500 vs 600 cfm for 0470 gpu

[elviswho]

I recently bought an older Panther airboat with a 0470 gpu motor. I have had to have the cylinders redone and it was recommended that I switch from the Zenith carb. to a 500 cfm Holley. A friend has since recommended going to a four barrel like a 600 or 650 cfm Holley. How much is too much carb. for this engine. I am running a thin blade three blade composite prop.

[Buck Thruster]

The 500cfm Holley has proved to be the best direct replacement carburetor for the Zenith on single mag stock 470 gpu's.

[rjonesboy]

A 470 ci engine is not capable of flowing more than 500 cfm at 3000 rpm. there are several cfm calculators available on the net if you want to check 4secondsflat.com is one.

[Waterthunder]

The four barrel looses to much velocity the 500cfm two barrel is much more responsive plus I'm constantly told the four barrels drop valve seats in 220's.

[Skeeter]

The jetting on the 500 Holley is very easy to change and in my opinion is the best carb for the 220.

[elviswho]

Thanks for all the input, sounds like the 500 cfm two barrel is the better choice. Does anyone want to trade a two barrel intake for a four barrel intake? A friend of mine just dropped of a four barrel intake he had, but it sounds like I better wait for a two barrel setup.

[MadSid]

Thanks for all the input, sounds like the 500 cfm two barrel is the better choice. Does anyone want to trade a two barrel intake for a four barrel intake? A friend of mine just dropped of a four barrel intake he had, but it sounds like I better wait for a two barrel setup.

Just pick up a 4 to 2 adapter

[elviswho]

That's what I will end up doing, just thought maybe someone might need a four barrel setup and this would end-up helping us both.

[elviswho]

Can anyone tell me what the cfm of the zenith GPU carb. is.

[MadSid]

Can anyone tell me what the cfm of the zenith GPU carb. is.

Do a search on GPU I saw a spec chart for all the motors on here a while back .

[Red Dwarf]

I bet it's less than 500

[swampjet]

elviswho,
If you go with the 500 2bbl, I would recommend changing the power valve to a 10.5 and the jets to 77. On either the 2bbl or 4bbl make sure the rise of the intake is about 3.25 inches from the top of the intake where all the tubes come together and the bottom of the carb mounting plate. Hope this makes sense.

Bob

[elviswho]

Thanks for the info. If i use the four barrel intake I'll have at least that much room if not more with the two barrel adapter plate.