This is on my '81 355 engine that I had put the flat-top 2 valve relief pistons in wrong...all intakes valves hit each piston..

Have removed pistons...and saw on one side only of several of the piston retaining rings (floating style pistons) that the outside groove wall has been damaged to the extent that I cannot get the wrist pin out.
Along with this I have wear on one side of three rod bearings down to the copper(engine has 1500 miles), bearing in the rod, not the cap.

Associated with these worn rod bearings is the piston retaining ring damage where the piston damage is on the opposite side of the piston from the rod bearing wear in all three cases.

This is on pistons 4, 7, 8. There is less damage on one or two other pistons, but no copper showing on the rod bearings.

Question is: was the damage due to the valves hitting or did the machine shop that turned my crank mess-up?

I think I know the answer in that all pistons were damaged by the valves hitting, but not all pistons had the retaining ring damage, so I had better plan on pulling the engine out and having the crank re-worked....or may be it is time to get that crate engine!!!

LannyL81

 

That's a bummer. You should replace all the pistons since they are cheap. The crank should be redone since the journals are tappered. I'm surprised the assembley rotated because of this. You learned from your mistake that's the important thing. It's your choice how you want to move forward. Good luck.

Chris

 

Took the rod bearings to a different machine shop (the one that I should have used in the first place)...his story was that he had been fixing the other machine shops mistakes for the past year or so!

He says that yes the crank is not ground properly...has had several of them with this problem. Also suggested that I bring the block in (again) and have the bores checked. He is currently fixing one that had a range of overbores of over 0.005", and no the decimal place is not in the wrong position!

Looks like I get to do another rebuild. Get the taper ground out of the crank...have the block checked and hope that its not junk!! Will probably have to go to 0.040 on the bores....of course I had already bought new 0.030 pistons. New main and rod bearings, seals and gaskets, plus the heads fixed. So much for my savings account!

 

That's what E-Bay is for!

Sorry you're taking such a beating on this one. As Chris said, at least you're learning from your mistakes.

 

Whats the end play on the crankshaft?

 

Make sure you check rods for being straight also.


JIM

 

I would document everything. This is the same engine that was decked so the pistons were .006 out of the hole and a .020 gasket. That is probably why the valves hit the pistons. now you find the bore is wrong, the crank is improperly ground, the heads are ruined, The block is junk from improper decking the snap rings on the pistons are galled to the point you can't get the pins out, probably done on installation. I think I see a pattern here CRAPPY Machine shop ruined your build!!! Sue them! Document everything with pictures, measurements and a written, notorized statemet from the new machine shop. Go for all costs associated with replacing ruined parts, removal and reinstallation of the engine, all machine work, reassembly, plus downtime on the car, pain and suffering, legal fees, time off work to go to court. Thes type of machine shops will keep doing this to unsuspecting customers unless or until somebody does something. I am not normally the type to sue but by doing so you may protect someone else from having the same thing happen to them!

 

All other issues aside ... valves hit the 2VR pistons because the pistons were incorrectly installed into bores ... pistons upside down ... 2VR were opposite of valves ... eyebrows not aligned w/ valves. In my experience, the assembler is responsible for verifying proper choice of components, their correct fit & proper assembly. The machinist is responsible for millwork. In a general sense, the assembler is the project manager when that assembler is neither employed by nor subcontracted to the machinist's employer.

 

I'm surprised you were able to put 1500 miles on it before you noticed anything.

 

Crankshaft tapered ? If you assembled the engine I'm sure you would have noticed that.What was your endplay measurement on the crank?The reason I ask about the endplay is I have seen bearings worn like your describing because of "too" much end play and I have seen the pistons worn on 1 side on 1 of them.I also had 2 different big blocks that broke the skirts off the pistons because of "too" much endplay.One of the big blocks had .050 endplay.I think you can only have about .008

 

I missed that:o Would have thought you would notice that upon preassembly to check valve to piston clearance especially knowing the pistons were out of the deck. As Jackson said though the machinist is responsible for millwork. Sounds like that part of the build was also grossly incorrect.

 

what head gasket?what pistons,are they domed?does it have the wrong length valves? something in the valvetrain is wrong.where is the piston at in the cylinder at tdc.

 

Correction on post #10....I stated .008 that should be .002-.006
(couldn't get my edit feature to work)

 

It's a given the pistons were upside down.

With that, I can also imagine possibility some/all rods were installed onto journals backwards ... chamfers incorrectly facing one-another. If so, it's quite possible that caused the journals to taper.

It seems some upper rod bearings got wrecked & skinned back to copper. That's not surprising; with the pistons slamming into valves, that action would drive the upper rod bearing into the journal ... wiping upper bearing and that could further the taper-damage.

True, the crank's stroke may not've been right/equal across all throws ... only one way to know. But, it's just as possible the cam's lobes may not've had equal lifts ... and/or ... valve train geometry not equal ... just a few of many possibilities that could explain disparity between some upper rod bearings wiped & others not.

 

That's what I was working at if the pistons where in upside down.sounds like one the problems

 

I have tried twice now to post into this thread and neither one has appeared..???

Anyways...

I wanted to state that I am not trying to dodge the responsibility here. I assembled the engine and although I was told wrong about the piston rotatation...I should have checked once I got the heads. But I did not as I was focused on determining what length of push rods I needed.

I did measure main bearing clearence using Platicgauge...and found that it was a bit tight...0.0015 instead of 0.002 as a minimum. I had the crank re-polished and it was measured again...still tight but the crank was hot from the polishing, so I went ahead and installed it.

I did check the end play and it was fine.

I probably only checked one or two rod journals though...should have checked them all. But that Plasticgauge to me is nto all the accurate and I do not have a mic' so I trusted the machine shop.

Now the wiping of two rod bearings could have been caused by the intake valves hitting the piston. I checked the orientation and one was on the same side as intake, the other on the opposite side. Same goes for the galling of the piston spring retainer groove....it was on both side of the intake valve hits. So I was not able to come up with a clear cause. Only two of the rod bearings were really wiped...two more had the outside edges only and then the rest were fine. This is what got me thinking it was the crank itself. The crank will be re-ground to be a 10-10 crank..or maybe a 20-20....I will let the shop tell me.

Hopefully the block bores and rods are good and I can just get the crank and heads fixed, install new bearings, pistons and get the engine back in.

The machine shop closes for the holiday, so it will be mid to late Jan before I know anything more.

Oh and the first machine shop is out of business, so no chance of taking legal actions there.

This has been a good discussion....
LannyL81