[mchell]

just for giggles......couple of squirts on the throttle to show what fuel pressure does at full throttle...slow street car with 1/2 Robmc fuel pickup, mallory 140 pump, stock 3/8 lines from pump discharge to Robmc regulator(deadhead)......QJET and RPM intake....rolling start at 25 to 30mph....less than 1/2 tank of fuel......275/60/15 tires



see link


http://youtu.be/RdJeSVpl9tc

[66bonne]

Out racing in the neighborhood again, heh, Mike !!

Jim

[se428bandit]

I wish i could get my car to respond like that.

[goatman65]

Wish we had weather like that here. I had to watch the vid twice. First time i watched the tach,second time i watched the tach and pressure.
Now my question, since you have 3/8 line are you really gaining anything with the 1/2 pick-up?
Maybe i should ask in one of the other fuel pressure threads.

[Tim Corcoran]

An electric fuel pump is great at pushing but not good at sucking (kind of like my ex-wife). So by going to a larger size fuel line from the tank to the electric pump helps the efficiency of the electrict pump considerably.

[Icefan71]

Where did all those donuts come from when you 1st pulled out onto the road?

[PontGuy]

...slow street car with...

Don't know about others but I started watching the vid expecting something else entirely. Sounds really mean!

Approx 5 psi at the carb at shift point seems pretty good to me pulling that hard. Going to see at least some pressure loss with the fuel flowing that fast. As long as it keeps the bowl full, right?

Interesting that the lowest pressure seems to be after the 1st gear shift when it is digging into 2nd, then catches up by the 2-3 shift. Wouldn't have expected that.

[66bonne]

Don't be taken in by Mike's comment of "slow street car". His Goat is not only drop-dead gorgeous but also deadly consistent at the track with ETs rarely varying more than a few hundredths.

See ya at the track Mike.

Jim

[grandville455]

Put that thing away it's winter time! ... Nice run's, How far does it drop at the track with excellent traction? Shifts nice too , conv looks and sounds to be a tad tight yet

[mchell]

Originally Posted by PontGuy

Don't know about others but I started watching the vid expecting something else entirely. Sounds really mean!

Approx 5 psi at the carb at shift point seems pretty good to me pulling that hard. Going to see at least some pressure loss with the fuel flowing that fast. As long as it keeps the bowl full, right?

Interesting that the lowest pressure seems to be after the 1st gear shift when it is digging into 2nd, then catches up by the 2-3 shift. Wouldn't have expected that.

Good eye....cool to see it side by sde like that....basically why I posted, you can see, as we'll as hear what the engine is doing........may help others

my take. : the first run was generating more wheel speed ( spin)..so it dropped more....on the second squirt it stayed relatively steady ( less spin )..after catching up to the tires the pump gains, then steadies out...listening to the engine, it did not seem to care that it dropped to that level and after catching up it stayed steady

At the track, if I keep the tank at least half full it does not exhibit that drop.....probably because I am not generating the big initial wheel speed until I get up in the rpm range, but by that time the pump has already recovered and will keep up

[ta man]

With my 1/2 inch pickup I need at least a half a tank of fuel or the pickup gets uncovered.I used to run the same fuel system 140 Mallory pump stock 3/8 lines also was good for high 11's at 114/115..but upgraded to all 8 AN lines and fittings and the car picked up mph and et runs mid 11's with traction at 116/117 in the middle of summer.

[Tom Vaught]

I ran a 1/2" line many years ago with a Modded 1/2" Pick-up to a GOOD Electric Fuel Pump, and then to a HP mechanical fuel pump. The fuel tank pick-up was longer and went to the rear center part of the tank. With the engine I had I could run 11.55 at 117 best times with a 64 GTO chassis. I always tried to run at least 1/2 tank but "ran out of gas" a couple of times with the gas level too low on the street to cover the rear pick-up.

Tom Vaught

[mchell]

Originally Posted by ta man

With my 1/2 inch pickup I need at least a half a tank of fuel or the pickup gets uncovered.I used to run the same fuel system 140 Mallory pump stock 3/8 lines also was good for high 11's at 114/115..but upgraded to all 8 AN lines and fittings and the car picked up mph and et runs mid 11's with traction at 116/117 in the middle of summer.

Good to know.....I am headed in that direction as well

[jonmachota78]

Cool vid! I see a similar drop on my system. I've got my bypass regulator set to 6lbs, and will drop to about 5lbs at WOT at high rpm. I don't get the pressure "creep" any more since I went from deadhead to a bypass reg. So my fluctuation ranges between 6 - 5lbs. I'm running a holley hp150 pump sumped tank and 1/2" lines.

You may be able to set your regulator down a bit and still never see your pressure drop below it's current low point, or "low water mark". May avoid some unneeded higher pressures at the stop light/drive through without effecting max flow because now your max flow pressure is below your regulator setting.

[Tom Vaught]

Holley Carburetors were designed to run at 6 psi for most applications.
When the engineers felt they needed more fuel into the bowl they upped the needle/seat size, not raise the fuel pressure.

Tom Vaught

[gold bird]

so adding a 1/2"line the rest of the way , will the pump keep up with the added volume if it was a holley blue pump ? nice car mike :}

[66bonne]

Originally Posted by gold bird

so adding a 1/2"line the rest of the way , will the pump keep up with the added volume if it was a holley blue pump ? nice car mike :}

Jesse: have you been encouraging Mike to street race !!??

Jim

[gold bird]

not at all Jim we do that at street heat at the track .

[gold bird]

like this just looking to see if my holley blue pump will keep up with the 1/2" line all the way to carb . good or bad time will tell see you at nmca Jim ?

[Tom Vaught]

Originally Posted by gold bird

like this just looking to see if my holley blue pump will keep up with the 1/2" line all the way to carb . good or bad time will tell see you at nmca Jim ?

Maybe, IF you take it apart and clean the screen really good. Maybe, IF the vanes are nice and loose and fly out properly to make fuel pressure. Maybe, IF you use two of the tiny little Blue Regulators (one for each bowl) to feed the carb bowls. Maybe, IF you install a decent hot wire to the thing vs using 16 gage wire to power the pump.

Course that does nothing if the blue pump is trying to suck/push fuel thru a 5/16" fuel tank line.

Tom Vaught