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 Intake / Carb and Fuel Delivery Tech
 Holly Mechanical Fuel Pump
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Vanmor
Cochise

USA
572 Posts

Posted - 22 Feb 2012 :  11:54:43 PM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
I have a donated Holly 12-837 mechanical fuel pump.

The mounting holes had to be drilled out to fit my 68' 400 block. Thought that was strange.

I went to the Holly site and they have no info on how to install the pump. I know it's simple, but I want to use all three lines. I have no idea where the lines go.

Also, the main body needs to be rotated.

Thinking about just getting a new stock type pump.

"A man has got to know his limitations." Dirty Harry

bnorris_74
Crazy Horse

USA
1410 Posts

Posted - 23 Feb 2012 :  07:28:50 AM  Show Profile  Reply with Quote
quote:
Thinking about just getting a new stock type pump.


I think that would be the best.
I had a brand new holley mechanical on mine and it now lays on the floor of my garage.
see:
http://psp.aquacomp.net/topic.asp?TOPIC_ID=3128
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PontiacMatt
Many Ponies

USA
1393 Posts

Posted - 23 Feb 2012 :  09:11:12 AM  Show Profile  Reply with Quote
I too run the Airtex 40931... to date haven't had an issue with fuel starvation. (12.86 @ 104, on street tires. motor didn't hesitate or stumble.)

I imagine it would run better with 1/2" fuel lines and a better pump... but for now the 40931 is serving me well.

*72' Pontiac Lemans* - Work in Progress
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BearGFR
Bear

USA
569 Posts

Posted - 23 Feb 2012 :  1:53:05 PM  Show Profile  Visit BearGFR's Homepage  Reply with Quote
I'm running one of the RobbMC "1100" mechanical pumps. It's way overkill for my engine, but it sure was nice the other day when the car acted like it was running out of gas about half way through 2nd gear. Just dial up the pressure on the pump a little (it's adjustable), double check the inlet pressure downstream from the regulator, and problem solved.

Bear
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Vanmor
Cochise

USA
572 Posts

Posted - 23 Feb 2012 :  3:31:13 PM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
Thanks for the input guys. I always wanted to run a Holley pump but you know how it goes. I know some people run them and have no trouble. However, I seem to read more about problems with them. I'm sure it has it's place.

I can get an Airtex local for $22. Think I'll try one.

bnorris, I remember the "cutting out" problem you were having. I can't get into your photobucket site to look at the videos anymore. Hows the engine working out since you went to the 1.65 rockers ?

"A man has got to know his limitations." Dirty Harry
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bnorris_74
Crazy Horse

USA
1410 Posts

Posted - 23 Feb 2012 :  6:02:36 PM  Show Profile  Reply with Quote
Engine runs great now.
I need a new converter and the tranny redone.

I can feel the motor really start to pull at around 3K but the torque converter is stock probably only stalls around 2K.

Edited by - bnorris_74 on 23 Feb 2012 6:03:17 PM
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Vanmor
Cochise

USA
572 Posts

Posted - 24 Feb 2012 :  9:24:29 PM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
I've read that stock converters can run the range of 1600 to 2000. I think a 2000 converter would work fine with the Summit cam. Then again, a 2200 or 2500 would be just about right.

I'm running a stock converter. The guy that built my transmission told me to run that and he drilled my valve body. He raced a 69' Judge sreet car for years. He said he set it up to shift firm but not harsh. We will see.....

I got an Aitex pump today for $25, tax and all. The parts place got it in just a couple of hours. That worked out nice.

"A man has got to know his limitations." Dirty Harry
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Phil
The Great White Buffalo

USA
6375 Posts

Posted - 24 Feb 2012 :  11:03:13 PM  Show Profile  Reply with Quote
Good idea crap canning the Holley pumps. Had nothing but problems with them over the years and I see nothing to convince me they have improved. Pressure all over the place up to 9+ lbs at times. Suppose to be internally regulated, yeah right. About as impressive as their carbs which make great 5 gallon bucket paperweights unless big bucks are spent for a rengineered one. But I digress...

"Chevy": even the name sounds cheap.

Edited by - Phil on 24 Feb 2012 11:03:36 PM
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bnorris_74
Crazy Horse

USA
1410 Posts

Posted - 25 Feb 2012 :  07:40:31 AM  Show Profile  Reply with Quote
I have a Hughes 2500 stall that I bought to put in it. With the porting I had done to the heads it needs a little more stall to get it closer to it's power band.
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Vanmor
Cochise

USA
572 Posts

Posted - 26 Feb 2012 :  03:30:55 AM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
When ordering my Airtex fuel pump, I noticed there was a three hose pump and a two hose pump. My GTO takes the three hose type.

One of the ports or outlets is for a vapor return. My old pump has this but it's fully open. The Airtex pump has a small orifice in this location. Hmmmmm......

I think the trouble with the Holly is that even though it has three ports on it, it's only really designed to run with two. So running one where the vapor port is needed my be the problem. Cars just needing two lines to the pump don't seem to have as much trouble.

"A man has got to know his limitations." Dirty Harry
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cortcomp
Coyote

USA
4321 Posts

Posted - 26 Feb 2012 :  09:30:01 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
we're talking 3 ports PLUS the fuel outlet right? My 71 had half that vapor system installed but all disconnected, and i just installed a pump with a fuel in/fuel tank return out/to carb out, the bigger canister style, and it's been fine FWIW. The holly that came on it was hard to prime (the chrome kind that's mechanical and has 100 screws around it) and finally i just replaced it because it looked wrong in the engine bay. Got $15 for it at a swap meet.
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Vanmor
Cochise

USA
572 Posts

Posted - 26 Feb 2012 :  11:06:41 AM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
On the stock pump there is an in and out, then the return to the tank.

There are four ports on the Holley. One is blanked off and not threaded. Then there is one port that has a brass fitting. Then there are the two open ports remaining.

From what I understand, the port with the brass fitting closing it off, cannot be used for the vapor or return.

Just thought I'd add that for clarification.


"A man has got to know his limitations." Dirty Harry
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