*a*jones*

Don't flame me about why i am asking this question, but what changes in the fuel system will i need to do to power a carb on an 89 N/A?

Evil Aviator

At minimum, you will need a low-pressure fuel pump with a fuel pressure regulator. I had a Holley Blue fuel pump in my carbed 12A 1Gen, and it seemed to work pretty well. You may also need larger fuel lines, depending on your projected hp level because low-pressure fuel systems need larger lines than high-pressure systems. I am not sure about other items because I don't have any experience with this particular task.

Since you are asking such a basic question, I want to make sure that you understand that you will need to use a different ignition system if you convert to a carb, and the rotary engine has a very low vacuum signal that requires a higher cfm rated carb than you would think, and low-end carbs like those made by Holley don't work well without modification. You may want to check in the Race Car Tech forum for more info. I just don't want you to start a project that is going to be more expensive and time consuming than it first appears.

MPM

I did my carb conversion without replacing any fuel pumps. My way is not the ideal way to do it though. Evils description is the proper way to avoid potential problems.

I used a simple brass T adapter after the fuel filter to loop the fuel inlet into the return line. With the remaining leg of the T adapter I ran a fuel line to the carb. I run a pressure regulator and pressure guage in the line going to the carb. You will need to experiment a little on the return line with some type of orifice that will create enough restriction to get the fuel to back up in the line leading to the carb. I don't remember what size the orifice I used is.

This is obviously the poor mans way to do it but if done with a little thought will work well. Mine has been working just fine for over a year now.

*a*jones*

I'm planning on running a dizzy ignition and just ordering the complete holley kit from racing beat. they say a Mallory 4070M would be a good pump?

moremazda

iTrader: (4)

You will not need to change out your fuel pump!!!! In fact your N/A fuel pump in a carb'd application will be very good match. What you will need is a return style pressure regulator such as http://www.jegs.com/cgi-bin/ncommerc...54&prmenbr=361
and an accurate low pressure fuel pressure gauge.

Ryan

680RWHP12A

nope, use a low pressure return style fpr like the one ryan mantioned or use a mallory #4309 and you will be fine

*a*jones*

won't that cost just about as much as just switching out the pump? what would you reccomend for a good fuel pressure gauge since i will need one either way

moremazda

iTrader: (4)

Well if you use an aftermarket pump, you have the cost of the pump and the cost of the regulator. Then you have remove the stock pump, rig a fuel pick-up since you just removed the factory one, mount the aftermarket pump and then route fuel lines to it and from it. Then mount the pressure regulator.

Or you could just mount the regulator, have the reliability and quiet operation of the stock pump, not to mention a few extra hours to do something else.....

But I guess if you like the noise of a Holly Blue, then by all means put it in.

Ryan

PS Autometer mechanical pressure gauge's are pretty reliable. Although I would remove it from the engine bay after you are done tunning the initial set up.

*a*jones*

thanks, i think i'll use my stock pump with a regulator then. if it's burns up my pump guess i'll just have to go the other way, no reason to throw out a good pump i suppose