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hey all... i just got a truck advenger carb and im havin some problems with it, im sure its just adjustment problems. here is whats goen on; it idles just fine, but when i hit the gas hard (WOT) it backfires threw the carb, a big fireball, and when i drive it when taking off at a green light (not to much gas i think it does it because of the weight of the truck) it will bogg down real bad, or mabe die like its flooding. i have checked the float levels and they are fine, and i have tried to lean it out as much as i could with the low idle screws and it seemed to run the best with the low idle screws 1 turn out. i have a chevy 350 with a weiand intake manifold, everything is stock, the plugs are newer ( about 150 miles) and my timing is at about 6deg, its a k5 blazer so you here you go... plz help me out, im not to sure where to go from here, thanks ~Matt
 

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Sounds like it could be your timing and you might be running it to lean causing your bog.. Here is a link that might help CLICK HERE

If not you can type ''CARB BACKFIRE'' in Google and find a lot of info..

Oh yeah you should have got a Quadrajet :flipoff2:
 

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mudslinger99 said:
Oh yeah you should have got a Quadrajet :flipoff2:
should have gone fuel injected :flipoff2:

I have the truck avenger too...I also have similar problems... however seems your timing is off.... and maybe running too lean...

my truck idles at 1200rpms... I have it that way because now and then I pull up to a light and the truck dips down to 400rpms.... also while driving it seems to be running on 7 cylinders.... I hear that there is a problem with the floats sticking from time to time..may wanna call holley... mine isnt under warranty so I dont care.. drives fine... cuz when I go wot she just goes and doesnt have the stupid problems..... :smokin:
 

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From what I've learned the Truck Avenger requires a lot of tuning to work properly on smaller cubic inch motors/stock motors. I've got a 670 CFM on my 305 (with only bolt on mods and a tiny bit of cam). I've ended up changing the accelerator pump to the 50 cc version and also changed the accelerator pump cam to allow more fuel to get in the carb from an idle (mine was bogging pritty good also).
With the back firing out fo the carb, I've first look at your timing/ignition first before looking firther. I know that when I installed the Truck Avenger for the first time it ran really really smooth @ idle (better than my old edelbrock ever did), it's when I start driving it that I noticed that these Holley carbs need lots of tuning to get them dialed in to your specific motor (even though Holley advertises out of the box performance).
 

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Discussion Starter #5
ok, so i talked to someone @ holley who this time sounded like he could help. he told me exactly what you did about the accelerator pump and is sending me a new one. one question i have for you guys is how should i time it.... i meanscence my problems happen when i drive should i keep advancing from zero until i find a good spot, im just cureous on the fine tuneing, what are the eazyest methods?
 

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I'm running a 670TA on a 427 BBC. I had the same problems with carb backfiring. What I found...well a couple things, but anyway, was that the linkage from the cam on the throttle shaft to the arm that pushes on the acc-pump was out of adjustment and adjusted too tight and wasn't allowing the accelerator pump to have a full pump of motion...like it started half way up and didn't get enough fuel out the squirters. I tightened up the locknut and spring-bolt thing to shorten it until it was barely loose from the arm that pushes on it. That gave me quite a bit more fuel from a full stroke on the pump. I also bumped my timing up just a tad. Oh, they also prefer a little bit of heat in the engine before they'll work real well. It's working a whole lot better now...now they just need to make one with mechanical secondaries and squirters so you can thump on them hard off the line and really pour the fuel to it...AND still climb and sidehill with the best of them on the trail. OH, my float levels were low as well from the factory. Hey factory settings- :flipoff2:
 

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too bad it was just your fuel pump, haha, gotta love stupid little problems that you overlook, but now the power valve is KO'd, oh well, should have bought a Yota! :flipoff2: :flipoff2:
 

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s10bogger said:
From what I've learned the Truck Avenger requires a lot of tuning to work properly on smaller cubic inch motors/stock motors. I've got a 670 CFM on my 305 (with only bolt on mods and a tiny bit of cam). I've ended up changing the accelerator pump to the 50 cc version and also changed the accelerator pump cam to allow more fuel to get in the carb from an idle (mine was bogging pritty good also).
you have a serious problem somewhere.
there is no way you need a 50cc pump on that carb.
 

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I run my timing at about 8 deg... still have a little stalling when the engine is cold, but the backfiring stopped...
 

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mj said:
you have a serious problem somewhere.
there is no way you need a 50cc pump on that carb.

That's what holley tech said to do, did the swap and all problems gone. I'm not the only one that has done this to a 670 CFM Truck Avenger to solve the problems (there are quite a few other threads in here where the 50 cc pump was the cure, it's something to do with the added volume and the degree of the new pump cam). This seems to be common on smaller CI engines running the 670 TA.
 
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