[Cammer-6]

The other big question I have is your transmission cable.
Theres a ratio of cable pull to throttle opening position
that must be adhered to regardless of cable slack etc

Im pretty sure I was the beta tester for a 200-4R behind an OHC-6.
I think it was late 80s I did swap to a Monte Carlo SS(same trans as the Grand National)
I had an engine on a stand with carb set up and put the trans minus pan next to the engine.
When the pan is off you can see how much slack is in cable until it bottoms out.
I made my own bellcrank and slotted it for adjustment.
As it turns out my benchtop adjustment was spot on and havent touched it since.
Glenn(aka Birdman or Einstein) and I drove to a buddys shop with trans in the trunk.
About 4 hours later we were test driving with the ST300 in trunk.
Again the ratio of throttle opening to cable pull is paramount.
Many a trans has been fried in short order if its not correct.
Im not near my notes for that,perhaps I posted it around that time,
but PY has crashed a few times since then so may be lost.

[einstein]

Originally Posted by Cammer-6

The other big question I have is your transmission cable.
Theres a ratio of cable pull to throttle opening position
that must be adhered to regardless of cable slack etc

Im pretty sure I was the beta tester for a 200-4R behind an OHC-6.
I think it was late 80s I did swap to a Monte Carlo SS(same trans as the Grand National)
I had an engine on a stand with carb set up and put the trans minus pan next to the engine.
When the pan is off you can see how much slack is in cable until it bottoms out.
I made my own bellcrank and slotted it for adjustment.
As it turns out my benchtop adjustment was spot on and havent touched it since.
Glenn(aka Birdman or Einstein) and I drove to a buddys shop with trans in the trunk.
About 4 hours later we were test driving with the ST300 in trunk.
Again the ratio of throttle opening to cable pull is paramount.
Many a trans has been fried in short order if its not correct.
Im not near my notes for that,perhaps I posted it around that time,
but PY has crashed a few times since then so may be lost.

That was a fun day!

And it performed very nicely I recall, as I got to get some miles at the wheel on a trip we took, somewhere.

[VCho455]

Have you synchronized your carbs? Getting dual Weber setups to sync up is a pain but a necessary step. Having your carbs snchronized means that both idle circuits in the separate carburetors are matched and supplying their respective cylinders the same amount of air and fuel. Otherwise the engine is running one carb and half the cylinders. When that happens and your adjusting the weak carb you will find it unresponsive then it goes over responsive and round and round you go chasing your tail.

There is lots of information on interweb about synching Webers, especially from folks with boxer engines. Those mostly run downdraft versions so you want to look to the inline engine folks as some the tools used on downdraft carbs won't work on sidedraft engines.

What are your camshaft specs? That could play into your high idle and low vacuum numbers.