It's all in the timing!

[grumpin]

I found this on RA’s website, instructions for the vacuum advance.

I did not realize you could come back to the stop. I was always careful, leery if you will, to not damage it.

When I get the timing where I like it and start with the vacuum advance, I’m going to start at the mechanical stop.

https://www.rockauto.com/genImages/154/GF3767.pdf

[Gary Lewis]

Sorry, I missed the previous post.

Glad you are getting the pinging sorted.  Maybe you are "there"?

And, glad you are finding that taking up the clamps, or adding one, seems to solve minor problems.

As for the dizzy it is from a 1980 truck, and these are the possibilities:

CALIBRATION PARTS LIST NO. 1
(Calibration No, 0-51F-R0) - 6 Cyl. 300 C.I.D. (4.9L)
1980 F250 - - 2/W/D-M/T exc. Calif.
1980 F-U150/250 - - 4/W/D

CALIBRATION PARTS LIST NO. 5
(Calibration No. 0-51M-R0) - 6 Cyl. 300 C.I.D. (4.9L)
1980 E250 - - M/T

CALIBRATION PARTS LIST NO. 49
(Calibration No. 0-51F-R10) - 6 Cyl. 300 C.I.D. (4.9L)
1980 F250 - - 2/W/D-M/T exc. Calif.
1980 F-U150/250 - - 4/W/D

And here's the full #1 parts list:

[FuzzFace2]

I was given some links & info on the dist. numbers, mainly the lower number.

9J 27
9 = year
J = month think I seen they don’t use "I" so this would be the 9th month
27 = day
Sept 27 1979

This could be from the motor that was in my truck as the truck was made 11/80 and if I under stand motors could be built a year before the body.

Being the motor had gray paint I think it is a later year, the exh. manifold would not take the trucks head pipe so the dist was swapped over.
Just my guess
Dave ----

[FuzzFace2]

Ran to HF a few towns away, 105 miles round trip, truck run great and no pining so was happy with that.
First real driving since the spring swap that was more than around the block.

A little later, almost dark, my son helped do the timing curve mapping after the MSD blue spring to replace the weak Mr. Gasket spring.

Idle 850 14* BTDC
1000 14*
1500 14*
2000 14*
2500 16*
3000 23*
3500 29*
4000 30*

I then hooked up the factory vacuum can and IIRC it is turned CW to the end.
I dont remember where it starts to pull at and was to dark to hook up the vacuum gauge and the new hand vacuum pump was not working right to test.

Idle 850 14* BTDC
1000 15*
1500 15*
2000 24*
2500 44*
3000 51*
3500 55*
4000 58*

I am going to take the truck to work, vacuum not hooked up, and before the trip home I will hook up the vacuum and see how it runs. If it pings I can pull over and remove the hose and plug, trip in will be to dark for this if needed.

I also like where the AF meter has been reading, between mid 14's and high 15's most of the time.
Dave ----

[Gary Lewis]

Man, that made a huge difference in the advance.  You shouldn't have pinging even with the vacuum advance connected.  

But on the way to work w/o the vacuum advance see if you think the truck has as much power as it previously had.  I think you may have given some away with the slow centrifugal advance.  You may want to put that heavy MSD spring in if it is lighter than the factory heavy spring.

And I'll bet on the way home with the vacuum connected the part-throttle response is better.  However, since the vacuum, and there for the advance, goes away with much throttle I fear you are still leaving power on the table.  Maybe boost the initial to 16 degrees if it starts ok?

[FuzzFace2]

That did make a big difference, I was shocked when I saw the readings.

I think the power is pretty good the way it is.
The way it was when pinging you had to get out of the throttle to stop the pinging were now you don't, you can give more throttle climbing hills now.

I do think I left some on the table but now I can sneak up on it were before the pinging was in my face.

More adjusting and testing and I will get it dialed in.
Thanks
Dave  ----

[Gary Lewis]

That's the right approach - sneak up on it.  And since earlier it seemed to be starting ok at 16 BTDC I think I'd dial in up to that pretty quickly.  You want to get your initial + centrifugal timing nailed down before working on the vacuum advance.

But you should be at work right now, having driven the truck to work with the initial at 14 BTDC and no vacuum.  Then you'll connect vacuum to the can for the drive home, so I'm looking for a report when you get home.  

I believe what you will find on the vacuum is that will give you a whole bunch of advance.  That's because it is set up for EGR but you don't have EGR enabled on the engine, right?  The addition of exhaust gas to the air/fuel mix slows the combustion significantly so they had to dial in a whole bunch of advance to compensate.  However, the exhaust gas is only added when the engine vacuum is high, so they added the advance through the vacuum advance unit, so those vacuum units can add a whole bunch of advance.

Looking at your previous notes your unit appears to give 35 degrees of advance with the screw all the way CW.  I believe that may be too much, but maybe not with the really slow centrifugal advance.  Still, I'd want to get the initial set to 16 before I did much tuning on the vacuum.

Good luck!

[FuzzFace2]

Report:
Drive to work: timing set to 14* BTDC, no vacuum advance, it ran like it did on the 105 mile trip, I thought pretty good.

Drive home from work: (vacuum was hooked up only as a test) Started it up to warm up a little as it was 48*f. While warming up I hooked up the vacuum to the advance can. Start up / hook vacuum up / close hood and drive. Even cold  it was pinging.

Anything below 1500 RPM it pinged and forget around 1000 RPM!
It seam to ping at light throttle but stop at WOT.
It felt like it had more get up & go with vacuum hooked up.

I only drove about 5 miles and I pulled over to pull the hose off and plug it for the rest of the drive.

Now when I was working I was looking over my notes and I figured with the can  turned all the way CW the vacuum would kick in sooner to make up for the late centrifugal. It did not like vacuum hooked up.
I would have adjusted it just to see what would happen but did not have the tool with me and it was just a test.


So I may do as you said and replace the heavy factory spring with the weaker MSD heavy spring and see if I can get the centrifugal to kick in a little earlier.
The only thing that you pointed out, or was it Bill?, before was the factory spring has a longer loop at 1 end where the MSD dose not so dont know what that may do to the readings?

You are also right on not having a working EGR

More testing & tuning to come!
Dave ----

[Gary Lewis]

Dave - I wouldn't bother to pull the dizzy and change out the spring until I'd tried turning the vacuum advance full CCW.  Maybe that will back enough out to make it work.

Then, if that doesn't work I'd go for the big spring.  It probably won't work, but it is a whole lot easier than pulling the dizzy, and you really should start with the least vacuum advance and add some until it pings and then back off instead of starting with all you can get.

As for the loop in the heavy factory spring, it lets you get a little advance early on and then slows it down when you hit the end of the loop.  But I really don't think you want to start the advance early, so the MSD spring might do the trick.

[FuzzFace2]

Well it is easy enough to adjust the can and put the hose on & off so I may give that a try.

Pulling the dist. and swapping the springs is not bad once you have done it.
I think I could have it done in and hour, R&R and running.

Think I will do the adjusting and / or spring swap later in the week if I have time.
Tomorrow the high here is 38*f and if I have to spend time out in it for work like today, cement you have to watch the gauges outside, I will not want to work on the truck.

Besides I put the Javelin back in my garage so I would have to move it out, truck in, fire up the heater, etc. after a long day so it can wait.
Dave ----

[FuzzFace2]

I got lazy today when I got home where I should of just pulled the dist. and did the heavy spring swap
Then again up at 12am, at work for 2am and it was 27*f. My last LP load at 11am it was only 36*f and the cold just sucks the life out of me!

Tomorrow it is going to be warmer and hope I have a little more in me to do the swap.

But for the heck of it I adjusted the can and hooked the hose up. (back roads home)
Timing still at 14* BTDC
Did 4 turns CCW to start, had pinging but better than with the adjustment all the way CW.
I pulled over and did 2 more turns CCW for total of 6. It still has some pinging but was less.
When I got home I did 2 more turns CCW for a total of 8. Will see how it goes going to work tomorrow.

It feels a little sluggish off the line but cruise feels a lot better.
 
I think if I can I will plot the timing curve the way it is now so I know what I have as I have the centrifugal side already. Then will do the spring swap and no vacuum and see what I got.
Still sneaking up on it
Dave ----

[Gary Lewis]

Do you now have the vacuum advance all the way CCW?  I fear your current vacuum unit is too sensitive and you may never get it to work w/o pinging.  It is surely one for EGR and those bring in a lot of advance at little vacuum.

Nonetheless, you are making good progress.  

[grumpin]

I got the vacuum can I ordered today.

One thing I don’t like is that the stop is full CW, it just seems to get a little stiff then clicks if you go past that point going CCW.

I ran it to the stop CW then counted turns till it got stiff going CCW. 14, so I went 7 turns CW and I’ll install it and the 180° thermostat when I can.

[Gary Lewis]

Dave is at 8 turns CCW from the stop, so maybe he has another 6?  

[grumpin]

A good assumption.

[FuzzFace2]

Gary Lewis wrote

Dave is at 8 turns CCW from the stop, so maybe he has another 6?

Yes it was 8 from CW stop.
When I went CCW I don't remember it getting hard just clicking that I would guess was off the adjuster?

I tried to count the turns to CW stop but it did not want to thread in the first 20 or so turns so don't really know how many turns from CW stop till the end but will use the 6 more as a reference.

So far I bought 2 cans the first was not even  close to bolting up and no adjusting.
2nd one could be adjusted but did not bolt up.

Thanks
Dave  ----

[FuzzFace2]

At 8 turns CCW from all the way CW and no pinging that I heard going to work.

I may go back 1 turn CW for a total of 7 just to see what happens but want to change that heavy spring and test with out vacuum to see what I get.

Don't know if I can do the swap when I get home as it's going to be a long day at work with 3 loads of LP gas.
Dave  ----

[Gary Lewis]

Yippee!  You are, as you said, sneaking up on it.

And that's the right way, get the initial sorted, then the centrifugal sorted, and then do the vacuum.  But sometimes you have to iterate.  For instance, you could now dial in 2 more degrees of initial and see if the engine has a bit more spunk and still doesn't ping - w/o vacuum.

[grumpin]

Good to hear! This thread is helping me plan my attack!

[FuzzFace2]

grumpin wrote

Good to hear! This thread is helping me plan my attack!

Sorry to say there is no easy way to recurve our distributors.
Plot it, pull it and make a change, put it back in, test & plot curve, repeat till its right.

I have 1 more spring swap, test and plot curve and if ok then move on to the vacuum side of the advance.

Again as a test only as I still have that spring change, I adjusted the can 1 turn back CW for a total of 7 turns CCW from stop. Vacuum hooked up

I have a vary slight ping and not all the time.
Still a little sluggish off the line but throttle response is good when cruising.

I would say if the spring swap dose not work I will go back the the springs I have now ( MSD blue & factory heavy spring) bring the timing from 14° BTDC to 16° BTDC  and see what I get.

I don't want to bring the timing up just yet as all my testing has been at 14° and has been starting pretty good.
Dave  ----