Having trouble with my truck avenger carb

Having trouble with my truck avenger carb

smokindiesel

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grande prarrie ab
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80 cj with a 304
So put on a truck avenger carb, and just can't get it to run right. It idles good, but doesn't build much power, and stubles/bucks when the secondarys kick in. Sometimes bucks/misses at high RPM. I've checked the plugs at mid RPM and high RPM when its bucking, they always look nice and brown wich should tell me the jets are the right size. Carb part number is 0-90470 ITs a 470 CFM four barrel truck avenger carb. What should I do to this carb to get it running better? Anyone have a simmilar setup?
 
So put on a truck avenger carb, and just can't get it to run right. It idles good, but doesn't build much power, and stubles/bucks when the secondarys kick in. Sometimes bucks/misses at high RPM. I've checked the plugs at mid RPM and high RPM when its bucking, they always look nice and brown wich should tell me the jets are the right size. Carb part number is 0-90470 ITs a 470 CFM four barrel truck avenger carb. What should I do to this carb to get it running better? Anyone have a simmilar setup?

I'm willing to bet that the jets ARE too big.. I have the similar set-up, stock 304 w/edelbrock performer, 470 TA, HEI ignition and headers.. mine dumps fuel through the engine.. yet my plugs look perfect.. the back of my Jeep however, is just black with extra fuel and you can't even breath. They are known for being over jetted from the factory, try getting with a Holley tech to work out the issues, I'm working through them myself, but I like to tinker.. it'll be worth the trouble, they are awesome carbs!
 
I just put one on my wifes stock 304 same issue's I'm gonna rejet it and change the acclerator pump smaller and cam lobe one or the other one step at a time to see the changes it has .
 
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My son went through the same thing, over jetted. I would talk to Holley's tech people. They have good techs.
 
I ran one a few years back, I ended up with smaller jets, a cam that came in sooner, and a different power valve just to make it work half way good.
After all that it still didn't work good off road.:mad:
 
Yep, power valve was the first thing I changed.. it came with a 2.5, and when I tested cruising vacuum I found that to be waay to low.. I had a 6.5 laying around that I installed and I could probably go as high as 8.5 but I want to wait to re-jet before I change it again. I also bought as secondary spring set, but so far it seems to come in to the secondaries pretty well, it's just the cloud of black smoke when it happens I need to work on now...
 
Another thing to check would be your bowl levels... to work well off road they need to be set as low as possible..
 
Yea floats were set pretty low, rear one was really low. I've got them both set just below the sight holes. I'll have to get some smaller jets and see what happens. probably change the power valve too.
 
Yea floats were set pretty low, rear one was really low. I've got them both set just below the sight holes. I'll have to get some smaller jets and see what happens. probably change the power valve too.

The lower the better on the bowl floats, mine are at least a quarter inch below the sight hole.. Is your carb new? Just wondering what size your jets are if it is..
 
If the carb is good and just needs tuning - Here are my suggestions.

1) Get an O2 sensor installed in the exhaust close to the manifold. This way you can tell exactly what is happening. I welded in a spark plug bung and used a common O2 sensor. I just connected my digital meter to read the voltage. Summit Racing sells a slick gauge system, but it costs more.

2) Connect a good vacuum gauge to the engine intake. I used my large vacuum gauge and duct taped it to my dash temporarily so I could see the response easily while zipping down the road at full throttle.

Once you have an O2 sensor for air/fuel ratio and a vauum gauge, you can really tell what's happening. This may seem overkill, but I solved my carb troubles and learned a lot once I did this. I got this apporach from a website from Gerald Forgnone. You can probably still search for this on the web. He sells an oil recovery stand and explains carb tuning very well.

I found my CJ with an AMC 360 needed an 11" power valve and the black secondary springs to operate properly. The standard avenger carb or other Holley for that matter came with a 6.5" valve. With my 4.56 gearing and the torque of the 360, my vacuum never dropped below 8 to 10" under full throttle. This is why I stumbled and starved for fuel no matter much I adjusted the jets, accelerator pumps cams, and secondary springs. I stopped goofing with advance cams and springs and adjusting my timing all over the place trying to guess my way through this problem

I grumbled a bit welding in the O2 bung. But when I could see the actual results while driving down the road and testing what was going on under load and wide open throttle, I was amazed and very pleased. I actually had the data to figure out exactly what I needed. I could tune the carb to work perfectly in my vehicle and understand what was happening. It works great and I learned quite a bit about how my Jeep actually responds.

This is really the long term solution to getting a good tune on your carb and enjoying your jeep performance.

John
 
My memory says I have around a 65 jet in mine. But I have a 360 and a larger 600cfm or so carb.
 
MY holley 470 truck avenger carb and stock motor , Was spitting and popping also so far only thing I've done was move the accelerator cam bushing from the # 2 hole to #1 hole . That changes how much fuel squirts out of the pump discharge nozzles . Maybe put stock jets back in and try that and see it helps you get power back .
 
Are you making any progress? How does it run going down the road at 50mph? Does it surge?? Or black smoke? Assuming all else is ok (timing, ignition, etc..) try this method.

1) find a main jet that allows solid performance at cruise without surging. A little on the rich side helps provide engine cooling.

2) Move the power valve to a higher number until you are certain you are getting it to kick in when you accelerate. It will bog real bad and starve for fuel until this is correct. Knocking, spitting, that kind of stuff.

3) Once you get this far, then work on getting the correct secondary spring. I would start with a stiffer spring (delaying the secondary fuel circuit) and then work down to a softer spring until you are getting good secondary fuel without black smoke.

My experience with adjusting the accelerator pump cam is that these are subtle changes that only work after these other settings are tuned.

Remember that a carburetor has several fuel "circuits" and each has to be tuned to properly feed the engine at various loads.

Hoping you find the right combo - John
 
I called the Holley tech line today on the trk avenger 470 . :( HE said the 470 won't work on a 304 it will always run to rich no matter what you do I asked him why He said its ment for 6 cylinder not a 304 it cant get enough air flow for a 304 I'm like really:( . He said said put the 670 on and rejet it 2 size at a time . the 670 has 68 primaries and 89 secondaries . So I bought some different sizes and put in 64 / 85 dumped fuel all way out pipe 2nd round took out jets on 470 which are 57's and put in and left the 85's in . Have not run yet will be doing tomorrow after work . will let you all now how it runs later
 
I called the Holley tech line today on the trk avenger 470 . :( HE said the 470 won't work on a 304 it will always run to rich no matter what you do I asked him why He said its ment for 6 cylinder not a 304 it cant get enough air flow for a 304 I'm like really:(
That is the dumbest thing I have ever heard it will work on on a 6 cylinder but not on a v8 :confused:
 
Call them yourself
 
How in the hell can it get more air flow on a 4 or a 6 cylinder??? I have a 470 on my 304, and yes, it does run rich, but I haven't even tried re-jetting it yet.. it runs pretty good, it just dumps a lot of fuel out the tail pipes.. sounds pretty crazy to me..
 

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