Hi Guys,
Not exactly sure which forum to put this one... Require engine building advice for a 350 I'm building. The block is an '87 TargetMaster GM Goodwrench 4 bolter. I recently purchased a set of ARP main studs for the build but on trial assembly I found the short outside studs were short from the top of the nuts by about 3 threads!
The instructions supplied by ARP say to screw the studs in 'Finger tight and NO MORE'. My question is this...
Should I screw the studs down to finger tight and install the nuts, and washers, so the nuts do not completely get filled or... screw the studs down fully and then back them off aprox' 1.5 turns in order to get the full threads on the nuts?
I have EMAILED ARP but get no response. Anyone out there got an idea of which way to go here? Rather baffled on this one... Thanks and kind regards...
Geoff.

 

not sure if it'd make much differance, but in everything i've ever inspected where thread engagement was checked the standard was 1 thread past the nut. my guess is you have a block from mexico, or even here, where the holes got drilled and tapped a little too deep.

 

What stops the studs when you screw them in? Do they just keep screwing in until they bottom in the hole?

If they go way down deep into the hole, I'd back them out until the threads are just below the surface, and check the nuts again. I wouldn't put it together and leave it with the nuts not all the way on the studs, or the studs not all the way threaded into the block. I'd suspect an issue with the block or cap machining and the factory's hardware selection, not ARP's QC; there's way too many motors out there that those studs do fit correctly.

 

Thanks for your replies... This is, indeed, a Mexican block and I think the problem is due to the holes and threads being slightly too deep.

My main concern is the effects of having the studs not bottomed out in the holes? Or does this have no effect at all? I guess, so long as there is enough thread at both ends it may make no difference?

Kind regards... Geoff

 

As long as the threads are fully engaged, it doesn't matter whether the studs are bottomed or not. There's no magic hiding down there waiting for them.

Is that the problem? the studs just screw way down into the block? if so, just put them in only far enough to fully engage the threads, with some blue Loctite on them.

 

Thanks RB83L69... This is what I suspected but thought it best to get some other opinions, better safe than sorry.

Appreciate your help... Kind regards...
Geoff

 

I was once working on a military project with a mechanical engineer. We had to bolt some high power microwave equipment down to a cooling plate, and the plate was rather thin. He had to figure out how many turns of thread engagement were needed to obtain full clamping force. He calculated that 4 turns were enough.

Now I don't know how this relates to a steel stud in an iron block, but I'd think if you have equal number of turns in the block and the nut, that's all you could expect in terms of clamping force.

You could screw one of the studs into the nut and count the number of full turns it takes to get the stud flush with the nut. Then screw the stud into the block at least that many turns and use locktite.