Why don't I get any of the easy ones?

Welding man

Well-known Member
Location
West Virginia
I am on here looking almost every day, not posting too often, but I am amazed at how so many engines get rebuilt by people that don't even have a manual, a good torque wrench or basic engine building tools and they stick them together and they run. I have been building engines for a lot of years and try harder than anyone I know to never have a comeback. Now for my story. Back in April customer brought in a rough 6610 with dual power, didn't run ,dual power didn't work and wanted it completely overhauled. We pulled the engine, stripped it down and sent it to the machine shop. It had already been bored and sleeved and the sleeves were worn badly. Head was junk, Crank had to be reground, rods reconditioned. Machinist did his thing, new sleeves bored back to standard, new valves, springs, seats guides etc. Reground crank. Ready to order parts. We could not find a set of standard pistons and rings anywhere. I am a dealer for half a dozen suppliers and my machinist is too. We finally found a set of .030. Set it back up and bored the new sleeves .030.While all this was going on we rebuilt the dual power and the steering sector. We put it on the stand and start assembly. New pistons, rings. recon rods and reground crank, new cam and lifters, the works. Plastiguage everything, everything is going good, Install pistons and check piston protrusion and then this is where it goes from bad to worse. Spec says .011 to .023 above block. Block had been decked before and who knows how much. We have ..050. Disaster, pistons will hit head. Call machinist, we find .075 head gasket. Do the math, might work, put head on roll it through by hand and nothing hits. Finish rebuild, start her up runs but very noisy in valve train. Readjust valves, run on dyno, still too noisy. Sounds like spark knock. Back timing off a few degrees, helps but still too noisy. Pull head back off, Pistons kissing head. Next move, pull front axle, oil pan, balancer remove pistons and rods, disassemble and machine .035 off the tops of the pistons and reassemble. You get rich working on these.
 


My last one was a challenge. I was restoring my '67 Datsun roadster. The block had some VERY bad taper to it. I had a parts car so I elected to use the block out of that. The machine shop called because it failed the initial inspection. the deck was eroded paper thin next to one of the cooling passages. I took the original block back. They went .050. over to clean up the bores. It appeared to have never been decked The head however was a very close run thing but just barely enough room. Then it was time to find parts and the fellow worked his magic and found me some unobtainable DOMED pistons to fit. Between the milled head and the domed pistons I was a little nervous about compression. I switched it over from bolts to ARPS studs. Then the quest was on to keep it from knocking. I have been running 93 octane with the timing backed off three degrees, and it has been happy for the most part. It has a little over 5,000 miles on it now and is doing well.
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If your pistons were really .050 over, that would have been a huge red flag for me. Either someone surfaced the block way too much or your new pistons were incorrectly machined. At that point I would have likely considered offset boring the rods to compensate.
 
The machinist and I discussed that very thing. He was a machinist for Caterpillar before going into business for himself. He came to my shop took the measurements himself to verify mine. He said he had done them both ways over the years with equal success. There is plenty of room above the top ring to cut the piston, because it it less work, We opted to go that way. We will see what happens.
 
My father worked for a Ford dealer back in the 70s. Ran into this problem. Turbo vs non turbo had different pistons or rods and the piston would protrude enough to hit the head. I dont remember whether it was an 8600 or 9600 they were working on. One piston protruded more than the others.
Anyway his boss handed him a rasp and a flat file. Told him to make it work.
So the story goes they filed the piston down and the guy ran that tractor for years after.
 
Not only those rebuilding their tractors but not even owning the ESSENTIAL MANUALS for owners and operators of their machines. How can one do any standard preventative maintenance without a basis Operator's Manual or a copy of the CLYMER I&T Manual??? That's why I constantly preach.

Tim Daley(MI)
 

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