Since you guys always have an answer, I have a question. Just built a 306 with big heads, .554 cam, single plane intake, equal length headers and a 750 Holley ultra street carb. Runs like a scalded dog above 2500 but bogs at the start even with a 1700rpm power brake launch and a 2300rpm trans brake launch. Carb adjustments have been done and the plugs look perfect. Played with timing from 10 to 22 degrees with no real change either. Any simple ideas before I take it to a tuner? Any help is appreciated and you guys rock!
Sam

 

Do you have your vacuum advance connected/setup properly? It should be connected to ported vacuum, you can adjust advance with an allen wrench in the nipple for the vacuum hose on the dizzy.

 

bogg on launch..........play with the accel pump circuit.........you can change cams on the holleys....to increase rate and delivery based on the cams used....but more often than not i CHANGE SQUIRTERS first.

 

Thanks guys, timing appears correct but carb may not be. May have to let a tuner dial it in. I'm a little out of touch since the last carb I worked on was in 1980! My girls love their Mustangs though!
Sam