rebuilding the 7 bolt

This is what I want to do. I cw'd and I want to stroke my motor, but if I wait untill next summer I can do it in school and have professional help and the school will pay for some of it. Also when I told my parents its going to be $2k for just the engine they kind of freaked out. That said I want to rebuild the 7 bolt just so it will last untill next summer(I dont drive it in the winter) Do you think I can get away with remanning the crank and replacing th bearings? I know you never know untill you measure it but I though maybe someone else tried it. The other option is my parents said that they would give me an early birthday and xmas present and pay for my to build a stroker but then I'll need a clutch and flywheel and everything else to do the 6 bolt swap so I think its better to wait

This is what I want to do. I cw'd and I want to stroke my motor, but if I wait untill next summer I can do it in school and have professional help and the school will pay for some of it. Also when I told my parents its going to be $2k for just the engine they kind of freaked out. That said I want to rebuild the 7 bolt just so it will last untill next summer(I dont drive it in the winter) Do you think I can get away with remanning the crank and replacing th bearings? I know you never know untill you measure it but I though maybe someone else tried it. The other option is my parents said that they would give me an early birthday and xmas present and pay for my to build a stroker but then I'll need a clutch and flywheel and everything else to do the 6 bolt swap so I think its better to wait


Well you can just buy a new crank. They aren't that expensive. The thing about 4g63 cranks, is no one machines them because when you machine a crank or remann it it degrades the quality of the crank. It's common to do this on big block V8's because the cranks are much more expensive. If I were you I would just buy a new crank. They are inexpensive.

Any idea where I can find a cheap crank?

go to machv.com.......look on the left side of the page under engine and scroll down, you'll see mitsubishi OEM crank(7bolt). thats where id start....its 600 bucks though. depends on if you wanna spend that much or find one in a junk yard

Ever think about stroking the 7 bolt?

Yeah I have thought about it, and I was strongly considering it at one point but I figured that If I'm going to spend that much money I might as well not take any chances

look at ffwdconnection.com they have the best cranks for pretty cheap I think.... well, the butcher crank for the stroker is fucking crazy.... check them out...

did you ever verify 100% it has walked?

I bought mine from a local shop. It was no where near 600 dollars. You can check junk yards in your area, you can probably find a good crank there.

Or if you have any DSM shops in th area they probably have one.

Why waste money? Junk the 7 bolt and do up the 6 bolt. Hey Scott, want to start our own car club?

New bearings and a reman'd crank should get you up and running until you want to build up that 7 bolt. Just make sure you go to a shop where they know what they're doing. I've had a couple cranks ground before and they turned out just fine.

did you ever verify 100% it has walked?
Endplay was close to .020 and according to what I've read the max is .015.

New bearings and a reman'd crank should get you up and running until you want to build up that 7 bolt. Just make sure you go to a shop where they know what they're doing. I've had a couple cranks ground before and they turned out just fine.
Thats good news. I should be up by the end of the month then

I just got back from the machinest and he suggested that he weld material on the crank and reharden it and then grind it down to stock size so I can use standard bearings and it will be a hardened surface again and its going to cost $175 for all of that plus bearings

I just got back from the machinest and he suggested that he weld material on the crank and reharden it and then grind it down to stock size so I can use standard bearings and it will be a hardened surface again and its going to cost $175 for all of that plus bearings


My shop is a dsm shop and I asked them about this, and they advised against this, but it's your buck.

What do they reccomend besides a new crank?

Don't do it. 7 bolt and rebuild should not be in the same sentence. My brother's car walked with less than 100 miles after the rebuild, he bought a rebuilt crank, and had a 2100# clutch, but still... I would save your time and money.

My problem is I cant afford anything else now and either way I'm not going to swap a 6 bolt untill next summer so I might as well try espically when its only going to cost $300 or less for everything. I think I'm going to trust my machienest on this one, granted he's not a dsm guy but he is so good at what he does it like cheating.

Hopefully it will work out. $300 isn't too bad either.

I would never rebuild a 7bolt that's already walked, just me though. I would have no problem rebuilding a regular 7 bolt, people just write them off.

Correct me if I'm wrong but walking doesnt effect the block just the crank and/or bearings.

Correct me if I'm wrong but walking doesnt effect the block just the crank and/or bearings.


that depends on what theory you believe is behind crankwalk, heh.

Also it may just be a bad luck thing but it you look around you'll see that a lot of people walk again after rebuilding a walked motor.

I'd never touch a 7 bolt, previously walked or not.

the way I see it is if everything is well within spec there shouldnt be any problem

I would never rebuild a 7bolt that's already walked, just me though. I would have no problem rebuilding a regular 7 bolt, people just write them off.
My brother's hadn't walked, he spun a bearing and it walked after the rebuild.

I'd never touch a 7 bolt, previously walked or not.

hehe that's cause you couldn't catch up :lol: :lol:






:icon16:

:owned:

I don't see any problem with him rebuilding his 7 bolt. Heck, If I was rebuilding mine stock I would redo my 7 bolt too. It made it well past 100k miles. If he is gonna drive it for another 100k and it walks again then you can either rebuild it again or buy a 6 bolt. Its cheaper than a brand new car in my opinion...

hehe that's cause you couldn't catch up :lol: :lol:






:icon16:
Oh, shit... yeah, I did get owned. Time to go sit in the corner and lick my wounds...

Bastard. ;)

my 97' gs-t has 163k on it and run great. it pulls pretty damn hard. when it comes time to replace the timeing belt Im going to do a rebuild. Eagle makes forged 4340 steel crankshafts. which would elminate the main bearings being harder then the crank right? SBR sells rebuild kits for the 7 bolts for $500.

Dont need a rebuild kit. Only thing that is coming off is the oilpan and mains. And my motor only has 65k on it

true. but I want to replace the piston rings. so why not replace it all. right?

in your situation yes

I don't know why all of you are bitching about rebuilding walked 7-bolts, I've done a few and they've turned out just fine. As long as it didn't walk so long that it ruined the block, he should be fine. Maybe you guys all have shitty machinists or something, but I haven't had any problems with a ground crank. I would strongly advise against re-welding material back on and then grinding it down to stock size, but grinding it down .010 and running .010 oversized bearings has worked for me. It's the least stressful and cheapest route to get him up and running until he can get something else figured out.

Perfect

Last winter I put together my motor which is a 7 bolt using Eagle rods and Ross pistons. Reman'd crank .020 over.

Lets just put it this way... I guarantee it will crankwalk, 99% of rebuilt 7 bolt motors do. I expect my motor to crankwalk, whether its sooner or later it will. But if you build them correct it can last 20-50k miles before it does, just like from the factory. My motor was thrown together on a drunken night where I had a picture in my head of doing something really stupid. GT42r + 45psi and nitrous. I dont know why I thought it would work but I went with it.

Right now I run a GT42r at 40psi on my 7 bolt motor. Even has a 2g head (thats majorly ported out) with stock valves. I havent added nitrous yet or upped the boost more but I have been flowing around 85~ lbs/min which is probably close to 750-800hp (rough estimate) and I beat the piss out of it everyday. If my motor can handle that, I think you will be just fine with a stock rebuild and a reman'd crank.

For now I would go with it, but make sure everything is in stock spec before starting the rebuild. Are you rebuilding it yourself?

My motor was thrown together on a drunken night where I had a picture in my head of doing something really stupid. GT42r + 45psi and nitrous. I dont know why I thought it would work but I went with it.
LOL That is by far the greatest story I've heard in a long while on here. :lol: