Flathead 239 still hard to start after much work...

[3twinridges]

Originally Posted by Flathead Fever

I had a hard time finding a picture of one with the adjustment knob. I guess that's old school. They are almost all digital now. Mine is a Sun adjustable timing light with the knob on the back. Here are some photos of a Craftsman one. Since our fleet was a licensed smog test and repair station the State had a list of mandatory tools we had to have. One tool was an adjustable timing light for checking total advance.

Say your timing is 4 degrees at idle on your flathead which you verify with your timing light. When the knob is set to zero the timing light works like any other timing light. You just need to remember to always set the knob back to zero hen checking the initial timing, or you will get the wrong reading. Then you raise the rpm and you will see the liming mark move away from the pointer as the timing light shows it advancing on the pulley. When you see it at its most advanced spot you rotate that knob until it brings the timing mark back in line with the pointer (were still at that elevated rpm). Rotating the knob offsets when the light flashes in degrees. By reading how many degrees you rotated the knob to bring that 4-degree mark back in-line with the pointer, plus the 4 degrees initial timing, you will know your total advance. I don't know how accurate it is compared to a distributor machine, but I bet its close.

We used it to independently check the degrees of mechanical advance the centrifugal weights made by raising the rpm, with the vacuum advance disconnected. Then at idle, when the weights were not working, we applied a handheld vacuum pump to the vacuum advance and checked its amount of advance. Then you raise the rpm with a vacuum gauge on the hose to the advance unit and make sure the vacuum advance is getting the correct vacuum signal. Many of those units are adjustable using an allen wrench through the vacuum hose hole so you can dial it in exactly to the factory specs. Same with changing the springs on the weights. You can make the advance come on sooner or later using weaker or stronger springs. Using a tachometer and that adjustable timing light you can tell how much advance at what rpm you are getting. I wish I could have found a video showing one in use and then it would made more sense.

Thank you sir, appreciate the time/response, going to get one of those lights. To the original poster, sorry to hijack your post.

JB

[rjlester]

I'm happy to announce, its FIXED!!!. I found the vacuum leak. I can start it with just a slight touch of the gas pedal, and it fires instantly. Every time. No more pumping the gas/feathering the throttle. No more idle speed increase with my hand cupping over the carb.

I knew the vacuum leak had to be INSIDE the carburetor, because when I poured the Marvel Mystery Oil in it, it would cover the throttle plates and keep running slowly until it all got past the plates. I couldn't stall the engine, it just slowly idled along until it "drank" it all down.

Tore the carb apart, and noticed the small o-ring type gaskets were so flattened where the transfer tubes (can't remember the official name) meet the carb body, one of them was open, and the neighboring one was crushed less than paper thin. Last time I tore the carb apart those little gaskets were very flat, but a complete circle. Made some new ones for now (until the rebuild kit comes in) and it starts up WAYYY better.

Now, I have the idle screw almost all the way out, the timing is dead on the timing mark (I checked the vacuum advance with my timing light, and it works now). It idles nice and slow. The idle screw was so far in before that I think the advance was always on, and showing the timing was advanced too far at an idle. I can also put it in Drive or Reverse, and it doesn't stall!

Super happy, now I can move the car in and out of the garage and work on it whenever I have time. I appreciate everyones input on this problem!

I was beginning to doubt my skills, but this definitely was a strange problem and tough to figure out.

Going for a drive after supper, will see how it does around the block now.

Again, thanks guys!!! Sorry for the long posts!

[AKCJ]

Good to hear you found it. Thanks for posting.

[rjlester]

Just drove it.

More power, an acceptable level of power. Was really gutless before.

Sometimes will start without touching gas pedal, most times just stab it once to the floor and it fires.

Compression test hot starting at number one: 100,110,110,100,115,120,100,105

When I started they were all 65psi and under.

Going to spend tomorrow with family and then Monday play with it some more.

Happy Easter guys!

[Eagle43]

Thanks for sharing. I had exactly the same problem and solved the same issue today with my Vermillion 1952 F1.

[rjlester]

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Originally Posted by Eagle43

Thanks for sharing. I had exactly the same problem and solved the same issue today with my Vermillion 1952 F1.

Thanks Eagle43. I see you are from Edmonton, I live near Stony Plain! Small world.

[Flathead Fever]

I had mentioned I did not think a vacuum leak would cause hard starting. That's the downside to commenting on these things. You get proven wrong sometimes. I hadn't thought about one inside the carb. I I've even seen that happen, but then I didn't work on early Ford carbs at work. I was thinking more of a leak around the carb base or the throttle shaft and propane would have found that immediately. It must have lowered the vacuum signal inside the carb to where it wasn't pulling fuel through the idle ports. It still should have started on the accelerate pump squirts and then idled like crap. We used to always had to take those ASE and smog inspection update tests. I always thought wouldn't it be great if the answer to the problem was only A,B, C, or D. In the real world there can be endless reasons for a problem. Good job on finding the problem.

[Flathead Fever]

Originally Posted by 3twinridges

Thank you sir, appreciate the time/response, going to get one of those lights. To the original poster, sorry to hijack your post.

JB

Don't get one like mine get a modern digital one that also displays the dwell and rpm. You would have everything you need to check the ignition in one timing light.

[rjlester]

Originally Posted by 3twinridges

Thank you sir, appreciate the time/response, going to get one of those lights. To the original poster, sorry to hijack your post.

JB

Not a problem at all! There is a lot of good info in this discussion that hopefully will help others.

[rjlester]

Originally Posted by Flathead Fever

I had mentioned I did not think a vacuum leak would cause hard starting. That's the downside to commenting on these things. You get proven wrong sometimes. I hadn't thought about one inside the carb. I I've even seen that happen, but then I didn't work on early Ford carbs at work. I was thinking more of a leak around the carb base or the throttle shaft and propane would have found that immediately. It must have lowered the vacuum signal inside the carb to where it wasn't pulling fuel through the idle ports. It still should have started on the accelerate pump squirts and then idled like crap. We used to always had to take those ASE and smog inspection update tests. I always thought wouldn't it be great if the answer to the problem was only A,B, C, or D. In the real world there can be endless reasons for a problem. Good job on finding the problem.

Thanks. I totally know what you mean about where vacuum leaks are traditionally vs inside the carb. If I didn't drown the carb with MMO, pretty much filling the venturi above the throttle plates yet the engine still idled, I never would have figured it out until I tried another working carb.

I still think it should start warm without touching the gas, but once I get a rebuild kit I hope that makes a difference. The Holley Teapot carb on my other car is a work of art. When I got that car, it was parked in a garage since 1966. Once I freed up the engine (dry seized) I put a fuel line on it and it ran great. Drove it around and months later even though it ran great I finally rebuilt that carb just for fun. It was full of gunk and rust, but operated perfectly. Cleaning it out didn't make it run any different but after that experience I became of big fan of that carb. I can bump the key on that car and it idles immediately. That impresses people.

[dean333]

Great discussion, thanks. As a matter of practice, whenever I get a new flattie the first thing I do is send the carb and fuel pump to Charlie, AND the coil to Skip Haney. No matter how good the car is running.

[BUBBAS IGNITION]

Originally Posted by rockfla

The fact that your Idle mixture screws are not effecting the idle as you back them back out is concerning.......BITE the bullet, box your carburetor up and send it to CharlieNY (Charlie Schwindler). This way you will KNOW with 100% certainty that is is working 100% properly and can eliminate that from the "cause" list of possibilities. After about 4 turns from bottom the idle screws "SHOULD" start effecting the idle again from bottom!!!!


Charlie Schwindler
5845 Cole Road
Orchard Park NY 14127
(716) 440-8952

I second send to charlie

[a4t6v8]

Hi have you checked for a blocked exhaust system