I recently replaced the old 302 Windsor in my 93 F150 with a 306 Ford Racing crate based on the same block, it comes with GT40 heads and a X303 cam (I think), along with a MAF upgrade, Edelbrock Performer EFI intake, and Pace Setter long tube headers I added to the mix.

It was running great until this past Tuesday, when I was stupid enough to bite on a challenge from a late model F150, he backed off once I showed the dual exhaust on my truck wasn't all show, but now my engine ticks loudly while idling and driving at a set speed, matching with engine RPM.

I originally suspected I did something to my valve train, but taking it in to where I work to check it out, I noticed the noise goes away under acceleration, or gearing down coming to a stop, making me suspect it isn't a rocker or lifter. I checked the bolts for my clutch and flywheel to make sure none of them has come loose, and I don't see any signs of damage to the flywheel itself. Draining the oil from the pan, I didn't see any metal shavings, but cutting open the filter (with a can opener, not a saw or anything that would create shavings), I noticed small amounts of metal shavings inside.

The engine only has around 550kms (340 miles) on it, have I messed up a wrist pin or connecting rod bearing? I want to see if anyone has had similar problems before I start tearing into the engine, hopefully get a little bit of direction on what to look for.

 

I would take a look at the cam and lifters. 340 miles isn't very much in terms of a break-in period.

 

You could've bent a few push rods, not enough for them to fall out, but enough to cause the rockers to clatter.

 

The noise wasn't coming from the upper part of the engine, it was more in the area of where the oil pan bolted to the block, so rods and lifters aren't very likely.

I've pulled the engine from the truck, got it on a stand and flipped it upside down so I could take a better look with the pan off, didn't find anything to do with the rod or main bearings like I expected, but the wall of #4 cylinder has been badly scratched up by the skirt of the piston. The belief at this point is, that the wrist pin seized, causing the piston to stick, thus not traveling in a straight up and down path, and the knock is it slapping against the cylinder when it's forced to change direction.

Either way, Ford Racing has seen the damage to the cylinder wall, and it looks like I'll be getting a new small block assembly under warranty.

 

Well, there's bad news and good news. I'm glad that Ford Racing is replacing it for you.

Let us know how everything goes from here on out!

 

Some pic of the rebuild would be nice

 

Finally got the new block, and a chance to get it prepped and in the truck, haven't been able to tune it and get it on the road yet though. I decided to remove the smog pump instead of leaving it as an idler with the cat removed when the dual exhaust was put in, can't find a proper set up for a shorter belt, so I'm waiting on an eliminator bracket.

I did get to fire it up briefly to see if everything else was working okay, and the knock is gone, everything besides the block, crank, rods and pistons coming from the old engine, and the old crank and rod bearings showing no signs of damage when I tore down the old engine, I'd say the seized wrist pin diagnosis was correct.

It should be running proper early next week, I'll see about doing up a proper thread about the truck itself then, and not one about the things wrong with it.