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Huston - I have a problem...

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Nunyas

Nunyas

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Wow... when it rains it pours. Last night I adjusted the valves on my B, changed the distributor cap, and replaced the rotor. After putting it all back together, I started the engine to see if I could notice any differences. First thing I noticed was the valve train is certainly alot less noisy. I also looked at the timing, it seems to be set a little too far advanced. I noticed that it seemed 'rock steady' at 1500 RPMs, but at 1000 RPMs it jumped up and down between 10 BTC and 15 BTC. After a few minutes, I noticed that the water temp got extremely 'hot' while it was idling with the temp guage pointing straight at HOT. I rev'ed the engine up to 2k RPM for a little and it forced air through the radiator (belt driven fan) and the temp came down. Out of curiousity, I looked under the car to peak at how the exhaust is doing. I noticed that from the catalytic converter to the front of the first muffler was all glowing red (this was at night so I don't know if I would have seen the glow during the day). After noticing this, the car eventually started to run really erratic and finally stalled. Once it stalled, the car would not start until I had let it set for a couple of hours to let everything cool down.

Fast foward to 3PM today, I get in my car to leave work. Start the engine easy enough, but then it stalls. Ok. I restart the engine, got it running relatively ok, and leave the parking lot. I got 3 blocks from the office and I notice smoke. I pull to the side of the road to figure out where this is all coming from. I look under the car, nothing smoking down there. While standing outside I notice the smoke is INSIDE the passenger cabin. So, I looked for the source, and found that the smoke was coming from the floor board directly over the muffler. The car would not restart after several minutes, and is currently parked on the side of the road.

I seem to recall hearing on these boards that an overly rich fuel mixture can cause the cat to glow red. However, the "metering needle" is set at 6 flats (1 turn) from full lean condition, and the air mixture nut and screw are set at their "middle" of adjustment setting. Spark plugs 1, 2, and 4 are light gray. While spark plug 3 is a dark golden brown. If anything, it seems to me that I should be running "lean".

When I had the car at the muffler shop the guy doing the work pointed out to me that my exhaust manifold was begining to 'crystalize' on its under side. I haven't noticed anything that sounds like an exhaust leak under the hood yet, but I guess it's still possible.

So, there's my plight for the day. I have a carb rebuild kit at home, and plan to rebuild it this weekend. Is the carb probable cause for my symptoms? or do I have some other deep seated issues that I really need to investigate too? Mind you I am still having some problems with electricals as noted in the other thread "electricals... grrrr"
 
Just an update. I let her set for about 2 hours, and had a coworker follow me as I limped 'er home. We stalled several times along the way, but the stalls were because I had the lights on and the car stalled precisely when I applied the brakes without maintaining higher engine RPMs. She started right back up each time, and allowed us to get home. However, the driver's seat was starting to get a bit warm (webbing is shot) by the time we got there.

I think I noticed a tinge of a sound of a leaky exhaust manifold on my way home. So, I'll be looking deeper into that this weekend. I noticed a I/E manifold on eBay earlier today that looks like it might still be good... I may bid on it just so I have a spare since the exhaust guy seemed to think that the original was about dead.

Incedentally, I never noticed anything that resembled smoke/burning until after I adjusted the valves. Is it possible that putting them into spec allowed other problems to become visible or more pronounced?
 
Is it possible that putting them into spec allowed other problems to become visible or more pronounced?

I know it doesn't make sense, but sometimes this happens. With improper valve adjustment (especially too tight), compression can drop a bit, reducing the strain on some internal parts.
I recall as a kid that my Dad did a valve job on a car that was running "just OK"....after he did the valves, the slightly better sealing forced oil past the worn rings and the car burned oil (it doesn't sound like you're car is burning oil...this is just an example of what can happen).

Anyway, tight valves might affect cat temps by allowing poor fuel burning. This would allow unburnt fuel to enter the cat......maybe. Did you adjust them too tight?

Getting the carb rebuilt is a good idea since you are correct that rich mixture can cause cat overheating.

One thing I would do is look at your cooling system. On a moderate day, your car should not overheat with prolonged idling and I'm not sure that moderately rich or lean conditons in the carb would affect this very much. Be sure that you have a good mix of anti-freeze (too little water in the mix can cause overheating due to reduced thermal properties of pure anti-freeeze). Check to see that the lower hose is not soft or collapsing (it's under suction, and can collapse and restrict cooling). I prefer to run lower temp thermostats in my cars. Usually, 180 F or even 160 F. It won't fix a bad cooling system, but it may give you a bit more "cushion" befoe overheating.
Sometimes, incorrect ignition timing can cause high engine temps, but your's sound OK.
The timing wavering at 1000 RPM is likly worn springs or distributor bushing. Mine does about the same thing....it's one of those things that should be fixed but I doubt it's causing the problem you have.
G'luck.
 
hmmmm... you know... it's possible that i might have adjusted them a tad too tight. The engine was still slightly warm when I did the adjustments, and I found it somewhat challenging to turn the back wheel to get the next valve ready to adjust. Not that the physical act was difficult, but I couldn't see the valves moving while I did it. Also, the other thing I had a problem with was my Haynse manual gave an adjusting order based on which valve was fully depressed/opened, but I could not find the valve numbering scheme in the manual anywhere. For example, it says to adjust valve 1 when valve 8 is fully depressed, but there was no key for which valves were which. So, I assumed that since the valves are paired off for each cylinder, I would adjust the closed valve on a given cylinder while its mate was depressed/opened. Was that correct? Or did I foobar that? I never adjusted valves before, but I'm familiar with using the various tools needed to do it, and I found the process to be alot easier than I had feared originally.
 
The front valve (nearest the radiator) is #1. The valve that is rear-most (nearest the driver) is #8.
If you adjust one valve when it "mate" in the same cylinder is depressed, this might be OK on some engines, but on others (due to camshaft design and valve overlap) it's not such a good idea. Using the "adds to nine" method is best.
My preferred way to turn the engine is to put the car in third or fourth gear and push the car (on level ground) until the valves are in the correct postion.
Be sure that the thickness gauge "just" drags and is not too tight. Generally, on British engines, you're better off too loose than too tight.
 
I see... in that case I'll have to revisit the valves.

Concerning the engine getting hot issue. I've noticed that it only happens when I have the bonnet up. Since my belt driven fan doesn't have a 'shroud' I suspect the low speeds from idle plus the lack of the bonnet restricting where the fan can pull air from causes an extremely low volume of air to be pulled through the radiator. I have the coolest thermostat that I could find from PepBoys in the car (160 or 120?), and the engine temps seem fine during normal driving. It's when I have the bonnet up and engine idling for longer than "normal" amounts of time I have the engine temp problems.
 
Nunyas, I just pull the plugs, and turn the engine over by hand, using the belt. Sometimes it takes a wrench on the alternator or generator pulley nut, while holding tension on the belt, but it's always worked for me.
The rule of nines that Nial mentions means that when #8 is fully open, set #1. When #3 is open, set #6, etc. But, I'm sure you figured that part out.
Jeff
 
Well, I've re-adjusted the valves. They're a touch more vocal with the tappety tap than yesturday. According to the plate that's rivetted to the block I have a 18V801AE engine installed. So I adjusted the valves to 0.013 with the engine cold. Which, I'm now seeing in my Haynes manual that I should have set it to 0.013 with the engine warm? At anyrate, todays adjustment made a difference in the exhaust temps, but I can still feel the warmth coming through the floor board under the driver's seat (still warmer than before I started messing with the valves). I'll have to recheck them again tomorrow or Monday, after I get the carb back on and the car running again.

After I adjusted the valves and test drove the car, I pulled the Zenith off and rebuilt it. There really isn't much in terms of parts on these is there. The rebuild kit that I got from Moss uses a ball-type metering valve for the float bowl. The one that was installed was a needle type valve. The new valve came with a thinner washer/spacer, and I noticed that it also required alot less travel to open/close. So, I installed the ball-valve with the thinner washer, incase the old one wasn't operating properly (I could *always* smell gas after driving around). The only other thing that I could notice as a substantial difference between the old and new parts is the diaphrams. The old one, while not torn was rather flimsy and had wrinkles on one side reminiscent of how a tire wrinkles on a top fuel dragster on take-off. The new diaphram felt as if it were made of slightly thicker rubber and seemed to fit a bit better while installing. I also replaced the o-ring that's on the plug in the bottom of the float bowl. I was lucky enough to be able to pull the plug out without it breaking. The old o-ring was rather brittle, and could have been leaking a bit, hence the ever present smell of gas. After I reassembled the carb I noticed that the rebuild kit had a bunch of gaskets, washers, and o-rings that I didn't use... is this normal?

Jeff - thanks for the tip on turning the engine. I'll give it a try the next chance I get.
 
If I remember correctly from my AirForce time as an A&E, loose valves are noisy but tight valves may burn, so if in doubt,err on the loose side!
 
Earlier this winter I had a similar problem with an old 1/2 ton pickup that I use on the property for plowing snow and hauling fire wood. Everything from the cat converter forward was glowing red, melting the snow under the truck. There was a build up in the converter, restricting the exhaust flow and increasing back pressure. I ended up cutting it out and running a pipe back to the muffler and it solved all of the problems. You may very well have other issues here, but I'd definitely check to see if the flow through converter is restricted. It shouldn't be getting that hot.
 
0.013 hot
0.015 cold

Set them to .015 first. Better to be loose than too tight.
 
Well, I've reset the valves to 0.015. I ran the car for about 15 to 20 minutes, and it seems to be much much better now. The floor board under the driver's seat gets a little warm to the touch, but compared to how hot it was getting before it's like a cool winter breeze (it was causing the floor mats behind the driver seat to smolder before).

Thanks again to everyone for the tips on getting my vavles set right.
 
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