Anthony wrote:
>
> GMCullan wrote:
>>
>> Yancey wrote:
>>>
>>> Hi Sean,
>>> Went and checked my taps just to make sure, cat ate
>> my
>>> sandwich while I was gone, thank you Sean! Seems the correct size
>>> for exhaust studs haven't changed since this morning... still 8X1.25
>>> m.m.
>>> I liked your advice on welding a nut on and screwing the stud out.
>>> The only thing I can add is: Make DAMN SURE that if you have to
>>> drill and retap, that you centerpunch the stud EXACTLY in the
>>> middle, drill a smaller hole first and then the bigger hole next. IF
>>> you get the hole off-center you will have problems. There are
>>> step-studs available if you have to drill oversize, (8mm on one
>>> side, and 10 mm on other side) or you could use a helicoil (if you
>>> need to drill larger hole.)
>>> Yancey
>>>
>>
>> Gentlemen, centered on the stud for sure! I have a neat little jig
>> that lets me center on a stud as long as I have a little nub to work
>> with. A flush break is more difficult to work with and requires
>> great care. Plus, as you've suggested, I always drill an undersized
>> hole first. At least I didn't have to look far to find a set of
>> studs. One of my older Yamaha motorcycles used the same size and I
>> have at least a dozen on hand.
>>
>> Sean, I did try your suggestion of MIG welding a nut on to the stud
>> stub. I also put a marking across the end of the stud. Using that as
>> a basis, I was twisting the length of the stud without turning the
>> portion within the head. So now it looks like drill time for both
>> studs. Or I suppose I can always take the easy way out, remove and
>> toss the SP heads and replace them with DP heads. Hmmm? Naw! Where's
>> the challenge with that?
>>
>> Thanks again for your help,
>>
>> Gerry Cullan
>>
> Gerry,
> Don't bother trying the easy out method. And don't bother with
> helicoil. Blind holes are the worst to retap, I am betting on you
> replacing the heads. I tried this not too long ago although the
> heads weren't any good to begin with. Good luck.
> -Anthony
>
Hi Anthony,
Except for the two studs, the heads are in very good condition. I
have no idea as to the mileage of this motor, but the pumping
compression is near the top of the range, leakdown is very low, and
it uses little to no oil between changes. It also starts right up,
idles well, and provides excellent "spunk"for the car.
Drilling and tapping studs out is nothing new for me, even working
with blind holes. I center drill the stud (using a positive depth
stop so that I don't over-drill) until I'm just touching the threads
in the head. They I chase the old threads out with the correct sized
tap.
Yancey and Sean provided the information I needed, i.e., stud size.
The rest is just drill (very carefully) and tap the threads.
And to tell the truth, earlier this winter I was so paraniod about
the prospect of welding a new front tranny mounting bracket to my
pan. I bet I used the better part of a two pound spool of welding
wire practicing. But when I finally got under the car to do the
weld, it was almost anti-climatic. It took me longer to clean and
prepare the welding area than to run the actual weld. In retrospect,
I should worry more about drilling and tapping out busted studs than
welding. But I've done studs for years. Learned from a friend that
builds NHRA V8's for the various "gas" classes. He wanted to teach
me welding, too. But I shied away. I'm sorry I did, for it is
relatively easy, great fun, and very satisfying. I'm already looking
for more welding projects. You know the feeling, new toy and just
gotta' play!
Best regards to all,
Gerry Cullan