Re-using heads bolts-Good or bad idea?

[Tim Ayers]

Well, if there is any doubt, it is better to do them rather than have it pull out on assembly. Mucho time lost then.

I agree with this as well. A few are dodgy and should be done now. I was hoping the stock bolts with the correct thread will help keep the remaining ones in good shape.

Besides plugging them with new threaded inserts, which bolt/stud company uses the correct threads for these flatheads?

 

[Pete]

I agree with this as well. A few are dodgy and should be done now. I was hoping the stock bolts with the correct thread will help keep the remaining ones in good shape.

Besides plugging them with new threaded inserts, which bolt/stud company uses the correct threads for these flatheads?

I have used both Threadserts and Helicoils which have the 7/16-14 threads available.
On my race engines I set the block in the mill and drill and tap the holes for a 3/8 pipe thread. I make the inserts from solid bar stock with the pipe thread and screw them in with a pipe wrench. Cut it off with a slitting saw and drill and tap with new thread. On some holes near water I offset the insert to keep away from the hole. With home made 4340 studs you can then torque the nuts tight enough to crush the head if need be...
I use hard high nuts with hard washers under them so there is no chance of pulling the top threads off.

 

[Pete]

I have seen studs that stretched in the center where there are no threads. Don't know if they were aftermarket studs or not. G.M.

Years ago I worked for a company that tested various bolts, studs and connecting links by stress (pull) testing them till they broke.
Almost always they necked down in the middle or in the unthreaded area first and then pulled apart there.

 

[cmbrucew]

Tim Ayers


Check with your local Caterpillar parts man for head bolts.
They are made with a rolled thread.


Bruce

Works good
Lasts long time

 

[Tim Ayers]

I have used both Threadserts and Helicoils which have the 7/16-14 threads available.
On my race engines I set the block in the mill and drill and tap the holes for a 3/8 pipe thread. I make the inserts from solid bar stock with the pipe thread and screw them in with a pipe wrench. Cut it off with a slitting saw and drill and tap with new thread. On some holes near water I offset the insert to keep away from the hole. With home made 4340 studs you can then torque the nuts tight enough to crush the head if need be...
I use hard high nuts with hard washers under them so there is no chance of pulling the top threads off.

Wow, I wish I lived closer. Sounds like you've got this down pat. A lot of thought and effort goes into what you do. Thanks for the advise/sharing the knowledge.

 

[19Fordy]

Really surprised to see you make such a statement. What are you using to determine this, a micrometer? Really? Never saw one like that. Then I never considered a microscopic evaluation a sensible thing to do.

Years ago I was tightening an 8BA headbolt with a torque wrench and I felt it "go soft" with no movement of the needle. I carefully reversed direction and removed the bolt. It was noticeably "necked down" on the shank. I saved the bolt for many years but lost it somewhere along the span of time.