Sniper Return line - Chevelle Tech
EFI Caution: Beyond here be monsters...

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post #1 of 13 (permalink) Old Jul 10th, 17, 12:00 AM Thread Starter
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Sniper Return line

Hi all, over here from NastyZ28. I am installing a RobbMC power surge and want to know if I can use the vent line on my gas tank as the return line. There are 3 lines at the tank in the pics below. Fuel feed, 1/4" return line and the vent line. In the picture of the gas tank below the vent line is at the bottom and is not being used. This is not my actual tank, just a spare for pictures.

1978 Camaro

Thanks!



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post #2 of 13 (permalink) Old Jul 10th, 17, 10:30 AM
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Tj
 
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Re: Sniper Return line

By 78 the vent would have been part of the sending unit. You don't want to use it for a return because it runs into a small baffle at the very top of the sending unit. The return runs closer to the bottom so you are not spraying fuel.

I should go out and hook a pressure gauge on the return of mine which is 5/16 back to the tank then into the original 1/4 sender line. The number I remember is below 5 psi is good.

Sorry no Chevelle, 73 Cadillac Eldorado - Fairly stock low comp 500cid.
FiTech Go4 600 - Timing control via gutted 7 pin large cap HEI - Fuel RobbMc Powersurge with returns.
Previous system was Megasquirt w/Holley TBI so I am not new to DIY EFI
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post #3 of 13 (permalink) Old Jul 10th, 17, 11:00 AM Thread Starter
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Great thank you. From the picture if my tank the vent line appears to connect to a separate point on the tank. I am pretty sure that ouxture is of a 78 or 79 tank. Definitely not earlier. Thanks for doing that pressure check if you have time. If not no problem.
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post #4 of 13 (permalink) Old Jul 10th, 17, 1:46 PM
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Re: Sniper Return line

Interesting. I know GM screwed around with some odd venting like 70-72 but thought they settled on having them all in the sending unit. Either way its likely a baffle right at the top of the tank so would not be ideal.

I will try and do that check, I need to do it anyway to make sure I'm not having a problem again.

Another tip, try and get that thing mounted in the coolest possible location. If its catching any air from the radiator or close to anything hot like the radiator you could have issues. The issues I had before I moved it didn't leave me stalled but sure made it run funny. Originally I was just forward but off to the side of the radiator so it wasn't in direct flow. I ended up re arranging some things to get it directly behind the headlights.

Sorry no Chevelle, 73 Cadillac Eldorado - Fairly stock low comp 500cid.
FiTech Go4 600 - Timing control via gutted 7 pin large cap HEI - Fuel RobbMc Powersurge with returns.
Previous system was Megasquirt w/Holley TBI so I am not new to DIY EFI
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post #5 of 13 (permalink) Old Jul 10th, 17, 3:29 PM Thread Starter
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Thanks for the tip. I have it directly behind the headlights where my charcoal canister used to be. It is immediately to the left of the radiator a good 6" away. I have some insulation wrap I will put on the tank as an added measure. The fuel lines are going to run down the drivers side over the wheel well turn and go back Along the firewall then make another turn directly into the back of the FI body. That should keep them away from any heat sources and I have insulation for those as well.
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post #6 of 13 (permalink) Old Jul 10th, 17, 9:00 PM Thread Starter
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Re: Sniper Return line

I took the sending unit out and took a look inside the tank. There is a bowl welded to the underside top of the tank covering the vent line. I assume it is a baffle of sorts so it looks like it is not a good idea to return fuel there although it may work.

RobbMC wrote me back and said basically the same thing, might work, but without being sure the tank is properly vented probably not the best idea.
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post #7 of 13 (permalink) Old Jul 11th, 17, 4:48 AM
 
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Re: Sniper Return line

I mounted my robbmc power surge on the passenger side as far away from the radiator as I could. I have yet to take a temp of the case after a trip but it stays very cool to the touch where I have it. Granted I have loads of room in a full sized Chrysler. 6 inches may be cutting it close. I've have about 500 miles on my setup now.




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post #8 of 13 (permalink) Old Jul 21st, 17, 11:37 PM
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Re: Sniper Return line

Quote:
Originally Posted by 8Pack View Post
I took the sending unit out and took a look inside the tank. There is a bowl welded to the underside top of the tank covering the vent line. I assume it is a baffle of sorts so it looks like it is not a good idea to return fuel there although it may work.

RobbMC wrote me back and said basically the same thing, might work, but without being sure the tank is properly vented probably not the best idea.
Robb is great about answering questions quickly. The best I've ever dealt with. I have a PowerSurge along with my Sniper too. You might consider a RobbMc sending unit.

70 Chevelle, Vortecpro 496, TH400, Moser 12 bolt, custom Tom's Eaton posi, 3.73, UMI/Viking front suspension, PMT rear. Sniper efi, RobbMc PowerSurge.
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post #9 of 13 (permalink) Old Jul 22nd, 17, 12:01 AM
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Re: Sniper Return line

what is that big blue-green thing in the pic?
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post #10 of 13 (permalink) Old Jul 22nd, 17, 3:56 AM
 
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Re: Sniper Return line

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Originally Posted by Tom Mobley View Post
what is that big blue-green thing in the pic?


I know....it's weird.


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post #11 of 13 (permalink) Old Jul 22nd, 17, 8:49 PM
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Re: Sniper Return line

Jimmy, is it a 440? cool that you were able to get a non-chevy up and running on EFI. I just had a guy wanting me to build a 440 for him. It's been so long since I did a Mopar I've forgotten all the little ins and outs of one. I'll have to do a refresher. Last 440 I did was at least 15 years ago, before aluminum heads were readily available. Still, it was a real ground-pounder. it was in a Roadrunner.

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Last edited by Tom Mobley; Jul 22nd, 17 at 9:34 PM.
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post #12 of 13 (permalink) Old Jul 24th, 17, 5:16 AM
 
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Re: Sniper Return line

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Originally Posted by Tom Mobley View Post
Jimmy, is it a 440? cool that you were able to get a non-chevy up and running on EFI. I just had a guy wanting me to build a 440 for him. It's been so long since I did a Mopar I've forgotten all the little ins and outs of one. I'll have to do a refresher. Last 440 I did was at least 15 years ago, before aluminum heads were readily available. Still, it was a real ground-pounder. it was in a Roadrunner.


No it's a 383 that's .030 over. So I think that puts it right around 389ish. I was kicking around a 440 but hell, the motor runs great. This is my first Mopar so it's been a learning curve for me. Being able to swap out intake manifolds with out spilling coolant is super nice!


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post #13 of 13 (permalink) Old Jul 24th, 17, 10:54 AM
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Re: Sniper Return line

Front distributor is one of my favorite features. No wonder Gm came up with that adjustment window for the dwell since many of theirs were in the back. Lucky for me my Cadillac is up front.

Sorry no Chevelle, 73 Cadillac Eldorado - Fairly stock low comp 500cid.
FiTech Go4 600 - Timing control via gutted 7 pin large cap HEI - Fuel RobbMc Powersurge with returns.
Previous system was Megasquirt w/Holley TBI so I am not new to DIY EFI
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