Aerovee exhaust manifold stripped

[Outlaw6]

I was adjusting the valves after 5 hours on the new heads and found that all the exhaust manifold were leaking. I figured that may be why I'm only getting about 38" MAP from the turbo. Anyway, I start removing bolts to redo the gaskets and find several bolts in bad shape, I guess I over torqued them even though I was careful not to. I used anti seize and thought I was able snugging them up. Only thing I can think to do is remove the heads and install heli coils. What kind of gaskets do you use? Saw some online that coat the gasket in Ultra Black or similar. Also if you pull the heads do you also pull the cylinders and redo the case seals? Thoughts?

[mike.smith]

I've had 2 of mine strip. In both cases I installed helicoils without removing the heads. For the one in the front I used a straight drill. For the one in the back I used an angle drill. I use the metal VW gaskets; the same kind that come with the original engine.

[Outlaw6]

Mike,
Thanks, I'll give that a shot. Got to find me a right angle drill and a M8-1 insert kit.

[mike.smith]

I got the inserts from Amazon. They're short, so you need to drill very little. I put a piece of tape on the drill bit as a depth guide.

[Outlaw6]

Getting a few orders together. Threaded insert kits at the local hardware stores are crazy expensive. Probably get the copper gaskets, I thought I had a stock set but they are 1-1/4". Most of the bottom bolt thread are smashed, I'm wondering if the exhaust flange smashed them when I was installing the bolts, it's a PITA getting them all in. Also need to find a cheap right angle drill, probably stop by Harbor Freight tomorrow.

[dbdevkc]

If you haven't picked up a right angle drill, you could get something like this from Amazon: https://www.amazon.com/gp/product/B019P7CWJ0/

[Rynoth]

If you haven't picked up a right angle drill, you could get something like this from Amazon: https://www.amazon.com/gp/product/B019P7CWJ0/

Wow, where was that tool when I was building. Cheaper than a dedicated right-angle air drill, and shorter than my die-grinder drill method (that used the same style of stubby bits.)

FYI you can get more of those style of bits from ACS, or a larger size selection at Pan American Tool.

[Outlaw6]

That looks like the tool for the job. Got a right angle drill adapter from Lowe's to try out Friday.

[Outlaw6]

So the cheap coiled wire thread repair off Amazon was garbage. Got the Heli-coil set and they very easy to install. Had a couple hours of good flying, the turbo was making +40"MAP and I thought I might have this thing running well. Not so, pulled the cowl to do the 10 hour re-torque on the new heads and found the exhaust is still leaking. The flange is not pulling the header tight or square against the gasket/head. It looks like the flange ears are bowing and making contact first. I put a metal ruler on the flange mating surface before installation and all four were flat. Did I torque them down to much? Are the stock Sonex gaskets better than copper? I previously had copper gaskets before the new heads and they didn't leak. Not sure what I'm doing wrong.

[mike.smith]

When I install the exhaust flanges with the Sonex-supplied gaskets (which are fairly thick) I can get the first gasket of the pair into place easily. The second one is bear to get in place because the second exhaust flange is already just about touching with the exhaust port. So I have to pull the second header with a good bit of force, to get the second gasket to slip between the port and the flange. Is your exhaust that tight? If not, perhaps you need to compress the header a bit before you install it. Then the flange ears have no distance to bow.

The Sonex gaskets are something like this:
https://www.jbugs.com/product/98-2516-B.html