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Discussion Starter · #1 ·
My engine revs well in park, tries to stumble and die when in drive when I try to give it a little throttle. The primary air intake area of the carb, a Holley Truck Avenger which is new is very clean, the air intake area of the secondaries is very sooty. Have wired the choke open and vacuum secondary closed to test run it and still get the same results, plugs are very sooty too, and new plugs soon get the same color. Any ideas. 81 318, Weiand 8007 intake, Crane PowerMax cam and new lifters, new head work including the valves, all new vacuum tubing even to the canisters and new fuel lines/ hoses. Site glasses show the levels of fuel to be right at the bottom of the sight glasses. Have tried timing from 5 BTDC to 16 BTDC.
 

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do you get black smoke out the rear when you accelerate ?? it sounds to me like you have a problem with being too rich.

are you sure the floats aren't too high ?? try lowering them a bit and retest.

timing should be around 10 deg btdc. Have you done any carb work lately ??
 

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Discussion Starter · #3 ·
It has been a long time since I did a lot of wrenching. Back years ago I was a Mopar maniac, had a power wagon, Ramcharger, Plymouth Fury III and the wife had a LeBaron. I have built engines, rebuilt Carter, Quadrajet and Holley carbs but as I mentioned it has been too long.
The Truck Avenger on this engine is new and has the clear site glasses which have a fuel level right at the bottom of the glass in fact I have to rock the vehicle side to side slightly to get the fuel to "slosh up to where it can be seen in the glass. I did lower the fuel level in the secondary bowl and am going to lower it more in both bowls as you suggested. Right now the timing is at 16 BTDC and will set it to what you mentioned. There was no black smoke but you can sure smell the gas at the exhaust enough that it will sting your eyes. Fuel pressure is a smidge over 6 lbs and the vacuum at idle is 18" of hg measured with a Actron model cp7911. Will post results of timing change and float level change. Thanks very much for the help!
Mark
 

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I haven't messed with the new Avengers... but, have a jillion hours on older Holleys; unless it's got a seep/leak somewhere, it sounds like the primary idle circuit is just too rich, is it adjustable on them ?

Is the throttle linkage actually allowing the butterflies to close all the way ?

1.5 turns out on the idle mixture screws ?

Accelerator pump adjustment ?

Look at the accelerator pump actuation lever, is there a tiny bit of gap between the lever and the cam at fully closed throttle ?
 

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Discussion Starter · #5 ·
The idle adjusting screws were out almost 2 full turns so I put the tach on the distributor and the vacuum meter on the manifold tree and the final best idle speed/ highest manifold vacuum at idle( 17" hg )is out 1 and 1/2 turns as you figured it would be. The maximum vacuum is 21" hg at 1600 RPM. There was no gap between the pump rod and the adjustable bolt so I made that adjustment. The big thing I found was the secondary was not closing all the way because when I looked into the top to check the butterflies it was wet with gas and of course sooty and just by putting hand pressure on the secondary rod the idle speed went down. On the passenger side there is an adjusting screw which was indeed holding the secondary open so I turned it counterclockwise and got that solved. The good news is the flooding and the smell of raw gas at the tailpipes has stopped. The stumble is still there and still cant give it much throttle or it will shudder and die unless I back off the throttle. The timing is set at 10 BTDC. What else do I need to look for. Thanks for helping me get those problems fixed.

Mark
 

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Do you have a 670 or 770 cfm carb?
 

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your fuel pressure may be too high...I am use to seeing 4-5 lbs for a holley....it may be overcoming the floats when you gas it and the rpm comes up, which willalso give you wet throttle blades. and will flood the engine.
 

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Discussion Starter · #8 ·
Carb is 670 CFM, fuel pressure is too high, did not know it was supposed to be 4-5 PSI (it is at 6 PSI now)so I'll get a regulator this morning and set it to 4-5 PSI. The secondary plates are still slightly wet. I intend to hang with this till it gets right! Blood pressure was way too high this morning lol. Wonder why? Thanks very much for all the help. The suggestions made by Smokey and others yetserday really helped, the flooding at idle and rich smell from the exhaust has stopped so we are making progress here. Again, thanks.

Mark
 

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Discussion Starter · #9 ·
A little more info:
The OSAC, EGR valve, Vacuum amp, CTS and Coolant Vacuum Orifice have all been removed since this is a non egr manifold. The only sensor left in the intake is the water temp sending unit. There is a metered port on the metering block of the Holley to port vacuum to the distributor and this is the one I am using to send vacuum advance to my distributor. The electric choke on the carb is working perfectly. So far as cranking it does so on the 1st spin with the starter. Also the air pump has been removed as I did not care to tap each runner of the headers etc. Hope this helps. Thanks for taking time to help me.

mark
 

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Discussion Starter · #10 ·
Got my fuel pressure set at 5psi. Now the engine is still trying to stall when you try to give it gas and it is backfiring through the carb. Any help on this would be great. Thanks. If I gently pump the gas pedal lightly it will finally get past the dead spot and then has plenty of power.
 

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search this forum for a post on carb issues. we went into great detail about theis and squirters and accel pump cams in it. you might want to read it.

it may be a vacuum leak problem now.....or still a timing issue for it to back fire thru the carb
 

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Discussion Starter · #12 ·
Finally got in touch with Rick at Holley technical services. I was informed there is a problem with the Truck Avenger carbs. They are sending me a .035 pump discharge nozzle to replace the .028 that is in it now. He said they get this same complaint about it a lot and what they were doing in most instances was giving folks a Street Avenger in place of the Truck Avenger, not what I wanted to hear as the main reason for getting this one was the claimed ability to climb a 40 degree incline and the 30 degree side tilt. As I am sure everyone who has experienced a stall on a steep hill knows it aint fun. Every bit of help I got in answer to this problem from all of you has helped and I thank you all for that as there were several little problems going on here such as the secondary adjustment and the accelerator pump adjustment which by the way he told me not to leave any gap in the adjustment just to make sure that at wide open throttle the pump was not bottoming out and causing any damage. Of course you got to get it past the stumble to experience WOT lol. Again my thanks to everyone taking time to help me out.
 
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