Thread: back fire ford flathead

Tweet

If/when this problem is solved I would like to know what happened and the solution.

Don Shillady
Retired Scientist/teen rodder

I did find the problem,after several trys ,first added fuel regulator,but that didnt help,,I pulled heads and inspected the valves ,and all looked good,tryed wd40 in dist.,and no help,so removed dist and and cleaned it and checked weights and regaped points, reinstalled and no change,I then used the ajustment that is supposed to be set by special bench machine,and rotated dist,back and forth till sounded best,took for a road test and ran great under all conditions.thanks for all the help from every one,this was my first problem with a flathead,and I learned a lot ,putting on a set of headers now.Dave

Great! I'm glad it's running good! At least you got a very good tune up!

Don Shillady
Retired Scientist/teen rodder

Just read through this,You have the stock '36 engine?,21 stud with the football dissy?,that where your problems lie,before you do anything check the plug leads are in the correct order,if one plug is out ,the flattie will idle and quite smoothly too,but as you said,give it the juice and she'll back fire,mostly out the exhaust.

If that checks,give her as compression test,eliminate any stuck valves.OK?
all eight got some sort of compression?
next,have you still got those pipes with the plug leads inside?
change the leads if they are older than 6 years.Use solid core NOT string type resistor leads.
Is your coil still mounted on top of the dissy?
If it's running it's still ok.
each side of the football (or divers helmet ,depends where you learnt to keep one going) the leads run into a round end ,check these are seating properly and the clips are tight.
Pull them off and shine a flashlight inside to see if there are cracks,they look like black hairline cracks.
If there are cracks you can fix them with nail polish,paint the cracks to fill them.Doesn't matter what colour...

If that all checks out,you have to look at the points,the rotor is a weird looking thing with two contact arms.
The best way to do this is to pull the dissy ,a couple of bolts and a little vacuum pipe and it's off.it only goes back one way so don't sweat the timing.
To set the points i just use a creadit card,it's about the right size and i don't buy anything with it anyway..
Work your way through this and it should stop the back firing.
Fuel problems will give you a miss fire NOT a backfire.
The same applies to the Crab dissy,It looks like a crab and you will find it easier to pull it off than try and work on it on the engine,unless you are rubberman...