The little 390 is pretty maddening...
It's about 95% dialed in, but the 'finer details' always goof something up...
So far it's a change that a little bit then other things aren't right...

Final Carb dial is:

Holley 8007
390 cfm
Vacc. sec. with purple spring in quick change pod
1/16" hole in the primary throttle plates only
53 jets primary
56 jets secondaries
pink 330 cam with a '37' shooter and hollow screw
I opened up my idle feed passages slightly and fuzzed open the transfer slots 1/1000" more to gain a better off idle transition.

That's about as good as it gets, I'm not goin to booger up my idle bleeds...


tomorrow I'll be starting to play with a Holley 80457 600 cfm vac. secondaries carb. In the morning, I'll be dropping it by the locl speed shop and Steve will be installing 4 annualar boosters in the bores instead of the stock ones. These should help in a couple of areas: 1)increased signal-needed for the long runners 2) decreased CFM...I think the mill would run perfect with a 500 cfm 4150, but Holley doesn't make one 3)Better fuel atomization out of the main circuit.

I'll let you know how that goes. The drags start up in march so I'm going with a buddy and we'll see what the difference is in the 390 vs. 600/mod carbs on the track...

I'm also to the point that I might peel open the mill this winter if I can make some more change, and put a taller bump stick in the mill.


so far with all the tuning at this point I'm pulling down about 13 city and 23 highway, but most of the mileage is from idling for a couple of hours playing with the mix, then driving it to see how the timing and mix is...

Tomorrow I have a long highway trip to do so I'll see how my 95% highway mileage rates.

-D.Idiot

There comes a point where you just have to stop "fiddeling" with it and just drive the car for a while. It sounds like you are at that point.

Let us know how your long drive mpg comes in.
DD

MPG count for today was 18.6 mpg 90% highway.

She spent most of her time at 70 mph, at cruise, the whole trip. I might change the jets back to 52's to see if that improves, I'm also running pretty rich at idle again, so something isn't totally 'que-d in'.... I think it could be slightly better.


I dropped off my throttle body to my local guy and monday morning I should have a nice Holley 600 cfm throttle body with 4 annular boosters installed...then I should be ready for another week of carb 'tuning'...


-D.Idiot