I have been fighting this build for a couple months. any help would be great. here is what I have

70 mach 1 351 c .30 over
roller rocker cam 240lift 560 duration hydr roller
headers 2.5 exhaust 2 stage flowmasters
msd ign
holly 750 mech 2nd

Timing is now at 18 deg lighest msd springs, smallest bushing. 36 deg total

Car still leaves the line like it has a trailer behind it, and sputters if I get into the 4 barrel hard.

Any advise would be great!

 

Most likely accelerator pump. And what heads? 750cfm may even be a bit much, especially a mechanical 2ndary carb, and especially depending on your gearing and vehicle weight. Chances are you'll just need to work hard at tuning both the pumps.

 

Thanks for the reply.The car is a 70 mach 1 (I will have to check weight)I am running the stock 4v heads. 350 gears in the rear. I started with a holly 650 and it seamed to be starving. I put a 750 proform center in the 650.

should I have gone with vacume 2ndry?

 

Vacuum secondaries are nice for street cars. Mech 2nds work, but you have to know what you're doing. 650cfm is prolly all that engine really needs, but regardless, it has to be tuned correctly.