Question for Keith

[hi-tech cobra]

I'm going with a nylon black 1/2" fuel line attempting to keep an original look. Two feed lines running down the drivers side. One to the mechanical fuel pump (Robbmc 550hp), and the other from the electrics (240-A's) up to a T above the mech fuel pump. I might add a check valve for insurance. 1/2" line to feed the now commonplace 600 hp KC482.

Question is about the fuel log. I want to keep things looking "original" but I'm worried the NOS fuel log that guys have used (Power Surge) will not flow enough to the carb. What do you think? Maybe fab something up with a larger diameter tube for the log with 1/2" outlets to the carb? Or get this one from Jegs: http://www.jegs.com/i/JEGS/555/15196/10002/-1

I hesitate to get the one from Jegs because of the non original look but it has provision for a return line. The 1/2" return will run back to the tank down the right frame tube.

I'm putting this post on the KC forum as well.

[undy]

Not speaking for Keith on this but that was a concern I had when I recently installed some dual quad QuickFuel 750s on a Tunnel Wedge that I was putting on my 600HP KCR Pond 482. I'd already ordered and received the Blue Thunder Re-pop OEM fuel log which I sent back. I ended up installing an aftermarket "AN" fitting fuel log. I too was real concerned about the restrictive inlets and outlets of the OEM style fuel log. I dwelled somewhat on the "originality" issue but I'd already used 8AN fuel lines and fittings throughout so originality would have been lost in a sea of aftermarket anyway.

Now... had I been really concerned about the "look", here's how it would have played out. I'd grab the three nipples on the log and pull them off. I then would have drilled/bored the inlet hole on the log to 1/2". The 2 outlets in turn would be drilled to 3/8". Being a HVAC contractor, I'd cut 1 small 1/2" x 1" copper tubing nipple and 2 ea 3/8" x 1" copper nipples. I'd slightly expand one end on all three to prevent any hose from slipping off then I'd silver solder (45% silver) all three nipples in the log. Having tools and materials available, it wouldn't take 30 minutes for the whole modification. Any local freon sniffer should be able to hook you up..

Dave

[hi-tech cobra]

Hey Dave,
Great info. Mickmate (Actoncustom.com) will fab up something like that for me.

What about your fuel lines? What size/kind of line(s) did you use? Did you put in a return line? If so, how is it plumbed? Do you run electrics and mechanical pumps?
Thanks,
John

[undy]

Originally Posted by hi-tech cobra

Hey Dave,
Great info. Mickmate (Actoncustom.com) will fab up something like that for me.

What about your fuel lines? What size/kind of line(s) did you use? Did you put in a return line? If so, how is it plumbed? Do you run electrics and mechanical pumps?
Thanks,
John

Hey John, I ran 8AN (1/2") braided hose from my "near tank" mounted Holley Black fuel pump 'n filter up to a 3 way bypass style Aeromotive fuel regulator mounted behind the engine's intake. I have a 8AN return braided hose running back from the regulator to and discharging into the top of the fuel tank. I have an 8AN fuel line running from the regulator outlet up to the inlet of the new fuel log. I've 6AN (3/8") braided hose/fittings from the fuel log outlet to both 750 carbs. It all works well, the fuel pressure stays dead nutz on and I NEVER starve for fuel. It's not OEM looking but it works great.

I had terrible probelms with single fuel line system with flooding the carb at idle. I'd originally thought it was a fuel boiling in the lines problem but found out otherwise. All is well now.

Dave

[hi-tech cobra]

Dave,
What kind of fuel line did you use braided stainless or nylon? Do you have a part number for the bypass regulator?
Muchas gracias!

[undy]

Originally Posted by hi-tech cobra

Dave,
What kind of fuel line did you use braided stainless or nylon? Do you have a part number for the bypass regulator?
Muchas gracias!

braided stainless on the fuel lines.

Here's the regulator: http://www.jegs.com/i/Aeromotive/027/13301/10002/-1

.... and a pic of the fuel system. I know, too much bright colored anodized aluminum..



de nada ...

[Keithc8]

The fuel system that Undy has looks more than over kill for the application. Better to be over kill than not enough. One thing you have to remember on these Cobras is that a lot of time the pick-up is the smallest place on the fuel system. A lot of the cars just have a 3/8 pick-up tube in the tank. This is something that I have talked with Kirkham about. Remember you will starve a single four much quicker than a 2X4 set up. You only have 2 bowls on a single 4 and 4 bowls on a dual 4 so you will drain the bowls down quicker on the same HP engine with the single 4V. I had a 2X4 set up on a Kirkham that made 750HP and ran the number 8 braided line to the front and went throught the manual fuel pump and used a stock log with it drilled out on the front for a #8 fitting. I had an electric fuel pump on the back feeding through the manual pump with the #6 pick-up and did not have any issues on the road course or drag strip. I think the fuel lines, log and the 4 bowls all helped this problem. Remember that you will drain the bowls on a 400HP single 4bl quicker than on a 700HP dual 4bl set up. I think you will be fine with what you are doing.

Thanks, Keith Craft

[misfit41]

I am using two 780 cfm's on my tunnel wedge with 760 hp and havent had any fuel problems. The electric pumps never worked and I have yet to fix them so still running on mechanical.I don't think you will run out of fuel .I think the most impoertant thing is float levels being correct for that.
Like you I wanted to stick with an original look ,you could always use the black nylon , the silver/nickle russell an fittings and paint the log .

[Tom Kirkham]

What is the diameter of the needle and seat in your carb? How does this effective area compare with the area of your fuel line?

The old style fuel logs bolt onto the intake manifold. This makes the original style fuel log an excellent heater for your fuel...and yes we have had problems with fuel boil over with the original style log. 2x4 are worse in this regard as the fuel tends to sit longer in the fuel bowls before being used.

The bypassing regulator we have had great luck with is a Mallory 4309.
This regulator cured all fuel boil over, and vapor lock problems.

http://www.jegs.com/i/Mallory/650/4309/10002/-1

[Cobra #3170]

Originally Posted by Tom Kirkham

What is the diameter of the needle and seat in your carb? How does this effective area compare with the area of your fuel line?

The old style fuel logs bolt onto the intake manifold. This makes the original style fuel log an excellent heater for your fuel...and yes we have had problems with fuel boil over with the original style log. 2x4 are worse in this regard as the fuel tends to sit longer in the fuel bowls before being used.

The bypassing regulator we have had great luck with is a Mallory 4309.
This regulator cured all fuel boil over, and vapor lock problems.

http://www.jegs.com/i/Mallory/650/4309/10002/-1

Tom, I agree, consider the BSFC of a 91 octane street engine and fuel volume would be more than adequate with the original set up.

[hi-tech cobra]

Tom,
I was planning on using a Holley 950HP carb out of the box. Will it be OK, or should I change the needle and seat to something else (obviously I don't know what I'm talking about)? My engine is a KC482 with a port matched Blue Thunder intake.

What do you use for a fuel log? I'm going to do a return line. Should it be on the end of the fuel log or use the bypass regulator you mentioned?
Thanks!

Originally Posted by Tom Kirkham

What is the diameter of the needle and seat in your carb? How does this effective area compare with the area of your fuel line?

The old style fuel logs bolt onto the intake manifold. This makes the original style fuel log an excellent heater for your fuel...and yes we have had problems with fuel boil over with the original style log. 2x4 are worse in this regard as the fuel tends to sit longer in the fuel bowls before being used.

The bypassing regulator we have had great luck with is a Mallory 4309.
This regulator cured all fuel boil over, and vapor lock problems.

http://www.jegs.com/i/Mallory/650/4309/10002/-1