TheSamba.com :: View topic - Air flow meter (AFM) plug

Tue Nov 17, 2009 9:51 pm

does it have a vacuum can on the side of it?

Tue Nov 17, 2009 10:01 pm

The TDC is not TDC. When I think I'm at TDC, the valves on #1 go back and forth when I move the pulley side to side 2".

Tue Nov 17, 2009 10:03 pm

Yes, it has something sticking out of the side - I'm guessing it's a vaccuum can because it's not the condensor.

Tue Nov 17, 2009 10:04 pm

Which cylinder are you calling #1? What happens when you turn the crank 360 degrees (direction doesn't matter, just 1 full turn) and do the same test?

Tue Nov 17, 2009 10:09 pm

When we rotate the pulley 180 degrees from where we thought TDC was, one valve on #3 and one valve on #4 alternate back and forth - not the jittery coffee fingers like I saw on #1.

Tue Nov 17, 2009 10:15 pm

And what happens when you turn it 360 degrees?

Tue Nov 17, 2009 10:20 pm

We found a spot where #3 is fluttering back and forth so we're calling that TDC. It's the spot 180 degrees off of what we thought was TDC. Now we're turning the distributor to align the wire for #1 with the direction the rotor is pointing. Next we'll add the other wires in the 1-4-3-2 order. Does that sound right?

In this position the rotor is pointing between 3 and 1 but closer to 3.

Tue Nov 17, 2009 10:28 pm

Possibly, what cylinder are you calling #3? The timing mark can't move unless you had the pulley off the fan and put it together wrong.

Tue Nov 17, 2009 10:41 pm

#3 is #3 (front left - to the left of the flywheel towards the front of the car).

Tue Nov 17, 2009 10:43 pm

If we're at TDC, can the valves in #3 and #4 be moving?

Tue Nov 17, 2009 11:06 pm

ziggybean wrote: If we're at TDC, can the valves in #3 and #4 be moving?

At TDC for the #1 cylinder the valves for #1 will not be moving, at least one valve on each of the other cylinder will be moving though, maybe both.

Tue Nov 17, 2009 11:43 pm

THE BUS IS NOW RUNNING! Sounds like shit (the catalytic converter is virtually non-existent - there's a huge hole through it) BUT it runs :D

Oil started coming out of the valve covers which leaked onto the exhaust manifolds and smoked like crazy. They have new gaskets but I didn't seal them in case we needed to pull the covers off again. What do you recommend sealing them with?

Also, it seems like the idling screw isn't doing much of anything - could be due to no back pressure from the catalytic converter missing. And the exhaust manifolds got red hot and were kind of sparking - is that normal?

Wed Nov 18, 2009 12:07 am

Someone else may be better able to explain this.

Quote: If we're at TDC, can the valves in #3 and #4 be moving?

The rockers on the inside are intake valves. Outside ones are exhaust.

Let's start with this just to refresh. This is a 4-cycle engine. The crankpulley will make two complete turns for every time the distributor turns once. Each full 360 turn of the crankpulley is divided into two strokes - a stroke is where the piston moves towards or away from the crank. This means there are 4 strokes for each full cycle of a cylinder. Since the crankpulley makes 2 full turns for these 4 strokes we can divide the pulley in half and just say that a piston makes a stroke either towards the crank or away from it for each 1/2 turn of the pulley. The 4 strokes are:

Intake Stroke piston is going towards center/crank - Intake is open and let's say that air/fuel is drawn in as the piston moves away from head.

*Compression Stroke - both valves are closed and piston is moving now away from crank and back towards the head. The mixture is being compressed. Spark will be near the end of this stroke which then leads to the

*Power(Combustion) Stroke - both valves are still closed and piston is being pushed away from head by fuel burning. The exhaust will open near the end of the stroke.

Exhaust Stroke - exhaust opens and the piston is coming back towards the head more or less pushing spent gasses out. It closes near the end of the stroke where this sequence repeats and the intake opens.

You are looking for the TDC between the ones I marked with *. Which ever wire the rotor is pointing to at that TDC is the one you should put on #1. If the distributor gear is in correctly it will be the one that matches RAtwell and there is a line on the distributor where the cap sits. #1 is to the passenger front. cylinders 1 & 3 are opposed. Cylinders 2 & 4 are opposed.

Another way of telling is feeling for the compression trying to build in the cylinder during the compression stroke by putting your finger over the spark plug hole.

Wed Nov 18, 2009 5:08 am

ziggybean wrote: Oil started coming out of the valve covers which leaked onto the exhaust manifolds and smoked like crazy. They have new gaskets but I didn't seal them in case we needed to pull the covers off again. What do you recommend sealing them with? You shouldn't need any sealant on the valve cover gaskets, you do need to get them installed correctly though. They tend to slip out of place if you let the valve cover move during installation. You can glue the gaskets to the covers before installation with something that is real tacky.

Quote: Also, it seems like the idling screw isn't doing much of anything - could be due to no back pressure from the catalytic converter missing. And the exhaust manifolds got red hot and were kind of sparking - is that normal?

You have something way out of time. If you have points I would suggest static timing the engine carefully to see where you are before running it again. Turning the engine very slowly in a clockwise direction the points should open just as the mark on the pulley passes the 7.5° mark on the scale. Use a test light or meter to determine exactly when the points are opening.

I am really afraid that you are doing your engine serious harm at this point. Why don't you find someone on the AIRS list that will help you out before you fire it up again.

Wed Nov 18, 2009 7:50 am

There are gobs of GREAT local guys out in the Portland area that would likely to come and give you a hand.

Go over here and see if anyone chirps up. You may have to buy a pitcher at the Lucky Lab though....

http://www.itinerant-air-cooled.com/

Wed Nov 18, 2009 8:56 am

Thanks for the info. We used a timing light while we had it running to set the timing dead on 7.5 degrees. The bus sounds the way it did before we started working on the engine - I'm guessing because of the catalytic converter being bad. I'm going to replace that today and will try to find someone locally to help to make sure the timing, idle and air fuel mixture are correct. I'd hate to mess up the engine after putting this much effort (and money!) into it.

Do you know if there's some sort of an instrument we can get to measure the temperature at the cylinders? Since this thing doesn't have a temp gauge like most water-cooled cars, I wanted to make sure that we're not overheating the engine on road trips.

Thank you for all of your help! If it weren't for all of you the bus probably still wouldn't start.

Wed Nov 18, 2009 9:00 am

I use a Dakota Digital myself.

http://www.dakotadigital.com/index.cfm/page/ptype=...prd347.htm

Make sure you install the sender this way (and it is a lot easier with the engine out)....

http://www.germansupply.com/xcart/customer/home.php?gspage=customer/main/tech/cht/cht_install.tpl

Wed Nov 18, 2009 11:42 am

Trying to set your timing at idle with a light doesn't work all that well unless you can get the engine to idle slowly enough. Otherwise your timing may end up way retarded. Setting the timing at 28° BTDC at 3500+ rpms, with the hoses off is the best way to go. Other than that, IMHO, it is better to set the timing statically than try to do it at idle.

Wed Nov 18, 2009 4:51 pm

Quote: I'm guessing because of the catalytic converter being bad

The only thing a bad catalytic would cause is if it is plugged then it would cause backfiring and dying. You'd hear exhaust hissing out wherever it could and the engine would die under load.

Rather than spend a ton of money on a new cat why not get one of these and see if it runs better. If it does then tune it with this on and replace the cat after it is tuned.

E. 021-251-541 Exhaust Pipe-Elbow to Muffler Note: For Models WITHOUT Catalytic Converter. NOT LEGAL FOR STREET USE IN USA! $59.00

http://www.bus-boys.com/

Wed Nov 18, 2009 10:43 pm

Got a new cat (have to because we need to pass emissions) and muffler and it runs AWESOME! It's not loud anymore. Just drove it 10 miles to the in laws. Man, we couldn't get it over 40. Going to take it to my mechanic tomorrow and have him look it over. Need to make sure the timing is good and air fuel mixture is right.