1BIGJIM

iTrader: (1)

454 .030 over
9:1 compression
Edelbrock Intake
5,300 RPM MAX
Looking at the HOLLEY 4150 series

750 CFM or 800 CFM?
Vac secondaries or Mechanical?
What is the biggest difference between the two
Thanks
Jim

MESABALANCING

There's many carbs out there with a crazy amount of diferrences if you don't want to go crazy use a 9022 holley which is a great marine carb which properly tuned will give you the performance you desire .

formula31

What he said. The 9022 is a standard hard to beat for Marine. I however am crazy and use whatever. Either of those sizes will be fine. I prefer a vacuum secondary myself. I little trickier to set up properly but better on the fuel consumption and cylinder walls if done right.

tomas_wallin

What about singel/doublepump. What is the most suitable for an 454 "std330" with other heads and about 430-450hp?

robyw1

You always should choose the carb that weighs the most. This way you can be assured it will perform to it's fullest potential for their most appropriate applications.

1, a door stop in an EFI shop
2, a paper weight for those important documents about injector rate

I could go on
Roby

formula31

On a single heavy deep v that needs time to get out of the hole, a double pumper probably works better. Actually, a Quadrajet is perfect if you can find someone to set it up right (I havent had any luck). My vacuum secondarys are single pump and with twins, have no hesitation getting up.

Again, hard to beat the 9022 unless you find a Quadrajet setup for that HP.

Rookie

iTrader: (4)

C.I. x Peak RPM / 3456 = CFM needed at 100% efficiency

454 x 5300=2406200

2406200/3456 = 696 CFM

Cord

iTrader: (2)

Rookie-my theory is that the formula was based on cars which spend significant amounts of time part throttle and at idle. I believe you can easily add another 50 or 75 cfm to that number and be ok. With boats it doesn't take long for the secondaries to open up. I've been using mechanical secondaries and they've been working really well for me. Plug the booster on the secondary and run them through the jets. Take a look at what rpm the secondaries start to open and then don't cruise at that rpm. You engine will run lean just before they open and an extended cruise could cause damage.

Whiteknuckle

Cord
The Holley Tech guy on their help line told me a rule of thumb is about 15% additional CFM required for Marine applications when using the formula that Rookie mentioned. From what I have seen on the dyno, that makes sense.

1BIGJIM

iTrader: (1)

OK 800 cfm it is then
Is that made with Vac secondaries?
I have only seen it with mech secondaries