Need an educated opinion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

larry may · 05-14-2009, 01:17 PM

Here is what I did. For the sake of saftey I removed the Electric fuel pump and installed a competive mechanical pump. Since that time this ole heap does not idle like it did before the swap. Also will stop running at a stop while in gear idling. Has to be feathered constantly.
From a dead stop on up the to the top it runs very well but not quite like it did before. So before I change back to the Electric I need some feed back . The mechanical is GM used on the like HP 350cid. during the muscle car years. I had thought it would feed this 4777-4 1145x2 pumper holley just fine.
However; the camshaft is a few notches above the old school stuff. I'm also running a notch above true blue octane. Might be 106 + or so. Thanks for any helpful solid information, May be one of you wizzards can work with this to help get me back on track... Larry

Marv D · 05-14-2009, 01:59 PM

Sounds like just a fuel pressure / float level issue. I'd adjust the float level (fuel should just slosh out of the site hole when you gently shake the car, or NO MORE than 1/2 the way up the hole if your using those clear plastic site plugs). Possibly you need to freshen the needle and seat as it stalling at stop signs are sure signs it's either too high of a float level or the needle and seat is not sealing and fuel psi is pushing past over filling the float bowl.

Definately not a wizzard but that's my 2 cents anyways

larry may · 05-14-2009, 02:20 PM

Done that Marv D. Am in the process of changing back o Electric just to see if the Mechancal pump is dragging A$$ .

None of these issue's were present until the Mechanical pump was in stalled. It ran smooth not choppy held its own any where any time.

larry may · 05-15-2009, 09:02 AM

Quote:

Originally Posted by Marv D

Sounds like just a fuel pressure / float level issue. I'd adjust the float level (fuel should just slosh out of the site hole when you gently shake the car, or NO MORE than 1/2 the way up the hole if your using those clear plastic site plugs). Possibly you need to freshen the needle and seat as it stalling at stop signs are sure signs it's either too high of a float level or the needle and seat is not sealing and fuel psi is pushing past over filling the float bowl.

Definately not a wizzard but that's my 2 cents anyways

I give you wizzard mention any way. I changed thepump back . Removed the braided line , and used a steel 3/8 line from pump to carb. Opened the bowl up where the site plug is. Gave that ole heap a right good shake from side to side. No fuel came out of the hole. Adjusted thefloat level for the third time and finally have fuel slooshing out. Put the machanical put back in service the problen reappeared. So changed the braided line to 3/8 steel and runs just fine off the mechanical pump. The whole reason for swaping this out is for the purpose that in a crash the elecrtic pump would probably keep pumping and offer up danger danger. Thinking the Mechanical would be safer in that precictament. Thanks for your nudge to stay after this as I was beginning to! never mind.
:-)) Thanks. Larry

05-14-2009, 01:17 PM	#1
larry may Senior Member Join Date: Jul 2005 Location: MISSOURI Posts: 3,256	Need an educated opinion Here is what I did. For the sake of saftey I removed the Electric fuel pump and installed a competive mechanical pump. Since that time this ole heap does not idle like it did before the swap. Also will stop running at a stop while in gear idling. Has to be feathered constantly. From a dead stop on up the to the top it runs very well but not quite like it did before. So before I change back to the Electric I need some feed back . The mechanical is GM used on the like HP 350cid. during the muscle car years. I had thought it would feed this 4777-4 1145x2 pumper holley just fine. However; the camshaft is a few notches above the old school stuff. I'm also running a notch above true blue octane. Might be 106 + or so. Thanks for any helpful solid information, May be one of you wizzards can work with this to help get me back on track... Larry __________________ The biggest problem people have, is other people Thou shalt be cool and not hassle Be a site supporter. The heart of the wise inclines to the right, but the heart of the fool inclines to the left." Ecclesiastes 10:2

05-14-2009, 01:59 PM	#2
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: Need an educated opinion Sounds like just a fuel pressure / float level issue. I'd adjust the float level (fuel should just slosh out of the site hole when you gently shake the car, or NO MORE than 1/2 the way up the hole if your using those clear plastic site plugs). Possibly you need to freshen the needle and seat as it stalling at stop signs are sure signs it's either too high of a float level or the needle and seat is not sealing and fuel psi is pushing past over filling the float bowl. Definately not a wizzard but that's my 2 cents anyways __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral. Last edited by Marv D; 05-14-2009 at 02:00 PM.

05-14-2009, 02:20 PM	#3
larry may Senior Member Join Date: Jul 2005 Location: MISSOURI Posts: 3,256	Re: Need an educated opinion Done that Marv D. Am in the process of changing back o Electric just to see if the Mechancal pump is dragging A$$ . None of these issue's were present until the Mechanical pump was in stalled. It ran smooth not choppy held its own any where any time. __________________ The biggest problem people have, is other people Thou shalt be cool and not hassle Be a site supporter. The heart of the wise inclines to the right, but the heart of the fool inclines to the left." Ecclesiastes 10:2



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