Ford 8N timing issue

[Eric Wheaton]

I've never seen this. Help. As the tractor runs, I note the timing mark slowly moves out of sight as the timing slowly changes; and finally, it quits running. Suspected the gear on the end of the camshaft slipping on the cam but nope; solid as a rock. Of course, I checked the pin on the gear at the bottom of the distributor shaft; in and tight. If I loosen and move the distributor manually as the engine runs (has to be warm for it to change timing), I can keep the timing mark in sight of the sighthole on flywheel, only until I run out of movement and finally, it lugs down like it's under load and then quits.
Now, the other issue re timing; I have the head off and the piston at TDC does not correlate to the two marks on the crank gear and the cam gear. If the two marks are lined up on the crank/cam gears, the piston is about 1/3rd from TDC.

So, what the heck is going on? I've rebuilt a few engines in my time and been to a few goat ropes but this one is a puzzler.

 

[souNdguy]

Id your distribuitor slipping around?

soundguy

 

[old]

Crank shaft key bad, broken cam, broken distubutor drive shaft. Any one of those can cause the problem and can be a bear to figure out
Hobby farm

 

[Dell (WA)]

Eric......time to "rebuild" yer sidemount distributor. The centrifugal weight advance underneath yer points plate is "bad" and probably missing the retard spring.

As fer yer camshaft drive timing marks alignment. While back, there was abuncha "miss-marked" camshaft timing gears. The true timing mark was very faint and eazily miss-confused. The true test of the camshaft/crankshaft timing is watching yer valves move uppsie-downsie. With #1-piston TDC (and surprizingly enuff, the #4-piston will also be TDC) BOTH #1-valves will be CLOSED ....but.... #4-valves will be opening/closing as you handcrank yer front pulley crown-head bolt back'n'forth thru TDC. This is NOT a "micrometer" kinda thing but very visual. You just gotta know where and why to look.........Dell

 

[Eric Wheaton]

YO; thanks for the help. Did that and when valves are closed; piston isn't at TDC. Mark on crank is almost verticle (not where cam gears mesh and where marks are supposed to be aligned. Strange. Seems to run fine with all this mis alignment but after a while, timing moves on its own. Using timing light in the hole on flywheel and I can watch it move slowly up. I'll do a recheck of the distributor. Thanks

 

[Eric Wheaton]

Gotta be one of those; that's the only elements in the equation. thanks.

 

[Eric Wheaton]

Gotta be one of those; that's the only elements in the equation. thanks.

 

[Eric Wheaton]

No; snugged down the screw (and got the fan with my finger once). Ouch. Still is sore. thanks

 

[OKDAD]

Eric...When the cam/crank gear timing marks are aligned the pistons with NOT be at TDC. It sounds like you have a mechanical advance problem in the distributor.

 

[Bob]

Ford "N" cam timing marks are NOT aligned at #1 piston TDC.

That's simply the way it is. Ford designed them that way.

There is NO need for the cam TIMING MARKS to relate to a specific piston position, so long as the cam-to-crank relationship is correct.

Another example... on the COMMON small block Chevy, when the cam and crank gear timing marks are aligned, the CRANK is 360-degrees from #1 TDC.

Starting with the marks aligned, if you turn the sbc engine crank ONE turn, it will be time for #1 cylinder to fire.

IIRC, when the marks are aligned on a Ford "N", the crank needs to be turned 90-degress to get to #1 TDC.

 

[Dave H]

Eric

That is an interesting issue. Do me a favor and post back when you find the culprit. My money is ruding on something being wacko in the dist advance mechanism-but not much money.

good luck

 

[souNdguy]

Then i agree with dell.. advance mechanism must have an issue.

take care of that finger!

soundguy

 

[Eric Wheaton]

That's what I was looking for. That issue is then, no issue. Thanks. I will go back to the
distributor; it's gotta be the culprit.

 

[Eric Wheaton]

OK; simple mechanical device; crank, cam and distributor. Crank and Cam ok; now the dist.
Gear on end of cam is snug; even when heated so it's not slipping. I will disassemble the Dist again and look very close at everything. Thanks.

 

[Eric Wheaton]

Thanks partner; have accepted that; was afraid I really had a problem but since it will run smoothly until warm, I just had to get the info on the TDC thing. Thanks; great info.
Wonder if my wife will mind if I work on the distributor on the kitchen island?

 

[Eric Wheaton]

To: Dave H, Dell OKDad, Soundguy, Old, and Bob: Think I have the culprit in hand. You were right; Mechanical advance arm "solid to the dist. drive shaft" is not affixed as it should be. This a.m., with wife out of town so kitchen island is free to work on, I held shaft with pliers and was able to move the mech adv arm (with the two holes in it) slightly. Cold and by hand. So, under heat of running (expansion), and pressure of resistance of points and centrifugal forces of weights, I know now it was moving. Will fix/replace and assemble motor (had an excuse to tear into to fix the danged blowby and smoke) and of course replace the worn cam gear. No missing teeth and dist drive gear solid to shaft so you folks steered me to distributor. Thanks again. Love the forum.