Need help with designing my AN fuel system

[makoshark]

I have a 67 camaro with a mildly built LT1. I am using the stock tank, so no suggestions into running an aftermarket won`t change my mind. I have read and read on this subject and I think I`m more confused now than when before I started researching this. I have a new stock tank, never had gas put in it, and a new fuel sender with 3/8 line and 1/4 line. I also have a new ss 3/8 line to run front to rear of car. I have bought numerous an fittings so far, but don`t have all I need. I bought weld on fittings for the rear of the LT1 fuel rails. I have bought fittings to adapt to the ss hard line. I also bought a 2 liter surge tank. I have an external walbro gsl 392 pump/ 255. What do I do about regulator and where is the optimal place to put it? Research is telling me in the rear. What about return line? I was thinking of making the 1/4 return line on the stock fuel sender as a vent line because research tells me that is too small for a return on my LT1. All help is greatly! greatly! appreciated.
Thanks,
Jeremy

[camcojb]

the surge tank is a very good idea, should work great. You need a pump from the main tank to the surge tank, and a bypass line at the top of the surge tank back to the main tank. The 3/8 line from the main tank is fine for feeding the surge tank, but the 1/4" line is probably not big enough. I'd think closer to 3/8" for that also, so I'd have someone mod your stock pickup to swap the 1/4" line for a larger 3/8". You figure the bypass line back to the main tank from the surge tank has to flow enough to handle two pumps (one from the tank to surge and one from the surge to engine) minus whatever fuel the engine burns.

Then you need a second pump from the bottom of the surge tank to the engine, with a "Y" to the rails. I'd probably put a crossover line from rail to rail on the side you don't feed the rails with; i.e. if the fuel comes in the rear of the rails, make a crossover line (either hard line or an hose) to go between the front of the rails.

On the second pump I'd place the regulator right after the pump, in the rear of the car near the surge tank. It will bypass to the surge tank also, to keep the surge tank full. That way you only have one line to run to the front of the car, and there is no hot fuel from the rails being bypassed to the tank.

Jody

[makoshark]

Great, thanks. Few more questions though. Where is the optimal place to put the surge tank? I was thinking about installing it in the trunk. What kind of pump do I use between the tank and the surge tank and what kind of regulator do I use? Aeromotive part #`s would be great. The fuel rails already have a front, factory, crossover tube on them. Do I use a T fitting on, say, the feed rail? I have a weld on an fitting that I was planning to install on my tank for the return and again just use the 1/4 line on the fuel sender as a vent tube. Does the surge tank need to be vented as well?

[makoshark]

This is the surge tank I purchased.
It measures 14x13x13

[camcojb]

Great, thanks. Few more questions though. Where is the optimal place to put the surge tank? I was thinking about installing it in the trunk. What kind of pump do I use between the tank and the surge tank and what kind of regulator do I use? Aeromotive part #`s would be great. The fuel rails already have a front, factory, crossover tube on them. Do I use a T fitting on, say, the feed rail? I have a weld on an fitting that I was planning to install on my tank for the return and again just use the 1/4 line on the fuel sender as a vent tube. Does the surge tank need to be vented as well?

the trunk would work fine. To fill the surge tank a simple internally regulated pump like the Holley red, Mallory, etc. would be fine, although most any pump with decent volume would work. You don't need a regulator for that pump, it just needs to be able to fill the keep the surge tank filled. It will have help from the main pump which bypasses back to the surge tank also. Anything beyond what the engine is pulling will flow back to the main tank through the top line from the surge tank to the main tank.

As far as a regulator for the main pump, I like the 13101 efi regulator from Aeromotive. I use their 11101 pump so this regulator will connect to the outlet of their pump with a #10 mail to male o-ring adaptor which makes a clean install. If you are using a Wal Bro or different pump that doesn't have a #10 outlet you'll need adaptor fittings to use this regulator. In that case a 13109 may work better for your application; handles good power and has smaller inlet/outlet.

A tee will work, I usually use a "y" as it flows more, probably not an issue on most installs. No vent for the surge tank, just a big enough line back from it to the main tank so there isn't pressure in it for the bypassed fuel from the main pump, which will screw with your fuel pressure at the engine. In other words, you don't want to restrict the bypassed fuel from the regulator as it will change your fuel pressure..

Jody

[makoshark]

Would 6-an be large enough for the return or would it be safer to go to say 8-an?
Also, let me try to decifer this. After the main pump is the regulator. One line feeding the regulator, one line going from the regulator to the engine and then one line from the regulator back to the surge tank. Then one line from the surge tank back to the main tank. Am I correct?

[camcojb]

Would 6-an be large enough for the return or would it be safer to go to say 8-an?
Also, let me try to decifer this. After the main pump is the regulator. One line feeding the regulator, one line going from the regulator to the engine and then one line from the regulator back to the surge tank. Then one line from the surge tank back to the main tank. Am I correct?

correct on the lines. I always use #8 return but #6 should be okay. Really very little cost difference so I'd still opt for the bigger line.

Jody

[makoshark]

Ok, I`ll go with the 8`s. I don`t want to have any type of issues with this fuel system. That`s why I`m going through so much trouble here. Just hope all the joints throughout the system don`t spring a leak.
Thanks a bunch! I think I got a good grasp on all this now

[BBC69Camaro]

Just be aware dual -8AN lines if routed on the same side you are going to fuss with, its tight, especially around the firewall/frame area. I am currently trying to get mine to fit just "right".

[makoshark]

I`ll only be running the -8an from regulator to the surge tank and the surge tank back to the main tank. It will be -6an everywhere else. I shouldn`t have to fuss too much with that, fingers crossed. Thanks for the tip though

[BBC69Camaro]

This is much a question for me as anything (trying to figure this out as well; don't want to derail the thread thou).

It seems from what I have read its split where to mount the regulator. Some seem to like as close as possible to the fuel rails / carb on the theory it keeps fuel pressure more constant. The drawback being the possibility of heating the fuel more, which is why some like it mounted at the rear of the car.

What about mounting the regulator on the firewall using some insulation on the lines and a fuel cooler back on the return line near the tank (or where ever you can fit it)?

Also Aeromotive has pump controller that slows a pump down at idle to reduce the volume at idle, less chance of heating the fuel on the longer cruises which is usually where the fuel heating / vapor issues expose themselves?


Thanks!

[makoshark]

I`m a dummy at this, but I have read quite a bit on this subject, so I`ll give you the info I have come up with on your question.

If your running a cooler on the return line, then mounting the regulator in the engine bay, I think from my research, would be the best place.

The fuel controller you mentioned lowers the voltage going to the pump. That in itself can cause problems to the fuel pump. What is needed is a PWM (pulse width modulator) that sends about 12,000 pulses of voltage to the pump, which seems to be the best way to go from what I have read. There is an aftermarket pump that is internally pwm modulated. I`ll have to dig that pump up for you to see, but it`s for a fuel injected motor. I have yet to find an external pwm module to control the speed of the pump at lower rpms. I believe this is how late model factory vehicles control their fuel pumps

[makoshark]

Here`s the pump I was talking about. I just may buy this pump and not use the walbro I have

http://sctuned.com/fuelab/fuelabprodigy-fuel-pump/41403cgrn/i-213679.aspx

[makoshark]

Do I need to add a filter between the main tank and the low pressure, holley red pump, or can I get by with the filter sock on the fuel sender? I have a 10 micron filter to go before the high pressure pump after the surge tank.

[camcojb]

Do I need to add a filter between the main tank and the low pressure, holley red pump, or can I get by with the filter sock on the fuel sender? I have a 10 micron filter to go before the high pressure pump after the surge tank.


sock should be fine. You want a 100 micron pre-filter, not 10 micron before the pump. 10 micron is for after the pump only, too restrictive before the pump.

Jody

[makoshark]

Ok, so I have a 10 micron filter to go after the pump between the pump and the injectors. Do I put the filter before the regulator? Do I need to get a 100 micron filter to place before the main pump? I was assuming the sock on the fuel sender would take the place of the 100 micron filter.