I was wondering if a 600 Holley would be too much carb for my 272. It is pretty much stock other than headers and electronic ignition.

"Good work isn't cheap and cheap work isn't good."



"If it ain't broke don't fix it."

It is a bit large. A 465cfm is closer to what you want. It will run with the 600 but will never be a efficient setup.

Regards

Rick - West Australia
Do Y Blocks Downunder run upside down? Gravity Sucks!!

It's always better to run a carb a bit smaller cfms for the application over a larger cfm carb. They just seem to work  better.

Dan      Kingman Az.      86409

The great thing about vacuum secondary carbs is that they are difficult to be too large for an engine simply due to the vacuum secondaries only opening up enough to supply engine demands.  With that being said, the smaller sized carbs are still more efficient in the lower rpm bands and that has to do with the constant speed velocity thru the primary side venturies being higher.  If going for lowend drivability, then go with the smaller sized carbs but if going for a more aggressive driving style, then the 600 cfm carb will be the more suitable choice.  While my own stock headed 272 ran well with a 750 cfm Holley, overall street drivability and fuel economy with the current 525 cfm Road Demon Jr. is better.

Lorena, Texas (South of Waco)

Well thanks for all of the advice and comments. I was afraid a 600 might be a bit much. My dilemma is this: I have a good 2 barrel carb to build that would work great. (Motorcraft 2150) But, I would like the looks of a 4 barrel and I love the sound and feel when the secondaries open. I guess I'll stick with the Motorcraft carb for now......you cant argue with their reliability....they just aren't cool lookin'.

"Good work isn't cheap and cheap work isn't good."



"If it ain't broke don't fix it."

According to the manual that comes with vacuum secondary Holley carbs, you shouldn't feel the secondaries open. They explain what's happening, but what it boils down to is if you feel it, it is not adjusted correctly.


Lawrenceville, GA

Too much carb. Well, yes and no. It will be fine because your Holley 2150 that you will rebuild has two verturies that provide about 270 CFM (cubic feet per minute )  while the Holley 600 has two primary venturies that provide about 300 CFM, so thats in the ball park. Then when you mash on the gas pedal with the Holley 2150, no more. Game over. While with the Holley 600 AND VACUUM SECONDARIES you potentially have a lot left. IF YOUR ENGINE REQUIRES IT, ONLY IF.

So, your choice. Pete

IF you have a 600 ready to go then give it a go, A 465 is better, As Ted said its all about velocity. I have a 600 on mine [ its what the car came with] and I have it set up quite well, however I will eventually go to the 465. I found you have to have fuel! I run ,64 jets, blue pump cam 2nd position, 35 squirter, at the moment a standard grey secondary spring, I think going lighter wont achieve much. I can mash my foot to the floor standing start and it wont flatspot.



"Came too close to dying to stop living now!"

fiftysixford,

You know a 390 or a 465 look like a 600 under an air filter. Buy a nice air filter and people won't look twice. Similar body same bowls. With you bum in the drivers seat knowone is looking at the engine.

Cheers

Warren

Grizzly (Aussie Mainline)

I had a 600 and sold it to buy a new 390 Holley so I could use their accessory throttle position sensor.



With only 272 or 292 (stock) cu-in, A 600 will work, but a smaller carburetor will probably have a little better throttle response. I don't think I would get any beter performance out of a bigger carb. A stock 292 can only suck so much through ANY carb.






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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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