[77TA]

THe accused : 1977 Trans-AM
RACE: Pontiac

Crime Poor performance given Parts used

Evidence:
Engine
462cid #96heads, 274XE Cam 9.65 compression
72 intake ,1 inch spacer, TKO TRans and 3.42 rear gears, Drag radials, Caltracs.

Performance 13.31@102.75 8.5@82 1/8 with 1.84 60 ft

Best performance 13.14@105.4 in cool weather with 1.94 60 ft

Car seems unresponsive to jetting or timing changes.

This is the therorized cause of the crime.
Gas weighs about 6 lbs per gallon I think
water about 9 lbs a gallon,

1 foot of water exerts .433 psi of head pressure.
1 foot of Gas should exert about .3psi

ok theres about 15 feet of line from the pump to the tank.

pump operates at about 5 psi under no load

Launch G's are slightly above 1 G

1 g= 9.9 meters per sec I think
works out some where around 30 ft

1.84 sec to cover 60 ft would +> 1g correct ?
15 ft of head *.3 = 4.5 psi
5 psi -4.5 only leaves .5 psi

Ok the pump has a reserve due to the size of the canister this reserve carries the car through 1st gear maybe part of second but the level in the carb bowl is dropping fast.
middle of 2nd gear the fuel bowl is low the pump is straining to pull the fuel and is beginning to win the battle due to lessening g-loads. The pump and carb continue to play catch up thru most of 3td gear and probably regain control by forth. This might also explain why the car indicated 109 mph on the G-tech on the street before and after going to the track but only 106 at the track. It does not hook as hard on the street so the pump keeps up and it is running more normally. In this senereo the lag is in part of 2nd gear and third as the pump has not recovered the fuel level in the carb. This would lower the 1/8 and 1/4 mph figures.
Well does this make sence. I'm just trying to understand whats happening.

sorry if Ive beat this to death !

I am going to put a new pusher pump on it before it will see the track again.

[77TA]

THe accused : 1977 Trans-AM
RACE: Pontiac

Crime Poor performance given Parts used

Evidence:
Engine
462cid #96heads, 274XE Cam 9.65 compression
72 intake ,1 inch spacer, TKO TRans and 3.42 rear gears, Drag radials, Caltracs.

Performance 13.31@102.75 8.5@82 1/8 with 1.84 60 ft

Best performance 13.14@105.4 in cool weather with 1.94 60 ft

Car seems unresponsive to jetting or timing changes.

This is the therorized cause of the crime.
Gas weighs about 6 lbs per gallon I think
water about 9 lbs a gallon,

1 foot of water exerts .433 psi of head pressure.
1 foot of Gas should exert about .3psi

ok theres about 15 feet of line from the pump to the tank.

pump operates at about 5 psi under no load

Launch G's are slightly above 1 G

1 g= 9.9 meters per sec I think
works out some where around 30 ft

1.84 sec to cover 60 ft would +> 1g correct ?
15 ft of head *.3 = 4.5 psi
5 psi -4.5 only leaves .5 psi

Ok the pump has a reserve due to the size of the canister this reserve carries the car through 1st gear maybe part of second but the level in the carb bowl is dropping fast.
middle of 2nd gear the fuel bowl is low the pump is straining to pull the fuel and is beginning to win the battle due to lessening g-loads. The pump and carb continue to play catch up thru most of 3td gear and probably regain control by forth. This might also explain why the car indicated 109 mph on the G-tech on the street before and after going to the track but only 106 at the track. It does not hook as hard on the street so the pump keeps up and it is running more normally. In this senereo the lag is in part of 2nd gear and third as the pump has not recovered the fuel level in the carb. This would lower the 1/8 and 1/4 mph figures.
Well does this make sence. I'm just trying to understand whats happening.

sorry if Ive beat this to death !

I am going to put a new pusher pump on it before it will see the track again.

[Dave A]

Your honour, I respectfully point out that pressure head due to weight of fuel is proportional only to vertical height change. For horizontal pipe, pressure drop increases with flow rate.

I bring to attention of the court the case of Dave A versus Pontiac T-37. Battled fuel delivery problems ever since getting car running again. T-37 was sentenced to receive a fuel pressure guage after the filter and several hard WOT runs (next year, when it is nice out again in MI). First half of sentence carried out, fuel pressure guage installed. Corrective action will follow if fuel pressure drops below 3 psi at any point during quarter mile.

(some have felt this sentence was too light, as it was very easy and inexpensive to install external fuel pressure guage).

That's all, your honour. Defendant, your witness....

[Half-Inch Stud]

Overruled. Acceleration will cause fuel to bee much harder to pull up to the inlet of the mechanical pump.

Also, Acceleration will cause fuel to bear down on a pusher pump.

Get the elec. pusher pump in the back, above the rear axle tube, and report back.

Soooo, what's your total Advance?
H.I. Stud

[77TA]

34 degrees total during runs at track.

[torqjunki]

Your Honor..If I may..
I have an expert witness that can shed some light on the data recieved by exhibit A, the G-tech performance meter. Go ahead Leroy..You've been sworn in. The G-tech meter in question uses precision accelerometers to calculate speed at precisely 1320ft. The drag strip uses "trap speed" which is obtained by triggering a beam shortly before the finish line and again at the finish line. It averages the time and distance to obtain MPH. For this reason, the G-tech will always show more MPH. You may step down MR. Roy [img]/infopop/emoticons/icon_biggrin.gif[/img]

[Brian Baker]

G-tech = nice "gee whiz" toy, not accurate enough to warrant the price

Sanctioned drag-strip = real world E.T.'s and MPH, that can usually be bought for an entry fee of $20 or less (on T&T night)

[Rashionality]

You're honor, with respect to the previous witness I would like to reinforce the notion of an electric Fuel pump. Take 12 volts and call me in the morning.

[Dave A]

I'd like to re-phrase my argument, your honour, on account of not knowing what the heck I'm talking about....

On the account of the fuel being harder to pull through horizontal line with 1g acceleration, I must concur with the prosecutor. Is that calcuation of 0.3 g pressure loss per foot of line based on a 3/8" ID line?

The prosecutor presented fuel pressure as evidence - is the guage mounted within view while driving, or is it underhood?

In the case of Dave A vs. T-37, his Holley mechanical pump was found to deliver 7-8 psi at idle and 5psi at WOT through second. Test conditions did not allow for third gear run. 5 psi seems a touch low....

Fuel pressure should be tied pretty well to the fuel level in the bowl, albeit by some time lag - if the hypothesized crime does in fact occur, then fuel pressure should take a deep drop sometime after the launch (fuel slosh can keep float high even with less fuel in bowl, so pressure drop may not occur right away), but towards the end of the run, pressure may creep up if fuel system is replenishing lost fuel level.

Agreed G-tech makes good expert witness for recording launch accelerations...

[Torment]

GOOD GOD!! Just get an electric pump already! If this continues I'm liable to buy the d#$N thing and send it to you-and please I really don't have the money. Holley's comes with a regulator-put the stupid thing in with rubber hose if you have to, just put it in.

[Bud Lyons]

AMEN!

[77TA]

Torment is found in contempt, please remove him from the court room !
[img]/infopop/emoticons/icon_biggrin.gif[/img]

LOL
I know Ive beat this to death guys, and like I said The pump is going in as soon as I can afford it. I thought this might be a good post to discuss why, so I and anyone else understands why this happens. I was settting on the deerstand the other morning trying to explain why it might act like this.
The fuel pump related problems Ive been exposed to were pretty evident in the car just shutting off and refiring really jerky. The fact that this is not doing that leaves a little speculation. The line size would not matter in the calculation of G-loading of the fuel colume. example a pipe standing vertical with 10 feet of water in it will have the same head pressure if its 1/2" in diameter ot 10 ft the difference is in the volume not pressure. The smaller line would have more flow loss due to friction though but thats another case. I would think now that when sizing your fule pump you need to account for G-loading as well as normal flow. I would think some cars that leave the line really hard would need a high pressure pump not a low pressure just to insure there is not a problem during the first 60 ft. A car running in the 1.3 or so range could develop close to 2G's so that would add about 8-9 psi head on the pusher pump maybe.

The g-tech is a tool thats all it seems to be fairly repeatable but Brian and others are right theres nothing like testing at the track. THe problem is that here my track does not have a test and tune night they run saturday eliminations only and 3 runs is all I get to test anything ! This leaves me with seat of the pants and or the G-tech for my testing.

[Rashionality]

I have a Holley Blue pump...give me your address and $35 and I'll ship you that and the proper regulator for it as well.

[Dave A]

I've gotta stop posting so late, my brain obviously doesn't work.

The size of the pipe does drop out when you translate force to accelerate the column back into pressure.

You have a puller pump...the 'head loss' would only be on the several feet of line AFTER the pump...it is a whole different matter to determined how much pressure drop the pump can generate on the suction side, because the 'head loss' for the 15 feet of line up to the pump applies to the suction side.

Of course if the suction side can't keep up with the 'head loss' caused by acceleration, it will show up as reduced fuel pressure all the same, because you're not getting enough volume into the diaphragm on the pump intake (up?) stroke.

Hmmm, is it the heavy return spring on the pump diaphram that does the pumping work in a mechanical pump - and does the tension of that spring effectively regulate the pressure the pump can generate, assuming adequate intake flow?

[Floyd Hand]

Go ahead and install a good fuel system and cure most of your problems.On my Lemans I have a 5 gal fuel cell (have both stock tank and fuel cell with switch to change from one to other while street driving) From fuel cell I use a 1/2 inch line into a 1/2 inch in and out canister style fuel filter, then to a Holley blue pump and up to regulator mounted on fender wheel away from the heat from radiator. While playing with a Holley 750 carb, I added a Moroso pressure spring to the blue pump. At the regulator it gave me 23 pounds of pressure.While useing Holley, I regulated it down to 7-to 7 1/2 pounds. With the Q-jet I never need more than 3 1/2 to 3 3/4 pounds. How much gas do you run in your tank? Before adding the fuel cell, I had to run at least 60 percent full or it would fall on its face off and out away from the line.Like I said before you need for all components to work together to run the best ET. Use at least 2 1/2 inch exhaust with good performance mufflers,( I use Walker Dynomax and a Dr. Gas X-pipe). Don't get carried away on the gear ratio ( I ran a 3.55 for years, but just this summer changed to a 3.42 with no performance loss). Also use a good converter ( you get what you pay for). I use a Continental 3200 stall. It was the best performance upgrade that I have made to my combination.

[Skip Fix]

I'll give a fuel delivery "history" of my 78 TA. Probably pretty similar fuel systems. Stock motor no problems. Freshened 400 with a 228@0.050 cam that ran mid 14s fuel delivery problem, small AC electric solved it and ran through a mechanical(Holley and Carter both tried).
455 Q jet 231/239@0.050, headers BIG fuel delivery top of second to third shift would catch up when let off throttle slightly Mallory electric 140 pump through mechanical. 12.90s ran fine, uncorked 12.30s delivery problem again until ran 1/2" line from electric pump to regulator no mechanical. Same system handling 11.70s @115 now.Still has 3/8 pickup in tank.

One other comment if you have no response to jetting once you do get the fuel problem fixed look at the ENTIRE exhaust system ie exhaust port on out. My RAIV 400 was very jet non responsive through mufflers(2 chamber 3" Flows) with 2" headers. A switch to 1 3/4 picked up .2 sec and suddenly was responsive to jetting. The larger tubes had poor velocity with even 2 chamber Flowmasters causing reversion back into the cylinder. Carb cahnges can't help as much if there is still old exhaust in cylinder. Smaller tubes better velocity less reversion less chamber contamination better fuel burn.

You may have multiple problems there.I haven't seen a description of exhaust system.

[Half-Inch Stud]

Let's see:
Stock 69Bird fuel tank, with sock, 3/8pickup line carefully leaned against the tank floor, about the middle of the floor.

Carter pusher, 2speed control because of the GM 1968 Wiper switch in place of the ciggarette lighter.

3/8 line gracefully bent and tied to the framing and leading to the GM tall Mech fuel pump.

JB Weld plugging the return port.

inline fuel filter junctioned at typical hiding spot beside the Alternator.

3/8 steel fuelline to Chevy Q-Jet inlet. No miniBronze bubbler filter.

viton Needle sits on side-slotted Bronze Seat, with largest capable inlet hole, limited by viton neddle diameter.

33716 foam float set arbitrarily around 1/4" or lower like 5/16...I never had appreciation for float level. Firm appreciation for leaky needle/Seat relationship though.

43 rods on medium tension Power Piston Spring, 71 Jets, DG SecondaryRods on J Hanger. Secondary Well pocket feedholes drilled for better refill rate.

Part-Throttle Enrichment top-Plate used for rich [ping-free] Part-throttle action.

12.0/112MPH and still charging.

Note:
Racecar had foamed fuelcell, braided/AN fitted BS lines and 1/2 aluminum piping, Reg, Gauge, splitter/Regs, and dual Holleys.
Looked pathetically Hot-Rodish and fairly unneccessary. But that did hit 11.0/123MPH and still charging.

I would like to see a dual pickup Y-hose design for the factory tank. A cruising pickup [front-bottom] and a Race/accel pickup[back-bottom]. A Ballcheck flow-valve could be used to "DECIDE" which Y-Branch to be the inlet. possibly a fluid-sense solenoid at each inlet? Lot's of time at work..

[77TA]

Rash, man thanks for the offer. I'll give it a try !!

My exhaust system Skip is 1&5/8" headers
into 2.5 " head pipes to 2.25 dynomax super turbos through mandrel bent tail pipes to 2.25 TA splitter tips . I do not have a crossover.

ON how the G-loaded fuel would affect the pump. I think that the effective vacume on the pumps suction would significantly effect the flow potential of the pump maybe not as much as it would if it were pushing that much head but it would surely effect it.

Whats the best way to route the wiring for the pump. Id figure I should route it inside and drill through to the underside near the pump.

Thanks everyone !

[PROBRD]

Is you battery in the front or the back?

[77TA]

The battery is in the Stock location up front.