[DeTomaso] Torquing head studs/nuts Re: Another Grenade Job - (sorry long)
Asa Jay Laughton
asajay at asajay.com
Tue Dec 29 19:13:18 EST 2009
Will,
Thank you for that detailed answer. ;)
Asa Jay
Asa Jay Laughton, MSgt, USAFR, Retired
& Shelley Marie
Spokane, WA
1971 Mach I Mustang [ASA JAY]
1973 Pantera L 5533 [ASASCAT]
******************************
http://www.asajay.com
http://www.teampanteraracing.com
wkooiman at earthlink.net wrote:
> I usually search for torque specs from ARP. If I can't find them, I use the specs from Ford, but I use the bolt specs, even though they are studs.
>
> Studs are supposed to require less torque, since they have a finer thread count, but the ARP studs are stronger than Ford bolts, so they need more torque to get the proper stretch.
>
> Fortunately, the studs (or bolts) normally come from APR with the proper torque specs.
>
> The reason the outermost studs loosen is because they're not cooled by oil. When the engine gets hot, the outmost studs are right above the exhaust ports. They bear the brunt of the engine heat. The innermost studs, while still hot, are not nearly as hot.
>
> So... when the engine gets hot, it compresses the bolt holes in the heads. The stud bolts don't loosen - i.e. spin the wrong direction. The studs/bolts are the same size, but the head is slightly smaller - and as discussed, moreso on the exhaust side.
>
> I don't think this would be the case with iron heads, and probably not with a more modern alloy. The A3 heads feel softer than Edelbrock heads, for example.
>
> BTW, when I take the engine apart, I sometimes run a 1/2" drill bit through the bolt holes to clean them up. That's how I know the heads are compressing - slightly. A couple of times, the studs were wedged in the heads. I had to smack 'em out with a punch.
>
> Asa - I wouldn't worry about the studs. Studs are fine. I've always been a stud
> kind of guy, but quality bolts work too.
>
> BTW2 - studs are "the" way to do your headers. I had my headers off the heads in 15 minutes. The biggest hassle with head studs is it's a hassle to remove the heads, and especially with the engine in the car. Even made out of aluminum, it's a fair amount of work. Bolts would be much easier.
>
>
> -----Original Message-----
>
>> From: Asa Jay Laughton <asajay at asajay.com>
>> Sent: Dec 29, 2009 12:08 PM
>> To: detomaso at realbig.com
>> Subject: [DeTomaso] Torquing head studs/nuts Re: Another Grenade Job - (sorry long)
>>
>> Okay, so Will used all head studs and presumably nuts on them torqued to
>> spec. However, in an earlier post, he also mentioned how it seemed like
>> those on the exhaust port side were not as tight when he went to
>> disassemble the head. So here are my questions.
>>
>> Is there a different torque procedure that should be used with regard to
>> studs versus bolts?
>> Is there a difference in how to install the stud that could possibly
>> make them loosen up versus the torque on the nut?
>> Is it a good practice to go back and re-torque the nuts on the studs at
>> some interval?
>>
>> I'm curious as I had thought of going the stud route at some point and
>> am worried by Will's finding.
>>
>> Thank you,
>> Asa Jay
>>
>>
>> Asa Jay Laughton, MSgt, USAFR, Retired
>>
>> & Shelley Marie
>> Spokane, WA
>>
>> 1971 Mach I Mustang [ASA JAY]
>> 1973 Pantera L 5533 [ASASCAT]
>>
>> ******************************
>> http://www.asajay.com
>> http://www.teampanteraracing.com
>>
>>
>>
>>
>> wkooiman at earthlink.net wrote:
>>
>>> I didn't use studs & bolts. I used all studs.
>>>
>>> I removed the outermost studs to make it easier to remove the heads.
>>>
>>> The rods are SCAT H-beam. I have the box with the PN at home.
>>>
>>> -----Original Message-----
>>>
>>>
>>>> From: jderyke at aol.com
>>>> Sent: Dec 28, 2009 1:42 PM
>>>> To: detomaso at realbig.com
>>>> Subject: Re: [DeTomaso] Another Grenade Job - (sorry long)
>>>>
>>>> In a message dated 12/27/09 10:01:10 PM, asajay at asajay.com writes:
>>>>
>>>>
>>>>
>>>>> I see studs installed at the top but nothing at the bottom. If this is
>>>>> the case, I'm wondering what others may think about:- using a combination of
>>>>> studs and bolts
>>>>> - using all studs and what the re-torque procedure on them should be.
>>>>>
>>>>>
>>>>>
>>>> If your engine used a torque plate during final honing AND you used both
>>>> studs and bolts then as during assembly, I see nothing wrong except for the
>>>> complication this brings- changing sockets etc. Studs will distort the
>>>> cylinder walls differently than bolts when tightened, which is why you should not
>>>> torque-plate-hone with one combination, then switch to another for use.
>>>> Re-torquing should be the same although some say that one should bring the torque
>>>> level up in 4 stages of only 25-30 ft-lbs in each stage -not necessarily
>>>> with studs or bolts but with iron heads to prevent cracking. I also like
>>>> composite head gaskets which are more forgiving in torquing and in use than steel
>>>> shim head gaskets. But none of this will cause broken rods. What brand of
>>>> rod failed, Will? Curious- J Deryke
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