289-302 ARP small block bolts on 250?

[simon]

Since the falcon six is of no interest for the ARP company, and since they don´t answer any emails concerning main and head bolts for the six, I thought of using 289-302 main cap bolts on the 250.

289-302 small block main cap bolts and 250 main cap bolts share some interesting similarities - both 7/16" coarse threaded, both have about the same underhead length of 3.5". (170-200 main bolts are way shorter)

Yet, they are not equal - the V-8 main bolts threaded part measures 1.025", where the 250 main bolt threads are 1.180".

when screwed in hand tight, the V8 bolts fit great on the 250´s main saddles, but I´m unsure if their threaded length will suffice if the bolts are torqued to specs.

How much will a 7/16" bolt stretch at 70 lb/ft?

 

[Does10s]

Give Mike (AZCoupe) a call at www.fordsixparts.com. He's got the correct ARP bolts and studs in stock.
That's where I got all of our stuff!
Will

 

[AzCoupe]

I only stock studs for the 250 mains. They are recomended (rather than bolts) for the following reason:

Studs provide more accurate and consistent torque loading. When you use bolts to secure the cylinder head, or main caps, the fastener is actually being " twisted " while it is being torqued to the proper reading. Accordingly, the bolt is reacting to different forces simultaneously. A stud should be installed in a relaxed mode, never cranking it in tightly using a jambed nut. If everything is right, the stud should be installed finger tight only. Then when appling torque to the nut, the stud will stretch only on the vertical axis. This provides even more clamping force on the head or main caps. Remember to make sure all bolts and studs are re-torqued after the engine has been run for a few minutes. Make sure to use thread lube when installing.

For more tips on how to install studs, visit the ARP website, or the FSPP website. http://www.cquesttechnologies.com/fspp/arp.asp?cat=44

 

[simon]

I´ll order my parts from Mike anyway, as soon as he has the 250 timing chain in stock.

Still, I´d like to know if small block bolts are suitable for 250 mains, with the given difference of .150 shorter threads.

 

[Does10s]

I would bet that the main studs are the same, but I'm not 100% sure. I do know that the 289/302 rod bolts are the same for the 250. That's what we used on ours.
Will