rebuilt Thermoquad issues

[bvberserk]

Well, I'm back. Although I found out what was wrong with my carb earlier (accelerator pump was stuck), now I have different issue, probably caused by my rebuild this time.
I wanted to set proper idle/mixture and timing after rebuilt - timing is set at 8 deg according to label, but idle is getting stuck high after snapping throttle - 1k instead of 750.
If I restart engine - it runs 750 again until revving up - then stuck high again.
I'm almost sure it sucks fuel to get rich, but I wonder how I can prove it and what could have gone wrong.
As for tests - I'll try remove PCV hose - as it provides massive leak, engine should start running rough or even stall - this is normal behavior. If it stays running - then is is reach.
screw in mixture screws completely - if still runs - then there is fuel leak. Right now I can slightly see any difference when turning in and out mixture screws.

I could mess left and right mixture screws installing in other place - is it crucial ? shall I try to interchange them?
Metering rods - also could change their location occasionally.

Made a vid if you're interested how it looks like. Any ideas, comments are appreciated. thank you.

 

[CBODY67]

If you remove the pcv valve from the valve cover, it should not affect idle speed or mixture. If you remove the hose from the pcv, with the pcf still in the valve cover, that's a huge vac leak, but one which should kill the motor, mot just let it idle higher by the amount mentioned.

Check to see that the fast idle cam is dropping out as the choke thermostat opens things up from a cold motor. Normally, they rattle around to not stick, but a bit of lube on its pivot pin might help. Otherwise, check the throttle return springs for correct tension. The one on the throttle linkage on the carb and the one on the throttle linkage.

Idle speed mixture screws are not specific as to side of the carb. Same with metering rods, usually.

If the car is not a Lean Burn computer car, the check the mechanical advance weights in the distributor for smooth operati0n and such. If you twist the rotor to manually advance the weights, it shouls spring back to the original non-advance situation, every time.

If you unhook the line to the vac advance, again on a non-Lean Burn motor, does the same behavior exist as to not returnning to hot base idle speed every time?

Just some thoughts,
CBODY67

 

[Mr onetwo]

If it was me I would invest in a wide band AFR guage such as this AEM. The only way to do a proper job of this without guessing. https://www.amazon.com/AEM-30-4110-...ngads-lpcontext&ref_=fplfs&smid=ATVPDKIKX0DER

 

[Big_John]

I wanted to set proper idle/mixture and timing after rebuilt - timing is set at 8 deg according to label, but idle is getting stuck high after snapping throttle - 1k instead of 750.
If I restart engine - it runs 750 again until revving up - then stuck high again.

I've had this happen a couple times.

What seems to happen is as the RPM goes up, the distributor advances, as it should. When it idles down, the distributor weights (or vacuum advance) don't quite go back to their idle positions and the advanced timing brings the idle up, which makes the weights in the distributor start moving into their advanced positions, which also increases the idle. It's a problem that makes itself worse... I hope that explanation makes sense.

So... What do you do? First, are you setting the timing with the vacuum advance hose disconnected and plugged? The next things to do is back the timing off a couple degrees and try to drop the idle speed settings down a bit. From there, try advancing the timing until it starts doing it again and back it off when it does.

I think you are right on the edge of having it right, just gotta screw with idle speed and timing.

Also, make sure you are connecting the vacuum hose to the correct port on the carb.

Leave everything else alone until you get this set correctly.

 

[bvberserk]

Hello and thank you for your replies.
As for timing - I set up idle with all vacuum ports capped off - no vacuum attached to distributor too - only base timing (8 degrees).
But maybe distributor weights get stuck - I will check these anyway (though I'm not sure it is the issue, since idle rpm get back to normal after restart - I don't think restart helps weights to unstuck).

Fast idle cam drops fine, checked this. As for throttle linkage - good idea. I've made a video before removing the carb not to mess anything with springs, will recheck them. Though again I assume, of springs or throttle blades get stuck - I would still see high RPM after restart.

Thank you for providing example of AFR gauge, will get one.