This is going to be for a blower box blow thru pro charged set up.I have done a few systems on fuel injection engines, but none for a carb, so if I come off ignorant, please bare with me.. From my understanding I will need to add a return line to the system, correct?? Next is I need a boost reference FPR that will have to be able to be set higher then the boost level, correct?? I plan to use a electric inline bosch FP that is good for the HP were are shooting for 6xx, as I have one that is not being used, see no need to run a huge A1000 pump.. Going to use a #8 feed, #6 return.. This is the way I plan to do the set up.. WILL THIS SUFFICE... Thanks guys


John jr

This is just a quick sketch up..

Check out this link sir....it may give you a little better understanding.

http://www.holley.com/data/TechServi...ech%20Info.pdf

Thanks for that link, based on it, I should be good to go, but did not see anything in there as far as carb'd-boost ref FPR's..

John jr

If I remember correctly (and someone please correct anything I am wrong about), it's the carbs that are boost referenced....not the FPR. Blower carbs have special power valves in them (I think), and the vacuum lines just go to a port in the manifold. I dont think you absolutely NEED a special FPR for your setup. You just need to make sure you have plenty of VOLUME sir.

Hmmm.. Never heard of that.. I just did a skim over on some blower tuning on a few diff sites, it did not mention this about the carb itself being boost ref, just that being in a box( pressurize, will require solid floats so they will not collapse under boost.. WTH is one of the blower guys when we need them... LOL Ot atleast carbed guys.. Fuel injection seems so much easier some time hahaha


John jr

The reason you want to run a boost referenced regulator, is because of the fact it is a "Blow Thru" setup. In a roots style setup, the carb has atmospheric pressure above it. But, with a "blow thru" setup like a procharger, you will have more psi on top of the carb. As boost goes up, you need to increase the fuel psi, to keep the needle and seats/floats from closing and shutting down fuel supply while under boost, due to the added psi on top of the bowl vents.

I believe the general rule of thumb is 1 psi of fuel psi increase, for every 1 psi of boost. So if you are say at 7psi at idle, and setup to run 7psi wot, you want 14psi at wot on your gauge. Keep in mind, I am no expert on any of this, and some may be able to give you some better info you can take to the bank!

I would also run a regulator with a bypass.

Contact Nickerson Performance for carb set-up on the blow thru box application.

Yes, return line to tank and boost referenced fuel pressure regulator are needed. You will probably set for 7lbs fuel pressure at idle, then add 1 lb. of fuel pressure for each pound of boost- controlled through your pressure line between box and regulator. Just need to be sure your fuel pump will provide the additional lbs. of fuel pressure under boost.

this is absolutly correct,u need to increase the fuel pressure pound for pound.

Ok that has cleared up some things. I am aware of the fuel pressure per boost PSI because of the blow through/box app. I just wanted to know if that sketch i whipped up would work.. Thanks for all the input...


John jr