23 HP Vanguard Stock 2 Barrel Carb Tuning

[slonomo]

Perf670 adapter is fine to use, I used that one initially due to cost, yes it's considerably cheaper than the Backwater one. I did have to drill and tap new spigot mount holes for the type that I had, but it's aluminum and that was easy. I also gasket match ported the inlet side since there was a nice sized lip there. The 670 adapter is an open plenum design, so the intake charge builds up into the plenum then gets distributed to the cylinders as they require it.

The Backwater adapter fits the Vanguard better, since it's made for it. It also is a little taller which is better for clearance for the carb. It also has a radius that puts the carb farther over the engine, also better for clearance. The Backwater adapter has individual intake runners going to each cylinder, so I feel it's a better design.

Having used both, I prefered the Backwater adapter. Not saying the 670 adapter won't work for you, that's just my preference. I still have the 670 adapter sitting on my workbench. Along with all the leftover carbs I've used, 5 in total. I sold the 34mm Mikuni with the 23 engine.

For the air filter, I prefer the Uni over the K&N. Just don't use a cheap filter and you'll be ok. I think I used a 6".