[Ivan D.]

Originally Posted by piecesparts

Ivan D, what are you running for a cam in that recently "refreshed" engine? If you are running a rather lumpy cam, then you are trying to make up for it with adjustments to your idle circuit on yur carb, to keep it at an even idle when stopped. This is especially hard to do when the truck is in gear, with an automatic tranny. This process takes the idle mixture out of the idle circuit and puts it in the "transition" area towards the primaries coming open, because you are trying to make up for the idle by making the engine idle faster. I solved some of that when I put in a different stall convertor in my tranny and got the truck to sit at a stop light without trying to pull the truck through the light on a high idle. Along with a bigger cam, comes that sweet heavy smell of gas fumes that you are talking about. I managed to get my 383 stroker to a 15 MPG with the lopey cam and an auto tranny.

Don't take the engine too lean or it will hurt your internal parts.

Howdy, my cam ain't nothing special, just a Melling towing/RV cam, MTC1:

- duration SAE - 278/288
- duration 0.050 - 204/214
- lift cam - .280/.295
- lift valve - .420/.443
- lobe separation - 107/117

As you see, definitely not a lumpy cam by any means. With the vacuum advance hooked up to ported vacuum I can go as low as 800rpms free idle, 500 in gear at the stop light. Now with the advance hooked up to manifold vacuum it idles beautifully at 600rpms free and 400rpms in gear at the light. idle screws are backed up 1 3/4 turns out from closed position, so nothing crazy rich there either...

Edit: I also tested my primary floats for pinholes - two hours underwater in an upright position, when weight was removed float popped right up, so I believe it's good. Still need to check the secondary float tho...