[Fot] TR4 ARP head studs

[Bill Babcock]

Certainly it's feasible that the brilliant designers who were whacking  
together a tractor motor carefully calculated the yield strength of  
each stud using their Lucas computers, and built in just the right  
amount of stretch to safely cycle the gaskets. But I doubt it. It does  
get done. Volkwagen Rabbit motors have stretch-to-torque single use  
headbolts, but that's that whacky germans.

You can always go back to the springy stockers. Some very good engine  
builders consider them adequate, and therefore not reasonable to  
replace. I just LIKE the ARP studs, with their broached allen head for  
fast removal, their smooth threading into the block, and their  
positive torquing.

As for leaks, I generally undertorque a bit, especially with a steel  
gasket, then look for mayo in the oil. If I see to much I go  little  
higher. That isn't the studs, that's the miserable head gaskets we've  
got to work with and the imprecision of the gasket surface with a wet  
sleeve engine. I wouldn't run an engine without them, but that just me.

On Jul 23, 2008, at 5:19 AM, Henry Frye wrote:

> I am running a set of these, but am not sold these are the way to go.
>
> Yes, there is a surprising amount of stretch in the stock head  
> studs. It
> made me nervous torquing the head to see the wrench swing so far to
> achieve the torque I was shooting for. I got used to it... Then the  
> ARP
> studs. The torque wrench does not swing nearly as far as it does with
> stock studs.
>
> I have to wonder, was the stretch designed into engine/head  
> assembly? As
> the engine goes through a heat cycle and things start moving, the ARP
> studs are not allowing much of anything to happen with the head/block.
> No doubt there is some expanding going on with the stock studs...
>
> Which goes back to the directions provided with the ARP studs. They  
> say
> torque to something less than published torque. When I followed those
> directions, my head gasket leaked.
>
> I really never had an issue with stock studs. I am wondering if the  
> ARP
> studs are helping me or hurting me...
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Bill Babcock
Babcock & Jenkins
Billb at bnj.com
503.936.7660
www.bnj.com