[TAQuest]

Originally Posted by Tom Vaught

Truth but most hydraulic machines are not trying to accelerate down the race track with under 1.6 60 ft times, lol.

In a static world the fuel line could be 2" in diameter and the fuel pump would just have a closer volume to draw off of.
Think Smokey Yunick and his fuel line driving home with no fuel tank in the car.

Tom V.

I'm thinking it's more about friction and less about G's.

If it's G's then it's most likely the float bowl or tank.

Fill the tank all the way and we can eliminate that one.

Try a different carb and we can try to eliminate that too.

Friction; One 90 degree turn is like adding 10 feet of line.

[Tom Vaught]

Easy test to prove your theory is to take a piece of plastic tubing of the correct diameter say 3/8" and attach it to a test fuel pump.

Pump the fuel from one Military fuel can into a second Military fuel can in a specific time.

Then do the same test with your vehicle fuel line and its length and measure the Free Flow difference.

That will tell you the Friction Factor for your fuel line wall surface and length. Do the test for a minute.
(4 times the actual time of a 15 second acceleration run.)

I would be surprised if you see any change on the stop watch worth reporting.

Same deal with a 3/8" line vs a 1/2" line. You do not compare the 3/8" line to the 1/2 inch line. You compare the small fuel line length numbers vs the stock fuel line length numbers or the larger 1/2" line numbers.

Tom V.

[TAQuest]

Originally Posted by Tom Vaught

Easy test to prove your theory is to take a piece of plastic tubing of the correct diameter say 3/8" and attach it to a test fuel pump.

Pump the fuel from one Military fuel can into a second Military fuel can in a specific time.

Then do the same test with your vehicle fuel line and its length and measure the Free Flow difference.

That will tell you the Friction Factor for your fuel line wall surface and length. Do the test for a minute.
(4 times the actual time of a 15 second acceleration run.)

I would be surprised if you see any change on the stop watch worth reporting.

Same deal with a 3/8" line vs a 1/2" line. You do not compare the 3/8" line to the 1/2 inch line. You compare the small fuel line length numbers vs the stock fuel line length numbers or the larger 1/2" line numbers.

Tom V.

It's not a theory. I stated the known friction for a 90 degree turn. It's published fact.

[TAQuest]

I believe that the fuel tank is the problem.

I reached this conclusion by studying acrobatic air craft. They have a problem with their fuel tanks and not G force on the fuel in the lines. Most of them have two pumps, one electric and one mechanical. However, they shut the electric one off after initial start up. Proving you don't need it for G force because the acrobatic planes far exceed the G force of your car.

They always have a problem with their fuel tanks starving their fuel supply. They invented a flop tube to help because the Gs always move the fuel away from the pickup. The flop tube moves with the Gs so it's always submerged in fuel.

Solve the problem with the fuel sloshing away from the pick up and you solve your fuel starvation problem.

For troubleshooting, cram as much fuel in your tank as you can before your 1/4 mile run and see if it changes anything.

[Cliff R]

Even with unrestricted flow to the inlet side of a high output mechanical pump it is NOT going to be as effective as a rear mounted electric pump pushing the fuel to the engine.

Two things work against the mechanical pump set-up. First it has to "pull" the fuel some 14' thru bent lines while under acceleration.

Second they are not "free-flow" so the when the valves in them open/close the fuel flow stops and starts many times per second.

The only way I could cure ALL issues with my fuel delivery system once I started making the power run really quick at the track was to sump the tank, high flow electric pump behind the tank, and -8 lines/fittings everyplace. That IMMEDIATELY and permanently cured all fuel delivery issues.

Prior to that I had already installed a larger 1/2" pick-up inside the tank, 1/2" lines to a high output mechanical pump, and even added a "pusher" pump at one point. Didn't work.

Right before installing the sump and 140gph pump behind the tank I tried putting it right in front of the tank pulling thru the 1/2" modified pick-up, still ran out of fuel at the top of low gear.

For my set-up rear mounted sump and pushing all the fuel forward after feeding it with rearward pressure from acceleration was the answer to any and all fuel delivery issues.

I'll also add here that my car picked up a solid .3 seconds and 3mph at the track with the sumped tank set-up, no other changes.

Something else folks might notice about these cars is that the gas tank sump is located in the WRONG location for hard acceleration or drag racing with good traction. It's in the front of the tank, and some tanks like the one in my car only have a few inches of flat area and most of the tank is sloped up toward the filler neck......Cliff

[TAQuest]

Originally Posted by Cliff R

The only way I could cure ALL issues with my fuel delivery system once I started making the power run really quick at the track was to sump the tank, high flow electric pump behind the tank, and -8 lines/fittings everyplace. That IMMEDIATELY and permanently cured all fuel delivery issues.




Cliff

You fixed it by changing the tank configuration. Not the pump.

Acrobatic aircraft use one mechanical pump and have no problem if their tank is set up right. No need for an additional electric pump.

["QUICK-SILVER"]

Originally Posted by TAQuest

Acrobatic aircraft use one mechanical pump and have no problem if their tank is set up right. No need for an additional electric pump.

Much cheaper to put electric pump in the back than it would be to put a positive displacement pump under the hood of a Pontiac. Right now we've got cam drive and cog belt drive to choose from. Neither would be cost effective or easy to install and maintain on a hot street car.

Clay

[Cliff R]

"You fixed it by changing the tank configuration. Not the pump."


Same pump and suction size, just move it lower and behind the tank. Less lift and using the forces of acceleration to feed it is far superior to "pulling" and "lifting" fuel to try to do the same thing.

This clearly shows that sucking from a front mount sump where the is running AWAY from it under hard acceleration is not nearly as good as moving the pick-up location lower and to the rear where the fuel is going when you launch hard.

Filling the tank is also a lame way to try to cure a poorly located pick-up location not to mention that you are adding "lift" to the fuel instead of putting the suction point much lower in relation to the height of the pump. The factory designed enough air space in the top of a fuel tank that you can't fill to allow for slosh and expansion, enough so that you can still uncover a stock located pick-up at the track in a fast car.......but you wouldn't know that because you don't have any experience, at least that I've seen in that area.........Cliff

[TAQuest]

[QUOTE=Cliff R;6056770

Filling the tank is also a lame way to try to cure a poorly located pick-up location .Cliff[/QUOTE]

You need to slow down and read my posts Cliff.

I said for troubleshooting to fill the tank as full as possible and see if it makes any difference.

I know, you just wanted to call me lame like a child.

Try to avoid that in the future.

[TAQuest]

Originally Posted by "QUICK-SILVER"

Much cheaper to put electric pump in the back than it would be to put a positive displacement pump under the hood of a Pontiac. Right now we've got cam drive and cog belt drive to choose from. Neither would be cost effective or easy to install and maintain on a hot street car.

Clay

Clay,
I'm making the case that one mechanical pump will do the trick if everything else is just right.
You can add all the pumps you want and not fix it if the gas is sloshing away from the pickup in the gas tank.

[78w72]

Originally Posted by Cliff R

but you wouldn't know that because you don't have any experience, at least that I've seen in that area.........

Ditto!

thats great if acrobatic aircraft figured out a way to deal with g-forces, but none of use here have acrobatic aircraft!

those planes do up & down & left & right maneuvers, they dont leave from a stand still & do 1.5-1.6 60ft times while trying to suck fuel through 15ft of line... totally different situation. but thanks for the unrelated info.

can you tell us about how you deal with fuel issues on your parade car that lifts the tires off the ground in 3rd gear? on the street. with street tires... now thats g-forces!

[TAQuest]

Originally Posted by 78w72

Ditto!



they dont leave from a stand still & do 1.5-1.6 60ft

!

Actually they do quite often exceed the straight forward g's that a car does on the track.

[78w72]

when is that? do you have recorded g's to back that up? i dont know either way, but you seem to be an "expert" on acrobatic aircraft now too so please enlighten us.

as far as i have seen of those types of aircraft, i dont think they take off fast enough to do that & they dont accelerate in a straight line while in flight as fast as a 500+hp car at a dragstrip. & regardless they dont have the same type of fuel system that cars deal with that we have described above so thats not really a very good analogy.

[78w72]

i stated i have ran 3/4 to a full tank, its not the pickup being uncovered, does it the same at full tank or 1/2 tank.

& one mechanical pump will not do the job on most cars at this power level & et's. thats been proven numerous times. yes there are a handful of people that have done it, but for the average heavy street car at 500+ hp, 1 mechanical pump runs into problems real quick.

[Cliff R]

"You need to slow down and read my posts Cliff.

I said for troubleshooting to fill the tank as full as possible and see if it makes any difference."

Just pointing out that it's pretty poor advice to fill a tank to see if it helps. What if you are stuck at the track all weekend in a big race, are you going to re-fill the tank after every run to avoid a potential fuel delivery issue like uncovering the sump on a hard run. Even worse if your street racing are you going to fill the tank up every other block so you don't risk running out of fuel at the top of first gear and get your door blown off by a Honda Civic with a couple of plug wires pulled off!

Seriously, there is also enough air space in the top of one of these tanks to uncover a front mounted in tank stock type sump when the tank is full, but you're only going to find that out if/when your starts hooking up and making quick runs. There are also a LOT of different size/shape tanks, some with very little front area for the sump, my car is one of those. So it's relatively easy to uncover the pick-up on a hard launch. I started having issues as also as 1.68-1.75 area and could NOT go any quicker without some significant changes.

What clouds the muddy water with these sort of topics is folks jumping in with next to ZERO experience actually doing it, and every once in a while you'll get someone claiming to run into the 10's with a completely stock fuel system using 5/16" lines and stock mechanical pump. Ten years ago we used to get one or two of those contributors to every one of these threads, not so much these days as they have all retired, died off or just quit posting........Cliff

[TAQuest]

Originally Posted by Cliff R

"You need to slow down and read my posts Cliff.

I said for troubleshooting to fill the tank as full as possible and see if it makes any difference."

Just pointing out that it's pretty poor advice to fill a tank to see if it helps. What if you are stuck at the track all weekend in a big race, .Cliff

That would be stupid. I would do it at test and tune or on my favorite street test area. That would just be common sense.
You threw your common sense out the window when you started hatin'. That makes you stupid Cliff.
When you quit throwing shade you might regain your intelligence.

[78w72]

Originally Posted by TAQuest

You threw your common sense out the window when you started hatin'. That makes you stupid Cliff.
When you quit throwing shade you might regain your intelligence.

"throwing shade"?? are you like 16 years old?!? you must be because you like to "clap back" a lot too. LOL!

this crap is getting ridiculous... your common sense & intelligence was never here to be thrown out the window! & the delusional comments you post throws any chance of credibility out the window! you are the best example of you cant fix stupid i have ever seen!

you are the king of "hatin"... & a disrespectful hypocrite when you post stuff like you do towards cliff & others. you call people names when they present facts or say things you dont like or even understand. how about you just stop posting unrelated or untrue jibberish & non stop condescending remarks? i bit my tounge for a long time on some of your older threads & posts about your cam & timing issues when you acted like a CHILD to people trying to help you, & now have you noticed very few even waste their time replying to your nonsense? but lately your comments are totally uncalled for & the majority of members here see that YOU are the stupid one, just another keyboard warrior/mechanic!

sometimes i wish this forum was like a facebook group & the moderators could just block or ban trolls like you!

[Cliff R]

+2 and well said

He has reached the point where a Moderator needs to step in and at a minimum provide him with a list of the rules for posting......IMHO......

[TAQuest]

Originally Posted by Cliff R

+2 and well said

He has reached the point where a Moderator needs to step in and at a minimum provide you with a list of the rules for posting......IMHO......

Well said? Really?

It's like you think you are king.

We are all equal here and get our say, as much as you hate it.

[Skip Fix]

I can tell you my 78's quest for fuel. Stock 180 HP 400 no problems.TH 350 2.56 gears. Early 80s freshened 400 and added a 228/228@ 0.050-ran out of fuel top of 2nd , small helper AC electric pump solved it. Then moved up to a 420 hp 455 had to upgrade to a 140 Mallory electric pump-and it is not below the tank but at the back. Uncorked headers and fuel issues. Upgraded to -8 line form the pump(still the 3/8 factory pickup in the tank) dropped the mechanical pump to reduce any heat soak and it will run in the high 10s no issues. Stock tank no sump stock pickup just no "sock".