1972 W108 M130 /transistor ignition anyone with same car

[jim 56]

Can anybody tell me what the dwell and approx point gap should be.Where is it timed at.It seems like a lot of things are different about this car I guess because of different emission than even a 1971. Where does the dwell meter hook up to I have found on the site something by Ja 17 with a couple of different places to try but they seem not to give the right reading. The plate on the engine says to time it at 6 ATC I am still getting a backfire when I have the points gapped at 14 and timed at 6. I have added oval shims still back fires. Also I am worried about the engine having only 13 inches of vac at idle I think it should be more. WRD does shut off after a few minutes.So I don't think it's getting stuck.

[jim 56]

Anybody? can maybe some one tell me if at least if that timing is right.

[Benz Dr.]

Aluminum distributors are generally set to 30 degrees dwell unless otherwise specified. You could be getting a lean backfire. Check your sparkplugs to see if you are running lean.

[bracurrie]

From the BBB. See attached.
Brad

[jim 56]

thanks for your answer. I will pull the plugs tomorrow and see. When I do the split linkage if I increase the air slightly idle increases about 50 rpm then dies.If I increase the FIP it does the same thing so I think this is right. It only backfires when I accelerate to about 20 mph and it doesn't do it all the time seems to happen onlky in the first 15 minutes of driving.The WRD seems to be working fine as the idle drops and air shuts off unless maybe water is getting past.I read maybe I should put sealant under the WRD thermostsat

[jim 56]

Bracurrie thanks for your reply but I can't read the page you sent it's there but too light to read

[Benz Dr.]

thanks for your answer. I will pull the plugs tomorrow and see. When I do the split linkage if I increase the air slightly idle increases about 50 rpm then dies.If I increase the FIP it does the same thing so I think this is right. It only backfires when I accelerate to about 20 mph and it doesn't do it all the time seems to happen onlky in the first 15 minutes of driving.The WRD seems to be working fine as the idle drops and air shuts off unless maybe water is getting past.I read maybe I should put sealant under the WRD thermostsat

If that's the case, it sounds like your warm up mixture is too lean but your running mixture is OK.

[bracurrie]

Bracurrie thanks for your reply but I can't read the page you sent it's there but too light to read

What pdf reader are you using?

[jim 56]

Sorry I don't know how to tell what PDF reader I have it's an HP laptop.How do  i make the warm up richer. I tried adding oval shims but it still did it. I also added shims under the can thinking that it would make it richer for all ranges but it still pops on acceration around 20 mph.

[ja17]

What is the history of the problem?

[bracurrie]

Sorry I don't know how to tell what PDF reader I have it's an HP laptop.How do  i make the warm up richer. I tried adding oval shims but it still did it. I also added shims under the can thinking that it would make it richer for all ranges but it still pops on acceration around 20 mph.

My wife has an HP laptop with a terrible screen, so that could be the problem. Have you confirmed that the required amount of fuel flow and pressure is getting to the MFP. My car has a similar problem and that's what I am going to confirm next.
Brad

[jim 56]

Sorry couldn't answer spent the last couple days changing my alternator. Joe the history of the problem is that I had a crane system in that went bad so I went back to points I'm old fashion I like points anyway. Seems problem came in last couple months. Maybe it is better if I say what I've done.

I'll go over what my problem is then what I've tried even though its long
I start car starts nice; idles high about 1000 RPM after a few minutes idle drops to about 800 RPM air at WRD turns off.Start driving away car will accelerate then will back fire once then drive normal I would say backfire occurs around 1100 RPM will drive another 20 seconds then backfire again It will continue to drive this way for about ten minutes then will stop for the most part.
1---Fuel pump 14 psi return to tank 1 liter in 15 seconds
2---split linkage increase air increase 50 rpm then wants to stall---add fuel same increase 50 rpm then wants to stall
3---WRD air intake from filter after a few minutes drops idle alot but slight air still suck in I read here that if I block this off and isle
      doesn't change it is ok.
4--- had points at a gap of 19 I cannot find the dwell I have two different meters and I have hooked them the two different  ways Joe
       posted in an early forum answer. Any way car still had problem now am gapped at 14 same problem.
5---sticker in engine compartment says it should be timed at 6 ATC (By the way sticker which tells timing does not say what dwell
      should be)I set at 6 ATC at both point gap settings same problem. Tried 0 degree ATC same problem one thing I should point out is
      my distributor number ends at 068 books bbb haynes and the forum tech specs do not mention 068 anywhere all end at 067
6 ---When I turn big air screw in starts to decrease idle backing it out increases idle.
7---Someone in forum said to add oval shim under WRD which I did same problem.
8---Will try to post pictures of plugs this weekend.

I've have said this before and haven't got any opinion my vaccum at the intake manifold is only 12 or so inches. Does anybody know is this too low I don't see or hear any leaks if I retard time it will increase.

This is causing me to pull my hair out and make me lean toward getting rid of the car even though it looks soooo good
Anyway said it would be long like a novel any opinions are welcome
 




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[ja17]

Since your fuel delivery and pressure are good, I would check the ignition coil next. You might also go back and connect the fuel pressure gage and take a reading when the engine is backfiring. A drop in pressure during the backfiring would indicate a fuel delivery problem.

[jim 56]

Thanks I will try a coil next.

[jim 56]

Swapped in a new coil still the same. Any other ideas .

[ja17]

Try hooking the fuel pressure gage up, then observe  the pressure as the problem occurs.

[jim 56]

Thanks still have 13 psi when problem occurs

[ja17]

How old are your spark plugs and what spark plugs are you using?

[jim 56]

Thanks Joe I am using NGK BP6E  I took a couple out today they only have about 500 miles on them they are a nice tan color. Also today I changed the point gap to .018 this appears to give me a dwell reading of 32 I retimed it to 6 ATC like tag in engine compartment says.I drove it for about ten minutes seemed to run a lot better. My vac increased to 16 at idle. Did the split linkage if I push on FIP lever car dies If I push down on throttle idle increase about 100 RPM then dies. I couldn't work on it any more today. I will drive it more tomorrow and see if problem is gone and let you know.
Jim

[jim 56]

Finally I think I got it right now backfire didn't come back today. Thanks for the help.  One thing I would like to ask though is when I push down on air side in split linkage and idle increases about 100 RPM then dies. Does this mean I am still lean? I push down on FIP it dies right away.

[ja17]

Pushing down on the air side, at idle, during the split linkage test should produce slightly more rpms when adjusted  correctly. If not, the air idle screw would not function for fine idle adjustments.

[jim 56]

Thanks, mine does increase about 100 RPMs so I assume it is adjusted correctly. I do believe I am real close to having this run good. I am waiting on a report on why the XR 700 pointless ignition I had to take out failed  so quickly. (after about 500 miles) and maybe I will put it back in even though I still like points better.Then I will take out the WRD device  and see if anything is wrong. It may be hanging up as somebody suggested because sometimes at idle it sounds great . Then other times it idles way too high.