I still need HELP

[skihor]

A few of you answered my post about the injector timing for our '69 MC 7 with a 6V92. Short of pulling the turbo out I can't find any numbers. Model or A/R. Say all you want about it WILL smoke, it's a big bus, air blockage, exhaust leaks etc...
All I know is it didn't smoke like this before the "tune-up". Literally @ 1/4 throttle it puts out HUGH AMOUNTS of black smoke that doesn't clear up. If I push down to 1/2 to 3/4 throttle it will block out the sun for a city block radius. I found the A/R number on another turbo from another engine. (It's a 1.60) from a Prevost 6V92. So I go out to the MC 7, look in the same place & and the number isn't there In the same general area on the opposite side of the housing it looks like someone welded over something
I'm out $800 to the Detroit shop and this needs to be dealt with now. I need to figure this out because obviously they don't know. They have to work "out of the book", and since this isn't a stock engine........
When I bought it it ran great for a 100 miles or so. Sudden loss of power more black smoke and a miss.
The Detroit shop diagnosed a "stuck" injector, cold cylinder. They replaced 1 injector, (9G90), timed the injectors to 1.480, (if I recall correctly), adjusted the valves, and the jakes. There isn't a throttle delay either.
It's not an air issue, it's not an exhaust issue, it's not a "heavy foot issue", it's not a throttle delay issue.
I can't afford to spend $100 + an hour to "experiment"
So... If the injector timing is dependent on the A/R ratio how do I figure out what the A/R is
Don & Sheila

[luvrbus]

I don't what to tell you Don both the hot and cold side have a A/R on the housing and a serial and model number on the center block do you have the tag on the valve cover ? 
You have no exhaust leaks, the turbo spins freely and the coupling is good where the turbo ties to air horn right ?

good luck

[belfert]

Did this shop do the "tune-up"?  If it ran better before the tune-up I would be after them to fix it on their dime.  Talk to the service manager and go up the ladder until they agree to fix it.

If it is drivable I would see if there is a good diesel shop in town that knows 2 strokes and is less expensive.  Many Detroit dealers have lost most of their 2 stroke mechanics as they have aged.  I know here in Minneapolis we have a good diesel shop that knows two strokes and charges a fair bit less than Detroit.

[zubzub]

Your post doesn't say where you are but...If you need to tune up a 2 stroke see if you can hire a 2 stroke mech from either a transit yard or a coach yard.  The 6V92 was in enough working transits and coaches in the 90s that a knowledgeable mech won't be that old/retired ...or you could be near Don Fairchild in his travels....