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Author Topic: 68 z fuel pump gph  (Read 1302 times)
janobyte
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« on: March 06, 2013, 04:29:20 PM »

Anybody know what the stock fuel pump was rated (gph) in the 68 302's ?
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GI JOE
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« Reply #1 on: March 09, 2013, 01:23:44 AM »

Listed in the 68 Chassis man...the 68 Z28 is 5 to 6.5 psi, pressure and volume is 1 pint in 30 to 45 seconds ....the same as all small blocks. 

So figure 1 pint in 30 sec.  8 pints per 1 gallon...then  figure 8 pints at 30 sec each equals 4 minutes per gallon

FYI the 68 Big Block is 8.5 psi pressure


GI JOe

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SFC GI JOE - Airborne Paratrooper
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janobyte
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« Reply #2 on: March 11, 2013, 06:56:02 PM »

Thanks ,better eyes than me ,looked twice through the manual ,only found pressure check. Did find it in my 68 motor manual range 20-30 sec/pt. general sbc, not listed specific for the Z ,sticking with the holley. Lets say 1qt per minute= 15 gph, low. Granted I don't plan on pulling 8 grand shifts ,any more, she still might be a little hungry. These were high performance engines. I'd still like to know what that particular pump was rated at . One would think in the neighborhood of the 396. I know the math lbs fuel/hp however our race car 686hp at the fly wheel sucks down about a gallon in a pass. This is all because I want to retain the original pump to carb lines ,but I'm a dragracer at heart and can't have performance suffer. Any input from the guys running the listed ac pump? thanks---steve
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68camaroz28
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« Reply #3 on: March 11, 2013, 09:48:22 PM »

Don't the F.A.S.T. guys have to have a stock looking fuel pump/lines etc. and some of them are flying (10's).
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Chick
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GI JOE
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« Reply #4 on: March 13, 2013, 03:10:22 PM »

Hey Janobyte,

My thoughts are on the same wave length... I too think the 1968 Z28 302 fuel pump would be the same or close to the same rate as the 396 Hi-Perf rate (even with an 8.5 psi pressure) since they both run the same Holley carb (#3923289-DZ - [#4053] 800 cfm).  I too think the 15 GPH is way to low for either of these engines.  (the 15gph flow rate was based off the listed 1 pint in 30 sec. to 45 sec.)

I am thinking just like you, those High Performance Chevy engines stay hungry and you gotta feed em good.  Grin  LOL

I also think that the SS 396 did use a different fuel pump from that of the Z28 302... but that may be just the difference of SB to BB.


gpm  = gallons per minute
gph   = gallons per hour

The required fuel flow rate might likely be more of a factor and determination based on the engines (heads, intake, cubic inches and exhaust flows & capacities) fuel air consumption flow rates.  

You probably already know this stuff but for the others reading these posts a little education (ed-u-ma-kating as some call it) Huh ... might help understand this subject.  Roll Eyes  I have found this information below in many automotive books...

Formulas:

air capacity = (rpm x CID)/2    (divide by 2 for four strokes, ie. 1/2 the cid)

cfm theoretical = ((RPM x CID)/3456)

VE = (cfm actual / cfm theoretical ) x 100

bsfe = fuel (#/hr) / brake horsepower (BHP) therfore => fuel #/hr = bsfe x BHP

Knowing this then.... Fuel #/hr x 6.25 #/gal = gph the flow rate of the pump

WHERE:
# = pounds
Gasoline weight ~= 6.25# at 72 F
1728 = number of cubic inches in a cubic foot (12x12x12)
3456 = 1728 x 2
cfm = cubic feet per minute
CID = cubic inch displacement, for example 302 cubic inches
RPM = maximum RPM,
VE = volumetric efficiency.  VE is the relationship between theoretical air capacity and the actual air flow of the engine.
BSFC = (Brake Specific Fuel Consumption), i.e. the maximum fuel system pressure, and the pump's flow volume at that pressure.


As Chick (an expert 68 Z28 member) points out the F.A.S.T. drag racers should have some info on this.   Wink

I would also give Jerry MacNeish an email shout out. Jerry is a long time Drag racer (and I think he's quite good at it too) who runs a 67 Z28.  Here is his link. http://www.z28camaro.com/

Also another good contact would be Ken Lucas, who has been restoring Camaro's at ConCours levels for years.  Here is his link http://www.lucas-restorations.com/

I am sure there are more expert members here at CRG who can give you a better answer than I have.  JOE Smiley
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SFC GI JOE - Airborne Paratrooper
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janobyte
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« Reply #5 on: March 13, 2013, 03:55:16 PM »

Thanks for the reply ,I'll try lucas restorations. I emailed Jerry, wasn't sure suggested service manual. (a few weeks ago) Called Heartbeat City yesterday ,didn't know. I figure I'm being anal but AC should be able to spec their #40725 pump.( # off the top of my head) Hey the hunts half the fun of this!
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GI JOE
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« Reply #6 on: March 13, 2013, 04:18:27 PM »

you could run it with the pump pumping to a gallon gas can and time it.  just an idea... but you would need to be extremely careful... good luck.

ps or pump 5 gallons, timed and get an average

PPS but you should really use a true measuring can along with the stop watch. Like the ones they use for weights and measures certification. Smiley
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SFC GI JOE - Airborne Paratrooper
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« Reply #7 on: March 13, 2013, 11:54:12 PM »

if that's a mechanical fuel pump, I think you'd need a special test device to run it at variable 'engine' speeds... in order to measure it's capability.  Smiley
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
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Kelley W King
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« Reply #8 on: March 14, 2013, 10:27:46 AM »

I read an article about one of the FAST guys where he said he hooked his sand blaster to his fuel line and went out to dinner while it blew to get more flow. I would say that his pump appeared stock but was probably tricked out also.
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janobyte
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« Reply #9 on: March 15, 2013, 03:50:39 PM »

Well nobody I've contacted knows---easy fix for cruising and "fun runs" sticking with my holley fuel pump along with the QA-1 shocks ,keeping. the spiral shocks and stock pump on the shelf for judged events. About that sandblasting procedure......
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