Timing Jumping Around

[Ricks70Duster340]

Was the vac adv hooked up while you were checking timing? Should be disconnected & plugged.

VC was disconnected while checking the timing

 

[Ricks70Duster340]

Just found this video. I am using the 440 Source bronze intermediate shaft like he showed in the video compared to the Milodon. Also, when I pull off the distributor cap I'm not sure how much I should be able to twist the rotor. Mine with the 440 Source shaft moves quite a bit. Edit: Duh, that is just moving the springs. Pulled the shaft out and there is a little play where the dist shaft engages the intermed shaft.

 

[Bewy]

A couple of comments.
He mentions the dist 'gasket' in the video. Early dists did not have the o ring to seal the dist to the block. The gasket is for those early dists.

I doubt that the backlash in the gears is affecting the timing, UNLESS the oil pump is sucking air [ aerated oil ]. A correctly functioning oil pump loads the int gear against the cam gear. Try driving an oil pump with an electric drill. Unless it is a very powerful drill, the drill will feel the load & slow down...Gives an idea of the pump load on that shaft.

If the engine has a roller cam, it could have too much endplay which will affect ign timing.

I would be looking at the dist internals for looseness/play in the weights & springs.

 

[AJ/FormS]

Does it take throttle, and rev ok?
I had one case in which like yours the timing jumped, and I mean it was here and then there, with no transitions of in-betweeness. In my case, the engine did Not like to rev up, and the jumping strobe got worse and worse.
I found the problem in the reverse connected pick-up coil. IDK how that works exactly, but after I reversed the polarity, I had to reset the timing cuz it was quite different. After that is was normal.

 

[Ricks70Duster340]

Does it take throttle, and rev ok?
I had one case in which like yours the timing jumped, and I mean it was here and then there, with no transitions of in-betweeness. In my case, the engine did Not like to rev up, and the jumping strobe got worse and worse.
I found the problem in the reverse connected pick-up coil. IDK how that works exactly, but after I reversed the polarity, I had to reset the timing cuz it was quite different. After that is was normal.

It seems to run ok, but I can feel it surge a little. I jetted up some but that did not resolve it. New engine so I'm just starting to work on the tuning.

 

[Ricks70Duster340]

Wanted to post an update. I installed the new Milodon intermediate shaft and the timing mark settled right down. I took some pictures comparing the new Milodon shaft with the one I bought from 440Source. Look at the difference in thickness of the gear teeth. Also, the hex end on the Milodon is a bit bigger so it fits into the oil pump more solidly.

 

[Yellow Duster]

Are you running a roller cam? Those bronze gears are for billet steel roller cams.

 

[Ricks70Duster340]

Are you running a roller cam? Those bronze gears are for billet steel roller cams.

Yes, solid roller

 

[Carnut68]

What advance springs in dist? I notice on my MSD with 2 light springs the timing mark would fluctuate.

 

[Ricks70Duster340]

What advance springs in dist? I notice on my MSD with 2 light springs the timing mark would fluctuate.

The 2 blue springs that came with the Firecore distributor.