How to adjust the factory Q-jet for 4 barrel 100% open WOT

[83hurst-olds]

I understand the 83 and 84's are designed so the 4 barrels dont' open 100% on wide open throttle. I remember reading about you could file something, or change the metering rods. Does anyone have any links how to do that, or if parts are needed, what those parts are? It has been a long time since I have been into a carb (10+ years) so I may take it in to get done, I think it needs a kit anyway as this car has sat more than driven and it doesn't seem as smooth as I think it should be and smells rich.
The mechanic that I have used forever only does stock work, not mods unless I can spell it out for him, but he is good at stock work and very trustworthy.

 

[dan2286]

Re: How to adjust the factory Q-jet for 4 barrel 100% open W

Check out this link link, http://www.oldspower.com/vb/archive/ind ... 20230.html

 

[Bonnewagon]

Re: How to adjust the factory Q-jet for 4 barrel 100% open W

If it's the original carb to the car, I'd leave it alone and just clean it. Original unmolested carbs are golden to find and you may like how it performs after a good cleaning. Some carbs were made to not open all the way because the CID of the motor couldn't support WOT. If it's an orphan than best to get Doug Roe and Cliff's books and learn before you play.

 

[sickolds]

Re: How to adjust the factory Q-jet for 4 barrel 100% open W

dude just take it to get done q-jets are good for performance IF done right there 750-800cfm so do it right

 

[azmalibuwagon]

Re: How to adjust the factory Q-jet for 4 barrel 100% open W

This is a pretty easy mod and it allows fine adjustment of just how far the secondary air flaps open. All you're doing is replacing a fixed stop with an adjustable one, so you could even set it back to the original setting. You can do it to an electronic carb and still pass emissions, too. Can't usually do that with the primaries and get away with it.

The instructions are in the Ruggles book. Buy it or just browse through it at Barnes and Noble. it's on page 107.

Tools needed are something to grind with, a drill and small drill bit, a tap, and a screw.

For adjustments, you'll need a screwdriver and a caliper. The adjustment is affected by the hangers, rods, and the air flap adjustment spring, Change any of those and you'll need to check the others.

 

[83hurst-olds]

Re: How to adjust the factory Q-jet for 4 barrel 100% open W

Thanks for the info guys. I am for sure not looking to butcher something up on this nearly 100% original car, but, if I can do something to it hidden and unseen, but helps the fairly anemic performance of it, then I will. That is largely why I want to have my mechanic do it, I haven't touched the inside of a carb in quite some time.

You are right, Q-jet's can be quite the performers. I had one in a dyno-proven 400 SBC at 425 RWHP.