302 Exhaust Problem?

[mdaspit]

I removed my 302 power head from the tower yesterday to check things out.
I am going to put on a new gasket, and I noticed that the old gasket has quite a bit of carbon/soot on it. Is this normal or is it an indication of the exhaust mating surfaces leaking due to miss adjustment of the exhaust cone?

It looks (on the gasket) like the sealing surface from the block to the cone is not leaking, but the carbon has to be coming from somewhere....

[B Walker]

Getting the tuned exhaust horn in the tower level and flat to the tower itself is an area of critical concern. Some exhaust horns take considerable shimming to raise up to the same level of the tower. It is something I check several times a season as the very high exhaust heat tends to change the shape of the aluminum horn itself and cause an exhaust leak between the tower/powerhead.

The smallest exhaust leak here will immediately take 100+ RPM off the motor.

As far as carbon buildup goes, at the end of the season I spray down the horn with BRP Engine Tuner. I have seen carbon buildup of 1/8th inch in the horn before, but I dont run that rich a mixture anymore.

http://theoutboardwizard.bizhosting....ine_tuner.html

read the directions, it is powerful stuff.

BW

[mdaspit]

Once again BW thanks for the advice.
I appreciate it.

Do you put any thing on that exhaust gasket when you replace it?

[B Walker]

I have used the permatex high temp silicone (orange stuff) but dont anymore as it did not seem to make any difference as long as I got the horn shimmed correctly.

gl

BW

[17W]

Once again BW thanks for the advice.
I appreciate it.

Do you put any thing on that exhaust gasket when you replace it?

Do yourself a favor shim it approx. +.003/.004 high & the gasket will compress nicely due to the clamp load.

[ZUL8TR]

Yamato exhaust

Does this discussion also apply to the Y80, 102 and 202?

[17W]

Does this discussion also apply to the Y80, 102 and 202?

It applies to all Yamato product which requires periodic pipe reshimming.

[ZUL8TR]

Yamato exhaust shims

Having never done the shimming wher exactly are the shims placed and what is the shape of the shim?

[seanp3]

Having never done the shimming wher exactly are the shims placed and what is the shape of the shim?

When you remove the powerhead you'll see the tuner pipe. Remove the tuner pipe and there will be some very thin washers (shims). I get my shims from Ric Montoya. Others make there own. They key is when you reinstall the tuner pipe that it is flush with the tower surface to get a good seal

[Team B&H]

Having the exhaust tuner level with the top of the tower housing is good enough for amateur people, but you'll be better served if you follow Brent's advice to have it a couple thousandths higher then than the outer surfaces. Same applies for the top of the clyinders. You really want to clamp the gasket most where the seal is most important.

[mdaspit]

When you remove the powerhead you'll see the tuner pipe. Remove the tuner pipe and there will be some very thin washers (shims). I get my shims from Ric Montoya. Others make there own.

Down here, I can only find shim material at my hardware store. It is sheets of brass (I think) sold by the inch in .oo1 .002 .003 thickness. I use a paper hole punch to punch the center hole, then I use a nickel to trace around the punched hole then I just cut it out with sissors. They don't look pretty, but I think they work. But from now on, I think I'll just call Ric. Thanks for the tip.