carb adjustments

[onebadazzsrt]

It seem as when I take the pedal to the floor it kinda shutters like it's flooding. Also I notice that it runs a little rich at idle. are there any screws on that carb to make some adjustments. 307 82 riv.

[sosuzguy]

GREAT question.... I finally found the last NEW idle load compensator for these cars. Now the book tells me I need to adjust the fast idle with the ILC. How many different adjustments for this car can be made manually?

Anyone ? ? ?

[Guest pfloro]

Hello onebadzaasrt:

First a little history:

The Rochester Q-Jet carbs (both 2 & 4 bbl) used between 1981 & the late '80s are controlled by the primitive computer (ECM - electronic control module). The ECM could vary the A/F mixture by about 30% for both the idle & main metering circuits. The O2 sensor allowed the ECM to monitor the O2 in the exhaust stream and adjust the A/F ratio to help the catalytic converter operate most efficiently. To keep folks from tinkering with carb adjustments, caps, covers and plugs are fitted all over the carb.

During a carb rebuild, it's customary to remove the caps, covers & plugs and leave them off (I didn't say that...). There are a few adjustments which <span style="font-weight: bold">must</span> be made while the carb is apart and these are critical to proper fuel metering (float level, metering rod lean/rich settings & idle air bleed). Special tools are required to make some of these adjustments.

What you should do (IMHO):

I suspect your carb needs a rebuild. A rich idle can be caused by a high float setting and/or leaking fuel needle and seat, dirty or plugged idle air bleeds, internal or external adjustments out of spec. I would either remove the carb yourself & have it properly rebuilt or take it to someone who can remove it & properly rebuild it. This is an appropriate starting point. I think that you have two separate issues: the rich idle is probably carb related but the 'shutter' on hard acceleration may be a vacuum leak or even an ignition problem.

These 'electronically controlled' Q-Jets are really fine when clean & properly adjusted. This was pretty sophisticated technology for the early '80s. GM engineers did their best with the primitive computers & sensors of that era...

Don't expect too much 'oomph' from an early 80's Olds 307. It's a very reliable engine (when reasonably cared for) but power is strangulated by the carb, emission controls, tall axle ratios (fuel economy) and older engine design.

Please keep us posted.

Paul

[onebadazzsrt]

I'm not to worried about performance as this is like my grocery getter. I'll start by picking up a new 02 sensor and see where that leaves me. I did however find a vacuum leak and I got that fixed so now the shutter goes away. Also it's not running so rich that it burns your eyes,

[Guest pfloro]

Hi Jason:

You can still adjustment several things:

1) Base ignition timing (twisting the 'ol distributor). However, all spark advance is ECM controlled via EST (electronic spark timing).

2) High idle speed via screw on carb (passenger side).

3) Curb idle via the ILC (adj. via hole under rubber plug on front of car side of ILC).

4) Idle mixture (if hardened plugs removed during carb rebuild).

5) Front & Rear choke pull off, air valve for secondary bores.

Be thankful for the above adjustments. Once distributors went away and fuel injection took over (even TBI), these adjustments disappeared...

In theory, at least, today's cars are monitored & optimally adjusted by their sophisticated computers & advanced sensors.

Paul

[Guest acboxer]

One possible problem to check and easy to replace is the float itself some of the resin or plastic ones can get soaked and be heavier than stock and allow to much fuel in or give the same results as the float level being to high.Metal floats eliminate this problem

[Guest TwoDoorBuickMan]

Has anyone encountered fuel draining into the intake manifold from the carburetor overnight? Is there an easy fix?

[RivNut]

This is a common problem with Quadrajets. The fuel leaks around a pressed in plug which is used to fill a hole in the fuel bowl. This hole is there from the manufacturing process.

Some people try epoxy over the plugs to seal them. This is a short term solution for the most part as many epoxies are not resistant to fuel. Also, the epoxy must stay bonded to the carb body though all of the heating and cooling cycles that the carb sees.

I recommend contacting Cliff at http://www.cliffshighperformance.com/ He has a solution which involves installing screw in plugs. These plugs are coated with a fuel resistant grade epoxy.

Ed

[tim63riv]

Two Door,

One of the ways that I have repaired ths issue on Quadra-Jets is to lightly peen the lead around the main jet well plugs. Scuff the area up with some medium steel wool and used a high quality epoxy with a thin coat, a thick coat may cause interference between the float bowl and the throttle plate. Because of liability issues, many two part epoxies won't state that they are resistant to gasoline, but I have found that the ones that are gray and black seem to be fine. I've used this procedure for about 30 years and a couple hundred Quadra-Jets and it seems to work well.

HTH,

Tim McCluskey