1971 slant 6 manifold gaskets

-
Johnny71dusty

Johnny71dusty

Well-Known Member
Joined
Jul 6, 2021
Messages
829
Reaction score
110
Location
Maryland
I'm having major trouble getting to seal . I got the fond thick gaskets that are silver and they are all torque properly . Any idea if putting 2 on would help ? Allow more crushing of gasket material ?
 
Biggest issue with them I have had is they got tweaked. I look at them with a straight edge across the runner faces and try to true them the best I can.
 
halifaxhops said:
Biggest issue with them I have had is they got tweaked. I look at them with a straight edge across the runner faces and try to true them the best I can.
Click to expand...
Mine aren't great . They are bolted together still and sitting face down on kitchen table . They don't match up well at all .
 
Also my studs into head keep leaking water . I've done them 3 times now with " loc tite" thread sealant and still water spraying through the threads
 
If I remember right (I wou l d have to find the old thread) I bought the paper gasket and soaked it in water first, it swelled up and I let it dry, then I installed it... hmm.. memory ain't what it use to be...
I do remember painting both sides with copper coat of witch ever gasket I used
 
Let's address a number of things that could help solve your issues.

Johnny71dusty said:
I got the fond thick gaskets that are silver and they are all torque properly
Click to expand...

I don't know what a "fond thick gasket" is. What brand and part number are we talking about?

Using two gaskets won't help at all and will make things worse, doubling your chances of a leak. If you don't have one, get a RemFlex gasket set for your intake/exhaust. They are expensive but worth it.

Are you following the torque pattern in the FSM (you do have one, yes?) to tighten down the manifolds? When I do a torque pattern, I do it in thirds. If it calls for 60 lbs on the bolt, I do the entire pattern at 20, then 40, then the final 60 lbs. The manifolds get very little torque, don't overdo these!

Are you using all the correct hardware, and are the special washers oriented properly?

Johnny71dusty said:
Mine aren't great . They are bolted together still and sitting face down on kitchen table . They don't match up well at all .
Click to expand...

If your intake is old, and the exhaust is new, it's likely they won't match up well. If the manifolds are all wonky to each other and not true/flat, no gasket on the planet is going to help you out. Best bet is to mount them together as close/true as possible using a straightedge, tighten them up, and then take them to a machine shop to get the mounting surfaces trued up. The guy that did mine used a gigantic belt sander to flatten and true the two to each other.

Johnny71dusty said:
Also my studs into head keep leaking water . I've done them 3 times now with " loc tite" thread sealant and still water spraying through the threads
Click to expand...

Others with more experience may jump in to help here, but I don't think Loc-Tite is the product you want to seal a stud going into a water passage. I used Permatex 2 on one head, and The Right Stuff black on the other. Neither one leaked a drop. Did you chase all the threads before assembling everything? You need to make sure all the old crud is out of the threaded holes in the head before assembling the new studs - and everything else.
 
halfafish said:
Let's address a number of things that could help solve your issues.



I don't know what a "fond thick gasket" is. What brand and part number are we talking about?

Using two gaskets won't help at all and will make things worse, doubling your chances of a leak. If you don't have one, get a RemFlex gasket set for your intake/exhaust. They are expensive but worth it.

Are you following the torque pattern in the FSM (you do have one, yes?) to tighten down the manifolds? When I do a torque pattern, I do it in thirds. If it calls for 60 lbs on the bolt, I do the entire pattern at 20, then 40, then the final 60 lbs. The manifolds get very little torque, don't overdo these!

Are you using all the correct hardware, and are the special washers oriented properly?



If your intake is old, and the exhaust is new, it's likely they won't match up well. If the manifolds are all wonky to each other and not true/flat, no gasket on the planet is going to help you out. Best bet is to mount them together as close/true as possible using a straightedge, tighten them up, and then take them to a machine shop to get the mounting surfaces trued up. The guy that did mine used a gigantic belt sander to flatten and true the two to each other.



Others with more experience may jump in to help here, but I don't think Loc-Tite is the product you want to seal a stud going into a water passage. I used Permatex 2 on one head, and The Right Stuff black on the other. Neither one leaked a drop. Did you chase all the threads before assembling everything? You need to make sure all the old crud is out of the threaded holes in the head before assembling the new studs - and everything else.
Click to expand...
Good gasket - the silver thick ones , best ones and most expensive ones far as I can tell .

the manifolds need to be bolted together where the carb goes first . 3 bolts that sandwich them together , where the exhaust heats up the intake . It has its own metal gasket there . That needs to be lined up too or it will leak .
My manfolds faces are not true . For sure that's the problem . I don't know how to fix that problem .

leave the two manifolds bolted together and take to a machine shop ?
 
halfafish said:
Let's address a number of things that could help solve your issues.



I don't know what a "fond thick gasket" is. What brand and part number are we talking about?

Using two gaskets won't help at all and will make things worse, doubling your chances of a leak. If you don't have one, get a RemFlex gasket set for your intake/exhaust. They are expensive but worth it.

Are you following the torque pattern in the FSM (you do have one, yes?) to tighten down the manifolds? When I do a torque pattern, I do it in thirds. If it calls for 60 lbs on the bolt, I do the entire pattern at 20, then 40, then the final 60 lbs. The manifolds get very little torque, don't overdo these!

Are you using all the correct hardware, and are the special washers oriented properly?



If your intake is old, and the exhaust is new, it's likely they won't match up well. If the manifolds are all wonky to each other and not true/flat, no gasket on the planet is going to help you out. Best bet is to mount them together as close/true as possible using a straightedge, tighten them up, and then take them to a machine shop to get the mounting surfaces trued up. The guy that did mine used a gigantic belt sander to flatten and true the two to each other.



Others with more experience may jump in to help here, but I don't think Loc-Tite is the product you want to seal a stud going into a water passage. I used Permatex 2 on one head, and The Right Stuff black on the other. Neither one leaked a drop. Did you chase all the threads before assembling everything? You need to make sure all the old crud is out of the threaded holes in the head before assembling the new studs - and everything else.
Click to expand...
I first used the black permetexk stuff I use in my industry as a steam fitter . That leaked . Guy I'm hear said to remove snd get lock tight brand " thread sealant " so I did that - twice actually . They still leak profusely .
 
halfafish said:
Let's address a number of things that could help solve your issues.



I don't know what a "fond thick gasket" is. What brand and part number are we talking about?

Using two gaskets won't help at all and will make things worse, doubling your chances of a leak. If you don't have one, get a RemFlex gasket set for your intake/exhaust. They are expensive but worth it.

Are you following the torque pattern in the FSM (you do have one, yes?) to tighten down the manifolds? When I do a torque pattern, I do it in thirds. If it calls for 60 lbs on the bolt, I do the entire pattern at 20, then 40, then the final 60 lbs. The manifolds get very little torque, don't overdo these!

Are you using all the correct hardware, and are the special washers oriented properly?



If your intake is old, and the exhaust is new, it's likely they won't match up well. If the manifolds are all wonky to each other and not true/flat, no gasket on the planet is going to help you out. Best bet is to mount them together as close/true as possible using a straightedge, tighten them up, and then take them to a machine shop to get the mounting surfaces trued up. The guy that did mine used a gigantic belt sander to flatten and true the two to each other.



Others with more experience may jump in to help here, but I don't think Loc-Tite is the product you want to seal a stud going into a water passage. I used Permatex 2 on one head, and The Right Stuff black on the other. Neither one leaked a drop. Did you chase all the threads before assembling everything? You need to make sure all the old crud is out of the threaded holes in the head before assembling the new studs - and everything else.
Click to expand...
Yes using all new factory hardware , and triangle washers and brass ones to where required
 
Yes I filled torq pattern and did it in thirds and again when hot . Also torq numbers are very low
 
Johnny71dusty said:
leave the two manifolds bolted together and take to a machine shop ?
Click to expand...

That would be the next step.

It sounds like you've done the other things I know about. If you are still having issues, we will have to get you help from someone smarter and more experienced than me. Which is a long list...
 
ESP47 said:
Do this + the good gaskets and you'll be leak free.
Click to expand...
? I keep saying I have the best gaskets they make guys. I'm taking the manikfos off tomorrow ans we'll use straight edge and see how bad they are as far as being true to each other
 
Johnny71dusty said:
? I keep saying I have the best gaskets they make guys. I'm taking the manikfos off tomorrow ans we'll use straight edge and see how bad they are as far as being true to each other
Click to expand...

Yeah that's why I'm saying you need to machine them down as well as use the good gaskets.
 
Another thing: if you still have a 1971 ('70-'72) exhaust manifold, save yourself a bunch of hassle and just replace it (get a good one)). The '70-'72 exhaust manifold has an open-hole type choke stove, with a stainless steel cup gasketted in. That junction is leak-prone, and the gasket is unavailable. Putting on a new exhaust manifold will solve the leakage problem and get rid of that factory-built exhaust leak at the top of the choke stove. You'll need a different choke thermostat, so save yourself some more hassle and get a № 1231 electric choke kit.
 
You must log in or register to reply here.
-

Back
Top