Fuel piping question

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rod7515

rod7515

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Im working on my 66 Dart. It will end up with a stroked 408 and will be running a Holley 750 DP that has been custom built by SMI. I plan on Drag racing a few times a year so I dont want anything that wont pass a tech inspection.
I have added a sump to the tank and thats where my question starts. The sump has 2, 3/8 NPT outlets which I was going to plug one and then run a 3/8 NPT - 10 AN fitting with -10 AN braided hose to the fuel filter which will have a 3/8 NPT inlet and exit the filter with a 3/8 NPT -10 hose to the fuel pump. Inlet to pump will be 3/8 NPT -10 but when exiting the pump I will be going to a 3/8 NPT -8 fitting to -8 AN braided hose where I will adapt to 1/2" piping to the front of the car where it will go into a regulator. All components are Mallory and the regulator has a return to tank which will be 1/2" return since that is my feed size. Not sure where I should mount the regulator yet and am looking for suggestions. Also should I go from the regulator to carb with -6 AN braided line or -8 AN? At some point I will try running my 2 X 4 setup as well but plan on the start up and break in to be with the single 4 BBL. When I do go to the 2 X 4 setup the regulator has an inlet and 3 outlets plus the return so each carb could get its own feed from the regulator.
I know that my restriction points are the 3/8 NPT thread areas of the fittings. My thoughts for using the -10 from sump to pump is to feed as much as possible to the pump or is this over kill?
Looking forward to your thoughts and ideas.
Rod
 
Personally I think the entire THING is overkill. NO6 supply up front is actually plenty. But you are not running a return? Big mistake in my book. I BELIEVE in return systems. They help relieve fuel boiling / vaporlock problems, for one.

Plus no10 is so much larger than 3/8 pipe I'm not sure you are really gaining anything there. I'd think no8 suction is plenty.

"Just how much" HP do you figure this will make?
 
I don't see what good the -10 lines will do at the beginning of the system. -8 is way more than big enough.

Normally the regulator should be as close to the carburetor as possible. If you get a regulator with one "in" port , one "return" port, and at least two "out" ports you can eliminate the dual feed carburetor lines/adapters by running a line from each "out" port on the regulator to the two fuel bowls. The two lines from the regulator to the carb bowls can be -6 which is again way more than big enough.
 
67dart273, I am using a return as I stated in my original post.
69 340 GTS, the mallory regulator I have has one inlet port and 3 outlet ports along with a return port.
I can reduce the fitting sizes of the tank thru the pump to -8 AN since I havent purchased the fittings yet. The one thing I have noticed is that the cost of fittings seem to be the same money for -10 vs -8. The hose is slighly higher in price.
You mention that the regulator should be as close to carbs as possible. I guess I will have to look for some pics of where others have mounted theirs.
Rod
 
I mounted mine high up on the passenger side inner fender, near the firewall. That's where your hoses come up from under the floor pan.
 
69_340_GTS said:
I mounted mine high up on the passenger side inner fender, near the firewall. That's where your hoses come up from under the floor pan.
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you planning on running an 812 c.i. rat later ??
 
I'm gonna subscribe to this one I'm starting to give some thought to building my fuel system. Just not quite ready yet
 
You are correct that your 3/8 fittings will be your choke point. Any line you incorporate bigger than that is wasted funds because at multiple points u are choking it back down. To what is basically a -6 (3/8). Im fine with -8. But you sure dont need ten. Thats what I run on a 650 horse...7500 rpm dedicated drag car. You fail to mention your power level, but I imagine its less.
Anyways... to get the benefits of -8. Since you already welded the sump in. You run both of those 3/8 bungs out of the sump, and Y block them into a single -8. Then you now have eliminated the choke point because you doubled your effective line size for a short stretch before the -8 union. Now pick a different fuel filter instead of a 3/8 inlet cheapo, and run -8 to your regulator. Then six to each fuel bowl. And yes, you want a return line, and yes again you want the regulator near the carb. The max distance you want it from the carb is the firewall or frame rail. Any further down stream is not where id want it.
 
69_340_GTS said:
I don't get this question/joke.
???
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Because -10 is way overkill for what you are doing. People will even argue -6 is good through 500. HP.
as I tell you above, im fine with you running 8. Leaves room for more hp later. Just eliminate your choke points.
 
johnnymac2k6 said:
Because -10 is way overkill for what you are doing. People will even argue -6 is good through 500. HP.
as I tell you above, im fine with you running 8. Leaves room for more hp later. Just eliminate your choke points.
Click to expand...

Yeah, but the reply was to my post, not to the OP.

But I get it now.
 
I think 3 different members have replied and ask the same question, how much HP am I planning on having. The number that was given to me by the builder was somewhere around 475 - 525. I am using a set of 915 J heads with some porting and that will probably be a bottle neck for HP. One thing I didnt mention in my earlier post was that at some point I plan on running a 2X4 setup that I have so I dont want to run into any fuel issues. Im not sure at what point I will go that way as I will start with a customized 750 holley DP from SMI. So the reason I am thinking of larger lines is because of the 2X4 setup. With that said I contacted summit tech, they were the ones that gave me the suggestion to use what I originally posted and the tech I spoke to said he would change the first hose and instead run 2, 3/8 -8 AN lines from the sump to the filter, then run the 3/8 -8 AN to the pump and from there to the regulator run a 1/2" line as well as a 1/2" return. He assured me the pump will have no trouble keeping the 1/2" line full with pressure and volume. Then from the regulator to the carb or carbs running -6 AN. He also said there will be many different opinions and most of them would work fine with no problems. Thanks for everyones thoughts and opinions. Hopefully sometime this fall I will get this piped up and be able to fire the engine.
Rod
 
rod7515 said:
I think 3 different members have replied and ask the same question, how much HP am I planning on having. The number that was given to me by the builder was somewhere around 475 - 525. I am using a set of 915 J heads with some porting and that will probably be a bottle neck for HP. One thing I didnt mention in my earlier post was that at some point I plan on running a 2X4 setup that I have so I dont want to run into any fuel issues. Im not sure at what point I will go that way as I will start with a customized 750 holley DP from SMI. So the reason I am thinking of larger lines is because of the 2X4 setup. With that said I contacted summit tech, they were the ones that gave me the suggestion to use what I originally posted and the tech I spoke to said he would change the first hose and instead run 2, 3/8 -8 AN lines from the sump to the filter, then run the 3/8 -8 AN to the pump and from there to the regulator run a 1/2" line as well as a 1/2" return. He assured me the pump will have no trouble keeping the 1/2" line full with pressure and volume. Then from the regulator to the carb or carbs running -6 AN. He also said there will be many different opinions and most of them would work fine with no problems. Thanks for everyones thoughts and opinions. Hopefully sometime this fall I will get this piped up and be able to fire the engine.
Rod
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AN lines are measured in 16ths. so FYI 3/8 is NOT -8an. 8/16 is a 1/2 inch (-8AN) 3/8 would be 6/16 or 6AN. I want to make sure you're getting it right, because you must have missed my post above where i basically told you the correct way to do it, and your last reply from this (summit tech) is similar, but it sounds to me like you are still incorporating 3/8 choke points in a filter, thus making any -8AN (AKA 1/2 inch) lines ineffective.
 
You run into less fuel starvation problems with multiple carbs than a single carb.
 
In reading the original post you will see that i referred to the 3/8 as the NPT meaning the thread size of the fitting not the size of the hose. Sorry if I mislead you but once it was stated I was assuming you had been following from the beginning. I will try to be more specific in the future.
Rod
 
I was reading from the beginning, however you are correct I overlooked your thread size as the hose id. Now for assuming...I assumed when I posted that you should run 2 lines out of the sump to increase draw size...that when you posted a summit "tech" gave you the idea, you had missed my post. lol but thanks for setting me straight. Glad you have a plan now and got it figured out! Good luck!
 
Time has slipped past and I am finally ready to run my fuel line up to the engine compartment. I've studied many posts about fuel lines but have not found one that really details what you have done going thru the frame where the trans cross member bolts to. I was thinking about drilling and using grommets but was wondering if there are any other better ways. I see many members here have sectioned the lines in 2 or three pieces. Is that in case you have to replace or service something or just because it is so hard to run a one piece line from front to back. Looking for suggestions!
Thanks Rod
 
johnnymac2k6 said:
You are correct that your 3/8 fittings will be your choke point. Any line you incorporate bigger than that is wasted funds because at multiple points u are choking it back down. To what is basically a -6 (3/8). Im fine with -8. But you sure dont need ten. Thats what I run on a 650 horse...7500 rpm dedicated drag car. You fail to mention your power level, but I imagine its less.
Anyways... to get the benefits of -8. Since you already welded the sump in. You run both of those 3/8 bungs out of the sump, and Y block them into a single -8. Then you now have eliminated the choke point because you doubled your effective line size for a short stretch before the -8 union. Now pick a different fuel filter instead of a 3/8 inlet cheapo, and run -8 to your regulator. Then six to each fuel bowl. And yes, you want a return line, and yes again you want the regulator near the carb. The max distance you want it from the carb is the firewall or frame rail. Any further down stream is not where id want it.
Click to expand...

THIS.................No gain having the # 10 in your case especially w/the 3/8 limit and you need a good sized pump to keep up w/the VOLUME the 10 requires. I run mid/high 9`s in my n/a 470 400 stroker w/a Magnafuel 300 pump, the 2 #8`s coming out of my alum. cell into a y block then a # 10 into a 100 micron filter attached directly to the pump. Then a # 10 to my regulator and # 8`s feeding the bowls. Simple and works great street/strip...........
 
I want to run my aluminum line from rear pump to front regulator. My question is about going thru the frame where the trans cross member bolts at. Have you just drilled clearance holes to feed the fuel line thru. If so have you insulate the fuel line with any type of protection. The original steel line was just fed thru but with the làrger line thàt I'm using plus I will have a return line as well and its àluminum not steel if I should do something different. Once I do get thru that frame àrea the headers will be about 2.5" -3" from the line should I buy some heat reflecting to cover the line. Should I use the aluminum that close to the header or switch to the1/2" braided at that point continuing to regulator?
Thanks in àdvance for your thoughts,
Rod
 
steel braided wouldn't need any, or very little grommet-ing when passing through the crossmember. If you use aluminum hardline, i would definitely use some type of insulation, and some kind of insulated clamp for sure.
 
I got to do a little work on running the fuel lines this weekend. My lines are now run up to the cross frame area for the trans cross member. I ended up having to loop the return line just before it goes back into tank so I didnt interfere with the shock on that side. I don't think it will effect anything. My next step will be to do the lines going thru the cross frame and up to the regulator which I will mount on the passenger inner fender. Where I have drilled to run the lines thru the frame I purchased double walled shrink tubing that I am going to insulate the line as it thru the frame. Then from the engine side of that frame I will be using a heat resistant covering to keep any heat from the headers off these fuel runs. You will see both insulating methods in the below pics.
Here are the pics so far:

View attachment DSCN0419.jpg

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View attachment DSCN0414.jpg

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View attachment DSCN0411.jpg

Any comments or thoughts are welcomed,
Rod
 
Finally completed the fuel lines all the way to the carb and ran the return back to the tank. I still need to make a bracket to support the fuel filter just from the regulator to the carb but other than that I am done with fuel until I install the 2x4 set up. I ended up using 1/2" line all the way. Here are the finished pics under the hood area.
View attachment DSCN0511.jpg

View attachment DSCN0514.jpg

Rod
 
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