I had a 403 rebuilt completely, bored 30 over #5 head, reground cam, balanced rotating assembly, port matched ect no corner cut at least I thought. The engine builder did not break in engine because he said his dyno was not set up for olds and wanted me to buy the equipment to do so. So I took the engine to another engine builder that could they broke engine in with their carb they always use. Then put my Quadrajet on to dyno. I got engine back put in my car got running drove maybe 45 mile to 60 mile noticed oil pressure was getting very low hot at idle when in gear and started hearing a knock. Took engine out got to builder a month ago he finally took oil pan off. The number 8 cylinder is scored he said he has not checked bearings yet but he thinks they are good along with cam. I asked him what caused that he says it was improper brake in with not enough fuel. I’m thinking he’s passing the buck.
what you think?

 

What are the clearances ???? Should still be able to get somewhat of a number . All those excuses would make sense if all the Pistons where scored. Sounds like sloppy work

 

1. Your first sign of trouble should have been his dyno was not set up for Olds.
2. Asking you to buy the equipment for him to run an Olds on his dyno is another clue he hasn't experience with an Olds engine.
3. There is also no way to know if the shop you took the engine to for dyno testing had a properly jetted carb for your engine.
4. The score mark in #8 cylinder is a sign of sloppy assembly. It could be a sharp corner on the compression or oil ring end gap. OR it could be foreign matter that got between the piston and cylinder wall during assembly.
5. Low oil pressure and knocking is a sign something is going seriously wrong.
I would start looking for a shop that is familiar with building Olds engines.

 

Engine builder is passing the buck.
The scored cyl wall won't cause an engine to start losing oil pressure, but bearings going south from junk running through them will.
My gut says the bearings are going to be trash. Do you have a sheet from the engine builder of the clearances for every main bearing journal and rods? At time of build, to cmpare to what they are now?

 

Without having the engine apart and in front of us, everyone is just guessing. If it started losing oil pressure and then started knocking, I am betting is started to destroy a rod bearing and the metal from the bearing got flung up on the cylinder wall. Thats where the scoring came from.

OR... it started detonating or was lean or had some other problem in that cylinder and it hurt the piston or rings and that is where it cam from.

Absolutely no way to know without taking the engine apart.

Did the dyno shop just do some mild break in runs or did they hammer on it ? Dynos are VERY hard on new engines especially if they are not monitoring air fuel ratio and timing. I dont have a dyno but use one of my customers' when I need to. I ALWAYS run the engine very very easy to get it up to temp and make sure there are no leaks or other problems. Then the oil and filter are changed and the filter is cut apart to look for bearing problems. Only after that is done do I really let them make some hard pulls on it.

So it could have just as easily been a problem with the dyno operator as much as the engine builder. No way to know till it comes apart and even then it might be very difficult to figure out what actually happened. Once he gets it apart, post some pictures of the parts and pieces.

 

I don’t know clearances machine shops will tear down further. As for the dyno shop they broke in cam and did do some easy runs before dyno. The carb that they used they use that on 90 percent of all there dyno. I talked with them they have never had an issue with fuel or engines running lean. It’s very frustrating for me.

 

I hope it's not the same machine shop. They will absolutely do everything in their best interest.

 

I just want to add that sometimes no matter how careful and precise you are, something will go wrong. Brand new cars from the factory have engine failures. How you handle it is what makes the difference.