It's all in the timing!

Truck is my 81 F100 flare side with a 300 six with a NP435 trans and added over drive unit.

I have been fighting a pinging issue since I got it on the road 2 years ago.
I pings when you hit some hills and the RPM is about 1500 @ 45 MPH but I have gotten it on the high way
at 1800 @ 65 - 70 MPH.
It will happen even worst if you go WOT and will stop if you back off the throttle.

The timing is set (IIRC) 14* BTC, vacuum off & plugged.
I dont remember what the mechanical timing was or vacuum was when I looked into this months ago but both were working / advancing timing.

Little by little I have been adjusting the vacuum can and at first it seams ok then start pinging.
Today I got crazy with it and turned the adjust meant clock wise all the way and it was worst, pinging between gear changes.

I then went what I think was all the way counter clock wise. Why I say "think", it did not stop turning but made a clicking noise like you were at the end of threads and it clicked back tillit happened again.
It still pinged but not as bad. No pinging on gear changes but WOT or hills at part throttle i did.

So more testing I removed vacuum and plugged the line and now only get a little at WOT or if the RPM is way to low, just above 1000 RPM in 3rd gear pulling out of a corner.

So this pinging with no vacuum advance is telling me too much mechanical timing. Again I dont remember  what that is but will test / check ASAP.

I have not looked into kits for springs or a different adjustable vacuum can or if I can install some kind of limit on the weights.
Am I on the wrong path to limit the mechanical first and stop the pining with out the vacuum then look into the vacuum side?

If not on the wrong path how would you go about this?
Limit the travel of the weights or stiffer springs or both?
I also need to pull out my Motor's manual for pros and see what it has for timing deg @ RPM so I have something to go by as a starting point.

Thanks for any help you can give.
Dave ----

ps: I should add it is not a lean ping as the AFR gauge reads any where from low 12's to mid 13's

Dave, if it is a stock Ford DS-II distributor, under the pickup plate are two weights, two different strength springs and a stop. The light spring is the first advance stage and it's total is limited by the heavy spring. First would be to see at what rpm the advance slows down, if it is above the rpm where you get the ping, then bend the light spring hanger out a bit and try it. If it is above the rpm where the rate slows down, put some more tension on the heavy spring. This can also be used to change the amount of the initial mechanical advance.

Pulled from my carb thread as it gets into the timing issue I am having.

Gary Lewis wrote

Glad you have the choke working well. But it sounds like you have too much initial advance. Or you have too much centrifugal.

At what RPM does it ping?

FuzzFace2 wrote

Gary Lewis wrote

Glad you have the choke working well. But it sounds like you have too much initial advance. Or you have too much centrifugal.

At what RPM does it ping?

At WOT now I would say anything above 1500 rpm
I get a little at 1500 rpm and lower, truck will pull from 1000 rpm, but I back out of it not to hurt the motor. That is with vacuum advance disconnected.
It was really bad when hooked up.

I need to throw a light on it again to get the numbers as I don't remember them but think it is set to 14 BTDC.
At 16 BTDC pinging was really really bad.
If ibackeddown to 10 BTDC I had to crank it more before it would start / run, now I just tap the key and it fires right up.
Dave  ----

Gary Lewis wrote

Sounds like the springs are really light in the centrifugal advance.  Check timing by running the R's up a couple of hundred at a time from idle and we can compare to what we found on David/1986F150Six's engine a few years ago.  We got it dialed in nicely.

FuzzFace2 wrote

Just got to find the time.
Been at work 2am and still have 3+ hours then a hour drive home.

I was going to look for that post also when I had time just to see what he had.
I also want to see what Motor's manual has listed for my truck.
Between the 2 I should have a good starting place.

I was looking for spring / weight kits bur kept coming up with GM parts even with the truck or motor listed?
I hate to get into the distributor and not have parts on hand.
Dave  ----

Gary Lewis wrote

You might be looking for David's Gas Mileage Recipe thread on FTE, and more specifically this post therein.

I looked up the dist. spec in my Motor's Manual for trucks (covers LT trucks also) even that it goes to 81 the dist. info stops at 74  The first year for non-points so I dont know how good it will be for 81?
I will list what it listed when I get the time.

I also have to check & note what my truck is doing. Right now I have been running with out vacuum advance and it still pings but no where as bad.
Dave ----

I found this note from Gary dated 9/14/2014:

David is on his way home as of about 6:00 this morning. And, he was wearing a smile.  His only concern was whether to get gas here, making this tank lower MPG due to the ~40 miles of testing we did, or getting gas at the end of the range to pull this tank's average up. Obviously there are swings and roundabouts in that, but the fact that he's thinking about those things shows his attention to detail.

And, he is very thorough. He pulled receipts from his wallet for the last six or so tanks of fuel and each had notes on it describing the conditions under which the tank was burned. Like "hot" or "75 miles of city" or "all highway". And one notes when he re-installed the chin spoiler, which has made a noticeable difference. So, I'm confident we will get a good and accurate report on his MPG.

For the records, here are our notes:
Overall Timing
On arrival:
Initial: 18 degrees
Centrifugal: 10 @ 1700 RPM/62 MPH
Vacuum:12 @ 14"
Total: 40 degrees @ 62 MPH on level ground
On departure:
Initial: 14+ degrees
Centrifugal: 10 @ 1700 RPM/62 MPH
Vacuum: 18 degrees @ 14"
Total: 42 degrees @ 62 MPH
Vacuum Advance:
On arrival:
10" = 8 degrees (advance starts here)
12" = 10
14" = 12
15" = 16
16" = 18 (max)
On departure (2 turns)
8" = 7 degrees (advance starts here)
10" = 10
12" = 14
14" = 18 degrees (max)

Thanks, David. I missed that note, and the details are what Dave needs.

Thanks guys
I got a feeling my truck may not like them numbers.
I am pretty sure mine is set to 14° now and with no vacuum hooked up I am getting some pinging at WOT and ever so little if climbing a hill normal driving.
With vacuum hooked up it is really bad and why it is disconnected.

As soon as I can throw a light & vacuum gauge on it I will.
Been at work since 2am, up at 12am and don't think I will be home till about 3pm and I get to it it all again tomorrow
Dave  ----

The distributor on the truck described by Gary had previously been "recurved".

1986F150Six wrote

The distributor on the truck described by Gary had previously been "recurved".

Going over the "before & after" information I see you puled out 2* Initial and have the vacuum pull it in earlier so at the speed and that given HG it adds the 2* back.
But where did the extra 2* come from as the total is now 42* from 40*?

When it was recurved do you know what kits were used?
I went looking the other day on line and both Summit & Jeggs only popped up kits for GM dist. even when I entered the "FORD" truck and the "300 six" motor.

Because everything is below the "breaker" plate if I am going to pull the dist. to mess with it I want parts on hand to do this (hopefully) once.
I know Bill said to "tweak this & that" but again it is all below the plate and a pain to get to.
Also because of my work hours I may only get 1 day shot of working on it.

Just a thought I believe this motor was from a later car based on the color (gray) and the exh manifold and head pipe as the trucks head pipe would not fit the manifold. Dont know if that would make a difference.

Thanks as always
Dave ----

ps what I would not give to have a dist. machine like we had when I was in Tech High School

1986F150Six wrote

I found this note from Gary dated 9/14/2014:

For the records, here are our notes:
Overall Timing
On arrival:
Initial: 18 degrees
Centrifugal: 10 @ 1700 RPM/62 MPH
Vacuum:12 @ 14"
Total: 40 degrees @ 62 MPH on level ground
On departure:
Initial: 14+ degrees
Centrifugal: 10 @ 1700 RPM/62 MPH
Vacuum: 18 degrees @ 14"
Total: 42 degrees @ 62 MPH
Vacuum Advance:
On arrival:
10" = 8 degrees (advance starts here)
12" = 10
14" = 12
15" = 16
16" = 18 (max)
On departure (2 turns)
8" = 7 degrees (advance starts here)
10" = 10
12" = 14
14" = 18 degrees (max)

Question(s)
I see you listed a RPM of 1700 @ 62 MPH and a vacuum of 14 HG as that MPH / RPM

Did you pick this for any reason or just a measuring point?
Trying to get a handle on what mine might turn out to be "recurved" to is all.

Thanks
Dave ----

I think we picked 62 MPH as that is the speed David typically drove.  But he may remember better.  (I think my memory used to be better, but I really can't remember.)

I think yours is better than mine

That would make sense if he drives that MPH most of the time.
I also want to say the peak TQ was around 1800 RPM?
I know at 55 MPH mine in direct drive is 1800 RPM and in OD that same RPM is 70 MPH, the speed limit here (not that anyone goes that slow).
Dave ----

Actually, it is a bit lower than that in most cases:

Gary Lewis wrote

Actually, it is a bit lower than that in most cases:

Ok so between 1200 & 1600 rpm depending on what type motor tune from the factory.

So David is just at the sweet spot at 1400 rpm at the speed he travels at.

I was sent a text on the spring kit it is Mr. Gasket #925D
Now to find one when I get out of work.
https://fordsix.com/archive/www.classicinlines.com/DSIIswap.html#Recurve
Dave  ----

I enlisted the recurving assistance from someone specializing in that. He asked what modifications had been made to the exhaust, what transmission, rear axle ratio, weight and whether or not it had EGR.

The later heads [1984(?) and up] were fast burn designed] and much more sensitive to the absence of EGR.

1986F150Six wrote

I enlisted the recurving assistance from someone specializing in that. He asked what modifications had been made to the exhaust, what transmission, rear axle ratio, weight and whether or not it had EGR.

The later heads [1984(?) and up] were fast burn designed] and much more sensitive to the absence of EGR.

Thanks for the information.
Wonder if my motor is 1984> with a fast burn head?
I also don't run a EGR, I hear it helps cool down the chamber to stop knocking.

With no valve and the head that could be my issue right there?
If the weather is in my favor tomorrow I hope to get some timing / RPM readings.
I was in the parts store today and forgot to check on the spring kit
I would like to have it before the holiday as that might be the only time I have to make the change.
Dave ----

$7.50 part and $10 to $12 SH fee through the 2 on line speed shops
I will have to see if local dose the same.
The exh system was a order and they charged me for it.

On a side note I have a hand full of dist. springs from my MSD dist. wonder if they would work?
Going to dig them out of my "pit box" to see what they look like and fingers crossed they will work.
Dave ----

They might work.  You can check their tension by hooking one of them to one of the existing springs and pulling to see which one gives first.  Obviously that is the one that will let the timing advance faster.

But, there's also the length.  IIRC, one of the springs has an oversized loop on one end that lets the other spring control everything until you hit the end of the loop  So the length has to be right as well.

So I have to pull the dist. and pull it apart to check if the springs I have will work, great
Dave ----

Yup.  Welcome to Ford distributors.  

The man who did my distributor is named William Ambler. I came to know him on another forum, years ago. His email address was/is billythedistributorman@live.com. I believe he went by WSA111 on the forum.