2.8L M20 build - Now with 2.7L!

[acolella76]

I know they aren't too expensive but I'm pretty sure the cost of oversize bearings + having a crank turned down would be a lot cheaper than buying a new M52 crank and having the counterweights machined down and balanced again! If it comes down to buying another crank I am going to pull the block and have it decked 2mm to run the M20B25 pistons with the 81mm crank.

Also not looking forward to taking that front crank nut and trans off again :p

[whodwho]

Having to pull it either way :)

Not sure the going rate to have one turned but you can pick up cranks pretty reasonable now days.

[acolella76]

Out of options as in... have the journals machined down? Or new crank?

[whodwho]

3 or 4 out of the 6 journals were perfect. Don't remember which ones exactly though. I was wondering if it was already undersized but it wouldn't make sense for someone to cut down only 2 or 3 of the journals lol

ahh, I though you only checked the bad ones. Nobody would turn a partial set of journals, sounds like you are out of options...

[TurboJake]

3 or 4 out of the 6 journals were perfect. Don't remember which ones exactly though. I was wondering if it was already undersized but it wouldn't make sense for someone to cut down only 2 or 3 of the journals lol

It costs more. 99% of people are cheapasses when it comes to maintaining vehicles.

That right there is explanation enough if it happened. It's cheaper to turn down only a couple and it's cheaper to buy only a couple oversize bearings.

The vast majority of people will always seek out the cheapest way to keep something running.

[acolella76]

You need to check the journal diameter, it is possible it was already undersize?? For a quick and dirty you could also try the plasigauge trick on a good journal and see if it registers.

3 or 4 out of the 6 journals were perfect. Don't remember which ones exactly though. I was wondering if it was already undersized but it wouldn't make sense for someone to cut down only 2 or 3 of the journals lol

That's what I'd do. I want to see this 2.8 running on the dyno, so please make it work. I know, I'm selfish.

You aren't the only one that wants to see this thing tuned, I promise! :)

[frankenbeemer]

Thanks for the offer, but I have two of them sitting next to me lol. Really don't want to have to go back to 2.7 though... but it looks like I might have to :(



I am pretty certain that the crank is bad. I just don't know how badly.

I think I may take the crank to a machine shop and see if they can turn it down for oversized rod bearings. Thoughts?

That's what I'd do. I want to see this 2.8 running on the dyno, so please make it work. I know, I'm selfish.

[whodwho]

You need to check the journal diameter, it is possible it was already undersize?? For a quick and dirty you could also try the plasigauge trick on a good journal and see if it registers.

[acolella76]

I'd just do a new crank.

ETA crank? I haz.

Thanks for the offer, but I have two of them sitting next to me lol. Really don't want to have to go back to 2.7 though... but it looks like I might have to :(

Measuring the crank with a micrometer will tell you if it is good or bad. A bore gauge will tell you if your rod big ends are ok. Make sure to use one that reads down to .0001 inches or .001 metric.

I am pretty certain that the crank is bad. I just don't know how badly.

I think I may take the crank to a machine shop and see if they can turn it down for oversized rod bearings. Thoughts?

[LJ851]

Measuring the crank with a micrometer will tell you if it is good or bad. A bore gauge will tell you if your rod big ends are ok. Make sure to use one that reads down to .0001 inches or .001 metric.

[TurboJake]

I'd just do a new crank.

ETA crank? I haz.

[acolella76]

Yeah. Pulled the piston out, nothing weird is really evident.


I have come to the conclusion that I either need a new crank, need to have this crank machined, or I need to use oversized bearings. Or just start over with an entirely new motor. I put good rods with good bearings on two of the worst journals and torqued them down with Plastigage. They were so fucked that they wouldn't even register.. so I am afraid that the crank is worn down pretty badly.

[whodwho]

You have the head off and the rod caps off, you might as well pull the pistons and inspect them at this point.

[LJ851]

I have 5 "i" rods and pistons you can have if you need them.

[acolella76]

Will do!

So at this point I may have rings that don't seal and might have to get new or resized rods... This sucks a bag of dicks