Justin Wagner wrote:
>
> In regards to the TR 4A type motor...
>
>
> I've heard different ideas over the years... but... when you re-torque
> the head...
>
> should you loosen each nut a little, before re-torquing? or what?
>
>
>
> So I'm interested to hear a consensus of opinion on this issue.
Here are some things to think about:
Do new car heads need retouqueing? Generally not, to my knowledge.
Why?
Is the tradition, advice, myth of retorqueing because of:
1. Used bolts/studs stretching?
2. Poor quality gaskets affected by initial heat?
3. Back in the shadetree days all the crap needed retorqueing?
When I put together the hot Spit motor, I omitted the use of studs. Who
uses them anyway, other than Standard and BMC? Instead I used AN grade
(Air Force/Navy grade) bolts from Pegesus Racing catalog. These are the
best non-government (and usually government) money can buy. They make
grade 8's seem like silly putty, I'm told. And, yes, I know all about
the arguement that studs keep the torque at the top (nut end) while
bolts put all the force into the threads in the block. (Maybe they used
studs because they wanted to go skimpy on the block thread
depth/quality. My risk now!)
But I lubed the threads good to use as much torque as possible for
compression and not be consumed by friction. I torqued to spec (the
block threads probably could not take over spec).
Result: no ill effects (so far) and I never retorqued the bolts.
My guess is that these bolts don't stretch. And if you think this
stretching business is far fetched, just try reusing a BMC stud about 6
times. After a while you cannot put 45 pound feet on it. It will just
keep stretching at about 30 pounds! Amazing!
--
Brian W. Neuschwander
Beach City Gas Station
Santa Cruz, California
1979 Spitfire, 1965 Spitfire, 1963 Consul Capri
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