Carb for a 385hp Ford Crate Engine?

[baypally208]

Engine: Ford Motorsport 351W 385HP
Carb: Rebuilt 750 Holley with Vacuum Secondaries

Problems:
- We keep getting misfires under load (during accelleration) with
3/4 throttle between 3500 and 5000 RPM.
- Minor Backfiring.
- We've been playing around with it but can't get consistant
accelleration.


We've Checked:
Timing Good
Distributor Replaced
Plugs and Wires Replaced
Premium Grade Fuel


Any recommendations?

[mrmustang]

Dump the carb........You need no more than a 650dp Holley (#04777C), Moroso 1:1 secondary linkage kit, and some dyno tuning time.........I should know, I went through 6 carbs on my last 351W/385hp Ford crate engine before finding someone with a chassis dyno.............After two hours on the dyno with the new carb, it was running at peak performance and efficency............


Bill S.

[baypally208]

No way to use the 750, huh?

What's the jetting and shots on the 650 you're using?

Thanks!

-Drew

[S_Beaudry]

Guys, not that I know much but.......


Cubic Feet Per Minute Needed Formula:

CID * max rpm / 3456 = CFM needed


Example:

302 * 5500 = 1,661,000 (divided by) / 3456 = 480.6 CFM


One of those things I could never get out of my head.....

[Curt C.]

Sounds like you are running lean. Look at the plugs to confirm and try upping the jets. That cam really needs a DP though. I run the recommended carb for that motor - model 9379 with 68 / 81 jets. The motor has bigger heads though - AFR 185

[mrmustang]

Shots were not changed, jets according to my notes are 72/68's with the Moroso 1:1 linkage kit and the choke horn milled off......

Bill S.

Originally posted by baypally208


No way to use the 750, huh?

What's the jetting and shots on the 650 you're using?

Thanks!

-Drew

[Goober]

Had a buddy with the exact engine and problem. Changed to a Holley 650 and problem went away. 750 to much.
Just my 2 cents