I decided because our '53 wagon needed exhaust, it was great time upgrade to dual carb, dual exhaust setup. Got the parts from Langdons and put it all together and had new exhaust put on.
The first problem was both the carb adapters at manifold side, and manifold at carb were both very un-flat causing vacuum leak. Langdon said to file both surfaces and all was well, no more leak after substantial machining.
The car starts perfectly and runs under no load perfectly. It will rev up, never stall or backfire, no problem.
If you go drive car under load it will backfire out tailpipe, backfire out carb, buck, vibrate, ect. It will literally not go.
I checked for more leaks at manifold to head and no leaks. We isolated just distributor with vacuum and also checked it to make sure it holds vacuum. no problem. Also confirmed choke was not on and also have heated coolant running thru manifold.
The car ran perfectly before. Like everyone else, I thought I would be cool and have dual carbs.
Any ideas? I have zero experience with 740s but It seems the mixture isn't right. I understand these carbs are nearly set it and forget it.
Thanks!
