It seems that on my Rochester Q-Jet that the secondaries aren't opening, and the car's starving for air, especially when I stomp on it.

I checked the mechanical openings for the secondaries on the throttle body, and the secondary lockout lever is holding the secondaries closed.

If the choke valve is open and I push the idler cam down by hand, the secondaries will open up, but I can't figure out what adjustment I need to make to get the idler cam to keep the lockout out of the way so that the secondaries will open up.

Anyone have any suggestions?

 

on the passenger side of the carb, closest to the firewall, there's a spring tension adjustment that can be made.... take an inspection mirror and a allen wrench to loosen the screw that holds the tension. then turn he screw on the side until you see the spring release... tighten 3/4 to 7/8 turn. see if that allows secondaries to kick n... also you might wanna adjust throttle cable too.

 

If the car is warmed up the choke should be out of the way allowing the secondarys to open.

 

If the secondary lockout is just catching the pin when the choke is off, file the end of the pin JUST A LITTLE to get some clearance.

If the lockout is fully engaged when the choke is off the mechanism is binding or dirty. The fast idle cam operates by spring when setting itself. It operates by counterbalance when the choke is off. If the mechanism is dirty it can stick.

Do you have a Rochester carburetor manual? If not you should get one.

http://www.ecklers.com/product.asp?p...QAR4L69ERV81D6

BigBlockk

Later.....

 

I figured out what the problem was...My father did a couple of things when I wasn't looking to the carburetor. The main one was that the Fast Idle screw was tightened all the way down, causing the cam to basically stay open and prevent the idle cam from moving.

That was problem number one.

The second problem (again, something my dad had done but didn't bother to tell me) was that he'd unhooked the bottom of the choke rod from the bimetal spring, telling me that the spring closed down when it got hot (I had to SHOW him that the spring expanded by pulling it off of the manifold and hitting it with a heat gun)...

With the frustrations I'm having with the manifold (found that the previous owner used some sort of rubber gasket sealant on the thermostat, and then painted the intake manifold with the thermostat in the manifold, but without the thermostat housing on the car) and the tuning issues with the carb (mainly, my dad keeps turning screws and moving vacuum lines without telling me what he's doing, which is causing the car to run poorly), I'm about ready to give up on the Rochester and buy a new square bore carb & manifold to replace it.

 

:o never give up on a q-jet! no matter how frustrating they may be, once you get them working they are a dream!

 

True, I know this from Tuning for Beer threads.

However, this thing is getting more difficult to find metering jets, needles, etc. for. Pep Boys, Autozone, Summit, etc...None of them seem to carry those parts for performance tuning. Or, if they do, they don't carry the parts that I need.

But I can get a TON of parts for the Holley and Demon carbs there; must be marketing.

 

In the past I used to just tie the lockout down with a wire. But that mechanism is there for a reason.....just don't pin the throttle till your fully warmed up.

 

Buying a new different carb won't solve your problems.
You have 2 basic problems one is easy to fix the other more complex.
1st is you need the rochester book or the shop manual, either will tell you all you need to know to adjust the thing. Performance adjustment on a quad doesn't need new parts, you already have the parts and just need them to operate in the right harmony. Adjust it and your done.

2nd is the hard one. Your dad. I can't tell you how to fix that one. Maybe by adjusting his engine? Maybe that will fix this problem but is more likely to cause much worse ones in multitude.
You might put indicator paint on the screws. This will at least tell you someone was messing with what you already did.

 

Actually, I talked with Lars already about the carb parts, and the jets/needles aren't the ones I need (someone rebuilt the carb previous to us, and put in different jets/needles).

As for a Rochester book, I found a copy of the Doug Roe book and have been picking it apart for BASIC tuning, and then once the car is running smoothly will go to the performance levels (gotta get a baseline first, so that I can figure out what's better).

 

During last summer's Lars tour in NH, Lars discovered that my 69 gas peddle was bent and that the throttle cable was not being stretched enough for the secondaries to kick in when I hit the gas. Lars quickly solved the problem by bending, using his mighty bare hands, and my problem was solved,that is until my engine died several weeks later. But that is another story...