GN block question

[chevy2480]

84/85 turbo cranks are the same. I know a few guys running in the 10's on both cranks. But as with anything someday it will let go.

 

[87regalkid]

Here's another question, when I was looking for different pistons I noticed this guy online selling a brand new set of v6 3.8l GN turbo pistons bored .030. Then I started researching about getting my block bored out, but I don't know if you need a bigger crank.

Also, there is another guy online selling three cranks and he says that one is std, one is .010 and one is .020, but he doesn't know how to tell this difference between them. I don't even know what those numbers for a crank means, would I need a .030 crank with .030 pistons or does that even relate?

 

[chevy2480]

Having the motor bored over for bigger pistons has nothing to do with the crank its only changeing the bore size of piston. The only time crank would need to be change is if you go stroker. The sizes he is giving you is the amount the crank's rods and mains have been cut thus you would need bearings to match to take up the extra meat that has been removed from crank. Stay away from anything cut more then .020 i wouldnt even recommend that but the more cut off they say the weaker the crank. My motor currently in my GN has a .030 crank but its all I could find.

 

[87regalkid]

Thanks, I'll try to get the standard uncut one from this guy then.

 

[87regalkid]

Alright, i started pulling this motor apart but i am stuck on the harmonic balancer center bolt, is it a normal thread (right-tight) or opposite, or is there a special way to get it off. I stopped the flexplate from moving and put some force to the bolt with a breaker bar, but it won't budge. And it gets better, my engine stand is being occupied by my brother's engine so mine is on jack stands, which obviously poses a greater problemwith the engine rocking around. Any input is appreciated.

 

[chevy2480]

Normal thread. Once bolt is out balancer simply pulls off.

 

[87regalkid]

Got it down to a bare block today, but I meant to ask earlier, do GN's have different cams or will mine work. Also, where does an oil galley need to be drilled into the block in order to make mine work.
Thanks,

 

[chevy2480]

Got it down to a bare block today, but I meant to ask earlier, do GN's have different cams or will mine work. Also, where does an oil galley need to be drilled into the block in order to make mine work.
Thanks,

Caps are the same. Oil return gets drilled on tge passenger side of block right above the timing chain cover you should see a flat boss that is where it goes.

 

[87regalkid]

Thanks for all your help chevy2480, I really appreciate it.

 

[87regalkid]

I forgot to ask, do you know the thread size for the oil return port that I have to ge drilled into the block, pretty soon I'm taking the block to the machine shop and I need to know.