I haven't tried to adjust mine yet but I know that Barrygrant.com provides comprehensive information on their products. Plus try ChevyTalk.com (assuming the best case scenario) and similar forums. Lots of information is available because of the carb's "uniqueness".
I have a 79 vette with a TH350 tranny and a 355 rear. The engine is a 355 cid with:
Comp cam kit #CS XE256H-10
Heads (HRS P#12401)
Carb (DEMON P#4402020ue) Road demon 725
Im running the timming at 14 BTDC. The problem is an off idle stumble and a very rich mixture at idle. Im unable to fix one problem with out creating another.
I have used both a tach and a vacume gauge. Is there any secret to tunning this carb using these methods? Im just not satisfied.
Any suggestions will be appreciated.
A 725 Road Demon would seem large for this combination, which could lead to a situation like this. We may be able to give you some things to try to crutch the situation, but a smaller carburetor would have been advised on this engine. At this point we'll need some more information:
Where do you have your idle mixture screws set at?
What RPM is the engine idling at?
How much of the front, and rear transfer slots do you have exposed at this point?