Crank Problems

I have just recently had a crank repaired from what I thought was a reputable grinder. I won't say who yet because I have to give them the opportunity to fix this problem. I had a journal welded and reground to STD size, (this is a big block chevy) I was checking clearances yesterday and found they had ground the crank .003" under on all the journals.
This gave me no less than .005 clearance. Can you get bearing that are +.001 or even +002 ? I spent $600.00 on this fix and don't want to spend more on a regrind if I can avoid it.

Thanks
Corey

 

In Federal Mogul 87200CH is available in a .001". The 3190CP is still available in a .002" but you may have to work on the radius a little. 3190A is also available in a .002" but these are not normally used in a performance application.

 

I'm from Canada and the crank grinder is in California, but when I talked to him before he did the work I made it very clear that I wanted the crank left standard.He also made no request for me to send him anything but the crank. I just got off the phone with them and they said they gave me " drag clearance". Which measures 2.747".I don't know what kind of engines they build but .005" clearance on the mains seems like your playing russian roulette.

Anyways, gotta bitch to somebody.

Thanks
Corey

 

For a hemi, that clearance would be perfect!

 

ran .005 on all my chevy stuff

 

This is a Big Block Chevy, I'm also running 60WT oil, so what your saying is if I use an oversized bearing and get around .004" I might be able to run it like that without too many problems?

That would be great,

Corey

 

I run 4.5 on my small chevy.

i run 50 weight oil.

lots of oil pressure.

Put a good pump in it, put the clearance to 4 and put 60w and you'll have a no problems.

 

I use a Moroso G Rotor oil pump with an adjustable pressure relief valve so oil flow is no problem. Well it sounds like I may not be too bad off after all. I am going to go and get some +.001 bearings tommorow and check it again, if I get around the .004" then I'll run it there.


Thanks Gents

Corey

 

We run .004 on the mains and.007 on the rods but you have to run the right oil and oil pump to maintain the pressure . We run a Titan at 110 lbs with Nitro 70 weight. I just spent the weekend checking every bearing and they look great.
Granted ours is a 392 hemi but the theory is still the same.
Rods clearence was set by Sonny Bryant at .0035 on the brand new crank, then when we installed the Childs and Alberts bearings they had .0035 in them for the .007. I had never experienced these clearences and contacted both companies right away and eventually got educated as to how this realy works.
Just my two cents worth..............

 

Ya ,I dont think Id worry about .004'' with heavy oil. I'm giong from .0028'',up to .0038 with a one thou bigger bearing in my BBC.

 

From personal experience, we had a lot of problems with straight 70, even with .005 clearance. The bearings looked like there was a lack of oil. When we switch to 60 or 50 wt, without changing anything else, the bearings looked great. We typically run in 50 or 60 degree weather up here, so maybe it was too cold for the 70 wt.

 

If you are running normally aspirated 3-4 thous is good. blown you need more. many guys I know running blown chevy use 5 thou. 50-60wt workd just fine. just make sure you are NOT using a stock type pump. a Titon is the best way to go. 70wt is used if you contaminate the oil alot. fuelers run it because at the end of the run its about 45wt.

 

usage

what are you using the crank in, how many rpm's?
that clearance sounds fine with 60 wt oil in blown alcohol with 7000 rpm

 

Its going in a Blown alcohol engine. Probably about 40 pounds Boost.


Corey

 

if it was mine

5 would be fine,