V-8 flathead problems

[BCA]

I'm getting an older restoration F15a running after it sat for a few years. I can get it to idle fine but there is no power above the low speed idle range. When I floor the pedal it just coughs and the only way to get it driving is to use very little gas pedal - obvious it won't go very fast. It gets worse as after about 15 minutes of 15-20 mph driving.
I have tried 2 carbs: the original and a rebuilt one. Same problems.
The spark is good (tried another coil just in case heat was a problem). I've changed the fuel pump (2-2.5 psi pressure) and also used an electric pump in line to be sure of good fuel delivery. Fuel is clean and fresh and lines are clear. Working the choke does not add to performance when trying to baby it along above 5mph.
My only guesses at this point are: bad ignition timing, spark break down at higher revs(divers helmet distributor, points look clean from what I can see with the 2 caps off - I have no idea about timing it) or high speed problems with both carburators. The rebuilt carb was professionally done and looks good. I looked for errant sparks along distributor wires when it was dark: no obvious shorting
Spark timing or Fuel? Any suggestions? .... Brian

[Lynn Eades]

BCA, I doubt it is the timing. Dwell is more important
Without being there it's not easy. Can you bypass your fuel suction line by running an alternative line to the pump?(incase you have an air leak)
Can you run a test on the fuel pump? Run a hose from the pump delivery to a tin, to see what volumn the pump delivers (the motor should run a bit on a carb full) I dont have specs, but should be a reasonable amount.
Does the accelerator pump work (carb) can you see it squirt the fuel down the carb?
The old coils and condensers are notorious for failing insulation. That includes NOS. In both cases, they deteriorate in storage.
I'd try a new (not nos) condenser. Anything you can hook up will do to try it for temporary.
I'd also try a direct feed to the coil (bypass the ignition switch and ignition resistor (not for too long)
It hasn't got a blocked exhaust has it?
See how you go.

[rob love]

Did the owner report that it was working OK prior to being parked? The symptoms you give are that of a bad camshaft or a timing gear out by one tooth. If all else fails you might want to check those items out. I just dealt with an engine that had both of those problems combined......either one is nearly fatal, yet this vehicle drove 70 miles out to me for repair. Add to that the timing was set at 50BTDC, and the vacuum advance was buggered.

Certainly work through the easy stuff, (the coil that Lynn mentions comes to mind) but if that doesn't work for you, you may have to pull the heads and get out the dial gauge.

[Yeo.NT]

I am not to familiar with the old ford V8s as of yet, so don't quote me on this. From a mechanical view I would say it could be your distributor, either the vacuum advance and or the mechanical advance.

The vacuum advance could be a vacuum leak, ripped diaphragm or or seized actuator. The mechanical advance could be the weights and/or springs are seized/broken/missing. No advance means the engine timing is set for idle RPM thus not letting you gain the speed or power through the different RPM range

[rob love]

The word "timing" seems to be the constant in this thread. Give the distributor/ignition the going over, then if that doesn't work you may have to go deeper.

[BCA]

Thanks for the input. I've eliminated fuel supply issues up to the carb (changed pumps, checked pumping pressure, added an inline electric pump). The coil is a fairly modern normal looking ignition coil (says 6V on it which may explain why the resistor has been by-passed - would too much voltage be a problem?). The wiring has been re-done and not exactly as original but ignition switch works fine and good power to coil.
I saw on a Ford forum that one problem may be with insufficient point gap: I just can't get up into the diver helmet distributor to check the gap etc. I can just barely see the one set of points with a mirror.
If I take off the distributor will I screw up the timing when putting it back on? I haven't been able to find any good information and photos on fooling with these distributors.
Oddly, right after making the post I went around the block with modest power, babying with the choke seemed to help a little bit. No idea if I tinkered with something that helped a bit.
... Brian

[BCA]

Lynn; I forgot to mention that exhaust system is solid and has no blockages. Also the accelerator pump worked fine for both carburators. When it is idling and I look down that carb throat I can see small but distinct drops of liquid fuel dripping slowly into the carb throat. I guess the fuel just hasn't vaporized yet or that this indicates a problem.
....... Brian

[Lynn Eades]

I based my suggestions on the statement that she has sat for a few years. If the distributor weights are seized, she would still rev with no load. The vacuum side doesn't really matter at this point either.
Things like cam timing, valve lobes, are not going to change. If she was a runner before, she should run again. If she idles, shes nearly there.

[rob love]

Originally Posted by BCA

Thanks for the input. I've eliminated fuel supply issues up to the carb (changed pumps, checked pumping pressure, added an inline electric pump). The coil is a fairly modern normal looking ignition coil (says 6V on it which may explain why the resistor has been by-passed - would too much voltage be a problem?). The wiring has been re-done and not exactly as original but ignition switch works fine and good power to coil.
I saw on a Ford forum that one problem may be with insufficient point gap: I just can't get up into the diver helmet distributor to check the gap etc. I can just barely see the one set of points with a mirror.
If I take off the distributor will I screw up the timing when putting it back on? I haven't been able to find any good information and photos on fooling with these distributors.
Oddly, right after making the post I went around the block with modest power, babying with the choke seemed to help a little bit. No idea if I tinkered with something that helped a bit.
... Brian

The timing is set inside the distributor by adjusting the plate that the points are mounted to. I used to just scribe the plate before removing it from the distributor.

Remove the entire distributor as a unit. It has been a while since I have done one, but I recall it was 4 5/16 bolts (1/2 socket size) and the distributor will come right out with the vacuum line and the wires removed.

MBF1, or any of the Ford CMP manuals will give you a good description on how to repair the distributor. Seems to me you used to have the timing fixtures in your inventory. They make setting the points and timing a breeze. Again, follow the steps in the manual. While you have the point plate out, that is when you check out the weights and the vacuum advance. Merely sucking on a tube you attach to the vacuum advance will easily indicate if it is working or not. Lightly oil the weights on their pivot points any time you are in a distributor.

No doubt about it....it is a tight fit removing the distributor. But once done right, you will not have to go into there again for many many years. If you find it too tight, remove the radiator....lots of room then.

[rob love]

Originally Posted by Lynn Eades

I based my suggestions on the statement that she has sat for a few years. If the distributor weights are seized, she would still rev with no load. The vacuum side doesn't really matter at this point either.
Things like cam timing, valve lobes, are not going to change. If she was a runner before, she should run again. If she idles, shes nearly there.

Agreed, but that is why I asked if it was running well before it was parked. We did not get an answer to that.

With today's modern oils, the old flat tappet engines can develop problems. The SM and SN rated oils are not meant for the flat tappet motors, but rather for the roller type lifters.

[charlie fitton]

too bad you don't know anyone who lives nearby that has a timing fixture - OH wait! - I do.....519 240 6001
f

[chris vickery]

Brian
I assume we are talking about my old 12 cab?
We both know she is a sweet runner, at least it was a few years ago.
Dad and I had to play with the distributor quite a bit back then to get it just right. The symptoms you mention sound familiar, due to the timing out of whack.
Pull the distributor out and reset the timing, making sure all is free as suggested and swap out the condensor as well with a new one.
The flatheads run like crap when the timing is out, especially when trying to accelerate as you describe.

[Tony Wheeler]

Originally Posted by BCA

I can get it to idle fine but there is no power above the low speed idle range. When I floor the pedal it just coughs and the only way to get it driving is to use very little gas pedal - obvious it won't go very fast. It gets worse as after about 15 minutes of 15-20 mph driving.

Based on my own experience Brian, it's a carby problem. I've struck these exact same symptoms several times when reviving long neglected Ford CMPs, in fact I've come to expect it! A good cleanout always gets them running properly, which leads me to suspect the problem is caused by blockage/obstruction of the main fuel supply passages. That would leave the motor nothing to run on but the idle fuel supply, which is only adequate up to around 1200-1500 rpm with very light throttle. You can sometimes suck a bit more fuel out by using choke, which increases vaccuum, but as the motor warms up it runs even worse on choke.

The question of course is how could your rebuilt carby be blocked? I can think of a couple of possibilities but the question is academic - the fact is you have NOT proved this carby, and you need to do so before looking elsewhere. The carby is the obvious culprit for these symptoms, which I think you already suspect, judging by your immediate replacement of it, and your attention to possible fuel starvation elsewhere.

As a first step you can simply remove it and blow compressed air into the main jets, by removing the main jet plugs (the two large slotted head brass plugs in the float chamber) and poking the air nozzle through. You can also backflow compressed air along the main fuel supply passages by poking the air nozzle into "G" Main Nozzle (see RH diagram). This is where you're seeing droplets emerging at idle, which is quite normal, but is NOT what the motor is running on at idle. It's a tiny insignificant amount of fuel, which will become a steady stream when the throttle is opened, and will be atomized by the greatly increased airflow. Unless of course there's a blockage!

This quick procedure has worked for me a couple of times with decent carbies, but more often than not I've had to deal with crusty old carbies full of rust flakes and scale and crap from years of running without a filter. Not to mention mud wasp nests after years outdoors with no air cleaner - that shit is harder than concrete! I don't know what the professionals do with these carbies, but no solvent known to man will get rid of that stuff, you need to completely disassemble them and thoroughly clear all fuel passages individually, which can only be done by poking bits of wire down them (preferably copper wire so as not to gouge them). That's what I do and so far it's worked like a charm every time, I don't even bother with a carby kit, just stick the old bits of gasket back on!

Anyway good luck Brian, and whatever the outcome it's worth getting to know the flathead carby, because it can save a lot of time and effort chasing non-existent timing problems in impossible to get at distributors!

[Tony Wheeler]

Any progress on the motor Brian? I'm interested to know where the fault turns out to be.

[BCA]

Thanks for all the responses. Chris, yes this was your Cab 12 F15A - getting dusted off after I got it from you in 2000 (!).
And Tony, I like your comments and they make sense. During this escapade I have changed fuel pumps, used an auxillery tank with fresh gas, checked fuel pump pressure and to day did a good flow test. With help from Stew Robertson we pulled the distributor and all looked good (no reason for the timing to have changed but points could have been bad or something). Two carbs have been tried. Two coils have been tried. No exhaust obstructions.: Still major lack of power over idle speed and no reaction when choke applied or accelerator pump activated. Spark always looked good from coil and at spark plugs. Couldn't see any errant sparking of the cables when it was dark outside.
So tonight I went for a test drive and it works great. Have no idea what solved the problem and I hope my luck continues. The only thing I can say is that tonight was cool, 65 degrees F versus 80 degrees F on previous days although there had been no reason to suspect a coil failing with high temperature. Maybe the rebuild carb just needed some exercise. .......... Brian

[Michael R.]

Ah yes, that wonderful rebuilt carburetor ... If the former carburetor is re-installed, do the lack of power issues return?

[BCA]

What do you think hold these parts in? Velcro? I wish it was so. I may revert to the original carb if only to eliminate other sources of the problem. If it works right off the bat then there is another unsolved problem.

[Lynn Eades]

Maybe all the squirrels hoardings blew out of the muffler? ( I saw a Canadian posted picture here once. We don't have them)