I dug into my old 351w tonight. It originally came from a $100 plow truck, 90' F250, that never saw the street. I ran it 80k miles after changing the timing chain, oil & water pumps with my dad. It started missing. Leak down suggested rings. Conanski on here said it could be a broken ring land, and be a time bomb. I built a 351w roller to take its place. Did the swap over this passed weekend.

Tonight I found #5 ring in many pieces, some melted into the ring land, which is destroyed. The block has slight scoring but likely can be over bored. Crank looks pretty good. Bearings all show copper. So, it was time to rebuild. I was concerned about the damage, because it looks like detonation damage to me. I thought maybe I killed this thing, despite being set to 10* base timing. I tried the 6 liter tune years ago, had deto at 11 degrees so I went back to 10, yet once in a while thought I could hear the rattle of deto.

I started measuring. It was a 0.030 over bore with 0.010 undersize main and rods. That was fine. The piston to deck clearance is a cool 0.070" with 0.050" compressed head gaskets! ! Yikes. No wonder this thing was a ******* to keep from pinging! No quench. I'm no expert but the reading I've done basically says that's a bad setup. Poor compression with poor deto prevention. The head gaskets were all leaking too.

Anyway, I thought I'd share. I'll post pics later. My phone camera won't focus so I need to dig up my old camera.

 

 

Its amazing how far an engine can be gone and still run isn't it. You should definitely notice a power and mileage gain with the new setup.

 

That's the truth.

 

Did it have a miss when running....:-) as said amazing what these things go through

 

Yes it did miss at idle. That's what got me to dig into it. First I figured it was just a tune up needed. But the miss remained. Compression test showed #5 at 60psi dry, 90psi wet. Leak down pointed to rings. It ran smooth off idle, still made adequate power, didn't burn oil, and got around 13-14mpg highway. I ran it like this for some time, with a 750 mile trip mixed there. I can't wait to get headers on the new engine and try it out more than 5 mile cruises.

 

This motor had E7 heads on it and 10cc dish pistons. Compression ratio calculates to 8.35:1 if the E7's are 64cc combustion chambers (I didn't measure but 64cc is what I've gathered searching the web).

 

Ever find a part # on the pistons?

 

Just "30" stamped in the dish of each piston. I spoke with my dad about this earlier today, he's guessing the engine had 302 pistons in it. I haven't measured pin to piston top yet, but that would be one way to check.

 

wtf is someone running dished pistons for with e7s. you should be glad that engine is gone lol.

 

The reman I pulled from the donor E250 I bought has dished pistons and one E5 head and one D8 head. It ran very well, but I'm guessing the compression was in the toilet. I need to check the piston to deck clearance I think the quench is going to be horrible.

 

There are some really white valves in that head suggesting those injectors were not flowing too well. Did you reuse them?

 

I did not. I cleaned and bench tested the injectors from the van engine I used for the roller build.

White valves generally means lean, correct? This is a SEFI instead of bank fire PCM, not sure if that would play into it.

 

Its almost impressive to see what length people go to to save a buck, but if it works it works.

Stock 351W pistons are 20cc dish but zero deck clearance. With around 64cc combustion chambers and a standard 0.039" compressed head gasket compression ratio is 8.8:1. I imagine that's why so many guys can get away with 13, 14 degree base timing. It's a safe design.