["QUICK-SILVER"]

Originally Posted by JMB36TA

Don't know about the screws but would they really make a difference?

I can't remember when the nose shape changed on the screws.

Pretty sure the long tapper screws would bottom out on the spring before cutting idle fuel off. That's if your base plate is suppose to have the blunt nose mixture screws.

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

Even with lots of bypass air, should still be able to cut off idle fuel.

Clay

[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.

[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.

[JMB36TA]

So the donor carb didn't work very well, it ran worse. It spit, sputtered, popped, and idled rough. It didn't have a choke so that was part of the problem when I first started it but it didn't idle well after it warmed up. I'm going to put my old idle pick up tubes and power piston spring back in mine and see how that goes. I got the new throttle plates without the holes in them and tried to put them on last night but all 4 screws broke off in the shaft and I can't get them out. I also ordered a distributor tune up kit. I'm at a complete loss.

["QUICK-SILVER"]

Did the throttle blade screws turn at all?

Threads get peened/bradded, from the factory, to keep the screws from coming out. Some more than others. I've had to file the threads flush with the shaft, on some, before they would screw out. Looks like yours has enough threads hanging out the bottom to grab with keen nose pliars and screw them out the bottom.

If the only problem with this carb was idle, not sure I would change anything but throttle blades. And find some one that knows about the mixture screws.

Something would be bad wrong if a weaker power piston spring changed how much idle fuel the carb has. Piston at its lowest supplies enough fuel through the jets to run at highway speeds.

May need to get part numbers off the top, main body and base plate to see if this is even "one" carburetor and not a frankenstien put together. Kenth or Cliff can probably help with that.

Clay

[Tom Vaught]

Originally Posted by JMB36TA

So the donor carb didn't work very well, it ran worse. It spit, sputtered, popped, and idled rough. It didn't have a choke so that was part of the problem when I first started it but it didn't idle well after it warmed up. I'm going to put my old idle pick up tubes and power piston spring back in mine and see how that goes. I got the new throttle plates without the holes in them and tried to put them on last night but all 4 screws broke off in the shaft and I can't get them out. I also ordered a distributor tune up kit. I'm at a complete loss.

Common event for someone who has not done it before.

This right process is you Take a file and file off the "staked over" portion of each throttle blade screw until the screw is flush with the throttle shaft. Then you take a GOOD screwdriver with a proper tip for the screw to engage in and carefully remove each screw.

Replace the blades with non drilled blades and either install new screws and stake them in place or use loctite on the shortened screws. With the loctite they will be just fine.

After the first screw broke off, the screw was trying to tell you something.
Most would have stopped after the second screw broke off.

Tom V.

[JMB36TA]

Originally Posted by Tom Vaught

Common event for someone who has not done it before.

After the first screw broke off, the screw was trying to tell you something.
Most would have stopped after the second screw broke off.

Tom V.

Yeah you're right, I've never done this before and it's turning into a good learning experience. Now I know the proper way to remove the screws if I ever need to do it again. I don't know why I kept going, I guess I figured they were just old weak screws. I've had a few bolts break on me during the whole build so I really didn't think much of a little screw breaking.