Conv389drv

I thought about this issue recently when I saw it mentioned in an article. It said you can correct a mis-match by machining down the intake manifold's distributor surface, or shimming the distributor.

But what I want to know is, how can you determine where the gears are hitting each other to begin with? My only idea was to take some machinist's dye (Prussian blue) and paint the distributor gear, then install it and turn the engine over, then pull the dist. again to look at the contact pattern.

Anybody have any experience with this?

Stekman

What makes you think your distributor is not fully engaging the cam gear? Keep in mind, if it doesn't fully engage the cam gear, it doesn't fully engage the oil pump driveshaft, either.

SSC

Its a really a waste of time. If you have the distributor out and there is no sign of wear on the gear then it meshes fine. This is the reason they make bronze gears they mesh better and wear into a perfect patten.

Good Information
http://www.carcraft.com/techarticles/72460/

Conv389drv

You're right, I'm sure that for 99 percent of people this is never an issue. The article I was reading stated that you could have a gear misalignment if you had had a lot of block decking and head decking done. This would change the position of the distributor relative to the cam.

There was a guy I talked to who had a Chrysler engine with this problem. He was asking me how to check the gear mesh pattern. That's what got me thinking about this in the first place.

Also, I remember reading a magazine tech question about a guy with a Pontiac engine that was getting metal shavings into the engine. If I remember right, the cause of that was a gear misalignment.

Streetiron85

You could check that by:
a) doing a mock up assembly of the engine with the camshaft, heads, intake, and all the gaskets in place and then look at it from below to see if the gears are aligned correctly.
b) apply prussian blue dye or some other machinists marking dye to the gear teeth and then install it in the assembled engine and remove it to see where the drive gear leaves a mark on the dist gear.

head milling, block decking or a combination of the two will leave the distributor lower than original position, potentially causing misalignment

Mis alignment can be corrected with shims that are sold in packs of 3 in various thicknesses.

Conv389drv

Good info, thanks everyone. I'm glad that some people have at least heard of this issue before.