Distributor Gear Lash
 

Is there an effective way to measure distributor gear lash? I bought a used set of heads off of eBay. They were milled enough to disrupt my distributor gear lash. It was way too tight. In just 20 miles, I managed to trash the distributor by overheating the housing (bluing observed) and sending fragments of shims that were between the housing and the distributer gear, into the oiling system. Luckily, the K&N oil filter caught most of it with minimal damage to my crank. I will go ahead and replace the mains and rod bearings to be safe. They showed signs of very minor scouring. I have purchased a Moroso distributor shim kit to use between the distributor and the intake manifold but I don't know the proper gear lash.

put an indicator on it, anywhere that would work, and measure it.
ok thinking about this you'd need the oil pump drive shaft removed. i'd also suspect your problem isn't caused by the heads being milled.

I came up with that possibility by reading the box of Moroso shims. It says the shims correct gear lash problems caused by excessive milling of block or heads. These heads came from AFR with 58cc chambers. When they were cc'd, they were 52cc which would mean they were milled. By how much and at what angle (straight or angle milled) at this point, I don't know. That was the most tangible clue I have right now.

I am open to any other explaination. I did find that when I spun the oil pump during pre-lube, I did get excessive heat from the drill motor indicating there may have been something binding to begin with.

When you say use an indicator, I'm assuming you mean indicate from the manifold surface to the top of the oil pump drive. Any clue to what that would be for comparison? A friend suggested that I should get a measurement from my good running motor and use that as a baseline. Sounds reasonable.

Instead of shimming it on the oil galley end can't you shim it up top on the manifold if that is in fact the correct fix?

That's exactly what the Moroso shims are for. Thanks.

You shim the dist shaft to about .015" - .020" (one business card) end play in the housing; then you shim the housing upward until the shaft no longer binds on the oil pump drive. You can verify that the oil pump doesn't have the shaft binding in the housing after installation, by simply grabbing the shaft and pulling up and down on it (not that shaft, I'm talking about the distributor shaft!!!) after you tighten the timing bolt, and make sure it still has play after the bolt is fully tight.

The drill motor thing just means your drill wasn't big enough. Has nothing to do with planing heads or any of that. It takes about 2 HP to turn an oil pump at 1200 RPM (corresponds to 2400 engine RPM) in thick oil. If you don't have a 2HP drill, which is enough to break your arm, then you're going to smoke your drill. Pretty much a given. There's lots of drills in landfills already from doing that.

Screw a dial indicator. That's almost similar to work, and nobody needs to go there. This is not rocket science here. It's just assembling an engine. In this case, all you're looking for, is "no bind". Go/no-go; yes I still have my .015" of end play, or no I don't so I need more shims. You don't need any tools at all, besides that 8-lb tumor growing out of the top end of your spine, for that. Hell even I can figure it out, so you know it's got to be pretty easy to grasp.

Thanks! I'll give it a whirl.

Thanks! I'll give it a whirl.

Thanks! I'll give it a whirl.