Crank Question: Do I need to regrind?

[Poulsbo]

Another rookie question...this time about a small scratch that developed after initial preassembly.

Here's the story.

I checked all main and rod clearances using micrometers and a bore gauge. Everything checked out.

I then installed the cam, crank and timing chain kit (using Napa engine assembly lube just like final assembly.)

I then test fitted my heads, and went to work on getting my valve train geometry right. (Thanks again for the help of this forum!)

I got everything where I felt comfortable with the set up...then I disassembled the whole thing.

The only trouble is that when I pulled off the rod caps on the #1/2 journal there was a new scratch about 1.5" long, right down the middle, between the rod bearings. (See attached picture for detail)

Question: Do I need to have my crank reground/polished? Or is this a non-issue?

Thanks again for any help.

Poulsbo

[68post]

That appears to just be a witness mark left from between the bearings ! As it seems to be perfectly centered and very parallel also.

Can you catch a fingernail on it ? If so can you get a much closer "close-up" pic ? ( even if you can catch a nail - if it's perfectly centered then it cannot cause a problem )

[Poulsbo]

Thanks for the fast reply 68post!

I can just barely catch my fingernail...and it appears to be exactly centered. But I'll get a closer, close-up tonight and repost.

Cheers,
Poulsbo

[GRX]

Ditto on what 68post said. There will be a mark like that on them all after a couple hours of running. Re-inspect everything. Then inspect again.

[Poulsbo]

Thanks for the fast reply 68post!

I can just barely catch my fingernail...and it appears to be exactly centered. But I'll get a closer, close-up tonight and repost.

Cheers,
Poulsbo

[Poulsbo]

As promised, here is a closer picture of the scratch for reference.

Let me know if you think I have an issue here.

Thanks!

[Marv D]

Being between the bearings it would be of no impact on anything. You must have goten something trapped between the rods as you mock'd things up?? If you were overly concerend I bet some 1500g wet/dry and some mineral spirits would polish it away in a heartbeat. But I wouldn't even mess with it. You should see some of the DEEP scars I've seen in engines that were assembeled dirty and it never showed anywhere except to the guy that disasembles and shakes his head.

[Poulsbo]

Thanks MarvD, GRX and 68post!

I'll put it out of my mind and get to final assembly.

Cheers!

[clinebarger]

Scratch from Feeler Gauge??

[Poulsbo]

Doh! You're probably right clinebarger!

I did triple check the rod side clearance with feeler gauges...and I probably did it myself.

This is my first build...so everything is new. I'll be more gentle next time.

Thanks!

[68gmsee]

As mentioned above by others. Just get some crocus polishing cloth at NAPA or at your machine shop and just smooth it out to make sure there aren't any microscopic burrs. Personally, I don't like to use wet/dry sandpaper.

I have a crank I used on my '69 with a slightly wider mark than yours and never had any problems with it. Used it for about 15 yrs.

[68post]

I didn't think it looked like much and it looks even lighter in a close-up , but if you can catch a nail on it - it is something ( a very little something !!).

[crazy longhorn]

Originally Posted by Poulsbo

Doh! You're probably right clinebarger!

I did triple check the rod side clearance with feeler gauges...and I probably did it myself.

This is my first build...so everything is new. I'll be more gentle next time.

Thanks!

My bet also....I would call it a non issue You have what, maybe .010 side clearance tween the pair of rods ....the bearings will never touch that line! Longhorn

[Poulsbo]

Thanks everyone!

I'll get some crocus cloth this weekend and touch it up.

Cheers!