Exhaust manifold

One thing I noticed about the '79 Polaris Cobra is that the front of the engine was really greasy. This extended down into the belly pan. At first I thought the exhaust manifold gaskets were leaking but then I happened to look into the exhaust manifold while holding it up to a light:

See the light peeking through in the middle of the pic? The manifold was made in 2 halves pressed together and tacked. It would appear its separated in the middle. I ground out the joint and welded it back together until I couldn't see light anymore. Then painted with some high temp.

While I had the grinder and the paint out I figured I ought to clean up the exhaust pipe some. Thats when I found:

A line of welds where one had pulled through the metal. Again and easy fix but then I discovered what I think is a cleanout plate on the other side that had been booger welded all around. You can see in the pic above where it looks like the plate as been swaged or tacked to the rest of the pipe. Apparently the other side leaked so somebody ran weld all around it. It looks awful but weld is really hard and after 15 minutes of grinding I'd only cleaned up maybe 1 inch out of 24. I'll work on it again in the spring. In fact I'll probably keep the pipe out of the sled all summer and just nibble away at it.

Anyway I did finish putting the engine together last night, took longer than expected because the fan housing was really dirty both from the leaking exhaust and the leaking crank seal. Then I realized I'd put the motor plate on backwards. That was the last straw and I gave up for the night...

3 years later...

Witness friends the accomplishment of 3 years of ignoring a problem and 2 nights of work! Here before you is the new and improved Mark 1 Mod 2 Wankle Panther replacement exhaust!

Seth used his metal cutting bandsaw to section the pipe last night, we took out almost exactly 1/2". Inside I discovered this is whats apparently called a "gun" exhaust. Inside it had a perforated tube running the length of the pipe with another short one running down the stubby end. I cut some disks of computer case that had holes all through it (think cheese grater) and welded those into the pipe and then welded longer perforated tube back into place and finally welded the two halves back together. Took about 2 hours each night.

To finish I need to come up with an input pipe, I thought I had one but its marginally too small. I'll need to stop at the auto parts store tomorrow and pick up another. Hopefully this new design will be quieter than the old one...

However Seth and I came up with at least 2 more designs last night....

Wankle Panther muffler

So after selling the El Tigre I've been jonesing to buy another sled. Then I got a $2300 credit card bill. The Christmas season was expensive this year, my car needed 2 new tires, the pickup needed ball joints ($700, curse you Ford!) of course I had to buy presents and so on and so on.

I decided the $400 from the Tigre was better spent on bills. Instead of buying another sled (although theres this John Deere...) I'm working on the poor old wankle Panther. The sled runs pretty good but is really loud. The muffler on this machine was ONLY for this machine, no other AC muffler will fit and every one I've found has rusted to pieces. Unfortunately its basically a coffee can and moisture can pool inside and rust from the inside out...
A couple years ago I'd bought a Cub Cadet muffler which is basically the right shape but it turns out to be about 1/2" too long... Its also still pretty loud. So tonight I'm going over to Seth's shop to borrow his metal cutting bandsaw. I'm going to hack 1/2" out of the middle of the thing. Then when I get back home I'm going to work out some baffles which will hopefully cut the noise some more. As a final step I'm going to pack some steel wool inside to eat up even more sound. I expect the steel wool to oxidize out pretty quickly but with luck my system of buffers should make that not matter.

Tonight's cutting is really step one, Thursday night I should be able to start welding. I've got some old computer cases hanging around. Computer cases are heavy dense steel so I'm hoping they'll make good baffles inside the muffler. Time will tell on that one. Time will also tell if my welding skills have improved enough to make an airtight buffer around the muffler...

-Curt