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Truck avenger guru's...?

rob h

rob h

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Looking for a lil help here, i have a holley 670 truck avenger on my 358. Ive always had a slight hesitation in the 1500 rpm range and a big dead spot when stood on. So i changed the nozzle to a 35, put in a stiffer secondary spring, changed the accel pump cam from orange to blue. The carb works awesome now and real responsive. Just cant get the slight hesitation out moving slow, (it is a -2 carb)

ive read to adjust the accel pump arm to .015 and that will make it go away. Any ideas on this..? Is that just done with adjusting the arm with the bolt and stick the .015 feeler guage in till its snug..?

The carb works great otherwise....let me know what you guys think
 
I was having hesitation issues with my demon, similar to yours but mine was right off idle.

My remedy ended up being the accelerator pump, I didn't use a gauge though. I just adjusted mine, blipped the throttle. And depending on if it got worse or better I adjusted again accordingly.

Not sure if tyat helps or no, figured I'd throw in my .02$$
 
You don't have to use a feeler gauge, on our Holley's we usually just set it to where the arm has just the slightest amount of slop in it. You can mess with it from there if you want, but it's always worked well for us.
 
ok ill adjust it to see where it goes, thanks. Would it make it run any better also..?
 
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Is the hesitation at 1500 RPM static or during acceleration? On the TA at 1500 it's on the main circuit at least in my 402.
 
Its from idle to 1500 when accelerating, after that it clears all up. Its more so the sound i hear i really dont feel much at all. Other than that it works real good...



I did adjust the accel pump arm for some slop but it seems to have to be turned a long way before it has and play, I have the blue cam in on #2 hole tho, i wonder will the black help any better. I have the #31 nozzle in also, ive seen alot use a #35, that might help also.
 
rcamacho said:
Is the hesitation at 1500 RPM static or during acceleration? On the TA at 1500 it's on the main circuit at least in my 402.
Click to expand...

Sounds like you have free play in the accelerator pump adjustment. Make sure you have the choke backed off when you set it to zero clearance at idle.
 
I have a question for you, does it ever do it at that RPM on the way BACK DOWN to idle when slowing down from a cruise? Because if it does then you will never tune it out with the accelerator pump.

If not, then try the pink cam with a 40 squirter. Any bigger than that and you definitely need a 50 cc pump. Also, make sure you use the hollow screw with the 40 squirter.

With that said, unless you are doing slow speed rock crawling you'd probably be a lot better off with a normal side hung holley. The TA has no high speed air bleeds so the check valves can work, which throws the fuel curve off. It will be lean at lower RPM and rich at upper RPM, sacrificing power and efficiency. But it will idle on a hill!

I love Holleys, but not the TA.
 
It doesnt do it when slowing back down to idle, just as i said up to 1500. I had the orange, brown and now the blue. So far blue seems best and the orange is right in there close.
 
Try the pink, it's the biggest 30cc cam. And you can also step up to a 40 squirter but you need the hollow screw. (should come with a new squirter).
 
ok i could try that, ill adjust the accel linkage play 1st with the blue on and if that doesnt work ill try the pink. Isnt a 40 squiter pretty big, now i just have a 31.
 
rob h said:
ok i could try that, ill adjust the accel linkage play 1st with the blue on and if that doesnt work ill try the pink. Isnt a 40 squiter pretty big, now i just have a 31.
Click to expand...

one would think.. however looking at your sig... 450 hp!!! WOW...

im running the pink one too... biggest you could use... well truck isnt running right now (still wiring it) but id put the pink in... and i got the 35 nozzle in...:crazy:
 
also just read this.. good reading info...

i may have to go back to blue pump in hole 2
turn idle down as i had it up high...

good reading..

http://4x4mecca.com/tech_article/holley-truck-avenger-tips-roading

this also makes sense of the blue cam...
510-20-12.jpg
 
I think ill try the 35 if adjusting the blue cam accel linkage doesnt work. The 31 with the blue cam works good just the hesitation a lil above idle. Ill mess with it when the rain is done here and its a little warmer later in the week....

And yes its a really healthy 350 .040 over with 12.5 : 1, with .220 dome pistons and a 515 lift cam. It turns my 39s like they are 31s now with the carb the way it is. Its getting better tho, makes it wake up more. I had a 750 dp and hated it, had it all done up to work good, jetted down to work but it sucked offroad.
 
RootBreaker said:
also just read this.. good reading info...

i may have to go back to blue pump in hole 2
turn idle down as i had it up high...

good reading..

http://4x4mecca.com/tech_article/holley-truck-avenger-tips-roading

this also makes sense of the blue cam...
510-20-12.jpg
Click to expand...


The only problem is that chart is wrong somewhere, because the pink cam is bigger than the blue cam. So you can't trust it, I called Holley and asked the tech over 2 years ago about that. He sent me a different chart, it won't let me load it because it's too big. Doesn't show the curve but it shows the total cc at ten pumps. The catalog writers in the graphics area must not be very well connected with the engineers/techs. Basically this is what it says...


#1 Hole
White.....17 cc
Blue.......18 cc
Red........18.5 cc
Orange...19 cc
Black......19 cc
Green.....24 cc
Pink.......30 cc

#2 Hole
Black.......18
White......19.5
Red.........20
Blue........20
Orange....24.5
Green......30
Pink........37.5

However, that also depends on your idle setting and where the cam contacts the lever. But, the blue is not near as big as that curve chart suggests. And if you try them, you will see that the colored chart is wrong, not the list. Also, does that mean pink on #2 needs a 50 cc pump? I guess you'll have to see if it still has a little more travel at WOT after you adjust for no slop at idle with your setup.
 
Blue cam on #2 with stock squirter works for me. Very responsive.

Also, adjust for idle speed and then check your idle transfer slot relationship. The transfer slot should be square just showing exposed. Any more and you will likely have a very rich idle and an off idle hesitation. The rear blades can be opened up a bit to help get you into the range.

For example, on my BBC402 the primary blades on the TA670 had to be opened fairly wide in order to idle at ~800-900 RPM. I adjusted for idle speed, removed carburetor and then brought the rear blades open to just before exposing the rear xfer slot in order to get the primary xfer square. It took some adjustment but the primary is spot on square now and no hesitation with blue cam at #2
 
ok, just messed with it in the past 2 hours. I have the 31 squirter, a hair more that .015 pump cam play and the blue cam. The only way for that to work good is the idle at 1000 rpm, under that it still does it. But the comp cam i have does best if the idle is in the 1000-1150 rpm so that could be some of my prob if my idle was too low. It pulls real nice up to 5500 then after that its the same. My cam goes from 1500-6500, the truck never sees about 4-4500 so i should be good. Its still not totally perfect so i might try the 35 nozzle, My timing is pretty high so i think ill turn it down some and re adjust.
 
What's your idle vacuum with that cam? If you need to turn it up over 1000 RPM to idle clean you very well may have to play with throttle plate adjustment to keep out of the transfer slot.

Single or dual plane intake manifold? .40 sounds a bit large for a 350ci engine unless you are running a single plane.

What's your ignition advance curve? 32-36 mech advance in by 3k would be good and a funcitonal vacuum advance limited to 10-15degrees helps.
 
At 1000 it has 8 lbs of vac, not too good. Dual plane rpm air gap intake. For now i have just the 31 nozzle installed. The ignition ,i have a mallory unilite set at 32 degrees in by 3 k, I mite turn it down to 28 or so to see what happens.
 
32 degrees in by 3K should be just fine and plenty conservative.

8"Hg@1000 RPM - sounds like a wild cam or massive vacuum leak. Curious about cam duration and lobe centers. If you have a big cam than 35 or larger shooter would be about right.

The TA primary mains come on early. If you are running a hot cam than the idle feed circuit may need attention from 1K through about 1500 RPM so I'm thinking that may be next depending upon how your accelerator pump tuning goes. If you can maintain a low RPM cruise 1k-1500RPM steady state with out misfiring or loading up than your IFR's are fine.
 
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