My fuel pressure started dropping off when running the engine up around 6500 to 7000 rpm so I decided to upgrade in prep for a 150 to 300 HP nitrous kit. I started with looking for a good pump that could supply the needed fuel for around 1000 HP and the need the lines to carry the fuel. I ended up with a Mallory 5250 pump and 5/8" lines. I also added a sump to the tank to make sure the fuel supply was adequate.

I pulled the tank and installed the sump, plumbed the lines to the filter and then to the old pump. I haven't had time to run the new lines to the engine so that will be next and then the regulator and the pump can be installed.

When I pulled the tank I found what I think was the problem, the suction line had crossed the supply line and smashed it just about flat. I was having a lot of issues with fluctuating fuel pressure and had changed out the regulator and pump a few times thinking I was having regulator or pump issues but I think it was due to the smashed line causing the issues.

Mallory recommends 5/8" lines with a Mallory bypass style regulator for this pump. I opted to go with Parker push lock line and fittings to plumb the system.

The sump has two AN 8 fittings so I decided to use both to supply the pump. My plans are to run both 8 AN lines to a 8 AN X 8 AN X 10 AN fitting that way I can supply the pump with a 10 AN line.

A few pics of the progress;

Smashed fuel line,























Neal

 

Looks great Neal. How are the nitrous plans coming along?

 

Still not complete with the fuel system upgrade,

changed positions and this was a negotiations year so things on the car got put on hold.

I'm still planning the nitrous system out, got to decide on either a single 300 HP kit or a two stage with 150 HP at a time. When I finish with the fuel system it will have no issues handling the extra 300 HP.

Did you make it to the Stars and Stripes show this year?

I went but didn't drive my car just walked around and looked.

Neal

 

Well thats a darn nice cut on the tank with hand tools. But the biggest problem i see is the filter is before the pump. Only screens can go before the pump - no restrictive filters. Next issue would be the pump is in front of the tank so when u accelerate the gravity feed from the tank goes back to the tank instead of the pump. No pumps dont suck, pumps push and every pump needs a positive pressure forcing the process fluid into the pump. Sorry but thats just the way it is.

My experience with an electric pump is that unless u have a recirc line the press gets uncontrollable when the carbs needle tries to seat at low rpm and idle speeds. Yes even with a regulator. I would highly suggest a recirc line return to the tank with a tiny 0.030"- 0.050" orifice to provide a continuous return flow. This will maintain a constant press a the carb inlet. I have one on my qjet and love it. U need a vented tank for this return though or u will have a pressurized tank.

Hope this helps and u did some nice work.

 

Appreciate the input Cardo0, the system is not complete at this point. I am using the factory return line at this time but will be installing a 5/8" supply and return per Mallory's requirements and I still need to install the pump.

I talked to a few well versed people in fuel systems and they recommended the water separator/filter due to its filter area. They all said that this particular filter would not create any issues.

I threaded the ID of the outlet fitting at the regulator and used a set screw to create a .050" restriction for the return line. I'm using the factory return line at this time until I get the 5/8" supply/return lines installed.

The 77 tank is vented to the charcoal canister in the engine bay

The Holley pump is temp until I get time to install the new lines and Mallory pump and regulator.

I worked in a fab shop for a good number of years so very familiar with the tools.

I've done some acceleration runs with the tank at less than 1/4 of tank of fuel and have had no issues with fuel pressure but will be keeping an eye on the pressure gauge for sure. According to Mallory if I follow their instructions I should be good to well over the 1000 HP mark I'm shooting for.

Neal

 

FYI the float check vlv in the tank to charcoal canister doesnt always do its job. When i filled my tank and made a sharp right turn the charcoal canister filled right up with fuel - because of my return line flow - and i had gas flowing down along side the exh header pipes. Since then i vent at the tank cap like the pre-70 C3 vets using a vented cap.

I dont know why u are running a larger return line with a tiny 0.050" orifice with a 5/8" return line? The 0.050" orifice restriction prevents large amount of vapor created in the tank. I dont see the need for a 5/8" return line with a 0.050" restriction.

No fuel sys design or even oil sys for that matter installs a filter before the pump - unless the entire system is pressurized with enough press on the suction side. I will say no more.

 

My last post wasn't very clear on the current fuel system,

I'm running the factory return line with a dead head regulator using a .050" restriction orifice to the return line to the tank. The larger line is not installed but when installed I will be using a bypass style regulator which requires the same size return line as the supply with no restriction.

When speaking with Mallory the number one cause of failures was trash in the pump. When I spoke with them they suggested a screen but agreed that a filter with enough flow capacity would work, as I said prior I'll keep an eye on the pressure under heavy acceleration and if there is an issue I'll start my troubleshooting with removing the filter.

Neal

 

I'm running a one-quart spin on filter ahead of my Carter 100 gph electric fuel pump so no debris can enter the pump and I'm also running a 5/16" hose return line (the tank nipple was also changed to a 5/16"). When you increase the power level of an engine the fuel system must also be upgraded to handle the additional power. The nice thing about using a constant-flow electric fuel pump is the fact the fuel has the chance to cool off.

 

I like that bolt in sump but I really think you will need some sort of baffle to make sure the pump doesn't get starved during a pass-especially with nitrous. Maybe something as simple as in tank foam to prevent sloshing-you just wont be able to see fuel level at the guage. Also usually any 90 degree fittings are a no no from sump to pump-especially for drag racing and even more so drag racing with nitrous.

 

Yes i agree. With a large NOx shot u wont have time to react. I dont want to bust anyone's bubble here but if your engine leans while pumped full NOx u will not make another run on that motor. Engines are much more expensive than fuel pumps.

 

appreciate the input

I thought about the baffle and adding it to the sump will be easy, the plates in the tank are 3/8" to 1/2" thick and can be tapped to bolt in a baffle if needed. I thought i would start with keeping at least a half tank of gas when making hard passes to keep the sump full of fuel.

The 90 deg fittings came with the sump but they also caught my eye when planning the fuel system out. I figured with two -8 (1/2") fittings feeding the pump the fittings wouldn't be an issue. I'll pickup some straight fittings and have them on hand when I get back on the fuel system.

Neal

 

I had posted my fuel system on YellowBullet forum a while back and I had to re do it twice Lol from all the feedback members gave me. I also had 90 a deg fitting and a 180 deg fitting that I thought was so trick but I got shot down.
That sump you have is for a deisel application correct? I had looked at something similar maybe the same one initially but I wound up bending up a sump for it and had my buddy tig weld it for me.
The blue line you used look nice and neat-what kind of line does it Y in to?
I have a ret reg mounted out back and like you a deadhead style up front.
I kind of have everything closely in line-just the way it worked out.

 

Hmmm that's interesting. I have my filter before the pump but I "could" swear when I spoke to Weldon (couple years back so maybe I'm wrong) that they instructed me to do filter first then pump.
Now I have to look into it ughhh
Here's my set up if anyone interested....

 

This is straight off of Weldons website.........so I'm not crazy, Lol

9. Should I filter my fuel before it enters the pump? Should I use a filter after the pump? What size filter(s) should I use?
Yes, Weldon Pump recommends the use of a 40 micron filter (WEQ1240) before the pump and a 10 micron filter (WEQ1210) after the pump. Either a paper type element or a stainless steel mesh type element will work for filtering fuel.

I do remember when I spoke to them that the 10 micron filter after the pump was optional for whatever reason, maybe because it's in line?

 

I put a filter prior to my pump also. I followed the information contained in this tech article from Aeromotive...


http://aeromotiveinc.com/wp-content/...etFilter02.pdf

 

Yes its for diesel applications, as they add them to their tanks for better flow.

The line from the Y to the pump is regular fuel line, once I get the Mallory pump installed I'll use a -8 X -8 X -10 "Y" to feed the pump using the blue push-lok hose.

The Weldon pumps are very highly rated around the race track and pricey but worth the money. I didn't want to spend the money so I settled for the Mallory pump.

Neal