Help! Marelli S112BX + Ignitor I + Perma Tune = Wrong Timing?!

[karlekroth]

So I am trying to find out a few things as I am upgrading my distributor electronics.

1971 911Targa 2.2
I have
Marelli S112BX
Pertronix Ignitor I MR-LS1 (Catalog only shows Marelli S112AX - note the A)
Perma Tune instead of BHKZ Unit

Currently at 900 rpm the car runs well at 35 degree timing! and CRAP at the normal top dead center timing area. New plugs, clean carbs, perfect valve adjustment. The Ignitor kit would only fit 1 way on the spacer - which is not what the instructions say to do even though its the only way it will fit - tried everything. It's very odd, maybe the instructions are incorrect? The catalog only shows S112AX and no S112BX.

I would like to keep the Marelli S112BX, get rid of the Perma Tune, get rid of my stock coil and add Pertronix flame thrower.

Has anyone done anything like this using the Marellia AX or BX?
Do I need anything else?

It should be simple answer for someone who has done this. I'm at a loss. It runs well but there has to be a reason for the mismatch in timing.

[mskala]

What you're saying doesn't make sense unless I assume that maybe you've taken
out the distributor without moving the clamp, then installed permatune, then just
put the distributor back in where it was? Relative position of trigger is very unlikely
to be the same.

[karlekroth]

So I forgot - and this was important - to add that the distributor holes that you mount the ignitor silver plate to do not exist - meaning we had to mount the silver plate to another position. This might explain the timing issue but was hoping someone else knew about this issue. I think it is very specific to the Marelli S112BX. I am going to take a picture later today of the manual vs actual.

[mskala]

I guess I'm not sure why you think any of this is an issue. Put a timing light on
it and turn to where 35 degrees = 6000rpm (at least on the earlier T models,
not sure on yours).

If it can't be turned far enough without hitting something, you may be off by a
tooth.

[69911e]

If it only runs @35dbtdc @idle, you most likely lost the rotor correlation to your Pertronix. You may be firing on the wrong plug at TDC
You also may be having a much larger than normal Pertronix Ignitor variance between cylinders (normally 4-8 deg); this is why I removed it from all my cars and went back to points.

[karlekroth]

I got the dizzy off finally to show everyone the problem with the Pertronix mr-ls1 ignitor against the marelli S112BX.

Look at the jpg. I pretty much figured out that the plate that comes with the kit (as of today's date June 2013) isn't correct for this specific S112BX distributor. The reason is simple - the holes on the distributor that you are supposed to screw the plate into do not actually exist on S112BX - on my picture the threads your diagram wants me to use would be at "a" and "b". There are no threads in "b" , and on "a" there wasn't even an attempt by marelli to make a machinable screw hole, its just a gap with no machinable area. So the only way we could get the plate on was to screw it into the actual threaded holes at "x" and "y".

So when I attach the plate to the only holes available - x and y - the timing is automatically off. We retimed to around 35 degrees for idle but we know this is not going to be a good thing since we can't physically see (using a timing light) if we are in the correct timing range at idle and 6000rpm.

The quick easy solution is to make 2 more holes on the plate for the Ignitor to compensate for this. I sent this information to Pertronix, I'm still waiting on a reply. A machine shop might be able to do this, but then the dizzy would still have to be tested for accuracy - you want the timing between the 2 ticks on the pulley wheel. My hope is that Pertronix will adjust the plate and instructions - which costs them almost nothing to do.



Here's an original dizzy with points:

[steve911T]

Karlekroth,

I read the entire post and from what I remember, the actual placing of the Pertronix is not important in the distributor. The important thing is that the distributor has the correct placement (gears) with the engine. As noted above, one tooth off will make it run weird. The other important thing (sure you did this) is when removing the distributor, make sure it is on TDC, number 1. This makes it much easier to reinstall the distributor correctly. Also, make sure the rotor contact is under #1 plug wire. If you have done all of that and it is all correct, make sure it is on TDC with a timing light, rev it up and turn the distributor until the light hits the 35 degree mark and you should be good to go. If not, and everything is right, call Pertronix and find out what is going on or go back to points. From what I have gathered many have gone to the Pertronix without too much problem. I am sticking to points because it teaches me patience when setting the dwell. Just one more note, after adjusting the timing correctly, at least with points, the final timing point is about 5-7 degrees to the right of TDC, at least in my 2.2 . Good luck. Steve

[rsscotty]

Originally Posted by 69911e

If it only runs @35dbtdc @idle, you most likely lost the rotor correlation to your Pertronix. You may be firing on the wrong plug at TDC
You also may be having a much larger than normal Pertronix Ignitor variance between cylinders (normally 4-8 deg); this is why I removed it from all my cars and went back to points.

This 4-8 ignition timing variance between cylinders is something very few people are aware of. If I had Pertronix on all of my cars, I would take them off also, and look for another alternative. The distributors that work great and have adjustable timing curves are made by JB Racing, twin plug or single plug. Individual cylinder timing is perfect. Just my opinion...

[karlekroth]

Well, I've been back and forth with Pertronix. They let me send in the dizzy and they say everything is working within spec. So I'm going to have to recheck everything from step 1. Regardless, I'm VERY VERY impressed with the customer service I've received from Pertronix. Carl at pertronix was my tech, very helpful. Will update after my dizzy comes back and I figure out what I'm doing wrong.

[karlekroth]

So took OUT permatune (the box and wiring harness), points are obviously gone. I now have just Pertronix Ignitor $90 and I put in a Pertronix Flamethrower $50. The car now runs great at idle after it warms up, and the timing marks line up - I DO need to check those marks today to make sure it was the correct mark.

I took out spark plug #1 and put a little extendable tool in there and had a friend crank the car a few times to make sure the dizzy was placed at the correct position. NOTE - IF you do this, make sure the ignitor and coil are not hooked up, you will damage them by simply having the key in the ON position and not running, according to instructions that is. They even say to disconnect the - from the battery if you need to charge your battery, as this will damage your ignitor/coil. I thought these pieces would be more vigilant. I did BOTH of these not to's and everything is still ok, but next time I will follow directions. I read them after the fact. I also read if you disconnect the battery from the car while the car is running, you 'll wreck your alternator.

So there is an extra green/yellow wire, it is a - wire, I think it was part of the permatune system or old system. I thought it was the + and when I hooked it to the + coil nothing worked obviously. The power is on the left side of the engine bay where the permatune box was. Thin little wires and crappy little fuses seem to run this car.

The purple/black wire I believe is the tach. I'm going to hook it up today, it may not work according to reports. Something to do with low/high volts. Might need a converter along the line else I'll just get a $3 digital display for now.

I ended up buying a nice snapon timing light on craigslist, used but works great. It is inductive with advance and tach reader. I had to use a separate 12v car battery to run it, since the power wires didn't reach all the way to the front of the porsche. The advance feature is nice for checking 33-35 degrees at 6000rpm. Youtube has good videos on that feature.

More later after I see which timing marks I'm really lined up to. I might have to make a video.

[karlekroth]

The pertronix and coil were/are working fine. I also found out I was 1 cog off on the dizzy. Great. Fixed.

Update. I had a vacuum leak under the manifold so we just tightened the bolts a little and it was solved. I should replace those gaskets eventually. The leak was causing improper idle and a whistle sound.

I also found out the stupid marelli dizzy isn't advancing very far, so the car won't rev up properly. I just sent that off to ************ to be rebuilt as I couldn't find a 008 bosch distributor. bosch 006 won't work for my car, sucks. I could rebuild the dizzy myself, but I don't have the $ dizzy curve machine that shows u the curve as it spins faster. This might actually be a factor in most pertronix make overs - maybe you need to have the dizzy recurved once you put on the pertronix ignitor.

Will update after the dizzy comes back.

[cvillegas71]

I need to revive this tread because I am having some issues with my 1971 911 T. I recently replaced the points and I also have a Marelli and have had nothing but trouble since.

1. I removed the dizzy by removing the bolt holing it down but did not loosen the timing nut so to maintain the timing
2. Once I replace the dizzy I set the point to .015.
3. The car started right up and I set the timing to 5degrees at idle and set it to 35 degrees at 6,000.00

This seems correct but the car was having performance issues as follows:

Boggs down when pressed to perform
Some times the idle is good at around 900 rpm’s but once I drive it a while it can go up to 2,000 by its self (?)
Some times the idle goes down so low that it cuts off


I thought I jumped a tooth so I put the engine at TDC using the marking on the pully which are 2 lines close to each other, the one in the front is TDC according to a repair book and I saw that the rotor was pointing toward the back lip (close to the front of the car) and not to the back lip (closer to the rear of the car) of the fan housing. Looking at the manual I saw that it said the rotor needed to point to the back of the fan housing lip.

So I thought I jumped a tooth. I removed the dizzy and reset it so it pointed to the back lip of the fan shroud. Started it and test drove it and I suddenly had valves knocking. Ran it home quickly to avoid problems but now need you help.

Questions:

1. Can some one help me as to the marking on the pulley, I seem to have multiple markings on set of 2 hashes toward the inner side of the pulley closest to the engine, and 2 hashes toward the front of the pulley further from the engine, as well as 1 hash on the inner side
2. Once I have that resolved I want to know if my rotor should point toward the back lip or front lip of the shroud or if that is a correct way to deal with the issue. Pictures would be greatly appreciated
3. What is the appropriate dwell setting, or is that different for all vehicles. I have a 911 T with the original engine in it, I did have it rebuilt by Harding automotive in South Gate California but I don’t have the specs anymore, it was done more that 10 years ago, (does any updates to cams and piston matter to the point and timing settings?)


I might have other question once I resolve these issues but any help is greatly appreciated and thank for the the help I have received in the past. I hope to one day be of service to someone else and "pay it forward".

[karlekroth]

So to get TDC, you need to look at the position of the spark plug wire #1 on the distributor. #1 cylinder is the very back left of the car. Follow that spark plug wire to the distributor. #1 should be one of two nearest to the fan. Mark that #1 plug position with a sticky note or whatever so you can guess the direction. Then pop off the dizzy (distributor) cap and move it out of the way. You'll now see the innards of the dizzy. You'll see a rotor cup. I mocked up an estimate of how it should look in position to #1.

Now go to the fan and turn the fan bolt with a wrench until it moves the crank pulley around with it. You might have to push on the belt to get it to move. Make sure the car is NOT in gear! Keep turning until the rotor of the dizzy lines up around the #1 plug position that you marked. It won't be perfect, it ll be pointing almost directly at the fan housing, but a tad to the back of the car from that direct point, like a 330 or 4 oclock position. The previous and next cog positions are like 1 and 6 oclock. 12 oclock being the front of the car, 6 the back. Once you are there, you should look back at the cam and you will see the 2 close notch marks on the crank pulley. The left one is 5 deg after, the right one 0 degrees. If you look further to the right eventually you'll see the 30-35 marks.

To verify, you can also pull the #1 plug from the motor, and put a pencil down the hole to see if the piston is all the way up. You can rotate the engine and it should go down and back up again.

I ll try to take a picture later this week of the dizzy in the car at TDC.

You won't jump a tooth, rather you'd have put the dizzy in wrong at some point which makes it run badly. If the car ran badly without you touching the dizzy, then its prob the carbs. The crank pulley notches should be correct.

I noticed you said you put the idle at 5 degrees? You mean 5 before (left notch), or did you do the right notch (0 deg). I think you really mean 0, which should be ok anyway as long as the car runs well.

Regarding points. I recently moved away from points to pertronix ignitor and coil. I sealed off all my vacuum lines, etc. However, I'm having trouble with the car overall, it starts up then dies once warm. I'm working on it again this week to figure out what the problem is. I checked the fuel pump, coil ohms, spark plug wire ohms, plugs themselves replaced and gapped, and the dizzy was rebuilt fully by ************ for $500 - well worth it. I think my carbs are just out of tune, via idle and main jet screws. Hopefully nothing more.

You have to systematically check all these pieces, takes a while, but you check it off the list. I even changed out the gas entirely by running the gas into a gas container - while doing so I was able to run the pump to make sure it worked at around 4 psi. If you have fuel injection, it'll shoot out at like 60 psi - very dangerous and not recommended.

What I have left is to check float levels, carb settings when warm, synch between intakes. I might have to reclean out the jets with an airtool. Hate doing it but might not have a choice to get it back to point 0. Once i get the car running well I'll post my findings.

You just rebuilt your car so the compression should be ok. If you're worried about that, check it. Valves also should be fine since its rebuilt - its a pain to check and change them. Air filter, cake.

Be careful when you check things. If you turn the key and leave it on for 30 seconds or more without cranking it, you can burn out your coil (unless unhooked) and fuel pump (if under pressure).

Hope this help a little.

[karlekroth]

I just thought of something else. If your car is surging without you pumping the gas, you probably have a vacuum leak. It could be coming from anywhere - usually the hoses, but I had one where the lower intake piece (under the carbs) meets the engine - I just tightened the bolts down a little and it disappeared. Usually you hear a whistle sound. Check your hoses around the carbs.

[karlekroth]

Update.
My accelerator pumps are not adjusted correctly. The car is flooding once the car warms up - its like having a choke on full time. Note, these carbs have no choke and the lever inside the car does nothing. There are adjustments on the carbs for this, but in order to adjust it properly the mechanic needs a specific fuel measuring tool that attaches to the accelerator nozzles. You open/close the throttles and eventually they fill with gas, that gives you the volume. The spray direction you simply bend the nozzles - supposedly - BUT DON'T DO THIS as they may break.
1 step at a time.

[karlekroth]

I just noticed a mistake. I said "The left one is 5 deg before, the right one 0 degrees. If you look further to the right eventually you'll see the 30-35 marks. "

It should be be 5 deg AFTER, 0 TDC, then 30 BEFORE and 35 BEFORE.

[karlekroth]

Took 2 hours to adjust and sync the accelerators. Used the online specs here.
Zenith 40 TIN Carburettor Manual

I took the carbs off, put them on a bench, unscrewed the float section from the bowl section, and use a gas can to pour fuel into the bowls to fill them up. Then i used 3 small medicine measuring cups that the bottom carb can sit on and measured 10 squirts of the pumps via accelerator. It took a while to get a process. I also was able to see which nozzles were not working. Cleaned and blew them out multiple times until they squirted nicely. Then measured the outputs - 10 squirts should be about 5ccs total.

One of the nozzles kept clogging up, its possible it'll have to be replaced. I soaked it with carb cleaner for 20 minutes then blew it out with air compressor - which was tricky as you have to blow from the small end and push the glass bead with something small so that the air comes out. Then reverse that direction. Back and forth, 1 hr just for that.

As this is the 2nd take apart of these carbs - the first cleaning obviously a slight failure - In retrospect I should have just bought all new accelerator nozzles to save 4 hours of labor. I can't find floats anywhere online. If anyone knows about where to get them please post it.

Will take pictures soon. Sorry I didn't post here.

[karlekroth]

Changed the spark plug wires even though the old ones showed perfect 4 ohm resistance. Sync'd up the accelerators to 5cc at 10 full throttles and made sure they gave nice healthy squirts. Put everything back together. Car runs great! FINALLY!!!!!

Note to self : CHANGE/CLEAN EVERYTHING EVEN IF IT SEEMS LIKE IT DOESN'T NEED IT. CHECK EVERYTHING 3 TIMES, NOT JUST ONCE.

2 years sitting in the driveway, finally able to drive it without sweating a breakdown.

[dicklague]

So good to hear that you finally have it back on the road. What a journey you have been through!

I think we learned a lot from your posts. Very interesting.

Now get out and drive that 911!!

[karlekroth]

UPDATE: For Zenith Carbs the fuel PSI was way too high at 10psi. It is supposed to be around 3.5psi. I was drowning the car. I changed the pump and the car works so much better. Other people put a regulator on a higher psi pump to control it.