I have a 1982 245, b21f with K-jet and Chrysler ignition system.

About a year ago, I was fiddling with tuning to improve performance. At some point the car went from good performance to major lack of power and knocking at large throttle openings and higher RPMs. I have done my best to return to stock settings paying attention to: idle richness, 12 deg btdc at idle with vac advance disconnected and plugged, idle rpm setting, valve adjustment, compression test, new cap rotor wires, and a lot of general checking around.

The engine exhibits its usual torquieness at low speed, low to mid RPM.

Today I thought I would check the timing at higher rpms. With vac advance disconnected and plugged the advance range from idle to max advance is 12 to about 32 deg. With the vac advance connected and no load (racing the engine) the advance ranges from 12 ish to 50 +-2 deg.

Anyone have experience or information regarding acceptable range of advance?

Best Regards,

Mark.
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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

If you reduce the timing setting below spec, say 10 or 8, does it stop knocking? Or may try running without any advance. I thinking it might be good to verify the problem really is too much advance.

81242DLB21FCA,

Thanks for the idea of retarding the timing adjustment. That does reduce the knocking. But power is still lame. I'm going to try something based on Bruce's post and disconnect and plug the vacuum advance hose and set the timing to 12 btdc.

Best Regards,

Mark.
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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

"Today I thought I would check the timing at higher rpms. With vac advance disconnected and plugged the advance range from idle to max advance is 12 to about 32 deg. With the vac advance connected and no load (racing the engine) the advance ranges from 12 ish to 50 +-2 deg."

Hi Mark,

I think what you're seeing is normal with the vacuum line plugged. The following is from something I found on the net relative to high NOx readings. I've often posted it (with more detail) here on the BB, with several successful results as far as lowering NOx. As I read it, it seems that all the timing control is in the V-C box (with none in the distributor itself).

============================>

Any 240 that has the Chrysler ignition box will pass NOx with flying colors,
provided the cat is at all sound and the ignition secondary is in reasonable
condition, when the vacuum hose to the control unit transducer is plugged.

On the dyno and on the street, unless you're really flogging it, you can tell no difference in performance. What happens is that the "limp home mode" for the Chrysler box closely matches a conventional distributor curve; i.e. advance [timing] retards 5 degrees when the throttle is opened and climbs with engine rpm to approximately 33 degrees instead of swinging immediately to 52 degrees and backing down to below ping levels.

It's this high sustained advance on the verge of ping that drives NOx high. There was a recall on the 83-84 models to install a vacuum delay valve in the distributor hose (to cancel the retard off idle) and a delay valve in the transducer line from before the throttle (instead of manifold vacuum) to delay the advance curve to quell high NOx readings and satisfy the EPA. I rarely see one of those cars that still has that particular modification intact. There were serious performance issues even on cars in a good state of tune.

By disabling the transducer you gain all the dwell extension features of the lean burn system without sacrificing the marginal at best mpg gains that were so highly touted at the system's inception.
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Bruce,

Thank you. That is very helpful. I don't think there is a knock sensor, but maybe I'm wrong. If the knock sensor went bad that explains the heavy detonation and bad performance. Time to look some more at the manuals.

Mark.
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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

"I don't think there is a knock sensor, but maybe I'm wrong. If the knock sensor went bad that explains the heavy detonation and bad performance. Time to look some more at the manuals."

No, I think the knock sensor didn't come until '83. And maybe that article I quoted was written with the later V-C ignition in mind. I guess all you can do is plug the vacuum to prevent the "jump" to 52° and see how it feels.
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I disconnected the vacuum hose and plugged it. I also changed the idle timing to 12 btdc. No knocking, power still limited, about the same as before. I put regular gas in. Around town no knocking. I'll try it on the freeway this afternoon. I'll probably leave it this way for now. I have bigger better plans in the wings time to stop agonizing over the old engine.

Best Regards,

Mark.
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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

Howdy,

I think you might have the wrong distributor. Check the Bosch PN. It should be 0 237 003 024.

Total advance for that distributor should not exceed roughly 42º.

This information came from the Ignition Systems Green Book available at www.k-jet.org.

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Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)

Shannon,

Thanks for the link to the manuals.

I am digesting this information now. I found my distributor and ignition control unit in the ignition manual. I am learning how to read the advance graph. Looks like I have the B21F-CI 1982. Is the "variation of ignition setting with vacuum advance" in addition to "variation in advance setting with engine rpm"? If so then 47 degrees of maximum advance is within expected amounts. If not then I'm getting way too much advance.

I'm running the car on premium and that is reducing knock but to eliminating it.

Best Regards,

Mark.
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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

Shannon,

I looked on the distributor and at the base under "Volvo" the number is 306059. Is this the parts number? I have had the distributor out of the car a couple of years ago and I believe there are no mechanical advance weights and springs in the distributor, unless they are way smaller than what I have seen in other distributors.

Best Regards,

Mark.
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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

306059?

I looked at every distributor listed. I did not see that number at all. But, I told you the wrong distributor to begin with. I looked up the B21FT, not the B21F. Belay my last.

You do have a B21F, right? The best thing you can do right now is read that book thoroughly, determine if you are seeing the correct maximum advance and then get back to it.

I was thinking about your outline of all the things you've done. I did not see where you verified system pressure and control pressure. Have you checked them?

--sd

Shannon,

I found the ignition controller for my car on the bottom of page 22. Volvo part number 1317873.

I am sure the distributer just goes around and doesn't have any advance or retard capability.

By "verified system pressure and control pressure" are you talking about the fuel system? I have an fuel air mixture gauge hooked up to a narrow band ox sensor before and after. The gauge indicates lean with small throttle openenings, O2 feedback operation at highway throttle openings and rich under full throttle.

Best Regards,

Mark.

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Mark Mueller, '82 Volvo 245 - Very Green, B21F, Strut brace, electric radiator fan, A cam, Urethane Bushings, Bilstein Sport Shocks, IPD lower springs, Perf Exhaust, 740 10 sp wheels, 2-7/8' stainless exhaust tip adds 20 hp.

Howdy,

I read Lucid's post and I think he is on the problem. I know he knows more than I do. I will just sit back and read the progress you make under his direction.

*edit*

I just read your response to Lucid's post. I dont think he was talking about the knock sensor. What he was getting at, I think, is to check for the delay valve and transducer and to plumb the system without them if present. He will correct me if I have that wrong.

By disabling the transducer you gain all the dwell extension features of the lean burn system without sacrificing the marginal at best mpg gains that were so highly touted at the system's inception.

Now, I will just sit back and read the progress you make under his direction.
*/edit/

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Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)