Topic: Vacum advance on 1986 22r

[86toyota4x4]

I have been having some issues lately with my truck not running right. It idles fine and revs at idle fine with a very small stumble right at the start. When you put it in gear to drive it, it doesnt seem to want  rev up. It will rev but you can tell somethings not right it just sounds like it's bogging maybe. I have cleaned the carb (Weber 32 36) completely,  it wasn't very dirty at all also installed new fuel filter. Fuel pump is basically new. While searching the sites I came across problems with the vacum diaphragm. I checked mine by suck on both hoses neither side will hold a vacum at all. Could this be the problem, the reason I ask is I've also read  that the vacum advance doesnt really affect anything accept at high altitude, at idle or at deceleration. At this point if this is not the problem I know clue what is.

[mwhite49]

Could also be a carboned up EGR.  I would check that.

[sirdeuce]

Could also be a carboned up EGR.  I would check that.

Not a carboned up EGR but one sticking open and not clogged.
Best way to check operation of the vac advance is with a vacuum pump. If the vacuum advance is not working the engine would seem sluggish, but only in the lower RPM, the Mechanical advance would smooth things out quickly enough.
The boggish feeling could come from a screwy carb. I've had issues with Weber carbs in the past with the power valve sticking open. With the power valve sticking open the mix goes full rich. Typically the carb's float bowl will empty in a short time and the engine will stall out in such a case. If the accelerator pump is not working properly stumbling off idle would be a symptom, but after a few hundred RPM that would go away and then would act normally.
Typically things that cause off idle problems lose they're effect when the engine gets past the intermediate operating RPM. If the bogging continues past that then it's time to look elsewhere. Pull your plugs to see if your mix is really rich(black sooty coating). Is your exhaust black? Check your ignition timing for increasing advance when the engine is revved (for the mechanical advance). Do a compression test, a small leak between cylinders could cause that problem.

[86toyota4x4 [OP]]

Thanks for replying. EGR is gone. Compression is good motor is new. Trying to pull a vacum on the advance  does nothing you just pump.away and nothing happens. I willpull  the plugs and see what they look like. This started as kind of a spitting and sputtering  and as the rpm built up the engine would clear up and run fine. It just recently started what it's doing now. It really doesnt spit and sputter it just feels like the motor is bogging all the time now. The engine doesnt run crisp and clean. Kind of sounds like is going BLAHHHHHH,   BLAHHHHHHH. I know that's weird but that's what it actually sounds like doesnt want to really build any rpm. It will hardly get down the road. It used to run as fast as you had balls to drive it. 90 to 95 was easy I just didn't want to push my luck.
   

[mwhite49]

Maybe a bad distributer.  Are you using a vacum pump?

[mwhite49]

If your distributer is bad when you go to purchase one don't get one at NAPA. My rebuilt one from them looked fine. Hooked up my vacum pump and it failed. Got a fresh new one from LCE. No garbage. Tested it when I received it and it's perfect.

[86toyota4x4 [OP]]

Yes Mity Vac pump.

[mwhite49]

If your using that pump I would say it's time for a new distributer.  Lce is having a 12% off sale right now. It shows up after items are in your cart ready to check out.

[Gnarly4X]

As usual, sirdeuce injected some empirical wisdom into the question. 

I'll just add a tad of my pomp n' stink.....

What is a "new engine"?... recently rebuilt?

How many miles on it?

What elevation are you at?

You might want to check the cam timing just to eliminate cam timing.

When was the last time you checked/adjusted the valve lash?

What cam are you running?

Whose intake manifold?

Have you pulled the distributor to inspect the condition of the gear and shaft movement?

It should be easy to see if ignition timing is the issue --- timing light?

Retarded ignition timing can cause bogging. - usually causing an increase in engine temp.

The misfire, then bogging sounds like fuel/air issue…. one word comes to mind - “lean”.  Is something leaning the mixture? … vacuum leak?

Sputtering or blubber is typically of an over-rich mixture.  A quick misfire is typically a lean mixture or no fuel.  - spark plugs should be read.

Weber carbs are very sensitive to contamination and fuel pressure – of course jet tuning.

A new distributor may solve the problem (and sounds like vacuum advance is malfunctioning), but it could also be a fuel/air/delivery issue. 

Just thinking out loud. 

Gnarls.

[sirdeuce]

I forgot to mention carb float level and needle valve sticking/dirty. Bad thing about carbs is they do ted to dry out between uses leaving a white 'powder' like coating and varnishes. Plastic floats absorb fuels (saturation) and become heavy. Metal floats have or develop pin holes in the joints allowing fuel into the float and causing the same problem. The needle valve has a spring and ball that can get gummed up sticking the ball in the needle body reducing the force on the valve seat allowing excessive fuel past the valve.
Cam timing.…. If the cam is advanced a tooth it would cause a low power out but not such a 'bogging' feel in the lower RPMs dying off early. Retarded would have a gutless low end with a 'coming alive like a banshee' feeling in the higher revs.

[sirdeuce]

OOooOOhHH! A break in the rain! Had to go out and rake leaves. Any way, Yeah, retarded timing can cause a bit of a bogged feeling, like 15* retarded. Advanced timing can cause similar effects as the peak pressures could be realized before TDC, which could be dangerous to the engines internals. Also, when peak pressures are in before TDC a condition that reads as rich on the plugs and out the exhaust could be present. Like a bad preignition issue without the knock.
Another thing that could cause such symptoms, carbon fouled, poorly ground or even worn intake valves, but that would most likely sound off in the intake manifold.
At this point I'd most likely be so ingrained in investigating the carb I'd miss something else. Good luck with it. Be sure to let us know what you find,

[86toyota4x4 [OP]]

Sorry for getting back with yall late families been sick. The motor has about 6,000 miles on a fresh rebuild. It has a  new head with all new parts and the block has a new crank, rods and pistons. Has a small Comp Cam slightly larger than stock(cant find the cam card), LCE header,  Weber 32 36 DGAV, stock intake and 2.25 exhaust. I live right at sea level in coastal Mississippi. The truck has always run very well until last year about this time. It would bog and splutter then clear up and run fine. I dont drive it alot in the summer because of the hell heat we have here. When it starts to cool off I drive it constantly. I have pulled the Weber apart twice to check for anything in it that could cause this problem, it has been clean both times. I'm going to go ahead and get a Redline rebuild kit and put it in instead of cleaning it. I dont believe that will change anything. I pulled vacum on the power valve to check it and it held vacum fine. I did go ahead and get a new LCE distributor.  It is now installed , I set the timing at 0° (pulled the vacum lines and plugged them) it goes to right at 12° when you reinstall the lines. The plugs look fine, it may be running a little rich but it has always been that way. The new distributor did help, the motor runs better but still has the off idle spluttering boggy sound. I thought of this the other day . When the motor was running really bad I did take the air hose snd shoot some high pressure air down some of the passages in the carb while it was running. Right after that is when it really started running bad doing the BLAAHHH BLAAAHHH stuff. But I went through the carb and cleaned it again after that and nothing was wrong with it. The motor is back to where it was this time last year. Thought about putting a new fuel pump on it but I dont feel like that would fix anything its pumping fuel also put a new fuel filter on it. Just not sure what to do now I'm stumped.

[sirdeuce]

When you disassemble the carb use a wire to snake out the ports, might be a loose something or other there. Make sure the jets and emulsion tubes are free of debris. Check internal ball seats, like the check valves in the accelerator pump and power circuits. If the "seat" area under any ball became corroded it could cause a lea or even raise the ball from the seat. You'll most likely need a jewelers loop. Be sure when reassembling the carb ALL springs and balls are installed properly, use the blow-up pic in the rebuild kit, it's a good reference.

I haven't been in a carb for some time, so what I can remember I'll pass on.

[86toyota4x4 [OP]]

Thanks I'm ordering the tomorrow!