Hi All,

Got round to installing the pertronix, it was easy peasy and the car started first time. The problem is that I cant advance the timing to where it needs to be as I've hit the limit on the adjuster. It was already close to it before I started !
Is there a way round this, do I have to take the distributor off and install it in a different position ?

Thanks for any help,
Gary

Could be indicating a stretched timing chain. To best of my recollection the distributor is driven off the oil pump that itself is timing chain driven, but i might be wrong.

i think on a benz it is a gear that drives the dist. so you can lift it out and move one tooth. be sure it is in the right direction. if that doesnt work you may need to move all the wires one hole and take the adjuster back to the other side of the slot.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Hi,

Thanks for the suggestions. The possibility of the timing chain being stretched scares me and makes sense, so I'll take the cam cover off and check before I try compensating for it.
I thought about moving the plug leads round but that would put the ignition out of synch with the electronic fuel injection which is triggered in the distributor as well. If the chain isnt stretched too far then I'll try moving it on a tooth.

Cheers,
Gary

oh yeah, forgot about that possibility.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

You do have the vacuum line disconnected and plugged, correct? There is no vacuum advance on the distributors. That is a vacuum retard diaphragm. It will draw the timing down about 14 degrees (initial static timing set should be 10 degrees B.T.C. with no vacuum) at idle vacuum.

I had to see your profile to see you're talking about a '73 450SLC.

I'm going to assume timing on this is specified on a plate on the radiator support and says 5° ATDC just like US-spec 4.5's - WITH vacuum connected to the distributor. Make sure the vacuum is plugged in when doing this - it will retard the ignition (not advance it) and you might be off by even more than indicated. What DOES your plate say if not 5° ATDC, just so we know?

The synchronization of the injection with the firing of the engine isnt THAT important - remember, the injector for cyl #1 fires while the valve is already open, at the same time it fires for #5 - which is still closed. It MIGHT make a change at idle but that's probably it. However, timing might possibly be TOO advanced if you try that with the wires. It's quite easy to reset the distributor rotor - mark (or remember) where it is when the rotor is fully counterclockwise (turn it to stop so the mechanical advance is not in effect). Remove the set screw for the dizzy and the EFI trigger point plug. Pull the dizzy out - the rotor will rotate as you pull it. Rotate the rotor slightly clockwise, reset the distributor, and that should do it.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

did you remove the dizzy for some reason while installing the petronix? if not then the vac line (needs to be plugged at idle) or stretched chain are your probabilities. if the chain is that stretched you'd most likely hear it grind, rub or whatever.

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72 W114/M130

RedMeat cartoon

I didnt remove the dist. just fitted the petronix in place, the trigger position based on the magnets is naturally slightly different from the mechanical breaker.
In terms of the timing setting I was flying blind as it is printed on a paper label on the cam cover and has burnt and fallen away after 33 years and I couldnt find anything online for Euro spec cars. I checked the timing before I started for this reason and with the engine warmed up and vacum lines in place it was 7 degress BTDC, after updating the ignition I could only get it to about 4 degrees BTDC when I hit the end stop.
I always run with lead substitute/octane boost additive and there's been no pinking.
There are no serious noises from the engine indicating imminent self-destruction and it may be that the dist. was removed in the past and just not put back in an ideal position.
Probably cant get my hands greasy again until next weekend so it will be bugging me all week that the chains are about to let go !!

Thanks again for the help

Have you tested the vacuum retard to see if it is actually working?

Also, I'm not sure if the euro spec is the same, as I recall the vacuum was retarded to help meet US emissions specs, perhaps on the euro model the timing spec is different or the retard is not 14 degrees...

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

i doubt that the euro has vac retard.

i expect total advance, including initial, mechanical and vac will be in the neighborhood of 36 degrees.

on one that old i would take it all apart and check to see that the advance weights are working correctly with no worn springs and other hangups. of course the vac advance too.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

if you will post year and model i will check to see what i might have in my old repair manuals.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I went with Tomguy's suggestion and lifted the dist. off and rotated the rotor arm clockwise, this put me back in the middle of the adjustment range with the advance I was looking for.
Its a 117 engine and from what I can figure out there are two vacum lines from the throttle body to the distributor and the ignition can be advanced or retarding through alternate vacums through these lines. I guess the vacums come from either side of the butterfly valve ?
It was interesting that in my first attempt I over advanced to about 80 degrees and the engine still started, it idled fast though !

At idle the retard side (closest to the dist body) should have vacuum. Follow the hose back and you should find a solenoid valve with a yellow top. That's the switch over valve. From there it should go to a port below the throttle. The advance side can go to many different places depending on the year. On my '76 450SEL, it has a four way tee that branches off to the EGR, branches to a 40C thermoswitch and then an above throttle port, branches to the red port of a vacuum control switch.

Michael

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Usta haves '69 250/8, '76 280C, 1971 250C 114.023, 1976 450SEL 116.033
Current have, 1983 300SD 126.120

Thanks Michael,

I had vacuum on the line closest to the distributor at idle but it made no difference to the timing when I unplugged it. I would have expected the timing to retard when it was removed. I need get to the bottom of this. The mechanical advance/retard seems to be ok based on what I've read in
related threads. If nothing else it would be nice to think that I've been
driving with an engine that could be improved further all this time

Cheers,
Gary