Engine set up for 68' 912 w/ weber 40's & 022 dizzy

[911 tweaks]

Hi Guys...just checking in on the best set up for this car ~ engine...I mostly work on 911's, but, of late more & more 912 work...its all good...

Anyway, I have the following q's and any and all info is welcome:

What I am working with is a 68' 912 engine # 750169; weber 40 carbs; bosch 022 dizzy which I am told is for up to 67' engines but will be fine to use...

1. Static timing: set to 0* or 3* btdc or 5* btdc...?? My understanding of static timing is that it is set without the engine running & easiest to position the notch on the front of the crankshaft pulley relative to the case line on the block by turning the crank w/ a lg wrench clockwise until on compression stroke the 2 marks line up OR I position the pulley mark an 1/8" before TDC to achieve ~ 3*btdc...

2. Firing order is 1-4-3-2 from the manuals I have read...

3. just before I install the dizzy, I want what static timing (0*tdc OR -3 OR -5 for #1 cyl) on the compression strike...

4. the actual dizzy setting (dizzy not in engine) is to rotate the rotar shaft until the sm end of the rotor points to the cut in the dizzy housing top sealing surface that mates to the dizzy cap, right...??

5. positioning of dizzy into engine...How do I align the dizzy to the engine...?? My guess is that the dizzy cap, when mounted on the dizzy which rotates clockwise, needs to have the sm end of the rotor be directly under or a tad before the #1 position on the dizzy cap...right ??

If #5 is correct, going in a clockwise direction the next position on the dizzy cap is for cly #4...the next position on the dizzy cap, the 3rd position going clockwise, is for cyl #3...the last remaining position on the dizzy cap is for cyl #2...right...??

6. How am I doing so far...??

7. If this is correct OR I follow the wiser instructions of those that reply here, I then move on to set the advance timing, right...?? If so, what rpm & what #* advance setting by twisting the dizzy...??

8. after the timing is set, onto the carbs...I will save my q's for that after we get the timing complete...

Thx for reading & hopefully you can share your experiences with a very similar engine
Bob

[Neil '67 911S]

1. Static timing: set to 0* or 3* btdc or 5* btdc...?? My understanding of static timing is that it is set without the engine running & easiest to position the notch on the front of the crankshaft pulley relative to the case line on the block by turning the crank w/ a lg wrench clockwise until on compression stroke the 2 marks line up OR I position the pulley mark an 1/8" before TDC to achieve ~ 3*btdc...

&&& Use a 36 mm or 1 7/16" wrench on the generator pulley to crank the engine pulley to TDC. Align the brass tip of the rotor sign to pointing toward the notch in the top side of the distributor. Doesn't need to be exact. Turn on ignition, rotate the body of the distributor slightly until you see/hear the points fire.

2. Firing order is 1-4-3-2 from the manuals I have read...

*** 10-4

3. just before I install the dizzy, I want what static timing (0*tdc OR -3 OR -5 for #1 cyl) on the compression strike...

*** Don't worry about this. Once the engine warms up, time the engine to 32 btdc at 3000+ rpm. What matters is full advance.

4. the actual dizzy setting (dizzy not in engine) is to rotate the rotar shaft until the sm end of the rotor points to the cut in the dizzy housing top sealing surface that mates to the dizzy cap, right...??

*** See above.

5. positioning of dizzy into engine...How do I align the dizzy to the engine...?? My guess is that the dizzy cap, when mounted on the dizzy which rotates clockwise, needs to have the sm end of the rotor be directly under or a tad before the #1 position on the dizzy cap...right ??

*** Unlike the 911, the 356/912 distributor drive gear is already in the engine. The gear's notch is off-set, so the distributor drops onto the top of the drive gear only one way.

*** With the crank pulley at TDC, the brass "pointer" needs to be pointing toward the notch in the top edge of the distributor.

If #5 is correct, going in a clockwise direction the next position on the dizzy cap is for cly #4...the next position on the dizzy cap, the 3rd position going clockwise, is for cyl #3...the last remaining position on the dizzy cap is for cyl #2...right...??

*** 10-4

6. How am I doing so far...??

*** Depends on if you're following directions!

7. If this is correct OR I follow the wiser instructions of those that reply here, I then move on to set the advance timing, right...?? If so, what rpm & what #* advance setting by twisting the dizzy...??

*** See above. Once timed as described, snug don't tighten the distributor clamp. Play it safe and shut the ignition off as the clamp is mighty close to the crank pulley.

8. after the timing is set, onto the carbs...I will save my q's for that after we get the timing complete...

*** Adjust the valves first.

[JT912]

Also it may be helpful to make sure the TDC mark on the crankshaft pulley is aligned when #1 is at TDC.

[911 tweaks]

Thx John & Neil...

John: Thx again...as far as aligning the dizzy corectly w/ the crank, you are correct that there is 1 big slot for the dizzy to mate w/ on the engine as the drive stays in the engine...I guess if I get no spark then I am 180* off + on exhaist stroke & NOT on compression stroke & need to re index the dizzy to the engine, right...??

Then valve adjustment. Then do initial set up on carbs. Then re check timing. Then re check carbs & all set, right...??

If you could also help me, what is the best procedure to set up carbs...?? It has webers. I have a synchronizer to see input air volume reading...need anything else...?? What are the best jet sizes ect for these carbs mostly running btwn sea level & 2k' here in New England...??

Thx again... Bob

[Neil '67 911S]

John: Thx again...as far as aligning the dizzy corectly w/ the crank, you are correct that there is 1 big slot for the dizzy to mate w/ on the engine as the drive stays in the engine...I guess if I get no spark then I am 180* off + on exhaist stroke & NOT on compression stroke & need to re index the dizzy to the engine, right...??

*** If the distributor is out 180 degrees, you'll still get a spark but the condenser is probably striking the oil line between the block and the oil filter housing. As you look down on the engine from the rear, the notch for #1 on the top edge of the distributor should be at about 4 o'clock. With the points closed and the ignition on, when you open the points with a screw driver, do you get a spark/hear a *snap*?

Then valve adjustment. Then do initial set up on carbs. Then re check timing. Then re check carbs & all set, right...??

*** Mess with the carbs after you've inspected/changed the points and condenser too.

If you could also help me, what is the best procedure to set up carbs...?? It has webers. I have a synchronizer to see input air volume reading...need anything else...?? What are the best jet sizes ect for these carbs mostly running btwn sea level & 2k' here in New England...??

John Willhoit is a highly regarded 356 expect. Here's what he he posted on the 356 registry a while back:

Subject: Re: To all you weber experts
From: John Willhoit
Date: Sun, 20 Jul 2003 16:09:55 -0700 (PDT)

First step in adjusting would be to screw the idle
bypass valves closed (the little screw with a nut on
it next to the idle mixture screw). Next make sure the
throttle linkage is balanced (back off the idle stops
until the butterflys just close and check that the
adjustment from side to side on the throttle rods is
even). Open the idle stops about 1/2 turn, the idle
mixture screws 1.5 turns and start the car. Adjust the
idle equally on both sides to get it at about 1K rpm.
Screw the idle mixture screws in individually until
the idle starts to slow down then back them out about
1/2 turn.

That should adjust the carbs correctly. Before doing
the adjustment, I would recommend changing to the
following setup with Weber 40s: 28mm venturis, 115-120
mains, 175 ac, F7 e-tubes, 50 idle. If you have an
050, set the max timing to 36 degrees (about 10
degrees at idle). We have spent a lot of dyno time
with Webers and this will produce the best running
engine, especially with a stock exhaust With the
smaller venturis you will give away about 2 hp above
5200 but will gain torque and drivability up to that
point. If you still have a hesitation it could be a
characteristic of the cam. Norris cams use older
profiles which have a slower ramp and a lot of seat to
seat duration. You can help this by opening your
valve adjustment to .008/.0010".

Try it. If you're not happy I'll eat a bug.

John Willhot

[RichardM912]

I have no professional expertise and you have been given a lot of good info which I agree with. However, based on my experience, these engines are quite sensitive to static or idle timing.

I agree that for best power you want the timing to be at 30 - 33 degrees BTDC at full advance (about 3,000 rpm). However, my approach is to set the static timing at 3 degrees BTDC, then check the timing at 3,000 rpm. If you set only at full advance then there is a danger, if your distributor's centrifugal advance is not functioning fully or correctly, that you will be well off the correct setting at starting and idle. This can lead to difficult starting, popping back through the carbies with the danger of a fire and a strange hunting phenomenon at cold idle where, if you just touch the throttle, the engine revs up of its own accord.

None of this is instead of the advice you have been given - it is as well as it.

[911 tweaks]

Thx Neil & all...I will install the rebuilt dizzy over the weekend, so i guess I don't need to worry about making static timing 3* btdc...I will set it to 0* tdc...

A couple of other q's:
The dizzy had elect ign before the rebuild...my questions are how to connect the 3 elect wires...??
1. the Green wire that comes from the condensor on the side of the dizzy...where does this connect to...??
2. their are 2 wires that are curley q'd at their ends that come fron the voltage regulator area...1 is Black & 1 is Red...where do these connect to...??
3. Based on this description, am I missing any wires...??

Thx again guys...I will post up some pics latter today or over the weekend when I get back to this project...& learn how to connect the wires from you all... :-)

Bob

[Jaems]

Do not worry about the centrifugal advance until after you have set the valves. You will have to do ti again. Also the carburetor adjustment after the valves have been adjusted.

You will also need to get a wiring diagram. If you are going to work on your car yourself.

With TDC set to the notch in the generator stand and the notch in the rotor matched up to the notch on the distributor. Then you will be either right on the #1 cylinder or a 180 degrees off at #3 cylinder. There are two ways to tell. One if the car will not start or backfires then you are 180 degrees off. or two which most mechanics use is to look at the intake valve for #1. If you 180 degrees out. There are two ways to fix that. one Just change the wires to make #1 to where #3 would have been. or Two remove the distributor and turn the pulley 360 degrees and put the distributor back in. Then set the dwell to 50 + or - 3 degrees then set the static timing, adjust the valves, then the carburetors, and then set the Centrifugal timing.









The red wire goes to the D+ on the generator, the Black wire to the DF, and the Brown to the D-. All brown wires on German cars should be grounds. However, these cars are over 40 years old. Most have gone through many owners.

Also the green wire from the condenser goes to the nut on the outside of the distributor as in the diagram. However there is a black wire from the same nut that goes to the coil on the number one side. There should be a black and purple wire from there to you tach.

Like I said before you need to get a wiring diagram before you burn something out.

[911 tweaks]

thx Jaems...

Do you or does anyone following this post have a wiring diagram they can post...??

I have lots of elect diagrams for most if not all 911's, but not for 912's... I guess hard to have EVERYTHING when you need it most...

Thx, Bob

[WFBowen]

http://www.texas912.org/912%20Tech%20Data/912%20Wiring%20Diagram.gif

[911 tweaks]

thx WFBowen...do you know what yr(s) this diagram is for...?? I guess 65-69'...??

Thx a lot...!!
Bob

[Jaems]

Someone gave you the wrong Valve adjustments.

[BryanM]

diagram for 65-68
Wiring Diagram for Early 912
69 uses a '69 911 diagram (and the 65-68 diagram for engine related stuff)

[BAO B]

Hi,

by any chance, do you know the gauge (size of wire) for the black/ red and brown wire from the generator??

Thanks
bao