Flat head back firing pop. pop over and over

[jtminor]

Drove my F1 1951 home after I purchased it. Back fired all the way home.
Had to choke it most of the way home...

What do you guys think...?

[Brian]

Stuck valve[s]

[Tim Ayers]

Check the spark plugs. Carbon fouled spark plugs can cause these symptoms. If not the spark plugs, could be valves. Run some SeaFoam in the gas and squirt some Marvel Mystery Oil in the spark plug holes to hopefully free them up.

[Terry,OH]

A compression test may point to the bad cylinder.

[corvette8n]

Had a similar experience, the shaft on the distributor was bent, CharlieNY rebuilt it for me, now it run fine.

[flatford8]

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Check the firing order......Mark

[chap52]

I once installed my dist. 180 degrees out. A learning experience... I would check plugs, plug wires, timing and timing order. Remember proper cyl. order, odd on passenger side, even on drivers. (I am working from an old memory...lol) Chap

[Seth Swoboda]

If the choke cleared it out, that would indicate a lean situation. I wonder if you have a vacuum leak or a valve(s) that stick. We might need more information.

How well does it idle?
Does pulling the choke out clear up the situation?

[marko39]

Originally Posted by chap52

I once installed my dist. 180 degrees out. A learning experience... I would check plugs, plug wires, timing and timing order. Remember proper cyl. order, odd on passenger side, even on drivers. (I am working from an old memory...lol) Chap

Firing order is starting from front 1-4 on right bank 5-8 on left with right side being pass. side on lhd vehicles.

[jeepguy1948]

The chance that this is the problem is slim but nonetheless I will share it. I was recently asked to sort out a very similar problem on a ‘51 F-1 V8. In the end I found that the owner had installed a new gas cap and it was not venting. A huge vacuum was created and eventually it started to starve for fuel. I would agree with Seth, if the choke cleared it up then clearly a lean fuel issue is the culprit. It could be the carb itself. Is your engine a V8 or the 6. If it’s a V8 and it still has the stock original Holley 94, well, I don’t care for those carbs. The power valve can fail (I don’t know if they have rectified it but for awhile Speedway was selling a rebuild kit that had a bad power valve in it). If the motor has the original ignition it definitely can be a problem, it’s vacuum advance only (no centrifical advance at all) I believe Ford called it the Load-A-Matic. If there is a vacuum leak then you wont get spark advance, it could be the diaphragm on the distributor itself leaking. Many old car guys are too young to remember a points type distributor and the cam in the distributor goes dry and grinds down the rubbing block on the points so that you get more and more dwell, the coil does not build up enough of a charge. That truck has positive ground and I have found many times that the coil is not wired properly. The + terminal on the coil should go to the distributor on positive ground. Let us know how it turns out.

[jeepguy1948]

I realize that I said it had to be a fuel issue but there are a few exceptions. If there is weak spark such as from a bad coil, or reverse wired coil, too small of points gap, then enriching the fuel mixture can help because a spark plug can fire a richer mixture if the spark is weak.

[chap52]

Thanks Marko...Chap

[TJ]

A bad condenser can cause a similar problem.

[pistonbroke]

Years ago my dad gave me a 72 f100 that had been setting for a few years. I had the same issues . Water in the gas was all it was. Tim

[Flathead Fever]

My dads '32 roadster sat for probably ten-years without being started. It ran fine when he parked it. He finally passed away and I hauled the roaster home. I found a plugged metal fuel line and the tank was full of junk, I gave it a one-gallon external can of gas and it started up. It started but an intake valve had stuck open (still is stuck). It's spitting back through the carb and disrupting the flow to all the cylinders; I haven't done a thing with it. I had stroke eight months ago and I still don't feel like doing very much yet. One of these days I'm going to change the cam to a Clay Smith 272 cam I had ground for it and change the valve springs. Just as soon as I get done putting a roof on the house. There is always something that needs repairing around this place and now it includes me.

If your engine ran fine with the choke pulled out it definitely could be a fuel problem but just for fun, I would make sure the firing order is correct. The cylinders are not numbered like any other V8. People tend to put the wires on wrong. Do a compression test (hold the carb open when doing the test). Check the fuel tank to make sure it's clean. This truck could have sat for a while and the fuel is fouled, Smell the fuel and see if it smells old. Block off the hose from the tank and give it an external can of gas to see if that eliminates the problem. And it could be everything else the guys have said. Start with what's free to check.

[jtminor]

Thanks for all the advice, I'll start working my way through each issue, hopefully I will be able to correct this problem,

Many great suggestions, much appreciated

Jim

[jtminor]

How about any guides to replacing the passenger side window, starting from scratch, i've ordered the new parts, what I need is a step by step guide, I've done two in the past, they were on 3100 chev, this time its own my F1

[Seth Swoboda]

Originally Posted by jtminor

How about any guides to replacing the passenger side window, starting from scratch, i've ordered the new parts, what I need is a step by step guide, I've done two in the past, they were on 3100 chev, this time its own my F1

You might want to start a new thread on this topic. It is my least favorite job. I'd rather pull a rearend and transmission.

[Ken/Alabama]

Check vacuum diaphragm on the distributor.

[rotorwrench]

Intake valves don't stick as often as the exhausts do. Compression check will tell which ones are sticking if that's the problem.

Backfire by definition is when the engine coughs back through the intake of the carburetor. It is caused by a very lean condition. Fuel delivery should be checked for proper fuel movement and pump pressure with a low PSI reading gauge. If delivery is good then something is blocking ports or jets in the carburetor. If it idles good then it's not the idle circuit. The accelerator pump function should be checked. If idle is good and accelerator pump function is good then it's time to open up the carb and clean it all out.

Vacuum leaks can be from a loose manifold or carb base gasket. A damaged intake manifold on rare occasions. Any rubber hose to a wiper motor may be bad. The throttle shafts can wear out and leak. Automatic choke systems can leak if so equipped. A bad vacuum advance servo can also leak which will affect vacuum and distributor timing and especially on an 8BA engine.

Door glasses are removed from the bottom through the open port there. The division bar has to be loosened on top and unbolted at the bottom to push it forward enough to slide the glass down and out. The longer it has been together, the harder it is to do this job. I'd suggest replacing the vent rubber and any worn out glass track components while it is apart if possible.

Glass setting tape will be needed to install a new glass in the support channel.