Another Timing Question

[RT DAVE]

Let me start off by saying I've read through all the posts on timing and am posting this new thread because I need some clarification because I am confused about some things.   

I was going through an old Mopar Action article "A Stitch in Time" because the mechanic that I brought my car to thinks that vacuum advance is non-adjustable.      Anyhow, I had the thing set to 35 at 3000 rpm and asked him to retard the vac advance.  His solution was to retard the initial timing because he said the vac advance couldn't be adjusted. 

Well, my question involves the following last step of Mr. Ehrenberg's article:

"with revs at 3000 rpm again connect vacuum hose from distributor directly to manifold vacuum.  Spark should now be at least 50-55 deg. if less, adjust vacuum chamber"

My question involves the bold portion.  Is he saying connect the distributor to the carbuerator fitting you would under normal driving conditions or his he saying connect it to some other source of vacuum?   Basically, which two things need to be connected to check this spark reading?  Please help.  Thanks in advance.

Sorry if I am sounding like too much of a Noob.  I've been trusting and paying others to work on my car because I'm looking for a job and watching my one y.o. son & three y.o. daughter about 14 hours a day right now.   No time to work on the car or really research it enough on my own.   Thanks guys or gals (there's a couple out there, I think). 

[firefighter3931]

Dave, fwiw i always disable the vacuum advance. I'm sure i've written those words here at least 100 times 

Just plug it up and adjust the total timing to 36-38*. After that has been done take a look and see how much timing you have at idle. It should be in the 12*+ range (at idle) depending on what cam you have in the motor.


Ron

[RT DAVE]

Dave, fwiw i always disable the vacuum advance. I'm sure i've written those words here at least 100 times 

Just plug it up and adjust the total timing to 36-38*. After that has been done take a look and see how much timing you have at idle. It should be in the 12*+ range (at idle) depending on what cam you have in the motor.


Ron

I had the thing at 35*@3000 and it was pinging pretty good at half throttle under load.   I'm running the MP Purple shaft with the .474 lift on a M1 DP intake.  I got 2.18/1.81 valves with a three angle valve job.   I'm in the 10:1 range for compression and am running a stock converter with 3.23 gears.   I hope my combo isn't too far out of wack.   

I'll do what you say soon and report back. 

[Chryco Psycho]

you will have to lenghten the curve a little & reduce teh initial / idle timing to reduce pinging & dial in some vacuum advance
generally it will only ping at low RPM & not at higher RPM
the vacuum adjusts with a small allen wrench in the vacuum port  counter clockwise reduces the advance

[RT DAVE]

Well, me and a new pal of mine from the MOPARTS board farted around with it today and tried a range of 32-36 at 3000 and the thing still pings like a mofo even with the vac advance disconnected/plugged.  Limped it home on the highway with the advance disconnected.   We also tried to decrease the vacuum advance and the thing wouldn't adjust down.   Had 65 total timing at 3000 with advance connected so we disconnected when it wouldn't adjust out.   In fact, with the vac advance connected, the timing light was jumping all over the place.  That wasn't happening with the advance disconnected.  Anybody else have this problem?   How far can I retard this thing to get rid of the pinging and not worry about hurting the motor.  I already know I'm not doing it any good as it is.    Some other variables to consider:

-Ten of the twenty gallons of gas in the tank are two years old.   The gas that sat in the tank had stabilizer in it, however
- We put some octane boost in the tank and topped it off with no result.   
-Motor has between 10:1 & 10.5:1 compression
-Cast iron heads with bigger valves, mp purple shaft .474 cam, mopar m1 dual plane, edelbrock 800 cfm carb.   

[TylerCharger69]

just a thought...but   could your timing chain be worn?....Or maybe misplacement of the distributor?   The solutions posted should've solved your problem between all the posts that are on this topic.  It's possible your balancer is not accurate.....the outer ring may have spun......that's a shot in the dark though.

[firefighter3931]

Dave, make sure the carb isn't jetted lean. A lean mixture will cause the motor to ping. Have you looked at the plugs ? If so, what color were they ? Also, have a look at the advance weights and the plate in your distributor...make sure the weights aren't sticking and that both springs are intact.


Ron

[RT DAVE]

Dave, make sure the carb isn't jetted lean. A lean mixture will cause the motor to ping. Have you looked at the plugs ? If so, what color were they ? Also, have a look at the advance weights and the plate in your distributor...make sure the weights aren't sticking and that both springs are intact.


Ron

What would the plugs look like if a lean condition existed?  Is there anything else I need to look at to make this determination?  I'll take some pics of the plugs when I get around to this.   

How much can I retard this thing to get rid of the pinging? 

Also, do you think I did/could have done much damage driving this thing 15-20 miles on the highway?  Basically, would I know if I've hurt the thing or will I have caused damage that will gradually get worse over time?   I don't know why I'm worrying because there ain't nothing I can do about it now.   

[firefighter3931]

The plugs will be white or light grey if it's lean. Tan/light brown is good. Black/charcoal is too rich. A plug with too warm of a heat range can also create issues, basicly you want to run the coolest plug that won't foul.

If you keep driving it while  it's detonating, the engine will be damaged. I doubt that you've ruined the motor at this point but don't push it until it's fixed. As far as ignition advance/retard....you can go either way as long as the engine runs well. Try retarding the timing to see if you can eliminate the ping.

Map out your ignition curve in 200 rpm increments starting off at idle and record the numbers right up to the point that the ignition no longer advances. Report back with your findings.

Here's some good reading material on tuning. Doug was having similar issues which were resolved with some hard work :

http://1970chargerregistry.com/70messageboard/viewtopic.php?t=1207



Ron

[RT DAVE]

The plugs will be white or light grey if it's lean. Tan/light brown is good. Black/charcoal is too rich. A plug with too warm of a heat range can also create issues, basicly you want to run the coolest plug that won't foul.

If you keep driving it while  it's detonating, the engine will be damaged. I doubt that you've ruined the motor at this point but don't push it until it's fixed. As far as ignition advance/retard....you can go either way as long as the engine runs well. Try retarding the timing to see if you can eliminate the ping.

Map out your ignition curve in 200 rpm increments starting off at idle and record the numbers right up to the point that the ignition no longer advances. Report back with your findings.

Here's some good reading material on tuning. Doug was having similar issues which were resolved with some hard work :

http://1970chargerregistry.com/70messageboard/viewtopic.php?t=1207



Ron

Thanks for the link and the suggestions.  I will report back shortly.  I've come to find my tools are inadequate for some of the most basic mechanic work at this point. 

On a related subject, I need to buy a timing light as I've been borrowing using other peoples tools to this point.  Can you suggest a readout style model to purchase?  I am currently considering this model below.  Cost is an issue to consider. 

http://www.sears.com/sr/javasr/product.do?cat=Mechanics+Tools&pid=00920927000&vertical=TOOL&subcat=Automotive+Testing+Equipment&BV_UseBVCookie=Yes

[firefighter3931]

Dave, that is an excellent timing light with all the good features. The built in tach & LEd readout is sweet ! Believe it or not, i still use my 25year old dc inductive Sears timing light. Of course it doesn't have an led screeen, dialback feature or tach readout, but it still works. 

If that light is in the budget go ahead and order it up. I would also suggest you order a vaccum guage while you're at it. 


Ron

[RT DAVE]

Dave, that is an excellent timing light with all the good features. The built in tach & LEd readout is sweet ! Believe it or not, i still use my 25year old dc inductive Sears timing light. Of course it doesn't have an led screeen, dialback feature or tach readout, but it still works. 

If that light is in the budget go ahead and order it up. I would also suggest you order a vaccum guage while you're at it. 


Ron

Any recommendations on the gauge or will any old gauge do the trick? 

[firefighter3931]

Any quality vac guage will be sufficient. Sears should have something available.


Ron

[Ghoste]

A fresh tank of high octane isn't going to hurt your efforts either.

[RT DAVE]

Here's two pics of the #1 plug.  Please advise at your earliest convenience.  Please note that I drove on these plugs for fifty miles with mild detonation and then made things worse and drove it fifteen miles.   I realize that's a bad thing.   Just putting that out there in case the plugs are showing inconsistent things.   Thanks in advance.

[myk]

The plug's burnt, obviously from the lean condition and the detonation you said you were having...

[RT DAVE]

Silly question, but can I correct the lean condition and run the same plugs or do I need to replace them?  Should I put bigger jets in now or try to adjust the air/fuel mixture first?

[firefighter3931]

Dave, the plugs are showing a lean condition. You should jet up before driving it again. Take it out for a short cruise after you jet up and pull a plug or two to see what they look like (color). Try to stay out of the secondaries....just run it on the primaries during the cruise test to see how close the primary jetting is.

How does the timing curve look ? Initial (base) timing ? Total timing ?


Ron

[RT DAVE]

Dave, the plugs are showing a lean condition. You should jet up before driving it again. Take it out for a short cruise after you jet up and pull a plug or two to see what they look like (color). Try to stay out of the secondaries....just run it on the primaries during the cruise test to see how close the primary jetting is.

How does the timing curve look ? Initial (base) timing ? Total timing ?


Ron

Would you recommend jetting up more than one size?  I'm running the stock jets on a 800 cfm carb.    I'm still working on checking the timing but will definitely check that as well before road testing.   Thanks again. 

[firefighter3931]

Would you recommend jetting up more than one size?  I'm running the stock jets on a 800 cfm carb.    I'm still working on checking the timing but will definitely check that as well before road testing.   Thanks again. 

Dave, go up at least 2 sizes. You're better off being a little rich rather than lean. What plugs are you running ? Are those autolite 85's ?


Ron

[dodge freak]

What size jets are in there now ? I would think 74 would be close but I would first see what you got in there now, seems like Holley put different size jets in the same model carb depending on the year

[RT DAVE]

Would you recommend jetting up more than one size?  I'm running the stock jets on a 800 cfm carb.    I'm still working on checking the timing but will definitely check that as well before road testing.   Thanks again. 

Dave, go up at least 2 sizes. You're better off being a little rich rather than lean. What plugs are you running ? Are those autolite 85's ?


Ron

Should I change the metering rods and step up springs at the same time or just the jets?  Also, the fuel mixture has not been adjusted to the best of my knowledge.  Should I try that first/in addition?  Unsure on the plugs as they were installed by my builder.   They are autolites.   Is that bad?

What size jets are in there now ? I would think 74 would be close but I would first see what you got in there now, seems like Holley put different size jets in the same model carb depending on the year

Not sure on that.  I'll have to find out when I get the thing apart. 

Thanks in advance...   That's a bad pun but I just had to... 

[firefighter3931]

Should I change the metering rods and step up springs at the same time or just the jets?  Also, the fuel mixture has not been adjusted to the best of my knowledge.  Should I try that first/in addition?  Unsure on the plugs as they were installed by my builder.   They are autolites.   Is that bad?

Dave, try making one change at a time. I allways start with the ignition first and get that straightened out before moving onto the carburator. Making a bunch of changes simultaneously can lead to further frustration and head scratching.

Autolites are ok....i was more interested in the heat range of the plug. The 85's are correct for your combination. Personally, i prefer NGK's but run those for now or until they need replacing.

Edelbrock carries a "strip kit" for their carbs....it would be worth getting. The website also has detailed tuning info as well.


Ron

[myk]

So....Will he be changing out the primary and secondary jets, or just the primaries?  Also, he'll be changing the step-up rods also, right? 

[Ghoste]

If you check the Edelbrock tech site, you'll find that there is range of jets to each rod.  Depending on where you are trying to be at you may or may not have to change the rods.  But get the kit that has the rods and jets and then go from there.