Porsche 4 cylinder Engine question, 1.6l 912 Options

[MattR]

Okay, I spent the day with some club guys today and we went over my 67 912 engine. We found a few things (some simple, some not).

1) The distributor is an 050, with the wrong cap. Whats the best readily available distributor for a 67 with weber 40s?

2) Is the mark on the engine pully for TDC? Or is it for the "correct" (factory) timing?

3) What is the factory timing?

4) What is the factory dwell?

5) The most difficult. On my #4 cylinder (furthest from the trans on the passenger side) its not firing. Its getting a strong spark, valves are adjusted reasonably well, and the plug is relativly new. Im thinking its either a stuck valve or its carb related. When the car is idling and I take off the plug wire the idle drops SLIGHTLY. Then when I put a rag over the stack on just this cylinder during idle the idle doesnt change note. When I put a rag over #3 the idle drops a LITTLE. Is this idle circuitry? These are weber 40 IDFs, remember. They look relativly new, but looks can be decieving.

I posted on PP forum. Lets see who is faster and more knowledgable (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif)

[McMark]

1. What's wrong with the 050? Just get the correct cap. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif) Looks like the stock distributor is 0-231-129-022 (Bosch #).

2. The mark on the pulley is TDC.

3. 3 ATDC at 900-1000 RPM. 30-35 BTDC at 3100 RPM. Harbor Freight has an adjustable timing light for like $12. Go get one of those.

4. 0.016" point gap. 47 - 53 deg. dwell.

5. Pass side, closest to the rear of the car should be #2 cylinder. Sounds like junk in the carbs. Probably has a rusty tank. The bad news is that when you take the tank out you're going to find rust in that area. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)


What do I win? I wish we had talked more at the breakfast. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

[McMark]

Okay, I was wrong. It's $30, here.

(IMG:http://www.harborfreight.com/cpi/photos/40900-40999/40963.gif)

I have one and it works just fine.

[Britain Smith]

I have a timing light that you can borrow anytime.

Nevermind, I though you were in the bay area...

-Britain

This post has been edited by Britain Smith: Jan 30 2005, 12:27 AM

[MattR]

1) I went to two parts places yesterday and neither had the correct 050 cap. And I wasnt sure the advance curve was right for that motor.

2) cool

3) I have access to one of these lights (Clayton - Twystd1)

4) (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

5) Oh, I thought it was #4... I cant get these buggers right. If there was crap in the tank wouldnt it foul all 4 barrels? Ive been driving about 2 tanks like this and Ive only had problems with the one cylinder.
Rust? What rust??? (see skline's thread 'The day at SKlines Garage' (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) )

[Dominic]

1) The distributor is an 050, with the wrong cap. Whats the best readily available distributor for a 67 with weber 40s?

The 050 is just about the best aftermarket distributor for your 356 / 912 engine. The original cast iron distibutors are very rare and 40 years old as well and the aluminum 031 distributors are just as rare and most used ones will be worn out. You should be able to find the cap / rotor /points at most porsche parts retailers for the Bosch 050.
They also make a pertronics ignitor that will fit these mechanical advance distributors

2) Is the mark on the engine pully for TDC? Or is it for the "correct" (factory) timing?

The middle of the "OT" mark is TDC

3) What is the factory timing?

30 Degrees BTC at 3500-4000 RPM or 1.5" to the right of the middle of the "OT" mark on your pulley

4) What is the factory dwell?

Don't remember of hand, point gap should be .016"

5) The most difficult. On my #4 cylinder (furthest from the trans on the passenger side) its not firing. Its getting a strong spark, valves are adjusted reasonably well, and the plug is relativly new. Im thinking its either a stuck valve or its carb related. When the car is idling and I take off the plug wire the idle drops SLIGHTLY. Then when I put a rag over the stack on just this cylinder during idle the idle doesnt change note. When I put a rag over #3 the idle drops a LITTLE. Is this idle circuitry? These are weber 40 IDFs, remember. They look relativly new, but looks can be decieving.


I have found some of the engines with bent pushrods, so your stuck valve theory is very possible due to a bent pushrod, go thru the valve adjust again, or just pull the rockers and take a look at all of the push rods, roll them on a nice flat surface to see how straight they are. Good Luck! (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[ArtechnikA]

QUOTE (MattR @ Jan 30 2005, 02:42 AM)

5) Oh, I thought it was #4... I cant get these buggers right. If there was crap in the tank wouldnt it foul all 4 barrels?...

cylinder numbering: #1 method - cheat. i think the numbers are i the tin.
#2 method - you know where cylinder #1 is - it's the one that by the notch in the dizzy body. you know where #3 is - forward, driver's side. you know the firing order: 1-4-3-2...

an 050 will work fine with that engine once you get the right cap. the "book" timing is a bit emissions-influenced and you might be able to advance it A BIT depending on what kind of fuel you're expecting to run.

sounds like a plugged idle jet, and those are luck of the draw. gunk will probably foul them all -eventually.- maybe all at once, maybe one at a time. pull it and check. clean out whatever you find.

finally - did you verify strong spark *at* the plug, or did you test for spark *to* the plug. IOW - the plug could be dead - it happens. even new, outta-the-box plugs. you'll want to pull it to see what's going on in the cylinder anyway.

tip: use a good, fresh spark plug socket with a good foamy rubber insert. i spent the longest part of a day chasing a spark plug that managed to slip out of the socket into the cooling shroud - allso #4, and it was no fun reaching back in there. ('65 912...)

[DJsRepS]

Hi there first off it sounds like you have driven two tanks of fuel with a cylinder not running right. Is this your sole transportation. I cant stand to drive a 3 banging 4banger. And its not good for the cylinder walls unburned fuel washing away the oil. And why no one mentioned a simple compression check on the dead cylinder? And even if the compression check is ok pull the push rods and see if one is bent. From the sound of things your carbbed with one barrel pr cyl. If you have spark and the motor mechanicly checks ok as in compression and pushrods then proceed straight to that carb and open it up and blow it out and post pic's of your carbs etc.. We all like pic's.

[skline]

He tore the carb all apart and cleaned everything. It still is not running on that cylinder.

[ArtechnikA]

do the easy thing first:

replace the plug. maybe the wire.

then a compression test seems prudent.

it is *possible* that there's a clogged passage in the carb. stripping it and a thorough cleaning *should* have disclosed it, but sometimes things get overlooked or are harder than we predict. but we'll presume for the moment that the job was done right and everything is clear. including all the jets with their teeny holes.

maybe try swapping carbs side-to-side to see if the symptom moves.

fuel, compression (implies air), and properly timed spark are all you need.
it's gotta be one of those...

[MattR]

Replaced plug. It gets spark (good wire). Done compression test (all 4 cylinders have over 125). Stripped carb. I had clayton (twystd1) and scott looking over my shoulder. I am pretty confident it was done properly.

[Aaron Cox]

tight valves? burned valves? stuck valves?

[ArtechnikA]

cool, it's getting narrowed down to one of three things, only one of which is horrible:

1) for some reason, the carb is not flowing fuel. if you direct compressed air through it, will it atomise solvent you have put into the float bowl ?

2) for some reason, it's not getting spark at the right time. flat lobe on the distributor (i forget what ignition you're using...)? gunk in the Crane shutter wheel? clip an inductive timing light on that plug wire and see where the spark is occurring relative to where the other cylinders fire.

the horrible possibility:

3) something you think you know, is wrong.

radical things to try -- twist the dizzy 90 degrees and re-run the plug wires for the new "#1" does the defect follow the spark, or does it stay with the cylinder? swap carbs side to side. does it stay with the carb, or with the cylinder?

i love this quote from Carroll Smith's first book: "the race car is an inanimate object; therefore, it must eventually respond to reason..."

i just re-read the thread from the top.

you now have the correct 050 distributor cap, right? 'cause there's no use trying to diagnose anything with the wrong parts installed...

[MattR]

Im thinking of putting a mallory I have sitting around in there. The type 4 dizzy should fit into place, right? The 050 cap still isnt right.

I also have two spare 40 idfs i could try. They are jetted for a 2.0l T4, but they will atleast let me know if the carbs are whats wrong.

[ArtechnikA]

QUOTE (MattR @ Feb 1 2005, 05:15 PM)

Im thinking of putting a mallory I have sitting around in there. The type 4 dizzy should fit into place, right? The 050 cap still isnt right. I also have two spare 40 idfs i could try. They are jetted for a 2.0l T4, but they will atleast let me know if the carbs are whats wrong.

the Mallory is reportedly a very snug fit in a 912 application but it has been reported to work.

just about any of the 4-cyl aircooled dizzies oughtta fit and work - at least at idle - although some are better matched than others through the power band.

donno if you can bolt IDF's to Solex manifolds but you're right - if you can make them fit physically, and turn the idle mix screws in a bit, it should at least idle reliably, although the chokes will probably be a bit bigger than you'd like, and it will probably run rich, so watch for plug fouling lest you confuse yourself even more.

it's gotta be *something*.

okay - here's an off-the-wall one. i don't recall if the engine used to run right and it suddenly developed this problem or what... but we've been concentrating on the top of the engine. what if there's a mouse body or something plugging an exhaust passage like a J-tube? probably wouldn't restrict enough flow to show up on a compression test, but the cylinder would probably be dead just the same.

does a UniSyn or SynchroMeter show equal flow through all 4 throats when it's running ?

(just trying to think of *everything* ...)

[Aaron Cox]

his car has solex intakes with weber adapters on them....

matt- you can borrow my flow meter

[ArtechnikA]

QUOTE

I posted on PP forum. Lets see who is faster and more knowledgable

so how we doing compared to those guys?
did they already solve it and you're just waiting for the right moment to tell us how off base we are ?

[MattR]

Oh, they're slow. It was kinda a joke posting there. The knowledge here is like 10x more plentiful (and about 5x more accurate (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)).

[skline]

Besides that, I think there are only about 5 people that go to the Bird board annymore. I got there about once or twice a week just to see if there is anything new. Its usually the same threads I saw last week still up at the top. Here, wait 20 minutes and the thread you were looking for is now on page 2.

[Twystd1]

OK,
There is something else you may have forgotten to tell the crew here at the forum.

On Matt's car i tried to move the timing around a bunch. I'm guessing I went from TDC timing mark to about 35 degrees advance. it never pinged once.

I thought that was strange. The engine SHOULD have reacted to this dizzy change with some kind of performance gain or loss. Yet it made almost NO differance.

So please add that to the equation of interesting facts.

Also someone stated that something along the lines if

ArtechnikA wrote:

1: Does a UniSyn or SynchroMeter show equal flow through all 4 throats when it's running ?

2: Radical things to try -- twist the dizzy 90 degrees and re-run the plug wires for the new "#1" does the defect follow the spark, (Effing brilliant idea)

3: Is the exhaust clogged up? (muffler?)

Clayton Wrote:

4: Me thinks the dizzy may well be PART of the problem because of the funky cap that DOES NOT FIT. You have to get that fixed before you pursue anything else.

5: I have a pair of Dells coming this week you can borrow for a test if needed.

6: If the Mallory doesn't fit. Throw a Pertrinix into the dizzy. This simply takes one more issue out of the equation. (hopefully)

7: Check the dizzy again for loose wires or a little shorted piece of copper wiring with a strand going to ground INSIDE of the dizzy body. (stranger things have happened)

8: Check the engine at night when it is dark and look for sparks coming off the wires, Plugs (pull boots up to see) or any sign of spark from the secondary ignition.

9: Is their a CONSTANT 12 volts or better going to the dizzy? (not intermittent)

10: Swap a plug wire. Does the issue remain on the same cylinder?

Thats all for now. Have to keep thinking about this...

By the way. I honor you for sticking with this. You did a good job on the carb from what Scott says. This is just part of the learning curve. Someday you will school us old guys on how all of this works.

And thanks for putting up my tools. That was tight.......

Let me know what I can do. You have my number....

Regards,
Twystd1


(never.. Hee Hee) (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif)