Hard to start when hot

[Rudolph]

Hello, I have been having hot start problems, seems to do it more when the weather is very hot, engine is a 1938 24 stud, has a bob drake rebuild kit in the fuel pump, I re kitted the carb not so long ago, it has a Pertronic ignition and corresponding coil, I had the same problem when I had the points in the distributor, the engine needs to be cranked over for a wile before it will fire but I found holding the throttle open it will fire up fairly quickly but it will want to die unless I keep the revs up but after a few seconds its fine, I took the top off the carb a few times and its always got a good amount of fuel in the carb bowl and there is no black smoke and its very economical, has a really good spark, its almost like its some kind of vapor lock, or is this just worn engine stuff? it docent use any oil but smokes out the breather, engine is in a 27 RPU with no bonnet temperature never goes over 170 in heavy traffic.

[grumppyoldman]

You didn't mention if it set for a while, that it would start right up. I was having that problem with my 41 and after I cleaned the connections on the Ballast resistor, no more problems. The resistor is under the dash above the steering column, on a fuse block. May be your problem also. Al

[Tinker]

It's hard to check ignition under idle. Try a condenser. I've had decent luck with ih200 from napa, buy a few. Not every is good out the box. There are other options also. Then maybe get a skip coil. Not a bad idea anyway.

[Angledrive]

I believe your carbs are dripping fuel into the intake when engine is off. By opening the throttle you are introducing more air and it is leaning the mixture so it ignites quicker.

[Tinker]

What kind of vacuum are you reading? Set carbs to vacuum.

[tubman]

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To expand on the above from "Angledrive", if you have a 94 model carb, the power valve may be leaking. To check this out, remove the carburetor top after it has been run. The fuel level should be high in the bowl. Put something (I use aluminum foil) over the top of the bowl and leave the top off overnight. Check the fuel level the next morning. If it is down substantially, you have a leaking power valve.

If you find this is the problem, you should replace the power valve. If you do, make sure you get the correct power valve. The power valves for the late model Holley 4 BBL's look almost identical to 94 power valves and will even screw into a 94. However, the seating of the power valve to the body is different and the later power valves will leak in the early carbs. If you get one from your FLAPS or the usual suspects (Summit or Jeg's) they will almost invariably be the wrong ones. Get them from Daytona Parts or someone similar. If you want to be sure. get one (or maybe even a complete rebuild) from "Charlie ny" on this board. You won't be sorry.

[Tinker]

Go to charlie or get some strombergs. Less to worry about.

[Rudolph]

yes ItÂ’s a 94 carb, I took the top off the carb 2 days after and it was still had a good amount of fuel, I have an electronic ignition, it has an internal ballist resistor in the coil,

I removed the plugs immediately after it wouldnÂ’t start and they were dry like it was getting no fuel.

I have never experienced vapor lock, is it creating a gas bubble in between the tank and pump or in the pump?

Because there is no big puff of black smoke when it starts, I guess I should spray some starter fluid into it next time it wonÂ’t go?

[Tinker]

If the bowls are full. It's getting gas supply i'd suspect. PV are designed to open under lower vacuum. It's not vapor lock I'd guess or never experienced.


Bubbles at the pump might be a air leak to the tank. So many things could be wrong really. If you have a full bowl you will have access to fuel. Might be a bad plunger. So much could go wrong.

Get some expert on the carb maybe. Some times some of the electronic stuff don't jive, but you said its the same points too.


I leave my cars sitting over winter 4 months and a few pumps and a choke pull they always start when gas hits the carb. Call charlie on the 94.

[deuce_roadster]

If there is fuel in the carb when it won't start it is either flooded or other reason. When you say it has a "good amount" can you be specific and measure down from the top edge of the bowl?. If fuel is not overflowing into the engine from the heat expanding it or too high of a float level, and it isn't flooded, then I would suspect a bad or loose connection on something in the ignition system, (primary wires, resistor, switch contact on steering column). You say good strong spark, is this during the time when it won't start? What is the compression like on the engine? If you have spark and not excessive gas it should run. As mentioned above, having the throttle wide open (like you do when flooded) helps I think that is a big clue. I once had a barely loose connection between the condenser and the distributor (crab) on a car act intermittently like that.

[Tinker]

It was mid year chandler-groves introduced 1938 the holley 94. Before that it was strombergs. So you okay.

[Rudolph]

On the wires from the ignition pick up to the coil are 2 bullet connectors, I will solder them together in case it’s those connections but I am pretty sure it’s fuel related as it did it with a 100% different ignition system,

It’s like it’s only running on the excellrator pump fuel when it 1st fires up

A lot of time time it will start as soon as you touch the starter, it will cold start pretty well to

[Tinker]

Cold start with a good volt meter you can learn a lot. Run it hot and test with a volt meter. But you have a electronic ignition. Not great advice. Shouldn't have a ballest between the perm and the coil wire to my understanding.

[Rudolph]

Originally Posted by Tinker

Cold start with a good volt meter you can learn a lot. Run it hot and test with a volt meter. But you have a electronic ignition. Not great advice. Shouldn't have a ballest between the perm and the coil wire to my understanding.

Coil has an internal ballest, I tried running another one before it aswell but had no spark

[Tinker]

Not sure you can run a ballast on electronic ignition. But I know nothing about that. Have fun!

[FlatheadTed]

Is the coil the same one that was used with the points ,did you check the spark when the engine was hot and failed to start ,

[Mart]

I agree with the post above re fuel dripping into the manifold.

That or any other of the reasons why a 94 wants to run rich.

I list them out in post no.4 in this thread.

https://fordbarn.com/forum/showthread.php?p=948285

There may be other reasons but all these have been experienced personally by me.

Mart.

[Rudolph]

As I sed befor every part in the ignition system has been changed when going to electronic and it still has the same problem, it dosnt allways do it.

I had a read of that other thread about how when you wind the mixture screws in the engine should start to die, mine will do that, main jets are tight.

I don’t even know if this carb is from a flathead?

[Rudolph]

Funny thing is it dosnt smell like fuel and the plugs are dry and there is no black smoke or any indication of flooding when it starts, it’s like it’s getting no fuel

[Old Redneck]

Check the firing order to make sure they are correct. I bought a 38 ford and drove it home and on the way home the car kept lousing power. I pulled over and the car did not want to turn over. I got a ride home to get my trailer and when I got back the car started right up. so my wife drove the car home and when we got home car did not want to turn over. [Problem was two spark plug wires were cross. I use a screwdriver to find the problem grounding out each cylinder out and two would not die down cross them and that worked. This was my problem then. Would check out?

[1931 flamingo]

You could try an elec fuel pump just to "prime" it before trying to start..............
Paul in CT

[Rudolph]

Took off my new bob drake distributor cap to find the NOS Champion rotor had collided with one of the contacts because the BOB drake cap is not the same size, also the brand new bob drake distributor rotor will not turn inside any crab distributor I have because its 2mm to long on the brass end, the bob drake cap and rotor together and you cannot even get the cap on.


Also the new bob drake distributor cap has 2 holes burnt in the side next to the contacts on opposite sides, button in the top has no burning

[Bill OH]

I had the same problem with a 38 24 stud with dual 97s. I run only in the warm weather. I blocked the heat riser with core plugs and installed about 5 gaskets under each carb, Problem solved.

[50fordcoupeman]

I had similar problem on two different engines.........turned out to be the coil on both even though one coil was brand new. Good luck!

[G.M.]

Originally Posted by 50fordcoupeman

I had similar problem on two different engines.........turned out to be the coil on both even though one coil was brand new. Good luck!

You found the root of the problem. ALL Old Ford coils including NOS
and ones sold new work great when cold. The problem is they ALL leak
voltage in the windings. The varnish on the wire and the paper between
layers of wire did not take the heat that the modern poly type coatings
and the treated paper made today by DuPont. Skip uses these modern
methods and materials and his coils don't fail and start under high heat
conditions. He has rebuilt over 25,000 old Ford coils over the past 25
years with very few failures and he replaced those few at no charge.
Along with the coil you need a good ignition switch and a good
condenser. We found an IH-200 condenser to work real good. The
contacts on the ignition switch are 3 little round balls that wipe on
the brass pads in the switch. Clean these pads with 600 sand paper on
flat surface so they are smooth. Stand the balls of the switch on 600
paper and put little flats on the bottoms of the balls so they make better
contact. Spring the balls down a little to get better contact with the
brass pads. A good original type resistor is best. G.M.

[Rudolph]

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I don’t know how I missed the bent rotor problem, I think removing the fan helped, i ser the advance to full now, engine starts at a flick of the key and makes a lot more power, I cannot get it to ping under load. Now that we are in lock down I cannot drive it. Bugger.

[Rudolph]

This was a few days before lock down https://youtu.be/hXxMxwFi7r4

[Tinker]

With modern fuel you won't get a ping, octane is to high (my opinion). Octane in the 40's is about 40-60. Gas is cheap, go do some burn outs, just don't hangout with people quite yet. Wear gloves at the pumps and take some precaution. Time will tell, but always good to be prepared.



.

[Rudolph]

Originally Posted by Tinker

With modern fuel you won't get a ping, octane is to high (my opinion). Octane in the 40's is about 40-60. Gas is cheap, go do some burn outs, just don't hangout with people quite yet. Wear gloves at the pumps and take some precaution. Time will tell, but always good to be prepared.



.

Yes, I run it on regular 91 and its happy, we are in total lock down and I would get set home or arrested if I went out in the Ford, it stands out too much.

[FlatheadTed]

With some electronic module's if the coil doesn't have enough resistance it will blow the coil and burn any plastic components

[Tinker]

Originally Posted by Rudolph

Yes, I run it on regular 91 and its happy, we are in total lock down and I would get set home or arrested if I went out in the Ford, it stands out too much.

I work from home for the last 18yrs. I'm used to be being "isolated". Started the 38 up today. Started up after a little bottle prime after a 4 month sleep. Sounded great. If it ever warms up here I'll take it for a cruise. Won't stop to hangout.

Some people can't help themselves. Went out on a drive in the f150 last week and saw a friend and stopped to say hello. 10 ft apart. He started creeping from 10ft to 5ft. Had to go.

Hope you get it figured out.

Have a little recore radiator issue showing up again. Might have a new issue to deal with. Might have to learn and prefect my brazing skills.




.

[Rudolph]

Originally Posted by FlatheadTed

With some electronic module's if the coil doesn't have enough resistance it will blow the coil and burn any plastic components

I was going to ask if you could put it on your mechine and set it up but it’s sorted now, it was just a bent rotor

[Rudolph]

Originally Posted by Tinker

I work from home for the last 18yrs. I'm used to be being "isolated". Started the 38 up today. Started up after a little bottle prime after a 4 month sleep. Sounded great. If it ever warms up here I'll take it for a cruise. Won't stop to hangout.

Some people can't help themselves. Went out on a drive in the f150 last week and saw a friend and stopped to say hello. 10 ft apart. He started creeping from 10ft to 5ft. Had to go.

Hope you get it figured out.

Have a little recore radiator issue showing up again. Might have a new issue to deal with. Might have to learn and prefect my brazing skills.
.

I am about 12 miles out on the coast from the town and work from home to, it’s not worrying me staying home and not seeing anybody but I am running out of grinding disks.

If you got caught having a social gathering here or caught driving for any other reason than going to get food you could get arrested



]

[FlatheadTed]

Yes I could do it if you road test it and it doesn't perform as you wish I could look at it Ted

Originally Posted by Rudolph

I was going to ask if you could put it on your mechine and set it up but it’s sorted now, it was just a bent rotor

[Rudolph]

Originally Posted by FlatheadTed

Yes I could do it if you road test it and it doesn't perform as you wish I could look at it Ted

It’s running very well now, I got a coil and module as a matched pair

[Rudolph]

I found the problem, was a worn out ignition switch, the weight of the keys swing on it caused it to misfire and when I was trying to start it it sometimes if I held the Jew to the left wile cranking it wouldn’t go, put a new ignition switch in and it starts easy, I don’t have to grind on the starter at all anymore when it’s hot.

[Aarongriffey]

I had one like that. Turned out to be gas dripping into the manifold.
Took a few seconds of cranking over when it was hot with pedal floored.
When it started I didn’t see a cloud. Did find ver short crack in the carb float bowl.
A different carb cured it.

[Veeder]

Make sure your gas tank cap is venting

[Kpar]

I had the same issue with my 33 tried everything no luck.
If I opened the throttle a bit it would fire up a bit rich though.
I lowered the float (single Carby) below what was recommended by 1mm.
End of issue it now starts up hot or cold on the first revolution.
Kpar

[JayChicago]

Sorry, posted on wrong thread.

[JayChicago]

Ditto

[Mart]

I just went through two carbs and paid particular attention to the seating of the power valve, the mating of the body and throttle plate and the needle valve and seat and float.
I test ran them on an engine and found no problems starting when hot.
As stated, an over rich condition requires that the throttle be held open while cranking to achieve a fireable mixture.
Thanks for the mention above.