs? I don't like to start any gas engine unless it's run long enough to fully warm the oil and burn off moisture. This would be 30 minutes or longer for car engines in the summer.

[Bruskie]

sounds like its loading up with fuel after shutdown

[sport coupe newbie]

I purchased the carb from a local A parts distributor. New repro. I will look into spark. I want to get some help tomorrow so I can go out and short each plug while it is running rough to see if I can easily see what is not firing. Will need to inquire on spark tester. Just seems like it is fuel related, because it has run fine both stone cold and hot at differing times. Should I be shutting fuel off when shutting down? Hate to ask these basic questions but I am finding my way through the dark on this car. Trying to get it on road for my 90 year old father to enjoy.

[Mitch//pa]

alot of driveabilty issues can act like fuel but its spark and visa versa... you need to diagnose which area is at fault first. i had a carb running to rich and by removing the vacuum line for the wiper off the manifold that let more air in to compensate for the rich mixture and it ran great...

[1crosscut]

Open up the distributor and pull the lower plate. Check to make sure the flexible wire under the lower plate is in good condition. One of my club members had issues similar to what you are experiencing and replacing the wire cured it. While you are there make sure the point gap is set correctly.

[Mitch//pa]

Originally Posted by 1crosscut

Open up the distributor and pull the lower plate. Check to make sure the flexible wire under the lower plate is in good condition. One of my club members had issues similar to what you are experiencing and replacing the wire cured it. While you are there make sure the point gap is set correctly.

exactly
a spark tester will point this out
a bad plate wire will cause the spark to flutter and be intermittent

[Tom Wesenberg]

I shut the fuel off about 30 seconds before I turn off the ignition. My valve doesn't leak, so if I would forget to shut off the fuel it still wouldn't matter. If a hot restart is the problem, then the fuel could be boiling in the carb, so turning the gas off a minute or two before the ignition might be worth a try.

[sport coupe newbie]

I'll try shutting the fuel off and see if that helps the cold start. Should be pretty quick to verify. Also sounds liek checking spark as a starting point is well worth it. I don't have a tester but they look pretty basic at local parts store. Any suggestions on brand or type? Next I' try point gap and review the cable. I assume the spark tester would cover a cable issue too but I'll look.

[Mitch//pa]

Harbor freight has them but they are hard to see and crappy..
I like the ones I get from the snap on truck
but it looks the same as this one
http://www.amazon.com/Lisle-20610-In.../dp/B0002STSC6
i would go with this
put it between the cap and coil wire first