I'll try to make this a brief as possible. I have put together a lot of engines over the years, but I am by no stretch of the imagination an "engine builder/expert." We have guys on here like Pat, Dave, and others who REALLY know how to put one together, checking every little spec and clearance as it goes together. Me, I might use some plastigage, and that is about it. But for the most part mine have worked ok.

But the 331 stroker I put together has me puzzled. I mentioned that the galley plug blew out after 5 minutes of running and oil pressure went to zero. We shut it down IMMEDIATELY, and after I put in the new (screw in) galley plug I prelubed it and fired it up. All was good. Oil pressure is 60 psi at idle and the engine sounds strong, takes gas well. However, after putting the exhaust system on (I had been running it with loud open headers) I could hear a noise coming from the engine. It is a rhythmic knock that sounds like a rod bearing.

First I pulled the valve covers as I thought one of the roller rockers had come loose or something, no, they are all moving as they should. The noise seems to be coming from deep in the engine. So, I pulled the engine tonight and turned it upside down on a stand. I fully expected to find some scored bearing(s), but they are all nice. A few have slight scratching on them, but nothing that wasn't caused by a little dust in the engine block. I saw no signs of the stroker crank hitting anything because of clearance issues either.

The only thing that I noticed was you can move a pair of connecting rods slightly sideways on the crank journal. It makes a slight "knock" as you move it sideways. I put a feeler gauge in there and an .008 feeler gauge will slide down into the gap between a connecting rod and the crank journal. Is that normal? I have also never done an engine with full floating pins before, so maybe these move more side to side?

Here is what I have:

90 Mustang 302 block. Align bored, bored 30 over, decked, finish honed with deckplate.

Scat 331 stroker kit, balanced, Probe flattop pistons. All 28 oz imbalance.

Ford Racing X303 roller cam, Comp Cam timing chain, Harlan Sharp roller rockers, Ford Racing pushrods.

Edelbrock Performer RPM aluminum heads, set up for roller rockers.

Melling standard oil pump with ARP hardened driveshaft.

Any thoughts on what I should do next? Thanks in advance guys.

Don