I was reading another older thread on her about someone that used JB
Weld on a cracked engine block. They said it worked well on a HOT
engine. Someone else said that JB Weld is rated to 600 degrees F.
OK, but will it work on an exhaust manifold? I have one of the 3
studs that refuse to thread into the manifold anymore. The stud is
new, so the manifold threads are shot. I am not willing to change the
whole manifold since I probably wont keep the car too much longer, and
the new stud will probably outlast the car. I thought that JB Weld
might keep it in there, and after it dries well, I can tighten the
nut, (but not real tight).
I have no clue how hot an exhaust manifold gets????? It it over 600F
This is a Chevy 307 engine (the olds engine they used). There is no
way to drill thru this manifold and use a nut and bolt (some can do
this, but not this one because of the shape).
Thanks for all help
JB ain't going to handle it my friend. They make an aftermarket clamp
that can be used instead of a bolt. You could rethread the hole to a
larger size. If you can get a bolt there, you can get a tap there too.
As a last ditch effort you can use two of the best quality screw clamps
in an X pattern between the pipe flange and manifold. This really works.
Of all the things suggested, and THANKS TO EVERYONE, that clamp sounds
like it would probably be the easiest thing to use. Do they sell them
at a place like NAPA / CARQUEST / AUTOZONE? Or can I order online
(website referals please), or do I need to go to a muffler shop?
I should note I live in a rural area and specialty parts are
impossible to find locally. We have a Napa and Carquest. If I drive
an hour, there's Autozone.
I have TWO of the THREE bolts securely tightened now, so I really just
need to pull that 3rd one tight. I used a custom made (at muffler
shop), split flange, and it's like 1/4 inch thick. So, drilling
oversive would require removal of the whole exxhaust system again, and
that does not sound like what I want to do. In reality, it's a 17
year old high milage car, and while a complete new exhaust system
including manifold would be the ideal, I just want to get the exhaust
quiet again, before the cops pull me over. Actually, Its very quiet
now. One pipe, one muffler one donut and the split flange did the
trick. But I already know that donut will burn out quickly if I dont
get that 3rd bolt tightened.
nope. a helicoil is what you need. you still will need to drill the
hole oversize and then tap the hole with the special tap provided with
the helicoil kit.
PS- there *was* a Chevy 307 as well; I think it was a 327/350 bore with
a 283 stroke, IIRC. My dad had one in his '73 pickup.
replace "fly" with "com" to reply.
The Olds 307 was originally a Chevy engine, which GM later used in most of
its car lines. After a class action lawsuit, GM took a lot of heat for
installing their "GM product" engines in Oldsmobiles, Pontiacs and Buicks .
Seems some people wanted an Olds 307, not a Chevy 307. At one time, each
division had unique engines, but that made little sense from an economic
view when the industry was getting creamed in the mid 70's. Anyway, it had
the 283's bore of 3.875" and the 327's stroke of 3.25". This is not to be
confused with the legendary 302 ci motor, which had a 327's 4.00" bore and a
283's 3.00" stroke. Sweet.
Looking at the blocks closely, they were entirely different blocks,
altho' they may have shared the same bore & stroke. Completely
interchangeable, engine-mount & trans. pattern, with the Olds 350--but not
with the Chevy 350, as was the Chevy 307.
Where you mentioned 'sweet', you were dead on! That Chevy 302, which
was basically what we hot-rodders had done years earlier, was a 283 bored
out to 4 inches--or, as you said, a 327 bore & a 283 stroke. Man, was it a
screamer--& "sweet"!!!. s
THere seems to be one problem though. This hole is not one that goes
all the way through. It goes into the casting and is "internal" in
the manifold itself. The hole is only maybe 5/8 inch deep. I know
taps are tapered, so I will never get it in far enough to make the
actual threads. What can I do to solve that?
Buy a "bottoming tap" or if you have a lot of old taps laying around
just cut one off after the taper and grind just enough of a chamfer on
the end to let it start in the threads, but no more. You will need to
start tapping the hole with a regular tap and then finish them up with
the bottom tap. I've actually modified a Helicoil tap like this just
for this situation (wasn't a manifold though, it was a blind hole into
a thermostatic fan clutch that was stripped in my case.)
I'm glad you mentioned cutting off a regular tap. Where I live, there
is no place to buy specialty tools like that. In these rural areas
one is lucky to be able to get a the brand of spark plug desired.
I read about someone who used JB Weld on a cracked
engine block. They said it worked well on a HOTengine.
Someone else said JB Weld is rated to 600 degrees F.
OK, but will it work on an exhaust manifold?
Probably not. One way to break down epoxy bonded
joints is to heat them with a torch. Bonds which
would work in a hot engine block would probably not
survive the temperature in a hotter exhaust manifold.
If possible, the cleanest fix for a stripped thread in
the manifold stud boss is to install a helicoil insert.
Another possibility is to tap-drill the blind stud hole
all the way through and re-tap the thread though
so you can use a regular hex screw or a longer stud.
Another possiblilty (not very elegant) is to drill or
grind a hole through the side of the stud boss until
the blind stud hole is exposed, then use tightened
loops of wire to pull the head pipe flange tight.
I agree, a tapped repair is best for studs, as for putty to
fill voids, I've heard of a product called Pyro Putty supposedly
made to withstand tremendous heat, used to fasten motorcycle
pipes to cylinder head. Furnace Cement withstands the heat, but is
short lived in Auto applications, vibration being cause. Nix to
High temperature Silicone too, it cooks away on head pipes can survive
aft of cat.
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