924Board.org

[blackhat]

Hey all!

I found the worse thing last night after I got the coolant thing fixed. I took it for a spin, stoped after noticing it didn't feel like all 4 cyclinders were firing and opened up the hood and was shocked to find something.

I saw a small spark between the exhaust manifold and the wheel well. I then relized it was one of the spark plug cables. The exhaust manifold had melted the jacket off down to the core and was arcing against the body.

I got it out of the way and will be getting a new set of plugs and plug cables but I was going to ensure my timing was dead on while I'm at it.

On older Fords I've worked on, I hook up my timing gun to the #1 cable and shoot towards the crank pulley and loosen the distributer to twist till I get the timing on. Does the same thing apply to the 924? Should I just be able to twist the distributer till my timing comes in.

Also, is there a suggested advance or retard that this engine likes or should it just be spot on 0?

Thanks all!
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My First Porsche
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1978 Porsche 924 N/A

[Chrenan]

Yes, clip the gun on the number one cable but you actually shoot towards the flywheel on the back of the engine. Stand by the driver side fender and look down at the bell housing on the back of the engine, you'll see a cut out that lets you see the flywheel, the timing marks are on the the flywheel. Twist the distributor to adjust timing. There are factory specs but I can't remember them, someone will chime in. I usually do it by ear, then drive and repeat the tuning until I get it so it feels and sounds best.

Did the old plug wires have metal jackets? The bosch ones you should replace them with will. If they did have metal jackets and they melted, I'd be very concerned about the temperature of your exhaust manifold, maybe a lean condition? I might even be concerned if it melted rubber ignition wire jackets, something seems too hot abou that.
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1987 951 - M193 Version for Japan

[Smoothie]

That bellhousing window to view the flywheels' timing marks appears just below-right of center in this pic -

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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[blackhat]

Thanks for the pic! I'll be sure to check it out this evening I hope.

As for the temp of the exhaust or being to lean, I'm getting there. The CIS system was pulled out and a Webber carb was put in. So, I haven't gotten a chance yet to play with tuning the carb at all.

The car does blow white smoke out the exhaust while running (not just at start up). I'm thinking piston rings but could it be that it is running to lean? Or, could burning oil because of the rings being bad cause the exhaust to run to hot?
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My First Porsche
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1978 Porsche 924 N/A

[gohim]

The early cars featured exhaust manifolds that crack into a million pieces. The cracking starts at the bottom of the exhaust manifold and cannot be seen from the top unless it is advanced, and the heat shield is missing from the top of the exhaust manifold (is that why your spark plug wires melted?). Cracked exhaust manifolds glow red hot where the cracks go all the way through and hot exhaust gasses escape.

In 1980 improved exhanust manifolds were introcduced for all 924s, and while the older/earlier cars used an exhaust manifold with smaller studs/stud holes and a different part number, Porsche did produce an improved exhaust manifold for the earlier cars.

Use a mirror and a light to check for checking on the bottom side of the exhaust manifold or crawl under the car and look up towards the starter motor.

At the tailpipe: coolant is while vapor, oil is usually blue, and gas is black .

Sounds like you have a blown head gasket, since your exhaust is white.

[blackhat]

[blackhat]

ARG!!!

I just got back from trying to time my new baby.

Follow with me and let me know if I missed something or if the previous owner knocked it off its timing that bad.

I found the little hole in the bellhousing (thanks for the pic). I went ahead and decided to cheat just a bit. I found what I thought to be the 1 TDC on the cam gear and rotated the crank till it lined up with the fin on the valve cover. Then I popped back behind the engine and looked to see if there was a mark on the flywheel. It looked like there was. It looked kind of like this... -- -- I thought that was what I was looking for considering the dot on the cam gear was on the fin. So, I marked it with my marker and marked the timing guide on the bellhousing.

I cranked my baby up and shot the gun at the timing window and I couldn't see the mark on the flywheel. I retarded it till it about stalled and then advanced it till it about stalled and I couldn't find the mark anywhere in the window.

I then decided to see what was up with the cam gear so I moved to the front with my gun. I shot at the cam gear and the dot was about 90 degrees clockwise from the fin. Odd...

I thought this all sounded wrong so I decided to just turn the crank and watch through the bellhousing window to find maybe another mark. It seemed like I did! I was surprised. So, I marked that with my marker. I started up the car and that mark never showed up either!

Is it possible that my distributor needs to be pulled out and sat back in to get the timing back to where I need it? Am I wrong for looking at the cam gear and fin?

I've had troubles before with over heating due to timing being this far off. The timing was so far off on my old Ford that I had to pull the plug wires out of the distributor and move them one spot over to make up for it. Does it sound like I may have to do this again with the Porsche?
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My First Porsche
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1978 Porsche 924 N/A

[Mike924]

The 924 engine is reasonably well-equipped with timing markers, but if the engine's been disassembled, some of them could be mixed up.

There is a TDC marker on the flywheel; it should look a bit like this. "0--", iirc

There is also one on the front of the engine (easy to overlook). There's a notch on the crank V-belt pulley that points to a 'pin' projecting from the oil pump.

And finally, there's a dot or a notch (dependiong on model) on the rim of the cam pully that lines up with a pointer on the cam cover. Of course, this being on the cam, it only lines up with TDC every second rev., i.e. when no. 1 piston is on its compression stroke.

Just as a check, it's worth making sure that all these mark line up at the same time. If not, the engine's been sloppily re-assembled and you'll have to try and work out which part/parts are out of position...
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[blackhat]

[blackhat]

Well, I got it timed finally. The " | " mark was my timing mark on the flywheel. I was scared at first 'cause I didn't see the mark on the back of the cam gear (facing the valve cover) and I thought my timing on the cam gear was off almost 45 degrees.

Anyways, she's timed and runs like a champ. Could use a little more fine tuning ( a short stall on hard acceleration ).

The short stall thing, I think, could be part of another problem. And that leads me to my question.

The previous owner pulled the CIS system out and went the cheap carb conversion route. They didn't do dual carbs on the head, they put one Weber carb where the throttle body was on the top of the intake manifold. It's odd considering every carb conversion kit I've seen is a dual carb setup.

My buddy (an SAE guy and a VW enthusiast) took a look at it. He noticed a low pressure fuel regulator on the side (set to 4 1/2). He said to be cautious about that because if it had some sort of fuel injection that the fuel pump could be a high pressure fuel pump. Is our fuel pump high or low stock?

So, now that you know about the carb and fuel regulator, my question finally arrives.

If I give it a hard acceleration using the throttle on the carb (just kind of dump it open) I get a back fire out of the carb, not the exhaust. He suggested it was my timing being to far advanced. But my timing is dead on. Could it have anything to do with the carb/fuel regulator or is it timing?

I'm clueless on the fuel regulator, does 4 1/2 sound right? What do the numbers on that thing mean?
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My First Porsche
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1978 Porsche 924 N/A

[Chrenan]

With dual carbs on a 924 you run somewhere around 3.5 to 4.5 psi of fuel. My guess is your "4.5" is the fuel pressure setting on the regulator. The 924 pumps are high pressure, can't remember exactly but something like 80 psi.
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1987 951 - M193 Version for Japan

[Rasta Monsta]

Thse cheap regulators can't fight back FI-level pressures. The pump has surely been replaced.

As for the intake popping, check for vacuum leaks.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Mike924]

I'm no expert, but I wouldn't have thought a carb on the intake manifold wouldn't work that well.

The intake manifold has a built-in plenum which, to some extent, isolates the carb from the cylinders. When you snap the throttle open, the carb has to fill the plenum with charge before it can reach the cylinders. Until that happens, the engine will be running lean for a second or so. I wonder if that's the cause of your engine bogging down under acceleration...
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org