[JMB36TA]

Originally Posted by steve25

What is that idle bypass mod, the holes in each throttle blade, or .110" holes in the base plate?

If you have both then that's the issue I would say!

The mod is in the base plate bypass.


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[JMB36TA]

Originally Posted by richardk

It looks like to me you have idle bypass holes drilled in the baseplate and holes in the butterflies. That's a lot of extra air, maybe that's part of the problem?

I don’t know. I sent Cliff a picture before I drilled out the idle bypass but didn’t hear back from him. Hope I didn’t make it worse by moving forward anyway. If that’s the case I guess I can replace the throttle plates with some that aren’t drilled. If I can find some.


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[JMB36TA]

Originally Posted by "QUICK-SILVER"

Might try taking a spring off to see if the screw will go in further and kill the engine at idle...???







Clay

I’ll try this tonight after I get home from work.



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[Kenth]

1. If you have drilled for .110" idle bypass air, replace the drilled throttle blades for undrilled.
2. If inlet needle clip is located in one of the float arm holes, relocate it properly, hang the clip in from behind of float arm
3. Check for excessive fuel pressure, no more than 5 psi for 1974 or earlier Olds Qjets.
4. Check for too high float, not higher than .250".

Hope this helps some.

[JMB36TA]

Originally Posted by Kenth

1. If you have drilled for .110" idle bypass air, replace the drilled throttle blades for undrilled.
2. If inlet needle clip is located in one of the float arm holes, relocate it properly, hang the clip in from behind of float arm
3. Check for excessive fuel pressure, no more than 5 psi for 1974 or earlier Olds Qjets.
4. Check for too high float, not higher than .250".

Hope this helps some.

Every tip helps some, thanks.
I'll start searching for replacement plates.
The inlet needle is not hanging from the hole, it's on the arm.
I don't have a pressure gauge but know a mechanic behind work who can check that for me.
I double checked the float the other night and its about 1/8

[400 Lemans]

1/8 float level is to high. Set it down to 1/4. Probably been getting noozle drip.

[JMB36TA]

Originally Posted by 400 Lemans

1/8 float level is to high. Set it down to 1/4. Probably been getting noozle drip.

That’s a big difference. I’ll check Cliff’s book. I think it said to set it level but I’ll double check that too. I got my check list going.


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[JMB36TA]

Ok here's what I got so far...

The first thing I checked was the hot idle compensator. As I said in a previous post, the cover has a rod coming out of it with a little spring attached. This was specific on Oldsmobiles but I forget why. I soldered the end of the rod so it wouldn't move in and out with the vacuum but it broke loose. So that caused a vacuum leak. I cut the rod, soldered the hole closed, put the compensator back in and put the cover back on.

Next I checked the idle adjust screw without the spring so it would close off a little more and that worked. I didn't want to leave it without the spring so I put it back on and tried the next test.

I lowered the idle really low, about 1/4 turn above sputtering and closed the fuel idle screw and the RPMs went down.

I brought the idle back up and tried the adjusting screws again with a vacuum gauge. The pressure changed as I adjusted the screws. It's sitting steady at 15 and seems to be idling nice and steady. The hole in the back of the hot idle cover may have been the issue.

I haven't pulled the carb to adjust the float yet. Cliff's book says it should be set at 1/4" so I'm going to have make that adjustment. The book also says to toss the little clip on the needle because it's not necessary so I'm going to remove that too.

[JMB36TA]

So after taking the airhorn off and taking a close look at it and the main body I found that not only do I have holes drilled in the throttle plates along with the idle air bypass, but I also have idle air bleeds in both the air horn and main body. According to Cliff's book it should have one or the other but not both. I'll probably never get this thing tuned.

Cliff I could sure use your input and help on this.

[gtobob67]

Your second picture shows the main air bleed. You don't have idle air bleeds in that air horn. See Cliff's Book pages 27 and 32 for pictures of both air bleeds.

[JMB36TA]

Originally Posted by gtobob67

Your second picture shows the main air bleed. You don't have idle air bleeds in that air horn. See Cliff's Book pages 27 and 32 for pictures of both air bleeds.

I see the difference. Thanks for pointing that out.

[JMB36TA]

I spent today going through the carb again. I pulled it apart and checked every channel and hole. I blow everything out with compressed air, pulled the idle down tubes and blew them out and measured the ends. Everything checks out fine. I can't find anything wrong inside. I adjusted all the rods and fast idle and put it back on. I closed the adjusting screws and backed them out 3 full turns to start. Started the car and let it warm up before setting the idle by ear. I had to make a few adjustments to the fast idle since it was way to fast. The adjusting screws have little effect on the idle. The RPM's drop slightly when they're all the way closed. I backed them out 5 1/2 full turns and there's no difference between that and 1 full turn so I left them at 4. I got in the car and put it in gear and it wanted to die. I kept adjusting the idle until it stayed running in gear. It seems high to me but I don't have a tach so I don't know what the actual RPMs are. Then I turned it off and got a little run on. I ordered new throttle plates that don't have holes in them but they haven't been delivered yet. I'll try again when they get here and hope they work. It's almost time to take it to a professional.

[David Jones]

DO NOT GIVE UP ON IT.
These guys will help you figure it out and YOU'LL fix it.

[JMB36TA]

Originally Posted by David Jones

DO NOT GIVE UP ON IT.
These guys will help you figure it out and YOU'LL fix it.

Thanks for the encouragement!

[JMB36TA]

I think the opinion I got about running lean was wrong. I pulled my plugs yesterday and they are all black. Not just one, but ALL 8! There's no oil on them so that's good, but I'm running rich. I'm picking up a doner carb to test today. If it ends up being the carb, and I'm almost certain it is, I'm thinking about putting my old jets, metering rods, and idle tubes back in to see if that helps. One thing that I'm confused about is that the old jets are 72 and my new ones are 71 so it should be getting less fuel.

["QUICK-SILVER"]

The '68' #16 heads use washer seat plugs. Not the small taper seat plugs. I've seen folks do that..but the taper seat usually doesn't seal good on the top thread of the spark plug hole.

Not being able to cut idle fuel off, without taking the springs off the mixture screws, tells me something is wrong. With all the extra bypass air this thing "should" have a lean idle....But from the looks of the plugs and no mixture control, it does appear to be running rich at idle.

Transfere/transition slots shouldn't be uncovered at all with the extra bypass air.

Was you able to clean up the stink when you had the springs off the mixture screws? You said the mixture screws worked with the springs off but didn't say how it ran.

Still say you need to find out if those are the right mixture screws. Still "thinking" 69 had the blunt nose screws but really can't remember.

Clay

[JMB36TA]

Originally Posted by "QUICK-SILVER"

The '68' #16 heads use washer seat plugs. Not the small taper seat plugs. I've seen folks do that..but the taper seat usually doesn't seal good on the top thread of the spark plug hole.

Not being able to cut idle fuel off, without taking the springs off the mixture screws, tells me something is wrong. With all the extra bypass air this thing "should" have a lean idle....But from the looks of the plugs and no mixture control, it does appear to be running rich at idle.

Transfere/transition slots shouldn't be uncovered at all with the extra bypass air.

Was you able to clean up the stink when you had the springs off the mixture screws? You said the mixture screws worked with the springs off but didn't say how it ran.

Still say you need to find out if those are the right mixture screws. Still "thinking" 69 had the blunt nose screws but really can't remember.

Clay

I'll try changing the plugs.

The transition slots are about half uncovered with the idle linkage adjusted, if I back the screw all the way out (not touching the idle linkage) the transition slots are almost completely covered with just a tiny part uncovered. They are never completely covered.

When I had the springs off I didn't set the mixture and let the car run. I tested them and put the springs back on. Looking back I should have seen how it ran. I looked at different screws available but can't find out which ones were the right ones for the 69 Olds Q-jet.

I'm hoping Cliff can help out soon. I haven't heard anything back from him in a while.

[Kenth]

The sooty throttle plate tells me abnormal amounts of fuel is entering the intake.

Does it drip fuel from the nozzles at idle speed in gear (A/T)?
Are you using a new float and a new inlet valve?
Did you check for no more than 6 psi fuel pressure (5 psi prefered)?

Since the carb is a 1969 vintage the bowl bottom plugs would be the non-leaking style. Or?

[JMB36TA]

Originally Posted by Kenth

The sooty throttle plate tells me abnormal amounts of fuel is entering the intake.

Does it drip fuel from the nozzles at idle speed in gear (A/T)?
Are you using a new float and a new inlet valve?
Did you check for no more than 6 psi fuel pressure (5 psi prefered)?

Since the carb is a 1969 vintage the bowl bottom plugs would be the non-leaking style. Or?

I don't know if there's fuel dripping while it's in gear, I haven't had any helper in my garage to hold the brake down.

I got a complete rebuild kit from Cliff when I rebuilt it a couple months ago. It has a new float, needle and seat, primary and secondary metering rods, power piston spring, jets, idle tubes, and choke pulloff. I'm going to try the old power piston spring which may be softer to let the piston seat better? The jets he recommended are actually one size smaller than what I had. I should check the primary metering rods to see what the difference is in those too. If the jets were bigger than I'm assuming the rods would be bigger too?

Not sure what the fuel pressure is, I don't have a way to test it.

[TedRamAirII]

Is there any good simple way to check fuel pressure on a QJet? seems like I would have to make a mickey mouse type of hoses and fittings to do it.