[lt1silverhawk]

I wired the choke plate open using a paper clip, sprayed some starting fluid, and started up the truck.





The truck started up find but the speed immediately dropped to below 750 rpm. I gave it enough gas to keep it at 1,500 rpm for the first few minutes. I did rev it a few times and then eventually just let it run on its own as it idled close to 1,000 rpm, when the temperature began to rise.







I then took the truck for a spin and saw no difference in how it drove.


Up next: timing. The reason I mentioned that I was planning on pulling the distributor is because the way I last installed it, the canister is hitting the intake manifold at this point, which means the only thing I can do is to retard the timing from where it is at right now.


On a side note, another member has expressed concern that since the fuel did have crud it in, there is a possibility that there is crud in the fuel lines and/or the fuel tank is rusted. I will be looking into the carburetor at some point as well.


As always, thank you for the continued help.

[lt1silverhawk]

While watching the video from yesterday, I just noticed that the fast idle cam wasn't raised up from the very beginning. Would that be because the choke plate was "locked" into an open position?

[T-bucket23]

Originally Posted by lt1silverhawk

While watching the video from yesterday, I just noticed that the fast idle cam wasn't raised up from the very beginning. Would that be because the choke plate was "locked" into an open position?

Yes they are connected. The closing of the choke also pull up the fast idle cam. The choke can open independently due to the linkage design which is why you need to kick the idle down

[lt1silverhawk]

Got it, thanks!

[T-bucket23]

Did you also clean the plugs?

[lt1silverhawk]

Originally Posted by T-bucket23

Did you also clean the plugs?

No I did not. I saw your post after I had already run the truck with the choke plate wired open. Should I clean the plugs first and give it another run with the plate wired open?

[T-bucket23]

I would just to see if they are black again. Could have been the choke fouling them

[ztwntyn8]

I'd check the plugs first but a bad enough vacuum leak can cause hesitation and I've also experienced hesitation with too little base timing and that will def rob the **** out of your power and mileage.

[lt1silverhawk]

In regards to timing and fuel issues:

The next step is definitely adjusting the timing and a look inside the carburetor itself. There will be a few days before I will post back with any results on this.




-------------------- On a Separate Topic --------------------




In regards to fouled plugs, intake gaskets and vacuum leaks:

Originally Posted by sbchevfreak

Is it just me, or do the "even" plugs look to be badly oil fouled? If so, I would be looking at intake gasket sealing on that side....

Originally Posted by T-bucket23

Block off plates with that style choke dont go together at all. if the exhaust is not allowed to cross over it will take forever for the choke to open.

Originally Posted by T-bucket23

I would just to see if they [plugs] are black again. Could have been the choke fouling them

Originally Posted by ztwntyn8

I'd check the plugs first but a bad enough vacuum leak can cause hesitation and I've also experienced hesitation with too little base timing and that will def rob the **** out of your power and mileage.

Based on the above comments, I immediately had two questions:

- Would the intake manifold gasket that is not sealing correctly be causing both the fouling as well as any vacuum leaks?

- And if that is the case, then the intake manifold vacuum line routed to the transmission would cause it shift poorly because there is no vacuum source?



A quick search online led to the following passage:

Vintage Engines:


Automatic transmissions on many older vehicles use a vacuum modulator. It senses engine load by using intake manifold vacuum to tell the transmission when to shift. If the diaphragm in the modulator leaks, transmission fluid will be sucked into the intake manifold. This can produce smoke that might be confused with engine oil smoke, even though the engine may be in perfect condition. One clue is when the spark plugs nearest the vacuum tab on the intake manifold become oil-fouled with automatic transmission fluid (ATF). A leaking modulator diaphragm can also cause rough engine idle because it allows air to leak into the intake manifold. Harsh, late transmission shifts, or no upshifts, are other symptoms.


Be sure to question the vehicle owner thoroughly. The combination of any or all these symptoms can lead an owner to believe that an engine overhaul is needed. The key to diagnosing a faulty vacuum modulator is that the engine is probably consuming ATF and the level drops consistently.


From: "Automotive Engines: Diagnosis, Repair and Rebuilding" by Tim Giles. Page 58. Copyright 2010. Found online on Google Books: http://books.google.com/books?id=VX4...vacuum&f=false

Although it is not about intake manifold gaskets, the fore-mentioned quote echoes points raised by cobalt and Augusto on page 2of this thread:

Originally Posted by cobalt327

That vacuum line to the modulator valve- bend the hard line so it's pointing directly at the valve so the rubber hose connection is straight. It might be the photo, but the hose looks like it's becoming delaminated where it's bent. If there is any question, replace that length of rubber hose w/a new piece.

Originally Posted by Augusto

about the modulator's piece of hose, it's a good idea replacing it for a new one even though I don't believe that's is your problem, but let me tell you that I have seen modulators that fail, they get the internal diaphragm riped and let the engine suck ATF, that makes them smoke and run terrible. easy check, disconect the lline at the carb end and stick a piece of white paper, a napkin or something, it should come out clean, no traces of red ATF.

The transmission's poor shifting is one of the issues. I will be checking to see how the transmission fluid levels look, if the diaphragm is indeed working, and check the condition of the vacuum line. I will be able to report back on this shortly.

[cobalt327]

Originally Posted by lt1silverhawk

The transmission's poor shifting is one of the issues. I will be checking to see how the transmission fluid levels look, if the diaphragm is indeed working, and check the condition of the vacuum line. I will be able to report back on this shortly.

Have you had a vacuum gauge on this yet? If so, what was the idle reading and needle behavior?
Was a compression test done on this beast? Results?

I hate to say it, but if the timing is right (or close) and the vacuum normal, etc., it may be time to go back into the carb...

[lt1silverhawk]

Originally Posted by cobalt327

Have you had a vacuum gauge on this yet? If so, what was the idle reading and needle behavior?
Was a compression test done on this beast? Results?

Haven't hooked up the vacuum gauge to it, but I thought of that immediately after reading the passage I quoted. No compression test on this "beast" of a crate motor either lol, but I will be able to do that when I check on the plugs again.

Originally Posted by cobalt327

I hate to say it, but if the timing is right (or close) and the vacuum normal, etc., it may be time to go back into the carb...

Well, luckily for me, if there is anything I am now comfortable tearing into, its the good 'ol Q-jet. That's two votes for re-tearing into the carb.


I gotta mention that when the timing was done by ear last summer, the truck ran perfectly. No issues whatsoever with driving. I drove it to work and around the block and whatnot. The only trouble it gave was the occasional refusal to start, but that turned out to be only super-old battery and ground cables and weak battery posts, which were replaced.The truck still does that after having been started and run for a while and then shut off. It takes a few attempts to get it started again.


The two reasons why I never adjusted it by using a timing light last summer was because the timing light I bought turned out to be a dud, and I mistakenly thought that in order for me to adjust the timing properly, the truck had to reach the proper operating temperature. Since the thermostat was never installed while doing the "3-6 hour coolant flush", I never bothered with the timing, choosing to wait until the flush was done.


With that said, yes, the timing is definitely in need of adjustment. But I don't see that being the major issue, unless the timing somehow changed that fateful day of February 1st. I did mess with it yesterday by moving the distributor back and forth, which is when it was most obvious that the distributor needs to be reinstalled so it doesn't hit the intake manifold when being advanced. This may or may not be of any significance, but back when I originally did the timing in summer, I had the idle mixture screws turned out a full six turns to provide enough fuel.

[cobalt327]

Originally Posted by lt1silverhawk

I gotta mention that when the timing was done by ear last summer, the truck ran perfectly. No issues whatsoever with driving. I drove it to work and around the block and whatnot. The only trouble it gave was the occasional refusal to start, but that turned out to be only super-old battery and ground cables and weak battery posts, which were replaced.

What has been changed between when it ran OK and now?

[lt1silverhawk]

Originally Posted by cobalt327

What has been changed between when it ran OK and now?

Between when the timing was done by ear last summer and when the truck first began exhibiting these problems, all I did was begin the cooling system flush, an oil change and added a can of Restore. The other stuff was the cables and battery posts. It drove just fine up until the day before the problems began.


After the truck began having problems, I was advised to check the ignition components. I check the spark plugs, the ICM and the coil. The spark plugs were fouled, more so on the passenger side (pictures in post #9). The ICM passed the test at Autozone twice. The coil was tested using a multimeter and while I was able to get a reading for the primary, but not for the secondary. The coil was swapped out under warranty, but the results were the same (post #9). Once I put everything back together, the truck began running just fine again. But there was some light smoke seen from the passenger-side of the firewall. It began a few minutes after the truck was turned off, and was there for a couple of minutes at the most.


Ever since after that, the truck only ran fin the next day. I cleaned out the glass-cased fuel filter in front of the carb which had crud in it (pictures on page 3, post #33). I checked on the choke. I tried running it with the choke plate wired open. Most recently, I moved the distributor back and forth and turned out the idle mixture screws on the carb to a full six turns (same as before). The distributor ended up in the same place as before, with the canister touching the intake manifold. I did not take for a spin after that.


----------



This morning, I started up the truck to move it for the street sweeper. I let it warm up for a about three minutes and then began moving it to park on the other side of the street. As soon as the truck began turning, the "Oil" light came on for a brief moment. I let the truck continue to warm up for a bit and then decided to take it for a spin.


The truck ran pretty good. Not perfect, but the shifting was happening a lot more quickly and softly and there wasn't much hesitation. Definitely no bogging. But I could detect slightly less power. I took it onto the main street and it got up well beyond 45 mph before I had to slow down. I parked the truck and it revved with no hesitation, even though it had been hesitating around the 2,500 rpm mark. The "Oil" came on only once and it was soon as I began driving and made a turn.


I turned off the truck and came back to it about 30 minutes later and took it for a quick spin. As usual, the idle was a lot lower than when it is first started in the morning (1,500 rpm vs 750 rpm). Again, the truck ran good, but not perfect. I parked it again and came back to it about an hour later.


Letting the engine run and leaving the transmission in "Park", I first checked the transmission fluid. Didn't see much on the dipstick. I put it back in and checked it again:






I then turned the engine off and checked the oil. Nothing showed on the dipstick. I then started truck, let it run for about 30 seconds, turned it off and checked again. There was quite a bit of oil after that:






So that's where its at. Some time tomorrow morning, I should be posting results from hooking up the vacuum gauge to the intake manifold, along with a test of the diaphragm. Maybe even check a plug or two. Distributor re-installation tentatively set for Saturday.

[123pugsy]

YOU NEED OIL!!!!!!!!!!!!!!!!!!!!!!

You don't start the truck to check the oil.

[lt1silverhawk]

Originally Posted by 123pugsy

YOU NEED OIL!!!!!!!!!!!!!!!!!!!!!!

You don't start the truck to check the oil.

Lol, I know that Pugs, but the reason I did start it was because I was wondering if it was weather-related (been pretty cold here during the nights and mornings for the past few days, well pretty cold for Los Angeles). Yes, it was risky, but I didn't want to overfill without checking to make sure that it wasn't because it was too cold (did that before and had to take some out). I promise it is getting as much oil as needed before the next start up. At this point, I'm gonna assume its been leaking/burning on the passenger side. I'll try the 20w-50 to be safe. The transmission fluid seems awful low too. I got nothing but crud on the towel when I wiped down the dipstick.