Warm start

[Lenny Bruce]

Lately my 30 Tudor has been starting a hit hard after it warms up.
Starts right up when cold. If I go to the store for gas or groceries it starts hard.
Getting plenty of gas. Any ideas why this may happen?

[Ernie Vitucci]

Good Afternoon...Prehaps clean your points and check to see if the condensor might be getting near the end of its life. Same with the coil...They begin to fail when hot...but work when cold...then nothing! Also...All connections clean and tight...Ernie in Arizonba

[nkaminar]

It may also be that the carburetor is leaking a little and the evaporated gasoline makes the mixture rich when you first try to start it when warm. Open the throttle wide to see it that helps. Just be quick to shut the throttle down when it starts.

[Marshall V. Daut]

By your words "starts hard", do you mean the engine turns over more slowly once the engine is warmed up, or do you mean the engine spins over as usual, but it fails to catch and start? Two different paths to follow in answering your question, depending upon your answer.
If the engine turns over slower when warmed up - making it harder to get started - the starter may be weak or the armature's commutator brass plates are dirty, or maybe the brushes are worn. Also check your grounding to the center cross member. There may be rust or oxidation between the ground strap tip and the center cross member. A six-volt system needs every bit of a good ground it can get to function properly. If the ground is compromised, the starter will have to work harder because of increased resistance. That translates to turning over slower.
If the engine turns over as usual when warmed up - but is hard to start - follow the suggestions given already. Be sure NOT to choke the engine when starting a warmed-up Model A engine. That will cause hard starting for sure. Just pull the hand throttle down a couple notches, press the starter button and let the engine start itself without additional gas poured into it via choking the carburetor.
Marshall

[Lenny Bruce]

The motor turns over as it should when warm it just won’t fire. I will surely check off all the boxes as you all recommended. Last time it did it I opened the throttle all the way and it did start. I will look into it further. Thank you all ….

[Marshall V. Daut]

Sponsored Links (Register now to hide all advertisements)

I once owned a '64 Corvette that refused to start when warmed up. In fact, Zora-Arkus Duntov was my passenger at a Corvette function in 1979 and the &^%# thing wouldn't start with the "Father of the Corvette" sitting next to me! Something had to be done. I sold the car the next day.
Well, that's neither here nor there. The point is, previously this had been a problem that confounded me. I had changed starters, wiring harnesses, carbs, condensers, ignition switches, etc. ad nauseum. $$$$$$$$$$$ The engine was still hard to start after shutting down unless I allowed it to cool back down. 'Turns out the problem was the coil all along. For some reason, when it got hot, it wouldn't deliver the necessary spark to start the engine. But if I waited a half hour or so, the engine fired up and ran without any problem, even though the coil must have been warm while driving. I finally changed coils (many dollars later) and that solved the problem. Too late too smart.
You might try temporarily hooking up a known good six-volt coil and see if that helps. Also, Ernie makes a good point about the condenser. They fail in multiple ways: gradually, suddenly or intermittently. They'll operate fine and then all of a sudden start misfiring. Then they work fine again on their own. Or they suddenly die and won't fire at all. Sometimes they even die overnight just sitting. Model A condensers are strange animals, to be sure. Always carry a spare condenser in your Model A because you just never know what they'll do. After trying a new coil and no change, swap condensers just for grins and giggles.
One more thing to check - and I've posted this story before about what happened to my 1928 Roadster on the German Autobahn in 1974. I won't reprint it here yet again, but I'll cut to the chase. Same scenario: when the engine warmed up and was shut off, it wouldn't start again until the car had sat for a while and cooled down. It was misfiring, too. The problem turned out to be a defective off-shore terminal box. The two stud heads were too big to fit inside their bores on the backside of the box, so just enough of the heads stuck out to arc against the heated firewall, which had expanded. This shorted out the ignition. Once the firewall had cooled down and contracted away from the bolt heads, the engine fired right up. When I removed the terminal box, I could see black splotches on the firewall where the bolt heads had been arcing. You might try loosening the four little bolts that secure the terminal box to the firewall enough to pull the unit out a bit. Shove a piece of cardboard between the terminal box and the firewall to keep it there. See if that makes any difference. If your car was restored in the 1970's or 1980's with the poor quality parts available then, you might have one of these sloppily-made terminal boxes. I have since fixed at least two other Model A's that had the same problem and the same off-shore 1970's terminal boxes. Rick's Antique Auto sold a ton of them and they're still out there somewhere. Maybe in YOUR garage?
Marshall

[Jim Brierley]

Try turning the fuel valve off and letting some of the fuel in the carb be used before shutting it off. If you shut the valve off before entering the store's parking lot works well.

[Y-Blockhead]

Originally Posted by Jim Brierley

Try turning the fuel valve off and letting some of the fuel in the carb be used before shutting it off. If you shut the valve off before entering the store's parking lot works well.

I do exactly what Jim suggests. Ever an issue starting.

[Marshall V. Daut]

"Try turning the fuel valve off and letting some of the fuel in the carb be used before shutting it off. If you shut the valve off before entering the store's parking lot works well."

If that solves the problem, then there is something wrong, loose or missing inside the carb itself, possibly a float adjustment issue. A float adjustment or tightening a loose jet would be the best of all possible worlds.
Check the tip of the cap jet. If its tip is bulbous shaped (rounded like a bullet tip), it's the wrong jet and fuel will dribble out of it after the engine has been turned off, which may be the cause of the hard starting after the car has been driven and the engine is warm. It wouldn't be a problem when the engine is cold because any excess fuel that would have dribbled out overnight (or after allowing the car to sit for a while) would have dissipated by morning so that then engine starts easily when cold. Some vendors' carb "rebuild" kits have this incorrect bulbous cap jet, probably from some tractor carburetor. Do NOT trust the jets supplied with rebuild kits! In many cases they were only tossed into the package because they fit inside the Model A carb, paying zero attention to tip size and shape, length and flow rates.
Marshall

[nkaminar]

Jim's suggestion is a good one. I have done that with my car before installing a new float valve.

[Big hammer]

Driving with the GAV closed or almost causes a lean mixture making it run hotter, try opening the GAV when your driving in town at lower speeds. Late timing can cause your engine to run hotter, clean and gap the points and adjust the hand lever according. When the weather is hot and I’ve been driving after stopping it will sometimes be harder to start, I’ll pull the choke for a few cranks and then it starts. I’ve thought is this vapor locking? closing the shut off gas valve and letting it run the gas out may help because no gas in the carburetor it can’t vapor lock ? With my riding lawnmower after it’s warmed and shut off, I have to choke it to start right up or I’ll have to crank it a lot before starting.
I would clean and gap the points, as the points follower ( rub strip ) wear down the point gap closes, which will cause the timing to be a little later, later timing will cause hotter running which may cause your harder starting when warm.