Motor Knock FZJ80

[TheBussman]

Yea never run a piston that's too tight it could seize up in the bore when it expands and ruin all your hard work. can you re arrange the pistons in the bores to make it in spec? is it just one big piston? buy another? if not it just needs a little platu hone to get it in spec. you can do it yourself, it is a learned skill and nice to practice on a junk block. id feel alot better about it if all the cyls were honed the same way, you don't want to hone any more on the ones that are ok. I would take it back.

 

[Malleus]

I'd be leery about trying to hone out a thousandth with a dingle ball. A couple of tenths, OK, but a thousandth is asking a bit, especially in 4 inches of stroke. IMHO.

Agree about tight pistons. Bad mojo.

 

[Addi]

I appreciate your guys input. I’d take it back but I don’t live in Santa Fe anymore and it’s difficult to find the time to get back out there. I was able to find a machine shop in town that could do it quickly, so I should be back in business by Monday! He’s also going to measure out all the cylinders himself, so it will be nice to compare it to my measurements and see if I’m doing an ok job.

 

[Addi]

Well it went worse than I could have expected. I told the shop that only the last cylinder needed to be honed, and I gave them the piston to match with. In an attempt to be helpful they went ahead and honed all the cylinders to match this single oversized piston I provided. I was already upset that half of them were out of spec per the fsm even before this. Now I'm looking at about .0033 on average for the wall clearance. I think at this point I can't justify putting the engine back together with these numbers, when the manual says I should have rebored even before this.

 

[Malleus]

That sucks

 

[Broski]

So hard to find competent shops these days.
It’s almost like you needed to tape off the other 5 cylinders, and put notes with arrows and diagrams

Are they charging you for the extra work that you didn’t ask for.

 

[Fj80oregon]

If that was my shop I would buy new .50mm or 1.0mm over pistons from Toyota and have them eat the machining. Not that expensive from Toyota if you buy from overseas. The rings are expensive. Always best to give them the pistons so they can measure to match the bore. Sounds like that’s your next step because of the situation.

 

[Fj80oregon]

How much did they grind the crank? Just curious.

 

[Addi]

I'm going to talk to the shop again tomorrow and see what we can work out. I have half a mind to just buy a short block so I don't have to worry about it anymore, but maybe thats a bit drastic. Luckily I went with .25 over for all my pistons to leave room for a future rebuild, so I guess that will be the route.

How much did they grind the crank? Just curious.

It was .25 off the mains and .5 off the rods. They shipped the crank to Denver for the work and it all turned out spot on.

 

[TheBussman]

I'd be leery about trying to hone out a thousandth with a dingle ball. A couple of tenths, OK, but a thousandth is asking a bit, especially in 4 inches of stroke. IMHO.

Agree about tight pistons. Bad mojo.

big difference between a dingle ball hone and a ridgid platu hone.

 

[TheBussman]

hopefully they can help you out with re-machining for the next size up that would be best. Just a thought: I have a few motors out there running with Line2Line Coatings™ - https://www.line2linecoatings.com/ they can spray on a coating to make the piston larger, they are very precise on how thick they apply the coating. Usually use this for engines where larger pistons are not available.