Holley truck avenger trouble
#1726968
01/11/15 05:29 AM
01/11/15 05:29 AM
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Joined: Jul 2010
Posts: 42
Ca
MikeT
OP
member
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OP
member
Joined: Jul 2010
Posts: 42
Ca
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Picked up a used Holley truck avenger 770 to replace aging edelbrock performer carb 750. The carb seems almost new built in 2009. It may be a bit big for my mild (maybe 400 hp) 440 but it should be able to work, I would think. Starts and idles fine, slowly press accel its fine but if you hit the throttle hard off idle the engine will stall, a couple of times a small backfire. Looking for ideas of were to start. Bigger or smaller squirter, Jets, accel Pump...? I attached a small video of what I am talking about. Some specs: preformer intake, 906 heads, msd ignition, electric fuel pump steady 6.5 psi, http://fullragerhome.redirectme.net/phot...7722d312e6d3476I havent even taken it out for ride yet so I am not sure what it will do under load.
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Re: Holley truck avenger trouble
[Re: MikeT]
#1726970
01/11/15 11:28 AM
01/11/15 11:28 AM
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Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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Good test. If it has a problem with no load, then it will be worse with load.
Open the throttle even slower. The objective of this test is to minimize the accel pump's influence. If you have a low rpm tach, hook it up. If there is any hesitation while opening very slowly with no load, then there is an issue with the idle circuit. If so, I'd check fuel level in bowls (float level), check PCV and vac ports, clean idle air and fuel passages thoroughly,in that order. Oh yea, this should be checked with the engine up to temperature of course.
The next tests would be the accelerator pump system. First look with the engine off, air cleaner off. The accelerator pump's lever should be just barely touching the spring loaded adjuster at base idle. Look down the carb while moving the throttle with your hand. Fuel should come out of the shooters into the primary venturis instantly and with every little movement. More movement, more fuel. If not, then the problem is in the accelerator system. Check the Pump cam, the adjuster, check valve and pump diaphram as well as the fuel level (float level). Clean passages if you have it apart.
Your Eddy should be a good carb even if old. Not much goes wrong on carbs except accumulation of dirt varnish (from old fuel) and deterioration of gaskets and rubber. Some of the larger sizes, might include the 750, have the booster higher in the barrel than ideal. This can be addressed by extending the booster with some tubing if you are into such things.
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Re: Holley truck avenger trouble
[Re: Mattax]
#1726971
01/11/15 01:48 PM
01/11/15 01:48 PM
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Joined: Jan 2003
Posts: 1,482
Lake Orion, MI
goldduster318
pro stock
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pro stock
Joined: Jan 2003
Posts: 1,482
Lake Orion, MI
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If you find out the accelerator pump is working properly, I'd ask if you were finding that it lean surges going up steep hills. If it does, you'll want to change the power valve out for one that has a higher Hg rating. Typically how I determine this is to use my wideband to see when it leans out and what the vacuum is at that time. I've found that in a lot of cases it's about 3" Hg below your vacuum reading at idle. If your vacuum is more than 13.5, use a 10.5 power valve. Sometimes the stock 6.5's just don't enrichen fast enough and cause a lean stumble
'70 Duster 470hp 340/T56 Magnum/8 3/4 3.23 Sure-Grip
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Re: Holley truck avenger trouble
[Re: MikeT]
#1726973
01/11/15 04:29 PM
01/11/15 04:29 PM
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Joined: Jan 2003
Posts: 5,447
So Cal
Sinitro
master
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master
Joined: Jan 2003
Posts: 5,447
So Cal
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Quote:
Picked up a used Holley truck avenger 770 to replace aging edelbrock performer carb 750. The carb seems almost new built in 2009. It may be a bit big for my mild (maybe 400 hp) 440 but it should be able to work, I would think. Starts and idles fine, slowly press accel its fine but if you hit the throttle hard off idle the engine will stall, a couple of times a small backfire. Looking for ideas of were to start. Bigger or smaller squirter, Jets, accel Pump...? I attached a small video of what I am talking about.
Some specs:
preformer intake, 906 heads, msd ignition, electric fuel pump steady 6.5 psi,
http://fullragerhome.redirectme.net/phot...7722d312e6d3476
I havent even taken it out for ride yet so I am not sure what it will do under load.
The avenger 770 has smaller nozzles (0.025), take it up to 0.031 will fix the lag..
Just my $0.02... 
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Re: Holley truck avenger trouble
[Re: Sinitro]
#1726975
01/13/15 01:58 AM
01/13/15 01:58 AM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Quote:
The avenger 770 has smaller nozzles (0.025), take it up to 0.031 will fix the lag..
Just my $0.02...
The idle bleeds are really small causing a lean condition the the transition circuit. You may want to check the power valve restrictions too?
This require pulling the metering block to use a small pin drill on the restrictions. Pull the jets at the same time and spray cleaner through the orifices to flush out any debris.
When I did that on my 670 cfm Truck Avenger, there was some metal in there from when Holley built the carb.
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Re: Holley truck avenger trouble
[Re: Sinitro]
#1726976
01/14/15 10:24 PM
01/14/15 10:24 PM
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Joined: Jul 2010
Posts: 42
Ca
MikeT
OP
member
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OP
member
Joined: Jul 2010
Posts: 42
Ca
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Quote:
Quote:
Picked up a used Holley truck avenger 770 to replace aging edelbrock performer carb 750. The carb seems almost new built in 2009. It may be a bit big for my mild (maybe 400 hp) 440 but it should be able to work, I would think. Starts and idles fine, slowly press accel its fine but if you hit the throttle hard off idle the engine will stall, a couple of times a small backfire. Looking for ideas of were to start. Bigger or smaller squirter, Jets, accel Pump...? I attached a small video of what I am talking about.
Some specs:
preformer intake, 906 heads, msd ignition, electric fuel pump steady 6.5 psi,
http://fullragerhome.redirectme.net/phot...7722d312e6d3476
I havent even taken it out for ride yet so I am not sure what it will do under load.
The avenger 770 has smaller nozzles (0.025), take it up to 0.031 will fix the lag..
Just my $0.02...
Just removed the nozzle and its a 35 which from what I have read is the stock size and should be big enough.
Guess I might have to open her up and see what I find.
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Re: Holley truck avenger trouble
[Re: goldduster318]
#1726978
01/14/15 10:30 PM
01/14/15 10:30 PM
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Joined: Jul 2010
Posts: 42
Ca
MikeT
OP
member
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OP
member
Joined: Jul 2010
Posts: 42
Ca
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Quote:
If you find out the accelerator pump is working properly, I'd ask if you were finding that it lean surges going up steep hills. If it does, you'll want to change the power valve out for one that has a higher Hg rating. Typically how I determine this is to use my wideband to see when it leans out and what the vacuum is at that time. I've found that in a lot of cases it's about 3" Hg below your vacuum reading at idle. If your vacuum is more than 13.5, use a 10.5 power valve. Sometimes the stock 6.5's just don't enrichen fast enough and cause a lean stumble
It has about 15 Hg at idle. Maybe ill try a a different PV.
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