Exhaust clamp! How tight?

[The_orange_beetle]

Hi all. Really simple one. The clamp between the heater box and the exhaust, how tight should I do that up? I have given it a good go but still has a leak. Do they need to be mega tight?

Cheers

[AirHead1966]

Do you have a new sealing steelwool-like mesh gasket and the sealing ring?
It should be pretty tight but with a good new gasket, it should seal right up.

#12 and #13 in this picture.

[Cusser]

I've found they need to be pretty tight, especially with aftermarket headers.

I do like the mesh donut gaskets though.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[The_orange_beetle]

Hi. Yep I have brand new everything. But have a leak on both sides. Was a little worried about over tightening them.

[Cusser]

[goober]

It depends on how well things fit and how thick the clamp and tapered ring are.

Many of today's clamps and rings are so thin the clamp ends and rings will deform or mash apart before applying enough squeeze. Along with sloppy fitting malformed doughnuts, oversize muffler holes and a possible undersized exchanger pipe, it's easy to see why today's parts leak.

I have a whole litany of crap I do to prep a new muffler and exchanger to make a tight well-functioning system....the clamps

I find as thick of a clamp and tapered ring as I can. I drill the holes out to 1/4". I use grade 5 or 8, 1/4-20 x 2" bolts and cut more threads about a 1/2" further up the shoulder. I try to find well-fitting well-formed doughnuts. But if all else fails, I still have an old bag of new well-fitting asbestos doughnuts that I purchased many moon's ago. (one time I was going try brazing the outer of a thin new clamp to see how well it strengthened...but never did)

With the above clamps I can tighten as much as needed. The muffler/exchanger joint normally doesn't require too much force. But to seal and hold the sloppier fitting stacks in place, usually takes quite a bit more.

[bnam]

I put some sealant along with the donut. The tips from the heater boxes tend to be corroded and uneven. The sealant deals with that better.

The bolts in some kits are only grade 5.x (metric) vs. the more common 8.8. I've bent and snapped a couple.
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1971 1302LS Convertible (RHD) owned since '74
Click to view image
1965 Karmann Ghia Coupe - under restoration
1966 Fiat 1500 Cabrio (with 1600 Twin cam)
1952 Citroen TA 11BL

[brando90gl]