What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Quadrajet vs holley street avenger

Qjet or holley

  • Qjet

    Votes: 13 100.0%

  • Holley street avenger 670cfm

    Votes: 0 0.0%
  • Total voters
    13
Mine doesn’t have a dead spot, it actually performs pretty good. My complaint is that when on the street and going to WOT it just doesn’t turn on fast. The secondaries come it and there’s lots of noise but no hard acceleration. I’m interested to see if a true performance mechanical secondary type carb makes a noticeable difference.
 
My Q-jet doesn't have any electronics on it but i did buy an electric choke conversion kit for it.



My truck runs really good with the qjet on it now (im sure it could run better with a proper tune from someone who knows more then me). Although i have no intention anymore to change carbs, i do kind of want to see what the holley will do to the truck. Im learning a lot (i rebuilt the both the qjet and the holley) and i would like to see the outcome of the truck and how the performance changed.



All of this is new to me btw. I use to think carburetors were intimidating but now that i know a little bit, i dont see them as scary anymore.
 
nvrenuf said:
Mine doesn’t have a dead spot, it actually performs pretty good. My complaint is that when on the street and going to WOT it just doesn’t turn on fast. The secondaries come it and there’s lots of noise but no hard acceleration. I’m interested to see if a true performance mechanical secondary type carb makes a noticeable difference.
Click to expand...
You need a bigger big block
 
Probably has a TBI camshaft. Which is basically a stick
 
I have a 670 Street Avenger on the stock 350 in my Monte Carlo and after a bit of tuning it runs great, starts up with a couple pumps of the pedal unless it's been sitting for a while. I don't even have the electric choke wired up yet, I just adjusted it fully opened. I wouldn't use it on a truck that will see off road time, Holleys aren't known for working well at odd angles.
 
nvrenuf said:
Mine doesn’t have a dead spot, it actually performs pretty good. My complaint is that when on the street and going to WOT it just doesn’t turn on fast. The secondaries come it and there’s lots of noise but no hard acceleration. I’m interested to see if a true performance mechanical secondary type carb makes a noticeable difference.
Click to expand...
I wonder if noise is a reliable indicator of the secondary air valves opening? I would assume yes, but I'd love to see video of one in action on a vehicle being driven.

I never did get into playing around tuning one as much as I expected, but if you know the secondary air valves are working properly, and you feel power is still down, it would be interesting to swap secondary metering rods with significantly richer ones and see if that alone made a noticeable difference.

Without a wideband O2 and a logging device, it would seem really hard to me to tune that aspect of the q-jet, outside of making a million runs down a track or something else you could repeat over and over with a way to measure the performance changes.
 
nvrenuf said:
Mine doesn’t have a dead spot, it actually performs pretty good. My complaint is that when on the street and going to WOT it just doesn’t turn on fast. The secondaries come it and there’s lots of noise but no hard acceleration. I’m interested to see if a true performance mechanical secondary type carb makes a noticeable difference.
Click to expand...
You should make sure that the lockout lever is getting held open by the choke backing off. Otherwise, it sounds as if the air door spring could be a tiny bit tight, those adjust very quickly when turning the screw. Be careful!
But you should put a bigger camshaft in too! :D
 
6872xtc said:
But you should put a bigger camshaft in too! :D
Click to expand...

UGH.... DON'T GET ME STARTED!! :doah: :rotfl: My current combo runs really good and is great for trail running but since about a month after start up I've been wanting more "shock & awe" from it. I find myself looking at Lunati's #20110712 cam a lot but so far I've resisted because it wouldn't be a good choice for trail riding and crawling (as if it ever left the shop :surepal: ). The motor in my old K10 was a pretty rowdy piece, I miss that one.
 
nvrenuf said:
UGH.... DON'T GET ME STARTED!! :doah: :rotfl: My current combo runs really good and is great for trail running but since about a month after start up I've been wanting more "shock & awe" from it. I find myself looking at Lunati's #20110712 cam a lot but so far I've resisted because it wouldn't be a good choice for trail riding and crawling (as if it ever left the shop :surepal: ). The motor in my old K10 was a pretty rowdy piece, I miss that one.
Click to expand...
From the sounds of it looks like it is a gearing problem not carb.
A cam might make a difference a bit but unless you add another 100ft lbs of torque you need to look at your tire/axle ratio
 
Yeah, i think i have the gear part covered.

imiceman44 said:
Or he has high expectations from the engine :dunno:
Click to expand...

This ^. It’s a nice roller bbc and it does exactly what I built it for, I just miss my old motor. The biggest difference between my carbs is vacuum vs mechanical secondaries and I’m hoping that’ll add some street fun to it.

I may change the cam at some point, who knows.
 
I'm no familiar with the street avenger, always figured it for a rebadge 4150, donno.
The Qjet is mechanical secondaries,. Which one is vacuum in your estimation?
 
Wes Harden said:
I'm no familiar with the street avenger, always figured it for a rebadge 4150, donno.
The Qjet is mechanical secondaries,. Which one is vacuum in your estimation?
Click to expand...

That shows how much I know about qjets. Since the secondary flaps open (I think) based on air demand I thought it was a vacuum secondary type.
 
The upper butterfly does open with vacuum
They follow the opening of the secondary throttle plates, which are mechanically opened.
As the secondary throttle plates open the vacuum created opens the upper butterfly, properly adjusted the secondary always gets the air it needs, ei no big.
That Holley will require fine tuning
 
You must log in or register to reply here.

Latest Posts

Top Bottom