Rochester Q-jet carb vs Holley 770 cfm

[kdsracing]

My holley is a squarebore and its just wasting gas. Ive had it for 14 years. I got the Q-jet for 150$ 10 years ago. Im reading about this carburetor as being a very good driver tool. Thats what I want. I want to save from having to buy a better street friendly holley.

I agree then. Especially if the manifold is spread bore and your current carb is squarebore. I’ve never seen that work well.

 

[Francesco]

Any special features on a 1980 Q-jet? I read that the 75-80 model has some interesting options. How so?

 

[Francesco]

I just realized the 4 barrel will not open on this holley when im on high speeds on the highway...Terrible.

 

[G72Zed]

Well, you have one of the "worst" Holley carbs in my opinion....80770 Avenger.....not surprised at all.

1980RS mentioned this right from the start.....reread post #4.

 

[1980RS]

I just realized the 4 barrel will not open on this holley when im on high speeds on the highway...Terrible.

Just like I though, all the ones I had were the same until I fixed my current 770 now it pulls as good as my old 3310. here's what needs to be added to make it work right.

 

[Fwyflier]

If you really want to know about Qjets, the best thing to do is buy the book. There is a lot about these carbs that you won’t find here. I can’t find me book right now but I’m sure there is not a lot to chose from, it has a big carb on the front. I’ve been doing carbs for a long time and both Holley and qjets have there own quirks. I find it easier to “dial in” a Holley but once you get the qjet right they run like a champ. Good luck trying to save gas with a carbureted V8.

 

[Lurchf350]

1980RS
Can you provide some details on the tube for the Avenger fix?
Thanks

 

[Francesco]

Well, you have one of the "worst" Holley carbs in my opinion....80770 Avenger.....not surprised at all.

1980RS mentioned this right from the start.....reread post #4.

Hi! Yes I know, Im putting in a 1980 Qjet in next week. This Holley is ok on the street but when you try and pick up speed it just feels like im going 80 km per hour on the highway...Wtf.

 

[Fwyflier]

Typical those 770 are jetted to lean. Have you looked at the spark plugs to see what color they are. It also sounds like your describing the vacuum secondary not opening. They make a spring kit to adjust how fast the secondary’s are opening.

 

[tom3]

I'm not familiar with the Holley you have but used to put screw in the linkage to force the secondaries open a bit when the throttle is about half way open. Have to experiment some to get it like you want it. Did see a dyno test on TV where the guys did this and it picked up quite a bit of HP. A dialed in vacuum secondary does work pretty good on a big inch motor but can be hard to get it right. Had a 67 Ford Fairlane GT with the 390 and it, bone stock, would plant you in the seat from idle to about 6k rpm. Also 19 mpg on the highway, pretty good for the time.