MTFCA Forum

The history; a low use, 3-28-15 motor sat in a barn without the 4 main in the motor and rats lived in the pan. Spent over a year off an on, on the rebuild. New or re-ground everything. The only changes, went to high compression pistons, adjustable lifters, stainless valves and added starter so it got a rebuilt coil ring and recharged magnets. The cam was re-ground to stock, a fiber gear was also added. All new babbitt, transmission rebuilt, everything static balanced. Coils rebuilt and set on a hcct. 26 coil box rebuilt and all connections soldered. New roller timer and new carburetor. Put this puppy it a test stand added oil and although tight it fired right up on mag. Ran it for about 30 seconds and shut it off. About once a hour I’d briefly run it for 2 days. Man it’s doing great and then about 10 seconds into a run it died and didn’t re-start. It would hit enough to kick the starter out but not run. Gas drained and new added, mag showing 10 volts with the starter. When I blasted the intake made sure it was clean inside. Can you guess the problem?

How much gas did you put in the tank ??
How much did you adjust the carburetor ???
Has the sediment bulb been cleaned out and Tank and fuel line ??

The motor is on a stand the fuel tank is about a foot above the carburetor with a 1/4 inch line feeding the carburetor. The carburetor was adjusted and it was running nice. I really like the old fiber gears, they are tough as nails and run so quite. The motor did not seize and fuel flow not an issue. Thanks.

I think Steve may have been alluding to the fact that fiber timing gears have a nasty habit of shedding their teeth. Hopefully, yours didn't in such a short amount of time, but it would be worth checking to make sure.

Are you getting spark at the plugs?

Guess? So many possibilities, how can one make an educated guess?

You already know your fuel supply and carburetor are good.

I would start by pulling the plugs and do a compression test. It doesn't take long, and that way you know your head gasket is good.

Then lay your plugs on top of the head hooked up to the ignition wires and make sure each has a good hot spark. If they don't, figure out why.

My best first guess to check:
I'd check to be sure the gas tank is vented. It sounds like you're burning fuel until it stops flowing due to vacuum in the tank.

Getting closer, at this point it was on mag with no provision for batt. Coils checked on a hcct— all ok. Pulled the plugs looked ok, no black soot laid them on the block, spun the motor and had random firings.

A possibility... Your fiber timing gear is too thick and causing a timer roller/contact alignment issue.

Bob, you wrote about the plugs laying on the block- "random firings."
That is how they are supposed to fire- sort of. The random firing must be in this exact firing order 1-2-4-3. If that is not the case then you have a starting point.

I always say goi back to basics - fuel, air, and spark. If the engine has good compression, is getting good fuel, and has proper spark at the right time, it will run. One of the previous items is either missing or not occurring at the correct time.

I really like the old fiber gears, they are tough as nails and run so quite [sic].

Yeah, tough as finger nails. This one is quiet for sure.

Two things you did not mention, but probably not the cause of the problem. Ran for 30 seconds on test stand. Not long enough to overheat, but possibly could cause a problem with expansion if you did not have a radiator on it. In that case, the engine would not turn over until it cooled. The other thing you did not mention was whether you torqued the head after it had been run. It should be torqued after it warms up.

Concerning the fiber gear. That stood out to me as a potential problem. Might not be as big a problem on a car without a generator, but a big no no if you do have a generator. Also probably too soon for a timing gear problem.

Two things I would suspect to be the cause of your problem. 1. lack of spark. 2. Fuel starvation. Since you so get a random firing I would not suspect the spark to be the issue, but as mentioned above, check the plugs for firing order. Each should fire in the order One half turn of the crankshaft between each firing. That is #1 fires and then when you turn 1/2 turn #2 fires, then another half turn and #4 fires then last 1/2 turn and #3 fires.

You might be getting good fuel flow into the carburetor bowl, but one of the small passages in the carburetor plugged. It only takes one small speck of dirt to do that. So if it were my car, I would take the carburetor apart and blow out all the passages with compressed air and then try it again.
Norm

My SWAG is the timer roller came loose.
Still sparking, but out of time...hence the bendix kicks out.

Or maybe the squirrel fell off the wheel

The fiber gears I have from the 60’s have a slick finish and look nothing like the one in the picture. Why is the pictured one eaten off the side, must not have had mesh?? Ok here’s the tail— the Spring on the new timer roller broke and the roller was only making random contact. The fix was to bend a new loop on the spring and reinstall it. Ben messing with T’s for over 55 years and never had this happen before.

Thanks for the replies.

Glad you found it...
Sounds like I was close, what'd I win ??!!

Glad you found it! Unusual that a spring on a new timer would break, but not impossible. Anyway glad you found it.
Norm

Bob, I was really close to posting that very thing. I’ve seen it a couple times. It randomly hits a little and quits like its out of gas, but the only time I’ve seen it is on older timers that had wear. You should check to see if the front cover is nicely centered on the cam. Roller “bounce” seems to be why they come apart. Of course it could just be a defective spring too.

The cover was centered when installe, cam re-ground, checked for straight re-poured cam bearings— the spring just shaped. Ruxstel, guess you get the bubblegum. I’d post a picture of a timing gear from back in the day but, I don’t know how. Thanks to all, for your input.