I went from a FI 2.8 to a carbed 350, will this fuel pressure regulator work? HLY-12-803. Ive seen other ones referenced from Mallory or some other, but theyre close to $100. This one from Holley is under $30. I would assume since it has two outlets, it should work for carb delivery and fuel return. Or is there something im missing?

 

That regulator will not work for what your trying to accomplish.

 

What is the difference between that one and say a Mallory 4309? Theyre both 3 ports.

 

The holley is a non return for a low pressure pump. The Mallory has a return for the excessive amount of fuel.

 

You're right, the catalog says it has dual outlets, but the website says it does not. I found this one instead http://www.summitracing.com/parts/hl...03bp/overview/.

 

looks like pretty much the same thing to me but with a return.

 

Isn't that what i need? It says not to be used with mechanical fuel pumps. Can you explain why it wouldnt work? I'm not seeing what the issue with that one is. It has an inlet, outlet to the carb, and a return for excess fuel.

 

call summit for product information.

 

I would think the BP one would work. It has a bypass built in. The Mallory 4309 has a bypass and a boost ref port to raise fuel pressure if running forced induction. The additional boost port is probably one of the key differences.

If anything I would just bypass Summit and call Holley Support directly. Most of the time people answering the phones at Jegs and Summit have to put me on hold to call the Mfr for support too.

 

"Bypass" and "return" basically mean the same thing. The idea is that the pump flows a constant volume, with what isn't needed to maintain pressure at the carb returned or "by-passed" back to the tank.

The information at the bottom of the linked page tells the story {bold added}: "These Holley carburetor bypass style fuel pressure regulators are designed for use in systems that require a return line back to the tank."