It's all in the timing.

Finally got around to looking at the ignition timing after changing the timing belt a couple weeks back. ('83 245)

12 BTD at idle, as it should be. Then the weirdness begins. Rev it up a little and timing retards to ~5 BTD. Rev a little more, say 3500, and it creeps up to 15-18. Rap it and it appears to go up from there. So, what's up with the retardedness? Can't be good for performance. btw, I have the vacuum line on the knock generator plugged so the motor doesn't ping all the time... and, so it will pass smog.
Reply to
clay
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If I understand what you're saying, that sounds like it's working as expected. Remember that BTDC is *before* top dead center, so a bigger number means more advance and a smaller number is retarded towards TDC. It takes time for the fuel burn to take place, so the spark fires prior to the end of the compression stroke.

Reply to
James Sweet

"Vacuum line on the knock generator plugged so the motor doesn't ping all the time." ?????

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

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void _-void-_ in the obvious place

Reply to
Boris Mohar

I was puzzled about this as well; I thought the knock sensor (generator???) was essentially a microphone bolted into the engine block, sending an alternating electrical waveform of varying amplitude, dependant on whether the engine was 'knocking', so where does a vacuum line enter this equation. The only vacuum line I can think of on an average 240/245 engine of this age (apart from emissions control, or possibly carburettor control) is either going to the distributor (probably not in this case), or to the ignition management computer. This allows the computer or distributor to properly act upon the varying load and throttle positions, by altering the ignition timing; surely blocking this function would severely affect the cars performance?

Best wishes, Ken Phillips

Reply to
Ken Phillips

Right. I understand about ignition advance curves, etc. That's why I said that the timing retarding initially can't be good for performance (or emissions...) Googling around for the correct name for the 'knock generator'... the Chrysler ignition control module, I found an explanation posted in this group back in 2002. Now to find the specifics of the recall to get rid of the retard, and figure out why I'm not getting more advance with higher rpms. Possibly because the motor has the Chrysler module but a Bosch distributer. As I understand it, the distributer cap should be white but it's a Bosch red one...

Reply to
clay

"Knock generator" = Chrysler ignition control module. A lame attempt to squeeze a little more performance out of an anemic four banger. See my reply to James.

Reply to
clay

There was more than one Chrysler ignition system. Early K-jet cars used the one with the white distributor cap, later LH Jet 240s used a different system with a normal Bosch distributor. You should be able to retrofit in a later Bosch EZK ignition system if you want, although I haven't heard of too many problems with the stock ignition. You can install a hotter cam and higher flowing exhaust system to gain some power as well, although the biggest improvement is converting to a manual transmission if the car does not already have one. The old slushbox saps a lot of power.

Reply to
James Sweet

I didn't know they used a Bosch distributer with the Chrysler module. Thanks for that. It's a slushbox. Not looking to hotrod it. It's too tired for that. Just want to get the motor running like it's supposed to. Off to track down that vacuum delay valve.

Reply to
clay

I can send you the service information for the delay valves if you like just let me know where it is 15 pages Glenn K Volvo Certified Technician 2008 ASE Certified Technician 2008

Reply to
GlennK

That would be great. Is it PDF or something could be sent email or paper copy? email is clayt and the domain is @pacbell not .com though, .net If it's paper, would FAX be easy? Snail mail is a pita. Stamps, envelopes, and all...

Not much about it on Google or in my anemic Haynes manual.

Thanks!

Reply to
clay

Got it, thanks!

Reply to
clay

Is your main pulley floating on its rubber the harmonic balancer gives up ant the timing goes accordingly ?.

Reply to
Jon Robertson

No rubber on the front pulley. Straight steel.

Reply to
clay

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