Farm Equipment - Cleaning out the head bolt holes in 301 block?

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Cleaning out the head bolt holes in 301 block?

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=180794
Printed Date: 04 Nov 2025 at 12:13pm
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Topic: Cleaning out the head bolt holes in 301 block?

Posted By: DougG
Subject: Cleaning out the head bolt holes in 301 block?
Date Posted: 27 May 2021 at 9:03am

There was a subject a bit ago on what to use to clean the threads in a 301 AC block,what is recommended to use?

Replies:

Posted By: DrAllis
Date Posted: 27 May 2021 at 9:10am

9/16" NC thread tap, brake kleen, compressed air, light oil or grease on head bolt threads when assembling.

Posted By: DougG
Date Posted: 27 May 2021 at 9:15am

Perfect! Thanks

Posted By: Northern Hoser
Date Posted: 27 May 2021 at 8:54pm

Having just done a 426 block I had the same question. Discovered that a 'tap' is too aggressive for cleaning and bought a thread cleaning tool for the job. Basically a tap but built to scrape clean the existing threads rather than cut new ones.

Followed that up with some brake clean and wire brush down the hole bores and make sure all the crud is taken out the bottoms.

Having measured there's only about 1/2" of room between the bottom of the bolt and the bottom of the block holes when the head is installed.

https://www.summitracing.com/parts/oes-27142" rel="nofollow - https://www.summitracing.com/parts/oes-27142

I purchased a similar kit to the one in the link. Use it all the time now

Matt

Posted By: DougG
Date Posted: 28 May 2021 at 4:17am

Thanks for that info Matt!

Posted By: Ed (Ont)
Date Posted: 28 May 2021 at 5:19pm

Those thread chasers work well. I use them lots. 😀

Posted By: Steve in NJ
Date Posted: 30 May 2021 at 8:03am

I always used a bore brush for cleaning up threads in anything, unless you obviously have a thread that's boogered up where it would need a tap to chase it and straighten the bad part of threads up..

Steve@B&B

-------------
39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife

Posted By: DMiller
Date Posted: 30 May 2021 at 11:50am

On the Cat I am building I did just as noted
Good penetrating or cutting oil with a thread chasing tap not a cutting tap
I also used Detroit Diesel International compound no 2 on threads washers and bolt head contact areas
Always did well for me and the common nickname is peanut butter.
Just bought a new can where it will outlast me.