iadr wrote:
Your D-jet must have been some messed up that SU's are an improvement....
I'd argue that SUs are a slight improvement to the D-jet for power. They don't require extremely frequent attention once rebuilt very carefully on an engine that isn't worn out junk (most OHVs are by now). By this time, they are probably easier to keep on the road, since they are pretty much a known entity with parts available and people available to rebuild them very nicely.
On a fairly "cookie cutter" 2.1 B20 with an R-cam and some fairly minor well done head work, the d-jet will really lean out as the RPMs climb. The SUs with the proper needle to go with that cam and some headwork will keep on pulling and put down decent power.
The d-jet works fairly well and reliably when all is right with it. Good luck finding a completely good wiring harness, injectors or MAP for it though. Fuel pressure regulators also do interesting things if adjusted up much from stock (not saying that is good or bad).
As to the SUs, one ought to be able to find the correct needle to run them with a D-cam B20, if that is what the car has. If the shafts haven't had bushings done and the carbs rebuilt, unless yours are in time capsule condition from 196x-1974, they probably need to be re-bushed before one tunes them or worries about orifices *chortle.*
Worn out carbs or engines won't ever tune correctly. Fresh stock carbs on a stock spec motor are quite painless to set straight and mostly stay that way. SUs are sensitive to elevation changes however, which would definitely describe Calgary-surrounding terrain many times. I used to lean them out a bit (2-3 flats from sea level to sun river (high desert) IIRC).
