running out of breath in the 1/4 mile

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Yeah the 12 sec burn out test will not prove anything usefull. Your 360 can burn up any street tires, in first, at like 1/4 throttle. In second maybe 1/2 or less, certainly still on the primaries. You will put down less than half power, and maybe half to 2/3rds rpm.If your brakes can hold it, she ain't putting out.

But man, you are living on the edge with all that rubber, or rather all those gearclamps, on the pressure side of the pump.
Also in your case the tank vent is very important, on account of that long flex line from the frame to the pump. Any good pump will suck that flat without venting.
Also the brass fitting at the carb; is it adequately sized internally? That one looks aweful iffy..
Also, I dislike those little gear-clamps. On the suction side they often allow the pulling of air, and require a second clamp, rotated 180*. This is especially important at the little jumper by the tank. That rear-most line needs a close watch and double clamped for sure if gearclamps are used.
I completely eliminated all rubber on the pressure side. I plumbed 3/8 line to within about an inch of the pump, and jumpered there with EFI hose. I installed a large canister metal body filter at the back with tube fittings.I ran that rear line right up to the modified sender line, and jumpered that with EFI hose. I fabbed up an all steel line from the pump to the carb. I installed an engine restraint to prevent unnecessary, and unwanted, engine movement. I run the Hi-po pump.I have no problems to at least 120mph, and at least 7200 in 3rd.Have not tried faster or higher.
Oh yeah; if the pump sucks air, well, you can't make power on air alone.
 
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318willrun said:
Just saying I like Carter fuel pumps.... and that the big boys of old all ran just fine off of mechanical fuel pumps feeding a lot of cubic inches and around 400 hp. My brothers '68 GTX with headers and a couple of other upgrades could be floored for a 1/2 mile and no fuel issues..... No, I'm not saying mechanical is better than electric, just saying that they work easily into the 12's
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OK, and I do to. It's just that the M6866 is rated at 25 GPH. You might get more our of any of them but none would be guraranteed to support 400 HP. I just can't in good conscience recommend one for the OP.
 
replicaracer43 said:
The fuel T at your carb has a allen head plug in it, remove that, get a nipple that fits, run a hose from there to a gauge at the windshield. Even doing a burnout is not going to load the engine the same as a all four barrels open run through the gears.
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Exactly correct.... no way it will load it properly to simulate a 1/4 mile drag run. And it won't be safe for you buddy.

That pump looks exactly like the Carter M6866. Rating is 25 GPH into 4-5 psi.... period. Don't believe what the Summit site says; follow the link that 318willrun provided if you don't want to believe it; it's right there in black and white. It cannot be counted on to do the 35-40 GPH rate needed for you engine. And running like this means you are hitting a lean condition at a bad time====> potential engine damage.

The line out of the pump look like 5/16".

I am glad AJ has not seen the fuel lines to our carb!
 
AJ/FormS said:
Yeah the 12 sec burn out test will not prove anything usefull. Your 360 can burn up any street tires, in first, at like 1/4 throttle. In second maybe 1/2 or less, certainly still on the primaries. You will put down less than half power, and maybe half to 2/3rds rpm.If your brakes can hold it, she ain't putting out.

But man, you are living on the edge with all that rubber, or rather all those gearclamps, on the pressure side of the pump.
Also in your case the tank vent is very important, on account of that long flex line from the frame to the pump. Any good pump will suck that flat without venting.
Also the brass fitting at the carb; is it adequately sized internally? That one looks aweful iffy..
Also, I dislike those little gear-clamps. On the suction side they often allow the pulling of air, and require a second clamp, rotated 180*. This is especially important at the little jumper by the tank. That rear-most line needs a close watch and double clamped for sure if gearclamps are used.
I completely eliminated all rubber on the pressure side. I plumbed 3/8 line to within about an inch of the pump, and jumpered there with EFI hose. I installed a large canister metal body filter at the back with tube fittings.I ran that rear line right up to the modified sender line, and jumpered that with EFI hose. I fabbed up an all steel line from the pump to the carb. I installed an engine restraint to prevent unnecessary, and unwanted, engine movement. I run the Hi-po pump.I have no problems to at least 120mph, and at least 7200 in 3rd.Have not tried faster or higher.
Oh yeah; if the pump sucks air, well, you can't make power on air alone.
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Can you post some pics of all your lines?
I'm having a similar issue with the 120gph pump and have too much rubber line. Finding fittings locally is not easy, starting from scratch and figuring out what you need from Summit or somewhere can be long winded trial and error. A parts list would be awesome, too!
 
nm9stheham said:
Exactly correct.... no way it will load it properly to simulate a 1/4 mile drag run. And it won't be safe for you buddy.

That pump looks exactly like the Carter M6866. Rating is 25 GPH into 4-5 psi.... period. Don't believe what the Summit site says; follow the link that 318willrun provided if you don't want to believe it; it's right there in black and white. It cannot be counted on to do the 35-40 GPH rate needed for you engine. And running like this means you are hitting a lean condition at a bad time====> potential engine damage.

The line out of the pump look like 5/16".

I am glad AJ has not seen the fuel lines to our carb!
Click to expand...

I would like to see your setup and parts list as well.
Hope it's not too much trouble, but it's cheaper to copy a proven method and get it right the first time.
Thanks guys!
 
KnuckleDuster said:
Can you post some pics of all your lines?
I'm having a similar issue with the 120gph pump and have too much rubber line. Finding fittings locally is not easy, starting from scratch and figuring out what you need from Summit or somewhere can be long winded trial and error. A parts list would be awesome, too!
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The pattern is already on your car.
I just duplicated it in 3/8 steel off a roll. I used a flaring tool to form the "barbs" on the ends.I rolled the tubing on a flat floor to make it look purtie.The last footage I rammed up the front stub frame and pulled it out through a slot I made,right near the pump.From the pump to the carb, I followed the factory route, just skipping the filter. Then another "barb" and a short EFI jumper to the Holley dual-feed. Since the Hi-po pump only puts out a few psi, those factory split-spring clamps do the job for years and do not cut the rubber like the gear-clamps do.
No AN for me. Too pricey for one. K.i.s.s for another.Too heavy? for 3, (maybe just looks heavy). Too shiney for 4. My car is not a piece of Army/Navy Equipment for 5. OK, I admit it; it was mostly personal preference, ..............................plus the price.

FWIW; I do know how to set cars on fire. It's real easy with a little gas, and unpreparedness. It boggles my mind how fast panic sets in when the little flame gets up...................If it starts under a closed hood at speed, just stop the car and run. There will be not much time. If you have an electric fuel pump..........Will you remember to shut it off? If it's wired to your ignition sw, will you remember to turn it off with the key. If your column still has a steering lock, will you remember about that? Panic can come in the blink of an eye, and is a powerful enemy, not easily overcome, when the flames are rising.
 
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I had an incident with my 1970 Challenger with a 383 motor at the track years ago. It would fall on its face when I was shifting at high RPMS. We checked everything over and it was ok, an old dude came over and suggested we change the fuel filter. SOB we cut open the filter and it was partially clogged, robbing the engine of fuel at high RPMS. Just something to think about!
 
nm9stheham said:
OK, and I do to. It's just that the M6866 is rated at 25 GPH. You might get more our of any of them but none would be guraranteed to support 400 HP. I just can't in good conscience recommend one for the OP.
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Yeah, it wasn't a recommendation. Just responding to the Carter Post. But in truth the big block six pack cars are a lot of cubes and a lot of horsepower that ran well on these types of pumps.
 
allright, so here are some thoughts so far, ill see if I can replace the filter (I have another one, I just never bothered to properly plumb it in) with one that screws right into the fuel line
then replace the bras hose barb with a aluminum one (that one I found kicking around at my job, who knows what the application was, air pipe most likely)

then, replace the rubber fuel line with EFI line?
whats the difference?

do you guys think there is any gain to be made if I replace the section of steel fuel line on the pressure side of the pump with 3/8th?

I'm actually considering making a braided AN-6 fuel line, which runs from the fuel pump to the filter, any thoughts on that?
 
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diymirage said:
allright, so here are some thoughts so far, ill see if I can replace the filter (I have another one, I just never bothered to properly plumb it in) with one that screws right into the fuel line
then replace the bras hose barb with a aluminum one (that one I found kicking around at my job, who knows what the application was, air pipe most likely) I'm not saying that the brass barb is bad. You need to check the I.D.

then, replace the rubber fuel line with EFI line?
whats the difference? EFI is thick wall, and good for mega-pressure. It will not collapse under suction.

do you guys think there is any gain to be made if I replace the section of steel fuel line on the pressure side of the pump with 3/8th? By itself,No

I'm actually considering making a braided AN-6 fuel line, which runs from the fuel pump to the filter, any thoughts on that? Save your money, go steel.If you can only do one, It is better to get the supply side up to speed than the pressure side.The supply side starts inside the tank, with the sender
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when I check it, what do I look for, a certain I.D. ?

and while I'm on the topic, it almost looks like the fuel line looks like a AN8 size, does it make sense to run an AN6 into that?
 
diymirage said:
when I check it, what do I look for, a certain I.D. ? The hose is clearly labeled, as what barbs it will fit. It is too stiff to be stretched or clamped,to fit a different size.

and while I'm on the topic, it almost looks like the fuel line looks like a AN8 size, does it make sense to run an AN6 into that? A/N is sized in 16ths,so a -6 is 6/16 or 3/8inch, and a -8 is 8/16 or 1/2 inch. At your power level, 3/8 is more than adequate, for full load/WOT. IDK where 5/16 runs out, but I think you might;top of second at 420hp?.lol
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AJ/FormS said:
Also the brass fitting at the carb; is it adequately sized internally? That one looks aweful iffy...
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got it now, I thought you may had questioned the inside of that bard (because it was brass)
it is a 3/8th hose barb


winstoninwisc said:
never mentioned your intake . No vaccum leaks > and yes check floats
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pretty sure there are no vacuum leaks
what is the best place to set the float level in one of these carbs?
I always had it set for the center of the sight glass, but I guess if they are the same as the old holleys, I should be at the bottom of the sight glass?
 
Saying it's a 3/8 hose barb, is like saying you have a Mopar. Rather vague.
You need to measure the I.D. to make sure it is not a restriction. Some of those need to be drilled out or replaced by a bigger 3/8 fitting.
 
Gotcha, thanks for clarifying that
I'll have a look at it when I replace the filter

(I am considering replacing the whole pressure section with 6AN line anyway, but still)
 
gotcha
ill see what my options are there

do you remember roughly how much you spend on the line you made?
I think I can get them prebend for about 85 bucks
 
Why are you asking the same questions repeatedly when they have been answered? You've already been told at least once because I answered you that the 3/8 line is not necessary........BUT it would be ok to go to it for future upgrades. Beating on the same questions just to get a different answer is wasting time that you could be fixin the thing.

I am beginning to think all you want is to hear the answers you are looking for.

Your car has a 408 stroker. You're talking about racing it on the strip. No way in HELL would I ever use a mechanical pump, but you seem dead set on just that. I don't give a rip how many say they've used them. The electric pump is the way to go.

Here's what I would do if it was mine. Throw that mechanical POS pump in the ditch. Replace it with a block off plate. Run new 3/8 line from get to go, "just because".

Pick out a GOOD electric pump. Mount it as CLOSE to the tank AS POSSIBLE. Pumps are made to push, not pull........even mechanical pumps. This is why they are at a HUGE disadvantage. When mechanical pumps are in stock to fairly mild applications, they work pretty good. But when you ask them to be in a REAL performance application, they can fall short.

You are experiencing CLASSIC fuel shortage symptoms. That's been suggested several times. Go to the strip. Look what people run that have similar engines and drive trains.

Take the advice and keep using a mechanical pump. You will keep having problems.
 
What RRR said for a remedy would certainly take fuel delivery out of the question.
 
Before you change everything. My 383 used the standard 5/16 fuel line, everywhere. The only thing I did was to swap to the Carter Street Super Mechanical Fuel Pump. I was running the stock 72 400 HP TQ and manifold.
 
I guess if I really had to narrow it down, to why I would want to stay with mechanical over electric, is because then, at least I have an idea of what I'm doing...and I'm a lot more comfortable replacing parts then I am removing them and reinventing the wheel, so to speak


but, lets see if I get this right, you suggest I get this pump
http://www.summitracing.com/parts/crt-p4601hp
mount it after the pick up, under the pump
run a 3/8th line into a regulator mounted as close to the carb as possible and then wire it in with a keyed positive?

i guess if you put it like that, it sounds pretty simple
 
Any electric pump will need a relay in the circuit. Very easy to install. I recommend "that pump" because it's a good compromise. It performs well and it won't put you in the poorhouse. It will require a regulator though and I highly recommend a return line.

Here's the main point. Yes, you can probably get a mechanical pump to work WHERE YOU ARE NOW. But remember you upgraded the car from what it WAS. How much longer before you upgrade again? Isn't it a peg leg? Don't you plan on a sure grip? You got any ideas about slicks or drag radials? When you get the thing to finally launch GOOD, that fuel pump is really gonna be workin. HARD. You get what I'm sayin?

Why use something basically for a band aid IN THE NOW when you can make a pretty affordable upgrade that will work WELL into the future?

That's just my line of thinkin on it. Not tryin to argue with anybody here........just trying to tell you what "I" would do.......already done, actually.

If you want to properly diagnose it, nothing in the world wrong with that. I think somebody already suggested teeing into the fuel system and taping a gauge on the windshield, right? Try it. Make sure you have a second person to watch the gauge.
 
Not to open up a hornets nest. I do not know why people say to use a electric fuel pump! The Hemi and 426 Max Wedge motors from the 60s and 70s use a mechanical fuel pumps and they had no problem running the 1/4 mile, some of those cars had the cross ram intakes and the mechanical fuel pump had no problem feeding the two carbs
 
Very true. Have you priced a REAL Max Wedge of a REAL Hemi mechanical pump? Those were real honest to goodness HP mechanical pumps. And I don't care what anybody says, they are hard to find now. I know Carter "supposedly" makes HP mechanical pumps, but they are piss poor off shore made junk that's hit and miss with quality.

It's a physics thing. The farther from the fuel source, the harder it is to pump. Why use 50 year old technology when you can use a modern return type fuel system that will keep the fuel circulating, cooler and probably result in lower ETs?


Seems like a no brainer to me.
 
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