Grinding a stroker crank

[John]

The shops that specialize in this work perform it daily on stock crankshafts, not a do it yourself level project. Some intense set up and process control beyond most shops capability. I have experience with Columbus Colweld and have spent time watching their processes. Just be very careful in selecting the shop to do the work, If this is not a routine task for them, you are at the wrong place.
John

[Alex22]

High quality steel, good forgings and billet crankshafts are generally ok to weld and offset grind, cheap steel cranks are borderline (judgment call by the crankshaft welder and engine builder). Griding cranks is one of the only things we don't do in shop; the crank grinder we use is the best in the area and all his work is top notch.

~Alex

[astjp2]

Offset grinding a crank is not rocket science, most machine shops have a crank grinder that can accomplish this task quite easily....I had my crank offset ground .020 and it was a short snout 4.2 crank. you do not have to weld anything for this minor procedure. I am running H802CP pistons, 4.2 rods and .020 rod bearings. Even with grinding the crank I still had to shave over .010 off the block to get a .000 deck height. Tim

[seanyb505]

Ive got to wonder, assuming you bored the engine .030 over, does the extra 24cc by only offset grinding the crank .020" make a difference?

[John]

Offset grinding a crank is not rocket science, most machine shops have a crank grinder that can accomplish this task quite easily....I had my crank offset ground .020 and it was a short snout 4.2 crank. you do not have to weld anything for this minor procedure. I am running H802CP pistons, 4.2 rods and .020 rod bearings. Even with grinding the crank I still had to shave over .010 off the block to get a .000 deck height. Tim

The grinding is not a issue. The welding is the issue we were talking about. How much welding was done on your crank? Sounds as if there is a bit of confusion about the difference between grinding a crank and offset grinding a crank. Did you weld it up yourself with a buzz box?
John

[yuppiexj]

High quality steel, good forgings and billet crankshafts are generally ok to weld and offset grind, cheap steel cranks are borderline (judgment call by the crankshaft welder and engine builder). Griding cranks is one of the only things we don't do in shop; the crank grinder we use is the best in the area and all his work is top notch.

~Alex

IF you were paying for a Billet crank wouldn't you just buy the stroke you want?

"SCAT can manufacture cranks for any application up to 40" length and 10" diameter"
from http://www.scatcrankshafts.com/CustomBillet.htm

Maybe when I win the lottery

[astjp2]

I never had any welding done, if you go .030 under on the rods and have it OFFSET ground, you will still use the .030 bearings but you will get .030 more stroke, they only grind the inside radius of the rod journal so it will not change t he outside radius but it does change the center point of the journal by .015 and gives a total of .030 more stroke. The crank grinders that most overhaul shops use are indexed, they set position of the crank in relation of the indexing, set the stone up for the dimentions to grind the journal and they can adjust the offset at that time. I sat and watched my crank get set up and watched it. It sounds wierd hearing it whap, whap, whap as it ground the inner portion of the journal. Just talk to a good engine machinist, they can show you how its done. Cheers!

[John]

And with welding, the crankshaft stroke can be increased from 3.895"' to 4.145". It all can help.
John

[1bolt]

too lazy to look it up on a calculator, what displacement did you end up with with the added stroke?

[astjp2]

Offset grinding a crank is not rocket science, most machine shops have a crank grinder that can accomplish this task quite easily....I had my crank offset ground .020 and it was a short snout 4.2 crank. you do not have to weld anything for this minor procedure. I am running H802CP pistons, 4.2 rods and .020 rod bearings. Even with grinding the crank I still had to shave over .010 off the block to get a .000 deck height. Tim

The grinding is not a issue. The welding is the issue we were talking about. How much welding was done on your crank? Sounds as if there is a bit of confusion about the difference between grinding a crank and offset grinding a crank. Did you weld it up yourself with a buzz box?
John

I did not weld anything, .020 is not much, I did it more as an excercise and so I didnt have to shave the block as much, I also went .040 on the bore. I think my biggest concern is losing the cam and when I swap it into my YJ is getting the correct injectors and fuel mapped out....Tim