Two Holley 4224 660's on a 600-incher

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Two Holley 4224 660's on a 600-incher

Post  JBR-3 on November 8th 2018, 11:52 am

I have these carbs already and am considering trying them. 600 inches and manual trans.

I have read about peoples' experiences using them on smaller engines, there are mixed opinions.
Most folks are saying a few mods to the carbs are necessary to run on the street on a tunnel ram.

Without trying for max HP in the motor, I would be more interested in "streetability".
My guess would be that sheer cubic inches would tend to tame any bog due to overly rich.

If anything, there might not be enough accelerator pump for that large an engine.

Interested in your experiences and educated guesses on using these carbs.

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Re: Two Holley 4224 660's on a 600-incher

Post  Carbguy on November 8th 2018, 12:18 pm

A pair of center squirter carburetors will have all 8 butterflies open at once, and may not be the most drivable thing to have. Being that under carbureted on a 600" engine may help with it, but will most certainly limit performance. The 660's were the hot ticket on 300" engines back in the day, probably a lot better choices out there today for an engine that size.

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Re: Two Holley 4224 660's on a 600-incher

Post  gt350hr on November 8th 2018, 1:49 pm

660's have a cam operated "progressive" linkage . The secondary opening can be delayed by altering the the cam shape BUT it has no effect on the center squirt discharge nozzle. It dumps fuel into all four barrels , open or closed. IMHO they are too little carb for a 600 ci engine but will work. The carbs aren't know for gas mileage but will work on the street. I have used them off and on for 40 years. A weiand pro ram is a good manifold choice.

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Re: Two Holley 4224 660's on a 600-incher

Post  dfree383 on November 8th 2018, 2:09 pm

Imo a pair of modern 1050 dominators will be more steetable and kill those in the HP department.

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Re: Two Holley 4224 660's on a 600-incher

Post  rmcomprandy on November 8th 2018, 4:20 pm

JBR-3 wrote:I have these carbs already and am considering trying them. 600 inches and manual trans.

I have read about peoples' experiences using them on smaller engines, there are mixed opinions.
Most folks are saying a few mods to the carbs are necessary to run on the street on a tunnel ram.

Without trying for max HP in the motor, I would be more interested in "streetability".
My guess would be that sheer cubic inches would tend to tame any bog due to overly rich.

If anything, there might not be enough accelerator pump for that large an engine.

Interested in your experiences and educated guesses on using these carbs.

Those carbs have no power valve circuits and are pretty much 1 to 1 throttles after a short amount of primary movement. I would not think that would be a pleasure to drive on the street.

Just for the record ... larger engines need LESS accelerator pump for the same given carburetor.




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Re: Two Holley 4224 660's on a 600-incher

Post  gt350hr on November 9th 2018, 12:18 pm

Agreed , more "signal" ( vacuum pull) on the boosters needs less accelerator pump shot. 660's were not designed with street driving in mind. No power valve certainly hurts fuel economy . Not the best choice but "will function".

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Re: Two Holley 4224 660's on a 600-incher

Post  JBR-3 on November 9th 2018, 10:30 pm

OK, many thanks gents. I may fiddle with them, I may offer them up for sale/trade.
I really don't have another application for tem.

I even learned something about the acc pump shot scenario !

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