Re: new scout 800 owner

[jlandry@domain.elided (John A. Landry)]

The aliens commander decided David Nedved <david_nedved@domain.elided> would
make a perfect specimen for dissection, and he yelled...

>My 78 Scout II 345 with glasspacks does this.  It didn't do it as
>badly before I put the glasspacks on (running "car mufflers"), but did
>it much worse when I drove it around with missing exhaust donuts!  I

David,

It's been my experience with vehicles of all types (featuring conventional
carburetors) that any time you have a hole of any appreciable size in the
exhaust system, you will get that loud popping, slapping and a sort of back
firing effect upon deceleration.  Even a tiny hole no bigger than 1/16"
diameter can cause this on a small exhaust system.  If you were to create a
huge leak by leaving out the donut, then I would think all hell would break
loose when decelerating.

I have no explanation for this effect, other than to assume air is being
somehow sucked in through the hole and contributing to combustion of the
unburned fuel loading the exhaust during the deceleration cycle.  The
solution is to fix the leaky exhaust system... which in really bad cases
might include lightly milling the heads and exhaust manifolds so they will
seal properly.  Use of the crushed foil exhaust donuts in place of the
original solid cast iron donuts will also aid in better sealing.

Regards,

John L.
-------------------------------------------------------------------------- 
jlandry AT halcyon DOT com      | 
Conservative Libertarian        |  "The road to  tyranny, we must never
Life Member of the NRA          |   forget, begins with the destruction
WA Arms Collectors              |   of the truth."
Commercial Helicopter - Inst.   |                     William J. Clinton
http://www.halcyon.com/jlandry/ |    10-15-95, speech at the Univ. of CT