I have a 72 with a 454. Here are the symptoms:

At first startup the car runs fine and does not make any noise. As it gets warmer, and under load starting about 2k rpm this unusual noise starts. The second I take the load off it goes away. It does sound like a hammer like noise, just deep. The part that makes me think it's a main is the oil pressure will drop off, way off.

I have not connected another gauge yet, but will. The engine only has about 1k miles and the oil does not have debris from bearing damage.

How can I test to be sure of problem?

What options do I have?

 

I'd drop the pan for a look see. Any bearing problems you'll be able to see. regardless of what the oil pressure drops to.
It's only making noise under load?

 

what is the psi knocking? what wt oil?
keep in mind the psi is ~15psi LOWER at the front.
so a 20 gauge is really just 5.

 

Could it be a pre-ignition problem ?
Caused by too much advance or fuel with not enough octane ?
What is your timing ? Does the problem still occurs with less advance ?
What about the spark plugs color ? Do they have signs of detonation / pre-ignition ?
And as Matt already asked, how much oil press do you have when it happens ?

 

I had an engine with a bad main bearing and it would knock twice as loud on initial startup when the engine was cold, I guess before oil pressure could reach it. Try letting the car sit over night, then pop the hood and start the engine. Listen for the first few seconds and see if the knock is louder. If it is it may be a main bearing. Just my 2 cents.

 

Sounds like pre-ignition "spark knock" to me. Don't allow that to happen, if you can help it; it is damaging to the engine. Since your '72 engine has 8.5-9.0 compression [depending on the engine], it should run fine with today's fuel choices. But, the standard 'plumbing' has the dist. vacuum advance going to some emissions device or to a 'ported' vacuum fitting on the carb. I'm guessing that the vacuum advance can on your distributor is 'kaput' and that the centrifugal advance mechanism in it is gummed up or frozen. If your engine timing is not advancing when you give it some throttle, it will 'ping' like crazy. And, yes, it will sound just like a bucket of bolts rattling.

The easiest thing to do is to hook up a timing light and see how the timing is operating as you give it some throttle and/or disconnect the vacuum advance can on the dizzy. If the timing doesn't change much as you rev it up from idle, then you have a problem in the distributor mechanical advance (weights and springs under the rotor). Check it out and come back with info on what is happening. I would not be pulling the oil pan until you figure this part out first.

 

no noise at startup but noise starts when oil heatsup
oil pressure drops off as oil heatsup
only 1000 miles on motor

this all points to wrong size bearings or you did not change the bearings in the engine when rebuilt but put a performance oil pump in that the bearings cant keep pressure against.

the oil pressure drop off is a main and rod bearing problem,if it was a detonation problem oil pressure would be fine all the time.
the noise you are hearing is most likly coming from a rod bearing

i have seen this many times.

 

You can approach the diagnosis with sound behavior. A main bearing will exhibit a somewhat deep metallic rap (spark knock is a sharp, much higher note) with the engine at idle or under a load at low rpm. The sound diminishes as rpm rises under light to no load. This seems at odds with your experience (louder with rpm). If it's a rod bearing, the noise, very similar to the main bearing, will be light at idle and get much louder with load at all rpm. You can do a superficial diagnosis of rod bearing issues by shorting the spark plugs one-by-one with the engine at idle. If you short a plug and the noise goes away, you have found the bad rod bearings(s). Then there is always the piston pin. This will usually be a sharper double rap with the piston at exhaust overlap.

Most bearing-related low oil pressure problems due to the cam bearings. I would approach the oil pressure issue -if there is one- as a separate issue.

 

All your input is great! I really appreciate it. Some are discussing timing. I bought one of those aftermarket hei that are cheap. We was playing around with the timing, he checked and I am only going by what I remember. The initial was around 32, but when he bumped the idle the timing went to 45. The timing was moved back.

I will take the advice for sure to look at the plugs and check the timing.

The motor was built by a machine shop here in OKC. It was disassembled, so they could not have used the same bearings, but mabe something to look at as well.

On the oil pressure. Of course it's the original mechanical and I do plan to put another one just to verify. Anyway, the car starts cold does great. The pressure is about 70. Then it warms up. It's between 0-35. I don't believe 0 is accurate.

If I am going down the highway at 3k oil press is great, sounds great. Jump off, 0 pressure, then it will climb back around 30, but never above.

The oil is the rotella 14-40 and looks great. I was changed after 500 miles.

The engine has 781 oval heads, and forged pistons. It's fairly low compression.

Again, THANK YOU ALL for the input! I will use this as a guide and check back this evening. I will not be able to work on until the weekend, but this will be a great check list.

John

 

Well for once it's not a crate engine someone bought on the opposite coast. Take it back to the builder and tell him to fix it. Don't take any BS, unless the guy is honest ( that's a crapshoot ) he will try and blame it on you.

Don't let him, he has been at it a long time so he knows what to say but tell him it's got 1000 miles on it, no oil pressure and it makes noise and you prefer your new motor not to make any funny noises.

If all that fails there's always the sandwich board routine outside his shop on you time off

 

 

An initial timing of 32? That's about twice what you need for initial timing. If the throttle was in fact just "bumped" and the timing jumped to 45 (gaining 13 degrees) then your centrifugal comes in way to soon or the vacuum advance is still hooked up during the timing test and also hooked up to a ported vacuum source. The vacuum advance needs to be hooked to a manifold vacuum source.

I had much the exact same problems you are experiencing in my '72 454but without the engine noise. Whenever I would start my car the oil pressure would read around 35 psi or so. Whenever the engine would warm up the oil pressure would go to 0. Nil, natta, zilch. As it turned out I wiped out a lobe on the camshaft and cleaned out my engine bearings.

My advice would be to remove the oil filter and cut it open and look in the filter paper for metal shavings. In order to avoid making small shavings with a saw, I use an air hammer with a chisel. I can have one of those buggers open in less than 2 minutes and make zero shavings in the process.

Good luck,
Mudbone64