Cant seem to locate a tapping in the engine so I suppose the best thing to do is take it somewhere and let them hear it run, then go take the motor out and let them do what they do.

Anyone know of a good Pontiac machine shop around Atlanta GA?

Thanks in advance,

David

Do you hear it knocking at idle? upon acceleration? Take a sparkplug wire off one at a time until you find it. COuld be a loose rocker arm, bent pushrod, bad rod bearing. My thoughts, rod bearing.

The plug trick will work with rod bearing failure.

You do NOT need a $75 an hour mechanic to troubleshoot that.

I am hearing lots of motor issues lately. My friend Mike just had a 400 built, we picked it up and installed it this past week. He has a VERY loud lifter tick, can not adjust it out. Personally, with modern day oils, I would not build an engine without it being a complete roller motor. I am hoping my newly built 400 will go well as it is now a complete roller motor with a brand new rotating assembly. I wish you the best of luck with your issue...

I vote rod knock...

i was thinking rod knock or wrist pin. The motor is so hot that you cant hear the knock above idle very well and the plug wire test doesnt change it.

can you pull the oil pan with the engine in the car and get to the rod bearings and caps to check both these possibilities?

David

No.

You could maneuver the engine after loosening up the engine and trans mounts to get to the pan, but if you have gone that far, may as well remove it.

So,

You asked a question and some have replied on when this knocking occurs.

Could you please elaborate?

Banshee, the noise is constant and located on one of the rear two cylinders on the passenger side. Pulling the plug wire is inconclusive as the engine is pretty loud and is probably a 450+hp engine. At idle you can hear it but you have to rev it a little to keep it running on 7 cylinders. I may have a timing issue as well, but the noise was there before i fiddled with the timing. At present, the trans is out of the car and i have test run it that way. Pulling it wont really be a big deal, as i want to clean it up while it is out.

My concern is that i will end up paying for a rebuild when it may not be needed. The PO said it only had 1500 miles on it since the build (done by him and a buddy in his backyard shop).

Gadjit, I know the feeling. I've been chasing a knock for some time and can't seem to find it. I've got a FAST EZ EFI system I've been wanting to put on, but I want to get the knock figured out before I do so I don't mask problems. I've never heard the spark plug trick, I'll have to give it a try. I like you have a fairly loud motor so not sure if how it will work on 7 cylinders. Problem with mine is that the knock is not consistent, sometimes its there on start up, and sometimes its just a small tick. Then once the car warms up it goes away or lessens...the other problems is I'm not much of an engine mechanic....I can put them together, but can't diagnose them well. I hope you don't have to pull it.

Pull the valve covers and see if all the valves are moving properly. Try re-adjusting them.

Also check around the exhaust manifold/header collectors and flanges for a leak. If you're using cast manifolds, you could have a small crack.

I'll be checking this weekend.

I had a 350 ho with the same noise in the #7 cylinder. couldn't find it. endup pulling it. turned out that the pistion was broken but the rings were still in place. causing it to slap. the weird thing was it did not smoke as far as i could tell at the time. my current motor before i rebuilt it just had the same signs in the same pistion i saved it before it was too late.

Gadjit, any luck on finding the noise? I was able to reset the valves and get rid of my tick. Hoping you were able to find a simple solution vice major damage.