My Tractor Forum banner

1 - 8 of 8 Posts

·
Gravely 2-wheeler
Joined
·
958 Posts
Discussion Starter #1
A local shop replaced the head gasket on my '69 C8 in 2011. I removed the head today to clean the chamber and exhaust valve and found that the head bolt at the exhaust manifold end (of course) has metal in some threads and a new bolt won't go in (not trying to reuse the old bolt which also won't go in even after cleaning the threads). I am planning to use a thread chaser to clean the threads in the jug. Never used one before. Any watchouts? All other bolts are OK and I used anti-sieze at reassembly.
 

·
Premium Member
Joined
·
2,614 Posts
I would use a tap covered in grease and take a little bit at a time and back it out. The bolt remnants should get hung up in the grease. Clean the shavings from the tap and repeat. Blow out with compressed air when finished.

Sent from my SM-G950U1 using Tapatalk
 
  • Like
Reactions: evsnova74

·
Premium Member
Joined
·
4,440 Posts
5/16-NC tap. If you have a bottoming tap in addition to a regular one, use that after you get a few threads in.

Just take your time. 1/8 turn at most and back it out. The material in the jug is not all that hard. You want to gently remove the extra crap in the threads, not do any heavy cutting.

I generally run a tap through all the threads every time I have a head off for any reason.
 

·
Moderator
Joined
·
2,819 Posts
Third the tap and grease motion. Great excuse to buy a whole set of taps and dies. (y)
 

·
Registered
Joined
·
78 Posts
When I pull the heads I run a starter tap and a bottom tap in the threaded holes. When running them in the holes I turn the tap handle 1/2 turn at the most then back a quarter turn. Be sure to watch the fins, you can break them running the taps to the bottom. Using the bottom tap after the starter tap will ensure the threads are cleaned. Watch out for the two holes at the manifolds, easy to snap a tap there.

Use oil and clean taps as you go......I buy mine at Grainger's.

RB in RI

2462826
 

·
Premium Member
Joined
·
2,614 Posts
You could start out with a thread restore tap and then jump to a cutting tap.

Sent from my SM-G950U1 using Tapatalk
 

·
Gravely 2-wheeler
Joined
·
958 Posts
Discussion Starter #7
I have a set of NC thread chaser/thread restore taps on order. On my regular tap set for cutting brand new threads, the lead in is long so the full diameter threads wouldn't be near the bottom of the hole where needed and the taps remove too much metal for a close bolt fit. I'll only use the regular tap for a short distance if needed to start the thread chaser tap. I can mark the taps with masking tape so that they don't go too deep. Good idea on the grease. I think there is some excess metal in the threads at the top of the hole. I have a variety of picks that I can try first in that area.
 

·
Professional Homeowner
Joined
·
7,467 Posts
I bought a really cheap (like maybe $50) tap and die set probably 15-20 years ago. I dunno... maybe like 80-100 pieces. Menards special? I don’t even remember anymore. What I DO know is that that el cheapo tap and die set has become one of the most used tool sets I’ve ever owned. It’s gotten me out of MANY jams. It’s #1 use is thread pitch gauge (use taps/dies to test bolts/nuts). #2 use is chasing threads. #3 is making new threads. I still have every piece except ironically enough one of the thread pitch gauges it came with.
10/10 would recommend moderately priced tap and die set with lots of variety, standard and metric.
 
1 - 8 of 8 Posts
Top