Thoughts on ex manifold extraction/heating
Thread Starter
Racer
Joined: Jun 2013
Posts: 412
Likes: 48
From: Auburn Maine
Thoughts on ex manifold extraction/heating
Hi all,
I'm looking at removing my (presumably), stock exhaust manifolds on my 74' L48(studs are snapped off)
I've received advice/tips such as , multiple treatments of e.g. PB blaster on the bolts,
and that followed by heating the bolts to red-hot then attempting removal.
The heating method seems to be almost universal in opinion.
Yesterday, I looked at the locations of the various bolts and two things stuck out to me.
1) I'm not able to even reach some of them with my can of PBB, although perhaps a blow-straw thingy
might help that: there's just not a lot of room in there!
2) More importantly, I'm curious to know if by heating these bolts to cherry-red hot, am I in danger of melting some other component(s) in the process?
3) Are there some things that ought to be removed to enable this process to go...smoother?
Does anyone have direct experience who can speak to this?
I guess there's perhaps a #4
4) Is the whole process made infinitely easier/doable by lifting out the engine, at least some..?
(wouldn't look fwd to doing that by any stretch)
Thoughts are welcomed
Cheers,
Rich
I'm looking at removing my (presumably), stock exhaust manifolds on my 74' L48(studs are snapped off)
I've received advice/tips such as , multiple treatments of e.g. PB blaster on the bolts,
and that followed by heating the bolts to red-hot then attempting removal.
The heating method seems to be almost universal in opinion.
Yesterday, I looked at the locations of the various bolts and two things stuck out to me.
1) I'm not able to even reach some of them with my can of PBB, although perhaps a blow-straw thingy
might help that: there's just not a lot of room in there!
2) More importantly, I'm curious to know if by heating these bolts to cherry-red hot, am I in danger of melting some other component(s) in the process?
3) Are there some things that ought to be removed to enable this process to go...smoother?
Does anyone have direct experience who can speak to this?
I guess there's perhaps a #4
4) Is the whole process made infinitely easier/doable by lifting out the engine, at least some..?
(wouldn't look fwd to doing that by any stretch)
Thoughts are welcomed
Cheers,
Rich
Thread Starter
Racer
Joined: Jun 2013
Posts: 412
Likes: 48
From: Auburn Maine
Burning Brakes
Joined: Oct 2002
Posts: 1,040
Likes: 109
Hi all,
I'm looking at removing my (presumably), stock exhaust manifolds on my 74' L48(studs are snapped off)
I've received advice/tips such as , multiple treatments of e.g. PB blaster on the bolts,
and that followed by heating the bolts to red-hot then attempting removal.
The heating method seems to be almost universal in opinion.
Yesterday, I looked at the locations of the various bolts and two things stuck out to me.
1) I'm not able to even reach some of them with my can of PBB, although perhaps a blow-straw thingy
might help that: there's just not a lot of room in there!
2) More importantly, I'm curious to know if by heating these bolts to cherry-red hot, am I in danger of melting some other component(s) in the process?
3) Are there some things that ought to be removed to enable this process to go...smoother?
Does anyone have direct experience who can speak to this?
I guess there's perhaps a #4
4) Is the whole process made infinitely easier/doable by lifting out the engine, at least some..?
(wouldn't look fwd to doing that by any stretch)
Thoughts are welcomed
Cheers,
Rich
I'm looking at removing my (presumably), stock exhaust manifolds on my 74' L48(studs are snapped off)
I've received advice/tips such as , multiple treatments of e.g. PB blaster on the bolts,
and that followed by heating the bolts to red-hot then attempting removal.
The heating method seems to be almost universal in opinion.
Yesterday, I looked at the locations of the various bolts and two things stuck out to me.
1) I'm not able to even reach some of them with my can of PBB, although perhaps a blow-straw thingy
might help that: there's just not a lot of room in there!
2) More importantly, I'm curious to know if by heating these bolts to cherry-red hot, am I in danger of melting some other component(s) in the process?
3) Are there some things that ought to be removed to enable this process to go...smoother?
Does anyone have direct experience who can speak to this?
I guess there's perhaps a #4
4) Is the whole process made infinitely easier/doable by lifting out the engine, at least some..?
(wouldn't look fwd to doing that by any stretch)
Thoughts are welcomed
Cheers,
Rich
If the studs ( bolts ) are broken aren't they just falling off already = who the hell broke them ?
pulling just the heads sounds about as bad as pulling the motor
sounds like you might need option #5 or even #6
Thread Starter
Racer
Joined: Jun 2013
Posts: 412
Likes: 48
From: Auburn Maine
Not sure how they would fall off..?
And to be clear, I'm talking about the exhaust manifold studs..
Who broke them? well, I'm proud to say I did.
Burning Brakes
Joined: Oct 2002
Posts: 1,040
Likes: 109
I would think about option #5
Team Owner
Joined: Mar 2002
Posts: 44,671
Likes: 1,830
From: Huntsville AL
Quote --> I'm talking about the exhaust manifold studs.
Unless I'm missing something the only exhaust manifold studs on a 1970 Corvette 350 engine are where the exhaust pipe attaches to the manifold. Just remove the exhaust manifold and deal with the broken studs.
However, if you are talking about broken/twisted "BOLTS" that attach the exhaust manifold to the head than just remove the head and deal with that outside the car.
Unless I'm missing something the only exhaust manifold studs on a 1970 Corvette 350 engine are where the exhaust pipe attaches to the manifold. Just remove the exhaust manifold and deal with the broken studs.
However, if you are talking about broken/twisted "BOLTS" that attach the exhaust manifold to the head than just remove the head and deal with that outside the car.
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Thread Starter
Racer
Joined: Jun 2013
Posts: 412
Likes: 48
From: Auburn Maine
apologies for how badly I word things so many times.The reason I’m asking about the heads is because the exhaust flange studs are snapped off, well, some of them anyway.And I don’t see how I’m going to get studs out of the flanges outside of pulling the exhaust manifolds off.
;/
;/
Melting Slicks
Joined: Feb 2018
Posts: 2,326
Likes: 721
From: Marietta GA
Here are my two cents worth. I purchased some oem used exhaust manifolds for my 73 small block. I am old dude and never had very big muscles, it took me about 30 seconds to break the stud on the exhaust manifold sitting on my bench, only using a 3/8 socket wrench. After reading a bunch of techniques, I ended up using a MAP torch and candle wax to get them out. I am old enough to realize that trying to remove the existing studs in the block were beyond my capabilities. I had the exhaust manifolds powder coated, then took them to a local shop that only works on vintage cars. My advice is to remove the heads and you can try the heat with candle method. There is a YouTube video on different methods. Once you pull the heads it would smart to have a trusted machine shop look at your heads to see if they need some work. Good Luck.
Safety Car
Joined: Mar 2009
Posts: 4,191
Likes: 951
From: Corpus Christi, TX
Take the manifolds off the heads. Then take the manifolds to your friendly machine shop and get the stud stubs drilled out. Heli coil the stud holes. Heli coil inserts are stainless steel. Then replace with stainless steel studs and use stainless or brass nuts to attach the exhaust pipe flanges. No more trouble with your exhaust studs, ever.
Race Director
Joined: Mar 2017
Posts: 11,947
Likes: 4,506
From: Virginia
Perhaps it's easier to get some of the exhaust manifold bolts from below?
Just cut the exhaust. You'll want to throw away that heat riser, and your downtubes are probably necked down anyway. Replace them with new manifolds (or better), and down tubes (or better) that are 2.5" all the way through.
Just cut the exhaust. You'll want to throw away that heat riser, and your downtubes are probably necked down anyway. Replace them with new manifolds (or better), and down tubes (or better) that are 2.5" all the way through.
Team Owner
Joined: Mar 2002
Posts: 44,671
Likes: 1,830
From: Huntsville AL
apologies for how badly I word things so many times.The reason I’m asking about the heads is because the exhaust flange studs are snapped off, well, some of them anyway.And I don’t see how I’m going to get studs out of the flanges outside of pulling the exhaust manifolds off.
;/
;/
Melting Slicks
Joined: Sep 2010
Posts: 3,306
Likes: 697
It wouldn't be fun but can you take the exhaust off after getting the car quite high on jack stands or lift. Then cut/grind the broken studs flush so you can drill and tap for the new 3/8" studs? Wouldn't be fun laying on you back with drill chips in you face. But I'm concerned that removing the exhaust manifolds you will break the bolts going into the heads making more work.
Drilling wise nice heavy center punch marks. Then a super sharp 1/8" drill bit. Then a super sharp 1/4" drill bit. Then finish it off with a 5/16" drill bit. Then a sharp 3/8" tap for new threads. Lots drill oil lube on each step.
Drilling wise nice heavy center punch marks. Then a super sharp 1/8" drill bit. Then a super sharp 1/4" drill bit. Then finish it off with a 5/16" drill bit. Then a sharp 3/8" tap for new threads. Lots drill oil lube on each step.
Melting Slicks
Joined: Jul 2004
Posts: 3,069
Likes: 220
It wouldn't be fun but can you take the exhaust off after getting the car quite high on jack stands or lift. Then cut/grind the broken studs flush so you can drill and tap for the new 3/8" studs? Wouldn't be fun laying on you back with drill chips in you face. But I'm concerned that removing the exhaust manifolds you will break the bolts going into the heads making more work.
Drilling wise nice heavy center punch marks. Then a super sharp 1/8" drill bit. Then a super sharp 1/4" drill bit. Then finish it off with a 5/16" drill bit. Then a sharp 3/8" tap for new threads. Lots drill oil lube on each step.
Drilling wise nice heavy center punch marks. Then a super sharp 1/8" drill bit. Then a super sharp 1/4" drill bit. Then finish it off with a 5/16" drill bit. Then a sharp 3/8" tap for new threads. Lots drill oil lube on each step.
I don't know how much stud is showing. You say cut and grind???? that means if you have 1/4 inch of stud showing then I would weld a bar right across the stud.
Then with two people you heat and use penetrating oil and or let cool and add wax and then lightly screw in and reverse it out with heat!!!
If the stud is broken flush with the exhaust manifold then drilling and small drill to just the correct width and then tap die it. The die will clean out the threads but do not have a drill so large to take out the threads.
Or go to You tube and you will see many methods.
Again a picture is worth more so we can see what you are against
If you are scared of breaking the bolts off the heads then take a look at You tube and basically you add heat to the head bolt are and should come out
G
Race Director
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Have you even tried just putting on wrench on the exhaust manifold bolts and see if they turn yet?
mine came right out with no issues at all after being in for over 40 years.
Why don't you just try to lossen them first before you freak out that they may be rusted in?
mine came right out with no issues at all after being in for over 40 years.
Why don't you just try to lossen them first before you freak out that they may be rusted in?
Instructor
Joined: Nov 2022
Posts: 158
Likes: 82
From: North Coast
Stuff like that gets soaked with rust blaster for a week before I even touch them.
use a punch to rap sharply on end of bolt/stud a few times to break the microscopic connections betwixt bolt/stud and mating surface.
then more rust blaster, more raps with a punch.
then i actually tighten ever so slightly just a touch, then back them off…
ain’t broke nothing yet…😄
use a punch to rap sharply on end of bolt/stud a few times to break the microscopic connections betwixt bolt/stud and mating surface.
then more rust blaster, more raps with a punch.
then i actually tighten ever so slightly just a touch, then back them off…
ain’t broke nothing yet…😄