This question has been on my mind for quite a while and I'd like to get some input from everyone. It seems that many people always choose to go with a Carter fuel pump as a replacement, but then they randomly choose between these two models. They are essentially the same pump, but one is a few psi higher than the other. Here are the links and specs for each Carter pump.

http://store.summitracing.com/partde...5&autoview=sku

Part Number: CRT-P4070
Free Flow Rate: 72 gph
Maximum Pressure (psi): 6 psi

http://store.summitracing.com/partde...5&autoview=sku

Part Number: CRT-P4594
Free Flow Rate: 72 gph
Maximum Pressure (psi): 8 psi

So this leads to my question. Which of these two pumps is the BETTER application for a 12A Nikki first gen? Is it best to get the higher psi pump and turn it down with an FPR? Is this hard on the pump to turn the pressure down to 3 psi with the regulator? They are the same price, so really it doesn't matter.

Give me your thoughts informed fellows,
Jamie

 

I have used both 4070 and 4594 in the past and present. For the price, I would use the 8psi . THis is to ensure that you dont have to buy another pump in case you want to upgrade to a holley or a weber at later date. Just use a good regulator such as a mallory.

 

Wacky, which Mallory regulator would you use for the Nikki? Can you send me a link? I've got one of the Holley 1-4 psi regulators right now, and it's a piece of crap. It doesn't matter what i adjust it to, it always stays at 0 psi. GRRRRR....

 

4309 is good. always "O"?? there is something wrong with your regulator or the gauge. holley is ok but not the best out there. I would like to change mine as well except, If I change one, I have to do the same to my other cars. Owning too many rotaries is no fun sometimes.

 

I think that the regulator is faulty. I've heard of other people's Holley FPR's doing the same thing. Both the gauge and the regulator are brand new, so I don't really know which one is causing the problem.

I took a look at that Mallory 4309, and it looks like a really nice piece. I see that it has a fuel return port, also. Another question for you. When you set that return port up, do you simply cap the fuel return line on the Nikki and hook the return port straight up to the return line on the firewall?

 

nikki's stock return line is good. So far, my newphew hasnt had any problem since he picked up my former tender blue FB in December. No issues nor vapor lock despite he lives in Las Vegas.

 

A return style FPR, like the 4309, allows cool fuel to circulate through the pump, as opposed to blocking it like the Holley FPRs do. This will generally yield a longer pump life. It also greatly reduces the chances of vapor lock. As far as using the stock Nikki return line or blocking it off and using the carb as a deadhead, that depends on where the FPR is mounted.

If the FPR is placed before the carb, plug the return line. Placed after the carb, make sure you remove the stock inline barrel restrictor.

 

Okay, just want to be sure that I've got all my ducks in a row here. Here is how I'll set it up. Tell me if this is right.

Firewall fuel supply line > Inline filter > Mallory FPR > Nikki

So in that case I can just plug the Nikki return nipple and run the Mallory FPR right back to the firewall fuel return line?

Jamie

 

Mods archive this one. Its got good info.

 

I'll stick this in the archives and clean it up as soon as we get some confirmation on the fuel return config from Wacky and/or Trochoid. Heck, I may even do a writeup with pics for upgrading the fuel system after I get all my parts purchased.

Jamie

 

Wacky or Trochoid, you guys around? Never got confirmation from you on this. If I'm running a Mallory FPR like this, can I just take the return from the FPR and run it back to the return fuel line on the firewall? Then I would just cap the return fuel nipple on the Nikki?

I believe this is called dead heading? Maybe not. Anyway, is this the right way to set up a FPR that has the built in return capability?

Thanks,
Jamie

 

either way is fine but I highly recommend installng a fuel jet on the hard return line to limit the flow back to the tank

 

Is this to keep pressure on the FPR return side? Just want to understand why.

 

I just like to keep a constant pressure on the supply side.

 

Some of my computer skills are sorely lacking. I've tried to upload the fpr routing diagrams for both the Holley non-return style and the Mallory 4309. Both PDF files exceed the 100 kb limit. Diagrams can be found on their respective websites. There is more than one way to plumb either one of them. Block the return line off of the carb, and connect the return line to the return port of the 4309. If using the Holley, block both the carb and underbody return lines.

As far as the pumps go, either is fine. Keep in mind that turning down the psi via fpr creates heat, which loads the pump more. Pumps generally last longer when using a return style fpr.

Stock, there is a oneway restrictor valve between the carb and the return to tank fuel line.