I'm currently fighting a persistent pinging problem with my truck. I recurved the distributor and even though my truck runs great, it has a persistent pinging problem that I've traced back the vacuum advance.

I currently have a governor that has been filed out to give exactly 20* advance, one blue spring, and one green spring on the weights. I tried the two green springs to begin with but the truck was total dog with that combo. With the blue and green combo the problem is that the truck will run fine unitl you get your foot into it and it will start rattling like crazy. Back off of it and it rattles less, push it on down and it rattles even more. It also will ping if you try to acclerate above 60 MPH (2500 RPM). I can turn the can adjustment in a couple of turns and it will stop rattling, but then it looses all of it's pep and is a slug around town.

I'm thinking that the 11R is pulling in too much timing when you give it some slack and I need a vacuum can with much less advance travel. What do you guys think? Currently the 11R can pings at 5 1/2 turns from the loose side, and stops pinging at 7 turns. Unfortunately I have the most acceleration and pep at 5 1/2 turns.

Here is my engine info:

1982 D-150 w/225
180* thermostat
Initial timing is set at 12*BTDC
stock cam advanced 4* and degreed in
Super six intake and super six Carter BBD
BBD has been properly adjusted and has no throttle shaft wear
Plugs are NGK UR6 (one step colder)
Stock exhaust with cat. removed
EGR is blocked off
No vacuum leaks anywhere (already checked)
727 w/lockup and 3.25 gears out back
HEI retrofit, plugs are gapped to .045
Gas is 87 octane

If yall need anymore information let me know.

_________________
82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

With those gears and a heavy truck it's not liking it much. When you get rattling/ping have you hooked up a vacc gauge to determine at what rpm and vacc reading it's at so you can see how much initial+mech+vacc you have. Also when it pings have you shut the truck off immediately and jack it into neutral so you can do a roadside spark plug reading, if so what color do you have on your plugs? It almost sounds like the 'power valve' or circuit enrichment is also possibly lean on carb if the 'demand' on the engine is called for.

If everything is 'in' on your curve 12+20+22=54...I'd be shooting for something closer to 47-49 for a truck if I could get away with it (light cars
can tolerate 52-54 all in, a brick with highway gears, and an engine lugging it around is less tolerant).

12+20+15=47 (7.5x from 1974...) might be a better choice, but let us know the other information requested above it will help tell us about what 'is' going on at that particular moment.

-D.Idiot

Disconnect the vacuum advance (plug at carb) and see what happens.

If it goes away, you can try adjusting when the vacuum start advancing (if end of can looks like a big nut)

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I've been doing that. I noted in my first post that it pings at 5 1/2 turns, and stops pinging at 7 turns.

With vacuum advance unhooked it doesn't ping any. But it's also rather lethargic.

_________________
82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

This is confusing…

At WOT vacuum advance should not be advancing timing at all as vacuum is low.

At part throttle is a different story, you may have sufficient vacuum to vacuum advance can to advance timing.

Light throttle on level ground or downhill, vacuum advance would advance timing fully as vacuum would be high.

Like DI said, you need to conduct a study charting when all the timing events take place in relation to advance in degrees, vacuum reading, at various rpm increments from idle to 3000 rpm. First do it with vacuum advanced disconnected from vacuum at carburetor, second with vacuum advance connected to vacuum.

By doing this little study you will find out how fast timing advances as rpm increases, and also be able to determine how different springs rates affect the curve, and idle advance.

Then get a long length of vacuum line, and bring vacuum gage into cockpit so you can see how ping & knock relate to various throttle openings & rpm (if you have a tachometer) inside on hills, and level ground.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I haven't mapped it out yet, but I will do so in the next couple of days. I was just going by the chart bigslant6fan sent along with the recurve kit. Do you guys want manifold vacuum readings, or a reading from the ported spark tube the vacc. advance is hooked too?

As far the carb jetting, it's definitely on the lean side. I have the rods all the way up with the little allen head screw. I'v tried lowering them back down but I get flat spots in my acceleration and even more rattling. So for now they are adjusted all the way up with the pivot bar adjusted all the way down as outlined in the manual.

It has super six rods, but the #'s are worn off of them so I can't give any specifics besides micrometer readings. I stuck a set of rods out of a 318 BBD in it for an experiment, and even though they were WAY too lean in the cruise side, when the power circuit was really fat and made the truck really quick when you pressed it on down. But those are back on the shelf and the super six rods are back in the carb.

Mileage runs about 18 on the highway at 60MPH (2300-2400 RPM). If you poke around at a slower speed (55-50) it burns way more gas. Guess it's pulling in the power circuit at that RPM

_________________
82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Manifold vacuum.


Also sounds like you have carburetor problems that need to be sorted out. Probably not very good to run an engine real lean, things will melt.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

See if your carb has a port that reads under the throttle plates at the base of the carb...that will let you see what happens at the carb, if you plug it into runner #6 there will be a difference in the reading between what the carb sees and what the larger volume in the runner is reading.

-D.Idiot

I agree with BIll (wjajr). The vacuum advance is not your problem. It only engages when you let your foot off or back off on the gas pedal. Then it kicks in. Not you when your foot is in it.........as vacuum drops so does the vacuum advance. Adjust your initial timing then play with springs....by unplugging the can as suggested, it is out of the picture......hopefully you had it plugged into ported vacuum!

With tall gears, the windage of a big truck and big or tall tires, automatic, etc......I would only go 6 degrees max on the initial. This way you will only see 26 degrees instead of 32 degrees (initial plus mechanical).

Let us know how it goes after you unplug the can.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ok, I've said it before and I will say it again, it does not ping with the vacuum advance unhooked! It's hooked to ported vacuum.

6* initial? This truck is a pig at 8*, can't imagine it at 6*.

I'm will try and get the advance mapped out this weekend. Been super busy with everything else lately. Also rechecked the metering rods and raised them up the rest of the way.

_________________
82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Ok I mapped out the advance today all the way up to 3000 RPM. My neighbor thought it was an airplane taking off. I hooked the vacuum gauge to the choke pulloff port since it gets it's vacuum from below the blades (at least that is what the chrysler film said). I also bumped the initial back from the 12* to 08* thursday to see if it would help. I left it at 08* for this test.

First run, no vac. advance

RPM Degrees vac.

713 08* 18
1020 08* 20
1540 13* 21
2070 23* 22
2480 30* 22
3000 32* 23

Second run, w/ vac. advance

RPM Degrees Vac

844 08* 20
1300 11* 20
1960 36* 20-24 (fluttering)
2240 53* 21
3050 53* 20-24 (fluttering)


So, I'm guessing the overeager 11R is the cause of my problems? The mechanical curve is pretty much where I expected it to be, except for the fact it gives a little more than 20*. What do yall think? BTW sorry if it's a little hard to read, I had everything lined up in nice neat columns while I was typing, but when I hit submit it skews everything.

_________________
82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

need same rpm at each reading///ie idle 1000 ,1500, 2000, 2500

Unplug and cap vacc advance line...
use screw driver to adjust idle screw to
hold rpm at your test points then check advance.

Next test, pull out your hand vacc. pump...set idle
to a stable setting (like 1500rpm), then use hand
pump gauge to see what the advance is at various
levels (20,16,15...10,8,7,6" of vacc.)

That will allow you to drive with a vacc gauge and
extrapolate what is going on:

So while driving in traffic if you are at 2200rpm (23 deg mech advance+static)...and your gauge says 11 "hg...and your chart
says the advance is at 18 deg...and it's pinging...then you know
it doesn't like the 41 degrees at that point and one or the other
will have to be adjusted to make that work...

-D.Idiot

Jeb,

DI is right on.....that is the way to do it so you can dial it in perfectly. Your map looks like you have some vacuum leaks if the rpms are not steady and/or the springs are too light not being able to hold the mechanical advance steady.

Some thoughts: When you mentioned bringing back the initial made your truck feel like a dog, it's surprising. For best spunk on this tired old stock 1979 engine I am running at the moment, 6 degrees initial, 20 degrees mechanical and 5 1/2 turns on the 11R cam. I run a little looser lash .022) on the exhaust. I keep the total timing under 50 degrees. It never pings and has crazy power from off idle to 2200 rpm. After 2200 it starts to flatten out a little with the one barrel. I think the wind drag starts to factor in at 55 mph. I run 26" tall tires with the 8 3/4 2.76 geared Sure-Grip.

Do you run a 195 stat? and is the exhaust manifold diverter working? In cold climates the SL6 can be doggy if the intake is not fully warmed up. Keeping the intake warm is key to a spunky engine. That is why I do not use a stock fan but use electric fans, which rarely engage this time of the year. I also run an aluminum heat deflector to help keep the intake warm and carb cooler during heat soak. I don't have the stock blanket, but the aluminum deflector helps. The intake warms up much faster.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG