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ALL Dial-Back features, no matter the age, nor make of timing light, use time to recompute timing. Now, if there is no timing computation, there is no need for a computation lag time resolution program in the timing light, is there!

But, all you that absolutely know different, please, go do it yourself, no need to make a fuss about it.

Enjoy the inaccurate timing numbers you crave.

Very frankly, I am done in with all the mis-information and other disasters caused by bad info. I have fixed a lot more than my fair share of those end of the world timing issues and problems for people that just plain don't want to do it right, then complain about it.
 

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So, "ZL", what else is new, you NEVER agree with me, because you have some sort of idiotic personal vendetta with me that only you cares about. And, you take it way too far with disagreeing with me on EVERYTHING, when you have been consistently wrong.

It doesn't matter the truth I write in these posts, you will never see the truth, only an opportunity to defame and flame me. That, you prove with every post done after one if mine, no matter the subject.

It ain't worth having a battle of wits with a completely unarmed person, so, I choose to not have one with you, being the person that doesn't get it.

OP, a PerTronix has nothing to do with computerized computation lag times, so, no heed to correct what isn't there, leave the dial-back off, please, sir.
Never agree? I complimented your choice of a 215 V8 in a Vega a short while back. So, I guess I have to disagree on the accuracy of your use of the word "never".

You say I've "been consistently wrong". Please point out those instances (in here or perhaps start a new thread). I've got decades of engine controller design and dyno work under my belt, just 50 miles down the road from your old stomping grounds. I have a decent understanding about this stuff, and as I've shown in my posts, I state in detail the reasons (data, formulas, laws of physics, etc) for my position on those topics. I welcome your detailed reasons why you have the position/conclusion you have, and the detailed reasons why you disagree with my position/conclusion. As a fellow (Delco) engineer, an engineering discussion should be a familiar endeavor. In my prior post I explained my reasoning regarding the operation of dial-back timing lights. I'm similarly interested in your explanation of how they work.
 

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Y'all, I'm not here to argue.

I also am interested in having a dialog.

My premise, theory, supposition, etc. whatever you want to call it,
described above in post # 60.

If, non dial back timing light shoots ATI balancer at 10* BTDC,
then dial back shoots at 10* BTDC zero when dialed in at zero
and when adjusting the pot to 10*BTDC and it shoots at zero
on the ATI balancer, there should be no issues at 10*BTDC.

I'm not going into an ECU.

It is still accurate when looking at 50* BTDC?
I guess I could check using both timing lights.

Dave, please have patience with those of us who have
less experience than you. I am not claiming anything other
then what I have stated. And if different, then I'm trying to
wrap my head around it.

Is the computational adjustment of a dial back significant?

Would Dr. Deming say it's "Unknown and Unknowable?"
until it IS properly defined?

AND

What is the error of a standard timing light with regard
to the ignition timing events them selves?

When I first got this engine running, I think there was
about 2*to 3* total variance in timing. I"d watch the ATI balancer
and see the timing bounce around from about 8.5* to 11.5*.

Would the dial back do the same? I don't know, I didn't check
and I cannot until I have a working starter again.

I'll go look and see if I can find the circuits the lights use.

Dave, please like anyone who's interested in this stuff,
probably just as you were when you first learned about it,
did you ask questions? Were they answered?
As part of the De Opresso Liber force, you were trained
to be a teacher, instructor, repport builder, what has changed?

Wouldn't you have the representative schematics of each?
Can you at least take me through them?
While yes, you have the knowledge,
can you share how to got there, please?

I'm in no way trying to harass you
or denigrate you at all. I come from
an educational background, and let me
explain that undergoing peer review of
anything you write and hope to publish
is a humbling experience.

-- Spike
 

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Discussion Starter #64
so I performed a deeper search on the forum and came up with tuning my exact cam, Lunati FT 60203.
https://www.chevelles.com/forums/18-engine/396227-lunati-60203-idle-rpm-vacuum.html

Scott Wheaton posted the following:

==============
I have tuned street perf 454's with that cam which isnt that lrg for that size motor and should have a few more " idle vac then it has which i bet is due to overlly retartded base timing.

With the conservative 34 deg total your currently running i bet the base/inital timing is in the dirt like 10 deg or less which is very retartded for a motor that see street duty,strip only motor is a different story.

You must check base timing at less then 750 rpm to ensure mech adv in dist isne patially activated adding timing at idle messing up base timing setting.

Could put car in gear with wheels chocked to reduce idle to 600 rpm max when checking base timing .

That cam in many cases seems to do well with 18 deg base/36-38total timing and in some cases esp smaller motors like 396-402 bbc 20 deg base & 38+ total.

If your base timing is in fact retartded like i think you will find it to be it will respond well to the additonal base timing on the street .

The additonal base timing (if you find its in fact currently retatded like i suspect) will give the motor much better throttle responce comming off idle,more power comming off idle,idle will be better,intake vac at idle will increase a bit for better pwr brk operation,motor will run cooler at idle,mpg will inc a bit too.

So since you say the motor wont idle below 750 rpm that there tells me base timing is likely retarded so you may need to adv timing like 5-8 deg just to get it to idle down to 600rpm.

Could also be base timing so retartded it made you have to increase/set idle speed screw
higher then normal to obtain a decent idle which often pushed primary throttle blades
out of proper position in idle circut which can affects ilde quality too.

Then after you adv timing a couple deg so you can then reduce idle below 750 rpm closer to 600rpm check the base timing to see where its really at and if its not at least 17-18 deg with that cam adv it to a min of 17-18 deg .

Then you may need to swap out busing in dist or recurve it to get max of 18 deg all in by approx 2600rpm max to go with 18 deg base = 36 total in by 2600rpm .

Thats fine with that cam,many people run 38deg plus total with that cam so 36-38 deg total is well within reasonable range.

So chk base timing (at or close to 600rpm to ensure mech adv isnt adding timing to base timing reading) ,maybe you could put it in gear with ebrake on and wheels chocked to reduce idle when checking base timing.

Then let us know where base timings currently at which i bet isnt near 18 deg with your current 34 deg total timing making the motor a lot lazier then it should be below rpm where total timing is fully in which wakes it up.

I am curious to see if i am on target or not thinking your base timing is well below 18 deg at this time/LOL!!!

BTW,with your conservative 9.1 comp,plenty of cam your will respond very well to more base and total timing for sure with the cam your running in a 454 and not detonate on todays crappy 93 octane ethenoled pump fuel .

Scott


I just adjusted the base timing w/o vac to 17* running at 650rpm.With the vacuum advance connected it went up to approx. 28* and 800RPM.

Just got back from a test drive. DAMNNNNN did that engine wake up. Thanks for everyone's help.
 
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Great to hear. Now be sure the total is still in that 35 - 38 degrees range.
 
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so I performed a deeper search on the forum and came up with tuning my exact cam, Lunati FT 60203.
https://www.chevelles.com/forums/18-engine/396227-lunati-60203-idle-rpm-vacuum.html

Scott Wheaton posted the following:

==============
I have tuned street perf 454's with that cam which isnt that lrg for that size motor and should have a few more " idle vac then it has which i bet is due to overlly retartded base timing.

With the conservative 34 deg total your currently running i bet the base/inital timing is in the dirt like 10 deg or less which is very retartded for a motor that see street duty,strip only motor is a different story.

You must check base timing at less then 750 rpm to ensure mech adv in dist isne patially activated adding timing at idle messing up base timing setting.

Could put car in gear with wheels chocked to reduce idle to 600 rpm max when checking base timing .

That cam in many cases seems to do well with 18 deg base/36-38total timing and in some cases esp smaller motors like 396-402 bbc 20 deg base & 38+ total.

If your base timing is in fact retartded like i think you will find it to be it will respond well to the additonal base timing on the street .

The additonal base timing (if you find its in fact currently retatded like i suspect) will give the motor much better throttle responce comming off idle,more power comming off idle,idle will be better,intake vac at idle will increase a bit for better pwr brk operation,motor will run cooler at idle,mpg will inc a bit too.

So since you say the motor wont idle below 750 rpm that there tells me base timing is likely retarded so you may need to adv timing like 5-8 deg just to get it to idle down to 600rpm.

Could also be base timing so retartded it made you have to increase/set idle speed screw
higher then normal to obtain a decent idle which often pushed primary throttle blades
out of proper position in idle circut which can affects ilde quality too.

Then after you adv timing a couple deg so you can then reduce idle below 750 rpm closer to 600rpm check the base timing to see where its really at and if its not at least 17-18 deg with that cam adv it to a min of 17-18 deg .

Then you may need to swap out busing in dist or recurve it to get max of 18 deg all in by approx 2600rpm max to go with 18 deg base = 36 total in by 2600rpm .

Thats fine with that cam,many people run 38deg plus total with that cam so 36-38 deg total is well within reasonable range.

So chk base timing (at or close to 600rpm to ensure mech adv isnt adding timing to base timing reading) ,maybe you could put it in gear with ebrake on and wheels chocked to reduce idle when checking base timing.

Then let us know where base timings currently at which i bet isnt near 18 deg with your current 34 deg total timing making the motor a lot lazier then it should be below rpm where total timing is fully in which wakes it up.

I am curious to see if i am on target or not thinking your base timing is well below 18 deg at this time/LOL!!!

BTW,with your conservative 9.1 comp,plenty of cam your will respond very well to more base and total timing for sure with the cam your running in a 454 and not detonate on todays crappy 93 octane ethenoled pump fuel .

Scott


I just adjusted the base timing w/o vac to 17* running at 650rpm.With the vacuum advance connected it went up to approx. 28* and 800RPM.

Just got back from a test drive. DAMNNNNN did that engine wake up. Thanks for everyone's help.
You realize that's a "top fuel" timing curves and its all wrong :grin2:

I suggest trying even more....
 
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