Fuel pump question.....

Hello all. I need advice on fuel pumps. I have a 66 with the V6 225. It has a Holley 4160 4bbl carb(600 cfm I believe) on an Offenhauser manifold. It came with a inline electric pump (blanked off mechanical port).Can I go back to the mechanical pump or does a 4bbl need more pressure than it can provide. I would like to use mechanical but will stay with electric if needed. Any advice is appreciated...Thanks

 

1.21 gigawatts? 1.21 gigawatts? Great Scott!

600 CFM is really really big for 225 cid. You'd have to turn 9200 rpm to pull 600 cfm into a 225. About a third of that is a more reasonable size.

Anyway, it's the fuel demand of the engine that determines the size of the fuel pump, not the size of the carburetor. I'd say the original mechanical pump will be fine.

 

Great Scott indeed. Yeah 600 cfm is way more than needed but it came with the jeep so I was planning on using it.Anyway thanks for the reply Tim.

 

The main problem with a too-big carb is loss of low speed control of the mixture. With a big hole and a small pump (the engine), the air velocity will be low for a given engine speed, so the vacuum signal won't be as strong as it could be. You can compensate by making the mixture richer than it needs to be, but that's not very economical.

 

Makes sense Tim. I could adapt a 2bbl onto my manifold.Any recommendations on carbs???? Another thing. I forgot to add I mounted a gas tank from mid 80's in the rear of the frame and removed the underseat tank. This added distance shouldn't make a difference with a mechanical pump. Should it????

 

Thanks Sparky...........

 

There's also a 390 cfm 4160 that was (is?) available. Have you checked the numbers stamped into your carb? The 390 would have been a popular choice for a 225.

The Truck Avenger (TA) is the current offering, AFAIK.

 

I spent some time last night confirming that the carb was a 600cfm. At least by the numbers on the carb. 1850-5 is the number that seems to point to 600cfm. I have a couple of other 4bbl carbs in my garrage from my 72 chevy stepside. One was a ANOTHER holley 600 cfm carb and a quadrajet. The quadrajet sems to be popular option with some. It is a California carb. Not sure if would be a good choice or not.