1987 318 Tuning with Summit Carb

Newbomb Turk said

Hang on a second…are you sure a 600 CFM carb has a .046 idle feed restriction?? What size is the idle air bleed?

I’m saying that’s a huge jet for that size of carb. Crazy huge.

I start at .029 ifr and a .070 air bleed.

If that’s the size it is, imho you’re going to need to drop the ifr way more than you did.

Click to expand...

Stock the Summit came with four .046 idle feed restrictors on primaries and secondaries. I don't know that this model carb has screw in idle feeds. But I think I am confusing myself here. Question - A bleed is what allows air into the idle circuit and a restrictor allows fuel into it, correct? Then maybe I've got my terms messed up. I went smaller on the bleed, from .046 to .043 and it went from rich to rich, lol. I thought that smaller on the bleed meant leaner, but as I'm sitting here googling stuff, bigger hole (more air) on the bleed will lean it out. I went backwards. The reason I was calling it a restrictor was because the Summit spec sheet states "Idle Feed Restriction" as .046. I'm thinking terms are messed up, so I took pics. So maybe I'll throw in a .049 and see if that leans it out.

In the pic, circled in red, are what the Summit spec sheet calls idle air restrictors. They came as .046 and I went to .043. I believe these allow air into the system, so going smaller will richen and bigger will lean.

As far as the rest of the carb, I'm not even sure where the idle circuit pulls fuel from.