670 Truck Avenger Problem

[8509kmv]

I have been having problems with my brand new 670 truck avenger (90670-2) and have searched ever thread on the site this is my last resort. The carb is mounted on a edlebrock perfomer intake manifold on a stock 350.

The problem is when I stomp on the gas it kills the engine instantly. Somtimes it back fires through the carb. If I ease into the gas it has a little hesitation but not much other wise the carb runs great.

Ignition timing is dead on and idle is good and smooth. The carb has been jetted for elevation at 2000ft it has 66 and 86 jets. I changed the power valve to a 6.5 to meet the idle vacum of 12hg. Idle mixture screws have been adjusted to get best vacum which is 17hg I know this is somewhat low compared to what Holley recomends but it is the best I can get. I have also changed the pump jet nozzel to 31, 32, and 35. I have also change the pump cams and tried them all. The pump lever is set perfect for an instant pump shot. I called Holley tech support and they thought it might be a check valve in the metering plate so they sent two new plates and I installed them and the issue remains. I had and edlebrock perfomer 600 cfm carb on before and it ran fine I upgraded to the truck avenger for offroading.

I know that the 670 is somwhat big for a 350 but the Holley techs seem to think that it is fine. Any ideas would be appreciated.

 

[folkenheath]

670 CFM is not too big, it's fine. The problem is in the title, you have a truck avenger. I am a Holley man to the max, I love Holley carbs. Simple and efffective, and very tuneable. But the truck avenger sucks. It has no high speed air bleeds and the check valves do a great job of preventing feul from spilling at idle, so great that they also frequently cause lean spots during the transition from the idle circuit to the main jets. And the lack of air bleeds throws off the fuel curve. They suck. The idle great on inclines. So if you rock crawl they might be OK, but for most driving they suck. They sacrifice off idle response, and midrange and high RPM power for idling on a hill. Not worth it. I have used one for 3 years and tried all sorts of different setups. But it would even hesitate on the way back down while slowing down.
Does it hesitate on the way back down from cruise? If it doesn't you might be able to tune it out. Try the pink cam with a #40 squirter and a hollow screw. If that doesn't fix it, then Get a regular 600 cfm side hung holley and you'll be much happier and it will be fine for most offroading.

 

[Chevy305]

670 CFM is not too big, it's fine. The problem is in the title, you have a truck avenger. I am a Holley man to the max, I love Holley carbs. Simple and efffective, and very tuneable. But the truck avenger sucks. It has no high speed air bleeds and the check valves do a great job of preventing feul from spilling at idle, so great that they also frequently cause lean spots during the transition from the idle circuit to the main jets. And the lack of air bleeds throws off the fuel curve. They suck. The idle great on inclines. So if you rock crawl they might be OK, but for most driving they suck. They sacrifice off idle response, and midrange and high RPM power for idling on a hill. Not worth it. I have used one for 3 years and tried all sorts of different setups. But it would even hesitate on the way back down while slowing down.
Does it hesitate on the way back down from cruise? If it doesn't you might be able to tune it out. Try the pink cam with a #40 squirter and a hollow screw. If that doesn't fix it, then Get a regular 600 cfm side hung holley and you'll be much happier and it will be fine for most offroading.

X2

Never ran a truck avenger but my side hung 600cfm Holley is the balls