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Holley truck avenger questions

mrk5 said:
Does the part number stamped on the choke riser have a "-1" after it. That was the 2nd generation. The first generation apparently was nearly impossible to tune the stumble out of. At that time (like 10 or 12 years ago) if you and one of the 1st gen carbs you could send it in to Holley and they would send you the new version as a replacement. That was a really good deal for me, because I bought mine used and then ended up trading it in for brand new.
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I’m pretty sure it’s a -2. I bought it from a guy that parted his K5 when he moved here from California. He said he only ran it for 2 months. But I’m at 7000ft elevation. Lol.
Someone told me that fuel pressure can cause that, that at low rpms the mechanical pump may not have enough pressure? What do you guys think? I hate to buy an inline pump and do all the work and money to have same issue.
 
I would suspect float level before fuel pressure. I would regulate my pressure down because the old carb wheeling theory was the lower pressure would ensure the needle wasn't being unseated too much. Or something like that.

I never experienced a problem until I ran it down to 2psi.

-2 would be a newer model. The other thing some carb tuners make a big deal about is the transfer slot. If you have the throttle blades open too far, too much of the transfer slot is exposed. This can also cause an off idle stumble.

Some info on that from here: https://www.onallcylinders.com/2012...ged through a,via the carburetor's idle wells. Most of their info is coming from Demon Carburetors.

01-TransferSlotsSetRLr.jpg

In the idle condition the transfer slots should give the appearance of a small square when viewed from underneath the base plate. Over exposure of the transfer slot at idle is the chief cause of carburetor troubles.

The top cause of carburetor troubles is the overexposure of the transfer slots at the idle condition. When increasing the idle speed of a four-barrel modular carburetor, adjust both the primary and secondary throttle blades. If you adjust the idle speed with the primary throttle blades only, you could upset their position relative to the transfer slots. Some of the adverse effects of an overexposed transfer slot at idle are hesitation, excessive richness, or poor running; it can even negate the idle circuit completely. In the idle condition, when the throttle blades are closed, the transfer slots should give the appearance of a small square when viewed from underneath the base plate.
 
mrk5 said:
I would suspect float level before fuel pressure. I would regulate my pressure down because the old carb wheeling theory was the lower pressure would ensure the needle wasn't being unseated too much. Or something like that.

I never experienced a problem until I ran it down to 2psi.

-2 would be a newer model. The other thing some carb tuners make a big deal about is the transfer slot. If you have the throttle blades open too far, too much of the transfer slot is exposed. This can also cause an off idle stumble.

Some info on that from here: https://www.onallcylinders.com/2012/10/10/carb-tuning-tips-part-1-how-to-overcome-common-tuning-problems/#:~:text=It is discharged through a,via the carburetor's idle wells. Most of their info is coming from Demon Carburetors.

View attachment 352110

In the idle condition the transfer slots should give the appearance of a small square when viewed from underneath the base plate. Over exposure of the transfer slot at idle is the chief cause of carburetor troubles.

The top cause of carburetor troubles is the overexposure of the transfer slots at the idle condition. When increasing the idle speed of a four-barrel modular carburetor, adjust both the primary and secondary throttle blades. If you adjust the idle speed with the primary throttle blades only, you could upset their position relative to the transfer slots. Some of the adverse effects of an overexposed transfer slot at idle are hesitation, excessive richness, or poor running; it can even negate the idle circuit completely. In the idle condition, when the throttle blades are closed, the transfer slots should give the appearance of a small square when viewed from underneath the base plate.
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I can take it off and check. But if my truck is in neutral it will rev fine if I hit the gas. Would that be the same problem whether it was under load driving down the road or in neutral?
 
I remember mine being the same way.

You're experiencing a lean bog. The engine wants more fuel because of the extra load in gear.

If you check the transfer slot and set it up like they say, you'll know it's right and whether or not it helps. Plus you can keep track of changes and get back to where it was.
 
i had the same issue with my 770 truck avenger. I had a really large cam and afr heads. After numerous calls to holley they said that carb wasn't designed for my setup. So I just lived with the stumble. Mine seemed to run lean below 2000rpm when I would mash the throttle. Then it ran rich above 6500rpm. I was shifting north of 7000 rpm. I ordered a complete jet kit from holley and tried all kinds of different sizes. I did up size the cam and it seemed to help. I sold the carb and still have the jet kit laying around somewhere.. I am done with holley carbs though.

It was great off road though. I flopped my blazer on the drivers side in a gully and the engine stayed running the whole time.
 
gonefishin said:
It was great off road though. I flopped my blazer on the drivers side in a gully and the engine stayed running the whole time.
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I had the exact same thing happen, except mine was the passenger side. I ran that carb for 8 or 9 years on a very mild 350. It was a 670cfm.
 
TJ1978 said:
Put the edlebrock back on...
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This is what I did on my 406 after fighting the Holley avenger....

It may be down on power a little bit one the top end, but I get to smile when I drive it the rest of the time.

But seriously, I usually lean out the primaries and fatten the secondaries on an Edelbrock, then go to lighter step up springs.
 
TJ1978 said:
Put the edlebrock back on...
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I just won’t. Lol.
I used to have to pump the shit out of it to start it in the cold, electric choke never worked right. Even after it was warm if it sat for an hour or so have to pump it again....I hated flooding out when I went up an incline especially having a sm465 and dying on a climb, then having to hold all three pedals with 2 feet to get it started and going again. Lol. I’m sure it needed a rebuild I’ve had it on the blazer since maybe 2003-04? and I read up on making it trail worthy, but I came across this Truck Avenger an hour away along with a ton of other awesome parts.
the pros far outweigh the cons on this carb. I give it one pump when it’s cold and fires right up, I can even drive it when it’s still cold where the edelbrock wouldnt wanna do shit until the engine was warm.
It’s nice getting a little more power outta my 305. It needs all the help it can get. And it’s really nice on the trail. Fires right up and doesn’t give me shit.
So far this is my only issue with it. I have found that the .35 nozzle with the green cam on 2 seems to be the best I can get it. Position 1, I really can’t tell much of a difference. Spent all day today in 4lo on trails and did great. But I also wasn’t mashing the pedal we were just enjoying the day.
I wonder if the holleys just don’t like underpowered 305s. Lol.
 
I'm gonna beat that dead horse for another minute and say that it sounds like you needed to spend some time tuning on the Edelbrock as you have done with this one. I see no reason to have put up with those problems. It's easy IMO to make a carb run rich enough to fire up cold, harder to find the mixture for every situation and engine temperature, of course.

I honestly hope that you figure out the last little thing. I got tired of trying to figure it out and went to an Edelbrock. I will shut up now.
 
i run an edelbrock now. I put the offroad kit in it and set my float level on the low side. No it isn't has good as the holley offroad, but I haven't had it stall out yet. For what I do it is working fine, at least until I flop it on the side again.. I'm sure it would die then.
 
As I have stated before,I've had maybe 4 Holley carbs that worked "good",one needed tweaking with different accelerator pump cams and secondary diaphragm springs (it was a spread bore replacement for a Q-jet)...two 2 bbl Holley Economaster carbs and a 450 CFM 4 bbl Economaster were the others that worked great without any putzing around..

I had a 3310 Holley off a BBC Camaro ,1969 vintage that ran ok at first,but the third day I had in on a 454 in my 74 C10 it started spitting back under acceleration,then the float levels kept changing by themselves,I'd adjust it perfectly and a day later it was pouring gas all over the intake..when it worked right the engine felt much more powerful,but after getting tired of having to mess with it almost daily,when it backfired and started on fire--I was done with it,traded it for a known good Q-jet...no more troubles,and it went back to getting 12-14 mph instead of 6-8 ..

I think Holleys are good for race tracks,not so much street or off road use..them seem to need the most tweaking and when the weather changes,your back to messing with it again..

I liked Carter AFB's for street use,the Edelbrock is basically a copy of them,but I admit they aren't that great if you get the truck bouncing or off camber off roading...my 400 SB stalled or wanted to every time I pushed snow up into piles halfway up the pile with one on it..if I had to stop at the bottom of a steep hill they would flood and want to die out too..funny thing is my '66 Buick Wildcat with a stock Carter AFB never did that on the same hill..

One of Rochester's best 4 bbl carbs besides a properly set up Q-jet is the 4GC used on many of the 60's cars with big V8's..my '66 Buick Electra had one,it never gave a lick of trouble all the time I had it over a 4 year period..thing had good power,idled smooth,and would get 14 mpg in mixed driving,not bad for a 3 ton land yacht..
 
From what I gather and I’m no expert.
Holley: drive track
Edlebrock: drive everything else
 
I've always been a Demon carb fan. Now they are under the Holley umbrella.
 
So today, jacked with it for hours.
Plugged PCV line, possibly tiny bit of difference hard to tell.
changed timing vacuum to manifold.
lower idle set screw down to 500 rpms to try.
Hooked up vacuum gauge again to set carb. I’m getting about 16 at idle.
Advanced timing couple more degrees, and then went more just to try it. Still cuts out if you mash on the gas under 13-1400 rpms. Even went down to 10 degrees to try and no change.
tried orange cam to get little more initial shot. Not change.
I have not taken the carb off yet.
My next step I’m thinkin is to order just some larger jets. I went down 3 sizes from 68-65s and 89-86s in rear because of elevation. But some people online say they fixed stumble by increasing jets? I cant find my original jets I may just order 71s for front and see if it helps or makes a difference.
 
I got my 7.5 power valve in To replace the 6.5 since the truck idles at 16. Waiting for my 70 jets to come in as well.
When I went to replace it..........well here’s some pics of the old 6.5. Not sure how this happens. I’m thinking I may have gotten water in it somewhere maybe from playing in the mud few weeks back. Not sure? But it didn’t make much of a difference replacing it, or if it did, it wasn’t much. But the problem is still there. I’m hoping the jets help. Hopefully they will get here soon!!

CF3F2705-8BEE-4BE3-8FEF-B5C7CE4616B1.jpeg

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Ethanol does that to small engine carbs too so....are you in a state that doesn't allow non-ethanol gas to be sold ?...
 
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