The Stovebolt Site Forums The Shop Area Engine Shop Distributor Problem?

Changed distributor to a new HEI. Starts right up. Timing is good. But I have a tapping sound coming from the distributor side of engine. Can't place it. Any ideas guys?

What HEI distributor did you use? Did you verify that it seats well into the oil pump drive slot?

Like baldy says we need a little more info. Has it still got the 6 cyl. engine?

57thekid,

I'll go out on a limb...you said "distributor side" of the engine. To me, this sure indicates a Chevy six...unless the V-8 relocated their distributor and didn't tell anyone.

The side cover, lifters and pushrods are all right near your new HEI, and they certainly can "tap". Did the side cover get banged or bent in during this install. There isn't much room in the side cover area for those moving parts! I can't put a tapping sound with a rotating distributor, but what the heck do I know!

Stuart

Yes it is a 235. I have good oil pressure. I just have a loud engine noise, seeming louder on distributor side. Could it be some kind of mess up in the plug wires. Engine seems to be running smooth, but loud engine noise, Tapping or popping, I don't know how to explain it.

Tapping or popping sounds like valve train. Lower end problems, like rods or pistons, have a deeper sound like pounding or banging.

You still haven't answered the question of what distributor you're using. Is the Stoveboltengineco HEI? A GM stock six HEI modified? Something else?

And what is good oil pressure? How many pounds? At what RPMS?

GM Modified

I had a "tapping" sound on one ot two of my rigs. It was the rotor inside the cap that was making the noise. It chewed up the cap contacts on the inside. The rotor was trashed as well. Had to replace them both and no more tapping noise. One thing also comes to mind, you may have a defective distributor. Either the advance plate is not lined up or properly seated or if it has mechanical advance the springs may not be in correctly or one may be missing. I would put in the old distributor and see if it stops. If so, then its the distributor. I would return it and get another one. Just a few suggestions.

Henry G's advice is excellent. Put the old distributor back in. If the noise goes away, you've located the source of your problem.

If you haven't already, double check to make sure that the distributor is seating properly in the oil pump. The noise you describe could be insufficient oil getting to the valve train.

You didn't say what good oil pressure was. It should be at least 30 lbs.

57thekid,

What do you feel when you lay your hand on the distributor. Can you 'feel' the loud tapping. Using a stethoscope, maybe you can pinpoint the noise. I still can't imagine a aluminum bodied HEI distributor transmitting a loud popping or tapping sound. Let us know what you find.

Was the body of your HEI modified properly to fit into the engine. Isn't the distributor drive gear held on by a roll pin..this wasn't left long and is hitting the cam as it rotates..these are just thoughts if this problem is really a result of the HEI install.

Stuart

I had refurbished my old distributor on my 235 according to shop manual and then reinstalled in engine, When I fired up the engine for the first time I got the same result loud popping or tapping on the distributor side. My oil pressure was some what low but close to normal. I put my hand on the distributor and could feel a definite vibration. I shut down the engine and pulled the distributor, backed off screw on the vacume clamp and reinstalled insuring the distributer seated all the way to the bottom into the oil pump tightened the vacume clamp and dist bolt. Presto problem solved. My distributor was not fully seated into the oil pump and poping up and out as it turned, the result was the loud noise you discribe. I do not know if this is your problem but I would suspect that it is. You can use a long scew driver to line up the oil pump connection with your distributor shaft. good luck.

I think I am seated ok. I have 30 lbs of pressure at idle, and it goes up to 50 or better as I rev the engine. And the collar is all the way against the block. I do feel a vibration on the cap. And the sound does sound like something hitting or tapping.

I thought I was seated ok as well but the collar was clamped on to far down shaft so it was flush against the block but not seating fully into the oil pump connection, the distance between the bottom of the distributor housing and the collar was considerably reduced once it had full seated down into the oil pump. let us know how it goes I had planned on replacing my distributor down the road.

But isn't my oil pressure good? Doesn't that show that I am seated ok?

Easy solution is to go out with a wrench and screw around with it for about 5 minutes and youll know for sure.

It could be the rotor hitting the cap like Henry says. Maybe the dist. is in too far push up om the shaft. Sometimes mechanics leave the ground term. out when they caps. That will make a popping with the spark jumping around in there. Pull the 3 wire inner connector from the cap & look up with a mirror. There should be 3 terms. in the cap. If the center one is missing the ground strap is missing.

Guys I pulled the cap and there are no marks where anything has been hitting the cap. I did find a pretty good exhaust leak at the end of the exhaust manifold where it joins the ehuast pipe. I am going to fix that first to make it easier to listen for different noises.