RCR Fuel System Help

We are just getting ready to start a RCR Mark I and looking through the manual it’s clear that a lot of steps are left are the imagination!

In particular, the fuel system is perplexing us. We have the two beautiful aluminum fuel tanks with five holes in each and no understanding of how to hook it all up. Clearly one hole is for the fuel sender, another for the fuel filler, presumably one for the fuel pickup tube, and another for the vent. What is the fifth hole for?

We will be using Weber carburetors and wondering if this set up includes a return line to the tank. Separately, we were sent one fuel pump. Wouldn’t we need 2 pumps to run both fuel tanks?

Any illustration/schematic/diagram or for pictures of how this system is to be hooked up would be much appreciated.

Some specific questions:

1. What kind of fuel line is needed to hook it all up?
2. What about the fittings to connect everything from tank to carb? Does it need to be attached to the frame here and there?
3. Do we need some sort of “Y” splitter to run the two lines into one?
4. Do we need a back flow preventer/one-way valve to prevent fuel running from one tank into the other?
5. How do you wire it all up and operate he system?
6. Is there a kit that supplies a pickup tube to sit at the bottom of each tank? Should there be a filter down there?

Surprisingly, none of this info is to be found in the manual so we are at a loss how to begin. Also, the senders we were sent (Speedhut) are about an inch too long. They hit the bottom of the tank and stick way out. Looking at the design, it appears that you can’t just saw it off at the right length.

Thanks in advance!
 
Hi Pasha,
I can only tell you how I did my system and it works fine. I have a single Holly carb but the fuel feed will be similar.

1. Fit pickup/sender to each side having measured and cut to length. I cut my end pipe at 45deg to sit about 10mm above the tank bottom. No need for filters providing you fit one each side before the pumps.
2. On top of each tank behind the bulkhead fit a filter, non return valve and a feed to a pump each side. I have Holly pumps which work fine and pull up the fuel no problem but they are noisy.
3. From each pump run a line to a Y piece fitted to the bulkhead rear RH side.
4. From the Y piece fit a fuel pressure regulator adjusted for your carbs
5. Connect the output from the FP regulator to the carb inlet fuel manifold.
6. At the front of each tank connect a small breather pipe with a one way valve to allow air in. The inlet orifice only needs to be small, say 4mm and is mounted near each tank inlet in a protected position
7. The RCR ‘swan neck’ metal inlet pipes were a poor fit and I had to modify them to clear the chassis.
8. Use specific large diameter fuel pipe to connect the ‘swan necks’ to the inlet and to the tank. I used the best clamps I could buy with two on each joint
9. Wire each pump to separate switches on the dash
10. Wire each sender to the dash gauges
11. In UK, to meet regs, the tanks have to be double skinned with drains to the outside of the car. This regulation came about during my build. There was no kit and it’s a complicated fabrication!
12. It takes a while to fill each tank and I use Shell 5 star 98 octane fuel and have a CR of 10.5:1
13. There is no cross feed between the tanks . I just switch each on as required.
14. There is no return to the tanks. You might need this on fuel injection but not on a low pressure feed to a carb.

Hopefully that covers it but I’m on holiday without my notes, pictures or the car to refer to. But hopefully it gives you a few thought starters.
Kind regards
Roger Allen
 

Peter Scontrino

GT40s Supporter
We are just getting ready to start a RCR Mark I and looking through the manual it’s clear that a lot of steps are left are the imagination!

In particular, the fuel system is perplexing us. We have the two beautiful aluminum fuel tanks with five holes in each and no understanding of how to hook it all up. Clearly one hole is for the fuel sender, another for the fuel filler, presumably one for the fuel pickup tube, and another for the vent. What is the fifth hole for?

We will be using Weber carburetors and wondering if this set up includes a return line to the tank. Separately, we were sent one fuel pump. Wouldn’t we need 2 pumps to run both fuel tanks?

Any illustration/schematic/diagram or for pictures of how this system is to be hooked up would be much appreciated.

Some specific questions:

1. What kind of fuel line is needed to hook it all up?
2. What about the fittings to connect everything from tank to carb? Does it need to be attached to the frame here and there?
3. Do we need some sort of “Y” splitter to run the two lines into one?
4. Do we need a back flow preventer/one-way valve to prevent fuel running from one tank into the other?
5. How do you wire it all up and operate he system?
6. Is there a kit that supplies a pickup tube to sit at the bottom of each tank? Should there be a filter down there?

Surprisingly, none of this info is to be found in the manual so we are at a loss how to begin. Also, the senders we were sent (Speedhut) are about an inch too long. They hit the bottom of the tank and stick way out. Looking at the design, it appears that you can’t just saw it off at the right length.

Thanks in advance!
 

Peter Scontrino

GT40s Supporter
I am at the same stage with the same questions. Josh at RCR told , me I could cut off the end of the black fuel gauge unit to fit.
Josh also suggested I use closed cell foam to fill the 14 inch space aft of the tank. The foam must be gas resistant.
 

Randy V

Admin
Lifetime Supporter
Centroid senders can be cut....
This is the manufacturer website -
http://www.centroidproducts.com/Prog-Senders.htm
F. WIDE CUTTING RANGE

Our preference is to provide the senders at the correct length to match your tank. However, the senders have always been shortenable in the field. There was a limit to the amount they could be shortened, however. For example, a 24" sender could only be shortened to as little as 12". The 2-to-1 limit in shortening was due to a tradeoff in calibration-adjustment "touchiness" versus range of shortening.
 
Thank you, all, for the helpful replies!

Speedhut ended up switching out the senders that were shipped too long and replaced them with units that were an inch shorter. They now clear the bottom of the tank by about 3/4". They told me you can only cut them exactly in half but no other fraction, so new ones were needed.

A few more questions have come up before we start plumbing these tanks:

1. The fittings on the bungs are 1/2" NPT which suggest AN-8 lines and hardware. We are going to run a 4-Weber setup from Jim Inglese, who tells me those can only handle AN-6. Is there any point to run AN-8 lines from tank to manifold? Or, do you use some sort of "step down" adapter to adapt the 1/2" threaded bungs to AN-6 lines?

2. Are there baffles in these RCR tanks? If not, do we need to use foam inside? I don't like the idea of foam that melts after 5 years or so and we are not planning to ever race the car.

3. What is a source for the fuel pickup tube and vent hardware? Our kit didn't come with either of these.

4. I have seen pictures of a fuel tank mod a couple of brothers did to their RCR and they show a metal "elbow" fitting on the tank fill line. Our kit didn't come with these. Can we just use a long length of 2" flexible fill hose from the tank all the way to the filler caps? Or does it need to go through a metal elbow where it runs through the chassis for abrasion resistance or some other reason?

Thanks!
 
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Pasha,

1- I used 1/2 Inch NPT to 3/8 Inch NPT adapters on the tanks to reduce the size and fit thread in 3/8 pickup and returns from Tanks Inc. (https://www.summitracing.com/parts/tnk-pt-13). I utilized a 3/8 NPT to -6 AN male fitting on the pickups and returns to run everything in -6 AN.

2- I'm not sure if they're baffled or not and I haven't planned on putting any foam inside of them because I have the same concern about it deteriorating and I don't plan on racing the car either. However, I am running a 1/2 gallon fuel cell in order to deal with potential fuel starvation issues...

3- Any of the auto parts sites (Summit, Jegs, Speedway) have everything you need to plumb the fuel system. For the vents I utilized these https://www.summitracing.com/parts/tnk-vvr - Just put in a 1/2 Inch NPT to barb fitting on the tank.

4- I have yet to complete the fill lines but this is what I plan on using... https://www.westmarine.com/buy/shields-rubber--series-350-355-369-fire-acol-fuel-fill-vent-hose-sold-by-the-foot--P011_333_001_002?recordNum=22
 
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