Timing frustration

[mduenas]

Hi guys,

I am trying to sort my timing again on my truck, and got a fancy new timing light to help. not sure if it is helping or not. It is the Innova 5568a https://www.google.com/url?sa=t&rct...Timing-Light&usg=AOvVaw0uNo2VssSpMlW758KQslwE

this is the dizzy I have
https://www.summitracing.com/parts/pnx-d130700

so I have check my TDC for my distributor, I marked where the rotor was, lifted, found TDC, and dropped back in and everything lined up exactly how it was before. The rotor is pointing at the #1 cylinder in the cap.

My pointer on the Damper is directly at 0 when at TDC. I am positive it it is at the compression stroke as I felt air gush out and the truck start immediately.

With vacuum advanced plugged (not hooked up) I have a total timing of 30 degrees when at 3000 rpm. I have an initial timing at 14 degrees at idle.

Then I hook the vacuum advance back up then my total timing is 20 degrees.

Without vacuum advance hooked up, shouldn't my timing be around 32-26 at 3000 rpm or so?

I am not sure how to remedy this, as I have pinging under load that I am trying to sort out.

any advice is appreciated, and if I am going about this all wrong, please let me know!

 

[Timmy390]

So the engine starts and runs fine......you just don't like the timing curve?

Not Bronco but my MSD "ready to run" on my 390FE had springs you could change to manipulate how/when timing come in.

Iron heads? Aluminum? What's the compression ratio? What fuel are you running?

Tim

 

[mduenas]

So the engine starts and runs fine......you just don't like the timing curve?

Not Bronco but my MSD "ready to run" on my 390FE had springs you could change to manipulate how/when timing come in.

Iron heads? Aluminum? What's the compression ratio? What fuel are you running?

Tim

It is not that I don't like the curve, I get severe pinging under load.

I run 91 octane, and the only way to get it to stop is to put in an octane booster.

It is a stock motor that was rebuilt. Each cylinder read at 150psi, but I am not sure what my compression ratio is.

 

[tirewater]

With vacuum advance, your total timing is 20? Did you mean 50?

What is under load? Full throttle? At full throttle you shouldn't have much vacuum, so the vacuum advance shouldn't be contributing timing.

What engine and what compression ratio?

You'll have to provide more info.

 

[Timmy390]

It is not that I don't like the curve, I get severe pinging under load.

I run 91 octane, and the only way to get it to stop is to put in an octane booster.

It is a stock motor that was rebuilt. Each cylinder read at 150psi, but I am not sure what my compression ratio is.

Just sounds like a static compression issue to me.
You can try and slow down the timing curve with springs in the distributor if it's capable or even push it back to a base of 10 from the 14 to see if it helps but it really sounds like static compression is high thus needing the higher octane. Those with much more experience will for sure chime in.

What heads does the engine have? Did you have it built or did you buy it already built? What plugs? Different head/piston combination can really increase static.....

Tim

 

[B RON CO]

Hi, My guess is you have too much initial timing. Your stock 302 should run fine on regular gas.
I would retard the timing to where the pinging goes away, and then check the timing like normal, vacuum hose disconnected and plugged.
I think you said the timing was set at 14* with the vacuum hose off, and went to 20* when you put the vacuum hose back.
Are you using full manifold vacuum or ported vacuum on the carb.
Most guys use the ported or also called timed vacuum, which is zero vacuum at idle. This is the way Ford did it.
Maybe Pertronix can give you info on the the timing curve. Maybe the advance is commong on too soon.
Good luck

 

[spap]

Seems like there are just a few unknowns,
If you back off the timing to where it doesn’t ping do you lose a lot of power? Or does it run good. Idle acceleration etc

In the past I have been wrapped up in timing issues and if it is set so it only slightly very slightly pings under hard acceleration I am usually good.

I used to tune carbs ( 4 x2 barrel down draft Weber’s for a 64 Maserati quad cam 5.0, 380 horsepower) by the smell of the exhaust old Italian mechanic taught me.

 

[SHX669]

I'm only a little confused - but - set your initial timing to 8* ; since a description of your distributor says it has an " advance limiter " set that up to give you 26* of mechanical advance this should give you 34* total .
The description also says the dizzy has a performance curve from the factory so try the 8* and 26 * set up - see what happens.
I'm not familiar with that distributor but my MSD " ready to run " had too much vaccum advance and no way to adjust it so i replaced the factory vacuum canister with an accel canister which is adjustable.

 

[SteveL]

I had timing problems on my 72 che*y when I bought it. We finally got to thinking something was wore out on the cam. We pulled the new flamethrower dizzy the po had installed. It had way too much end play. Replaced dizzy with stock dizzy laying around. Problem solved.

 

[blubuckaroo]

Did you use a distributor machine?
If you held the timing light with the engine at 3K you're crazy!

If you have any question that your timing marks are correct, fix that first. A finger over a spark plug hole isn't accurate enough.

 

[EPB72]

#What shx669 said is good starting point ..as for reving the engine I just turn the idle speed screw to the desired rpm and that gives you both hands to work with.. also u need to take the rpm above 3k to make sure your mechanical is all in and it dosent have springs that are to tight or if there are limiters that are set to conservative as usual with perf distributors out of the box…. By the way what do you have in the way of fuel control FI ,carb ,if carb what set up

 

[Broncobowsher]

Hi guys,

I am trying to sort my timing again on my truck, and got a fancy new timing light to help. not sure if it is helping or not. It is the Innova 5568a https://www.google.com/url?sa=t&rct...Timing-Light&usg=AOvVaw0uNo2VssSpMlW758KQslwE

this is the dizzy I have
https://www.summitracing.com/parts/pnx-d130700

so I have check my TDC for my distributor, I marked where the rotor was, lifted, found TDC, and dropped back in and everything lined up exactly how it was before. The rotor is pointing at the #1 cylinder in the cap.

My pointer on the Damper is directly at 0 when at TDC. I am positive it it is at the compression stroke as I felt air gush out and the truck start immediately.

With vacuum advanced plugged (not hooked up) I have a total timing of 30 degrees when at 3000 rpm. I have an initial timing at 14 degrees at idle.

Then I hook the vacuum advance back up then my total timing is 20 degrees.

Without vacuum advance hooked up, shouldn't my timing be around 32-26 at 3000 rpm or so?

I am not sure how to remedy this, as I have pinging under load that I am trying to sort out.

any advice is appreciated, and if I am going about this all wrong, please let me know!

At idle or at 3000 RPM?

 

[ransil]

14 is too high, start at 8 probably no more than 10.

 

[mduenas]

I am going to try and clarify a bit more.

1st I want to apologize as I may not know the proper terminology
2nd, I have a lot of unknowns with the motor.

I don't know what type of heads I have, or cam. I was told it was a fully stock motor.
I do have Fitech, but without timing control.

This is the story of my timing degrees.

The truck ran for a while at 10* and had pinging under heavy load. I had determined the degrees via timing light at idle, with vacuum connected.

I then set my timing to 6* in the same manner, and the engine ran much warner and still pinged.

I determined TDC, to the best of my ability with a straw in cylinder #1 and my finger to determine compression stroke. Reset the dizzy to what I believed was TDC. set the degrees to 14, still had pinging.

I checked the timing by idle and timing light, then I removed and plugged the vacuum. I raved the motor to 3000 and checked again and the degrees read 30, then I hooked the vacuum back up and it read 20 with rpms at 3000.

I drove and still had pinging. I then reset the timing to 9* and still had pinging.

So now I just moved it to 6 and I will take it for a drive.

I don't have a helper or assistant, so I am leaning over the engine, holding the throttle and timing light to read the markers.

Am I going about this all wrong?

The truck idles around 830rpm according to the fitech and the timing gun. Dakota digital shows the idle at 730 (not sure if that is relevant information)

And lastly, I am not sure this affects pinging, but at around 2700 rpm, the engine starts to have a vibration, so maybe something is off balance causing pinging? I may be really reading right now.

I hope all this information helps, and to show you were I am at. I may be misunderstanding things, and I am totally ok with being told that. Thank you again everyone for your help.

 

[DirtDonk]

What is the coolant temp range during all this?
Even though it's not controlling timing, the FiTech might be throwing too much fuel at the engine if it thinks the engine is not warmed up yet. A rich fuel mix might not cause a ping, but then again, it might if the mixture is wacked enough to cause mis-firing.
The funny running/vibration at 2700 is what made me think of it.

I would frankly be a little bit concerned about the two different readings for rpm. Maybe not too much, since it's only 100rpm variation. But it would sure be nice if the two computers were seeing the same signal and interpreting it the same.
Do they share the same tach signal source? Maybe it's just how they read things.

But depending on which one is more accurate, 830 is too high for an idle speed. With things running perfectly something like 600 would be better.
Nothing "wrong" with 730, but it's still a bit higher than it needs to be. Especially if you have an auto transmission? I forget what type of trans you're running.

If it still pings with the vacuum advance disconnected and the timing set to less than 6 degrees, then something is seriously wrong with the setup. Whether it's a fuel/air mix thing, or a spark scatter thing, or a mis-diagnosed sound (not sure what else would sound like pinging, but hey, maybe there is something?) or what.

I forget if you said, but does it ping only under hard acceleration like you would expect from too much timing advance? Or does it ping under light load too?

Paul

 

[DirtDonk]

Oh, and since you don't know what cam is in it, are you sure you have the correct firing order?
Are you using the 1542, or the 1372 firing order?

When you verified the number one compression stroke, did you go to the next cylinder in either order (either #3 or #5) to see which one comes up next?

Paul

 

[mduenas]

Dirt Donk,

Hopefully this answers some of your questions and brings clarity.
I know my firing order is correct, I tried the other firing order for the 302 around my year and it sputtered and shook and wouldn't start. I did feel each consecutive cylinder after as well.

This first data log is after I dropped my idle to 620 (according to the fitech) (not sure if the dakota digital is pulling the rpms from the same area).Previously, with my distributor at 10 and 14 degrees, if I lowered my idle below 780, the truck would die at a stop. At 6* it didn't die when I lowered the idle. It would sputter and then I could hear the fuel pump working and it would pick back up.

Here is a 40 min log, of traffic and freeway driving, and one quick hill climb, where I still had a marble sound in the engine.
https://drive.google.com/file/d/1OcG38B2KLkmmFVgDa7Q8ccGD9noSf6TH/view?usp=sharing

The shaking (vibration) I spoke about before actually starts right about 2200rpm and builds to about 2500, then slowly feels less(?) after that, but still there. Not a drive shaft issue, I have driven front wheel and then just rear wheel and the same thing. It also happens if I rev in neutral or park.

This is a log from when my timing was at 10* and I was driving up a mountain.
https://drive.google.com/file/d/1Og0xWsFAZ1tE5iNdEf35urL4X9rRXEpl/view?usp=sharing

I had severe pinging (marbles in the engine) I also had to stay in second gear to climb, because I don't have the proper gears for my 33" tires and 700r4 transmission.

To me it looks like I am running rich, which I think would help with pre-detonation? So does this mean my timing curve needs to be changed with the vacuum advance? A change of the spring? I am going to plug the vacuum and drive without it, and see what happens.

 

[nvrstuk]

So many unknowns... has it EVER run properly...like before the FiTech or adding the new distributor? This is important...we've got to start eliminating possibilities.

What type of distributor?

Another issue could be the mechanical timing (timing chain) being off a tooth or two... this could be another potential issue if the ignition timing isn't the culprit.You did mention it had very little power at times...

150 psi static can easily run on 87 octane UNLESS the pressure is bleeding off at idle because the cam has so much overlap...which it doesn't seem very likely from what you've told us so far.

 

[nvrstuk]

So I reread your original post looking for dist info. So I cruised to Summit and this was the FIRST post...


From Summit-
"I installed the dizzy (PNX-D130700) with its stock out-of-the-box settings and found the vacuum canister added 16° of advance and it is not adjustable. That sucks as it makes 45° of total advance at 2800 RPM. when it should be no more than 34°. Any suggestions?
Asked by DAVID on September 27, 2019

A:
We do offer an adjustable vacuum advance that can be bolted on it. The part number is D909005"

I am leaning towards a distributor issue with too much advance at part throttle (vacuum advance issue).

Call Summit tech line or wherever they got this distributor.

 

[Broncobowsher]

Have you tried to drive it without the vacuum advance hooked up?

To the comment above about 45° with full advance and high vacuum, that is correct. You do what that much advance. The 34° is correct if you have a good head design and no vacuum advance (full mechanical only). Sorry, but that Summit customer doesn't know timing. Yes there are some adjustable advance cans that will allow tuning, but tuning vacuum advance just about takes an engineering dyno to dial in all the part throttle driving that is nearly impossible to do repetitively any other way.

Couple more questions. Have you ever done a compression test? What are the numbers? Gives an idea what cylinder pressures you might be working against. Another, have you ever tried a tank of high octane fuel? Your stock build engine could have been built with just the right mix of parts to actually be a very high compression engine. Small chamber heads, generic flat top pistons, decked block and milled heads. That can all add up to some wicked compression ratio.