Exhaust Manifold/Front Pipe Fitment Issue

[philbert]

Hello all,
Am currently in the midst of a frame-off restoration of my 1970 Series IIa. The original front pipe was toast, so I got an aftermarket one that does not seem to want to fit the original exhaust manifold very well. After much manipulation, this (image below) seems to be the furthest that the rounded proximal end of the front pipe will insert into the exhaust manifold output. Any thoughts or ideas? It almost looks like there needs to be another gasket here but there is not one listed in the Green Bible, Haynes manual, 2a parts catalog, or series 3 parts catalog. Thanks in advance.



And for those wondering ,yes, I struggled mightily to get the 3 original manifold studs out...so many broken drill bits.

[vlad_d]

My 2 cents:

Take the bottom flange off...the one on the exhaust pipe. Go to the hardware store and buy a round file, or chain saw teeth file. Use the round file to enlarge the flange bolt holes a bit...make them slightly oval or slotted. Also, unbolt all the fittings on that exhaust pipe, so it has some wiggle room. Exhaust pipes are notorious for being finicky to get fitted right, and your best shot is if everything is loose. A half inch of play at one end might give you the angle you need. Only tighten everything when the manifold flange fits good, and take up any differences with different hanger straps and such.

I say to adjust the exhaust flange and pipes because those are easy to get. Any muffler shop can make those. But your exhaust manifold will send you on a wild.goose chase to order one from the other wide of the planet and wait 3 weeks and spend a fortune. If you have to grind one of them, grind the cheap and readily available one. Also, the flange seems to have a colar that keeps things aligned, and the bolts just hold things pressed together(compression force vs sheer or torsion). So, a slightly slotted hole in the flange won't wobble and shouldn't leak.

Good luck man!

[roverp480]

There is no gasket between the pipe and the manifold. To seal it relies on the the cone on the pipe fitting into a taper chamfer in the manifold . From your picture the nut on the right needs to be released a couple of turns and the one on the left tightened up a couple . the loose flange should sit squarely onto the pipe coupling . As Low Range mentioned it may well be worth opening the stud holes in the flange to allow things to move & align better.

[wrongway]

Yes you need to tighten it in a more evenly manner. Looks good otherwise.

[jimrr]

tapping it (vibrating it) as the tolerances close can do a lot to align it so there is even pressure all around.

[philbert]

Awesome, thank you guys for the info. Is the flange on the front pipe supposed to sit flush against the exhaust manifold or is there meant to be a gap? If so, any idea what a reasonable gap would be? Have tried looking for images of this connection but they seem hard to find. Thank you again-

Edit: also, is there any sort of sealant or liquid gasket that should be used between the pipe end and exhaust manifold?

[vlad_d]

No sealant on exhaust pipes. It gets too hot. Sometimes you might see a 'tin' gasket...like a thin metal thing. But not right there. As the other folks said, it's a press fit and the cone inner collar slides up into the chamfered hole on the inside of the flange and the tightness of everything makes it not leak.

As a sanity check, you can leak test it yourself. At the mechanic shops, they have a smoke machine that makes a harmless smoke you place around air fittings like that with the engine running and look for bursts of air(the leak) pushing the smoke away. You could do the same thing in your garage...even if you don't have a fancy smoke machine. Maybe some incese and a hair dryer duct-taped to your exhaust pipe? Get creative. Anyone walking in will think you're having a hippie smoke out...but you'll know better ;D

I would align it right(even) before tightening it up. Usually, people just wrench tighter on the bolts to eliminate the leak. But, you want to make sure the tightness on the bolts is coming from actually scrunched down and not just friction from being misaligned. You might think you're tightening it, but you're not even close and the bolts just snap on you. So, loosen everything up(all the way back, so you can freely wiggle) and just bolt it up without anything limiting you. After that, you can strap the pipes down with the hardware. It's easier to leverage an installed pipe closer to a hanger than line up threads on a Flange fitting. This works on fixed brake lines and fuel lines, too. Forget trying to get a fitting aligned with no room for movement!

[jimrr]

good reply viad, also you should use copper coat or anti seize on those bolts. a visible gap should be there, 3/16" or 1/8" or so, could be more.

[cedryck]

What they said, also, do not over tighten brass nuts, they will strip, don't ask me how I found out.

[philbert]

No sealant on exhaust pipes. It gets too hot. Sometimes you might see a 'tin' gasket...like a thin metal thing. But not right there. As the other folks said, it's a press fit and the cone inner collar slides up into the chamfered hole on the inside of the flange and the tightness of everything makes it not leak.

As a sanity check, you can leak test it yourself. At the mechanic shops, they have a smoke machine that makes a harmless smoke you place around air fittings like that with the engine running and look for bursts of air(the leak) pushing the smoke away. You could do the same thing in your garage...even if you don't have a fancy smoke machine. Maybe some incese and a hair dryer duct-taped to your exhaust pipe? Get creative. Anyone walking in will think you're having a hippie smoke out...but you'll know better ;D

I would align it right(even) before tightening it up. Usually, people just wrench tighter on the bolts to eliminate the leak. But, you want to make sure the tightness on the bolts is coming from actually scrunched down and not just friction from being misaligned. You might think you're tightening it, but you're not even close and the bolts just snap on you. So, loosen everything up(all the way back, so you can freely wiggle) and just bolt it up without anything limiting you. After that, you can strap the pipes down with the hardware. It's easier to leverage an installed pipe closer to a hanger than line up threads on a Flange fitting. This works on fixed brake lines and fuel lines, too. Forget trying to get a fitting aligned with no room for movement!

Great advice, thanks very much. Will keep on plugging away at this and the laundry list of items needed to get her back on the road!