What class of thread fit are ARP head studs and bolts ?
1A , 2A , 3A ?
What is a proper procedure for measuring thread fit into an engine block ?
What is considered too loose ?
Thanks
ARP studs/bolts thread fit
Moderator: Team
Re: ARP studs/bolts thread fit
Don't know about thread 'fit', but ARP need to lift their game. I have had instances where their fasteners are either too long or too short.
Not rocket science getting those dimensions correct.
Not rocket science getting those dimensions correct.
Re: ARP studs/bolts thread fit
There is a lot of detail on thread fit and tolerances in the SAE specs.
Broken down the specs say studs should be a tight screw fit into the female block thread, which theoretically will have been cut with a slightly undersize tap- maybe 0005".
Broken down the specs say studs should be a tight screw fit into the female block thread, which theoretically will have been cut with a slightly undersize tap- maybe 0005".
-
- Guru
- Posts: 1575
- Joined: Mon Apr 04, 2011 8:54 pm
- Location: central Florida
Re: ARP studs/bolts thread fit
Any High Quality Stud / Bolt produced has the threads Rolled into place, not cut with a tap. I really don't know how this process is done, i just know it to be so. Mark H.
-
- Guru
- Posts: 1575
- Joined: Mon Apr 04, 2011 8:54 pm
- Location: central Florida
Re: ARP studs/bolts thread fit
Correction to the above reply, i meant to type "Die" not Tap. Reminds me of a person calling a Nut a Bolt or vise-versa.
Re: ARP studs/bolts thread fit
Here's how ARP rolls the thread on their studs.
https://www.youtube.com/watch?v=UGqzj0CPx08
You can measure the diameter of the bolt or stud and determine its thread class, but it doesn't tell the whole story because the class of fit requires that the internal threaded part has the same tolerance. In other words, it takes both parts to keep the thread class in tolerance. AFAIK, connecting rod bolts (and some flywheel bolts) are the only class 3A (and their nuts 3B) used in automotive. Anything going into cast aluminum or cast iron will be 2A.
I'd suspect ARP's are no different, but measure and compare to the bolt's thread class tolerances.
https://www.natool.com/wp-content/uploa ... 01-102.pdf
https://www.youtube.com/watch?v=UGqzj0CPx08
You can measure the diameter of the bolt or stud and determine its thread class, but it doesn't tell the whole story because the class of fit requires that the internal threaded part has the same tolerance. In other words, it takes both parts to keep the thread class in tolerance. AFAIK, connecting rod bolts (and some flywheel bolts) are the only class 3A (and their nuts 3B) used in automotive. Anything going into cast aluminum or cast iron will be 2A.
I'd suspect ARP's are no different, but measure and compare to the bolt's thread class tolerances.
https://www.natool.com/wp-content/uploa ... 01-102.pdf
Re: ARP studs/bolts thread fit
Op did you read this article posted on the 26th, same as your post?
https://www.streetmusclemag.com/tech-st ... -in-depth/
https://www.streetmusclemag.com/tech-st ... -in-depth/
Channel About My diy Projects & Reviews https://www.youtube.com/c/BOOTdiy
I know as much as I can learn and try to keep an open mind to anything!
If I didn't overthink stuff I wouldn't be on speedtalk!
I know as much as I can learn and try to keep an open mind to anything!
If I didn't overthink stuff I wouldn't be on speedtalk!
Re: ARP studs/bolts thread fit
My question is: What does the factory use to thread the holes for the head studs/bolts on the engine block?
What class thread are they? 2-3
Are the tapped, rolled, milled?
Betting they are all done at the same time.
When the factory hones the block for piston fit do they install a plate or hone it with no plate.
What class thread are they? 2-3
Are the tapped, rolled, milled?
Betting they are all done at the same time.
When the factory hones the block for piston fit do they install a plate or hone it with no plate.
Re: ARP studs/bolts thread fit
With all the trash bots here clogging Speedtalk, you throw out my reply with a link to https://optitorque.com/
That's funny.
That's funny.
Magnús Aðalvíkingur Finnbjörnsson