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Timing / detonation at high RPM question

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#21 ·
retarding the dizzy.. CW, makes TDC timing mark on balancer move more to the left, away from zero tab mark...viewed from the front...?? thats what I see.. so timing tab goes higher in degrees from the zero tab mark.. ? I must be wrong with this thinking..? If my IT is 28* and I rotate dizzy anti-clockwise it will move balancer TDC mark closer to 27-6-5-4* etc closer to the tab, this is advancing...??? (therfore more detonation/pinging) help me understand. cheers.
 
#22 ·
denholden said:
retarding the dizzy.. CW, makes TDC timing mark on balancer move more to the left, away from zero tab mark...viewed from the front...?? thats what I see.. so timing tab goes higher in degrees from the zero tab mark.. ? I must be wrong with this thinking..? If my IT is 28* and I rotate dizzy anti-clockwise it will move balancer TDC mark closer to 27-6-5-4* etc closer to the tab, this is advancing...??? (therfore more detonation/pinging) help me understand. cheers.
Click to expand...
When you rotate the distributor counter-clockwise you are retarding the timing. The mark as seen with the timing light would move towards the timing tab. Anything above zero is advanced. Anything to the right of zero is retarded. Typically less advanced equals less detonation.

Are you sure you have the timing light connected to #1 plug wire?
 
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#23 ·
Thanks for the reply, yes #1 plug, We are both on the exact same track and correct with the mechanical process, we/they are both same. I think my difference is that I call Dizzy clockwise rotation 'retarding' and anti-clockwise 'advancing'.. I refer it this way because of the firing of the plug, turning dizzy clockwise makes the spark fire later in the cylinders rotation, hence retarding.. doing the opposite is advancing the "spark' , thats my understanding.. (some think advancing is the direction the dizzy is rotated when clockwise..its actually when the spark fires..it functions the opposite ) anyway I have photos in this post, check above for my post visual positions.. and the @28* mark at idle. Do I make sense with this..??? I guess it depends on peoples perception. Cheers.
 
#25 ·
To clarify.

Most folks here know that advancing the timing causes the spark plug fire further in advance of the piston reaching top dead center and retarding makes it fire closer to piston TDC.

Firing further away from TDC increases possibility of detonation. So if you rotate the distributor from 28* so it fire later, for example 18*, the chance of detonation is lessened.
 
#26 ·
Don't rule out carbon buildup and crappy gas. Pull the plugs and check. Seafoam + a good long highway run can do wonders for a motor that isn't used much. Running too rich too long = carbon buildup. I used to get ping if I applied full throttle below 2500 RPM. Now I add a bottle of VP Racing Maddative Octanium Octane Booster when filling up with 93 Octane, this has eliminated ping and kept my plugs clean.
 
#27 ·
Vega$69 said:
To clarify.

Most folks here know that advancing the timing causes the spark plug fire further in advance of the piston reaching top dead center and retarding makes it fire closer to piston TDC.

Firing further away from TDC increases possibility of detonation. So if you rotate the distributor from 28* so it fire later, for example 18*, the chance of detonation is lessened.
Click to expand...
I will investigate and check further, no answer why yet at idle 28* run ok ….. 14-18* detonation and pinging. ??
 
#28 ·
To Clarify..

"So to advance the initial timing, you must move the distributor against rotation (counterclockwise). To retard the timing, you would twist the distributor with rotation (clockwise).1 Dec 2005"

I was correct.
To adjust timing from 28* to 18* is advancing, detonation increases it is not lessened. any firing before TDC is advanced and depending on the degrees can create hammer/detonation, ATDC it is retarded..also depending on degrees creates no detonation but a slight loss of power...
 
#29 ·
Incorrect. If you adjust timing from 28* to 18* you are retarding the timing which typically lessons the possibility of detonation.

28* Is advanced 28* BTDC. Anything before Zero is advanced. 18* is 18* BTDC. So it is advanced 10* less than 28*. By making this change you’ve retarded if from where you were at 28*. It is still advanced but not as much as before. Retarding it further 10, 6, 2, all the way to 0 TD it is still advanced If you keep going to ATDC it would be retarded 2, 4, 6 and so on.

Example. If the timing is retarded to 10* ATDC and you move it closer to 0 you are advancing the timing from where it was set.

Again if changing timing to lessen detonation, reducing the degrees of advance before TDC is the procedure.
 
#32 · (Edited)
To advance the timing on a small block chevy, the distributor is turned counterclockwise. To retard the timing, the distributor is turned clockwise. When you advance the timing, you are making the spark fire before TDC. The further it is advanced, the earlier the spark will fire "before" TDC.
 
#33 · (Edited)
If you don't remember which way to turn the distributor, just look at the direction of the vacuum advance port and notice the angle . When vacuum is applied, it pulls the inner mounting plate CCW advancing the timing, same goes for moving the distributor CCW.
 
#34 · (Edited)
OK, now, we know. "The dyno sheet from the builder". Yet another Top Fuel/Funny Car engine for the street, more than likely a few things, no vacuum advance, too much total timing for the higher compression ratio, initial is finally where it should be at 14, but the rest of it is Dyno Hero insanity.

A dyno IS NOT a tuning device, never has been, isn't now, never will be, it is a PARTS EVALUATION DEVICE, noting more. If one is trying to "tune" on one, you lose. Dyno's like way too much timing, and rich mixtures, and that is why they tell you the engine is making 900 HP @ 9K, and will not back off the dyno under its own power.

Lets take a loo at reasonable setup. Initial, 14,, good. No properly set up vacuum advance, does not give the 24 IDLE, and no load added degrees the engine likes Total, 38, more than likely a lot more than the C/R wants.

We still need to know three key issues, what static c/r does the engine have, what is the quench distance, and... what degree does the intake valve close at???????

BTW.... EVERY Chevrolet small block, big block, Mystery, and "W" series engine I have seen, has a distributor rotation clockwise, right hand rotation. To RETARD timing, looking down from the top of the distributor.... rotate clockwise, to ADVANCE, counter clockwise.
 
#36 ·
I need to clarify, and possibly...edit something I said before, as to "no-one has ever driven a dyno around the block". This is true in every sense, except one, in that dyno's are firmly mounted to the floor, but... I, myself, say that "there is only one real dyno for final tuning... 'The Seat Of The Pants Dyno'".

I do believe it is time for explanation, and a change in the wording of my statement. I firmly believe there is only ONE method of final tuning, and it involves sitting one's BUTTOX in, for a car, or, on, for a motorcycle... seat, and DRIVING/RIDING the vehicle. The human body is, in fact, a very strange dyno... with sensors for a number of things, inputs for vibration, acceleration, sight, hearing, feel of input devices such as throttle, brake, gear, acceleration, deceleration, side thrust, and many more, with direct evaluation on the go. More so, than any fixed to the ground parts evaluator "dyno".

So, in rethinking my naming of the Seat Of The Pants "DYNO", I will change the last word, from DYNO, to "PERFORMANCE EVALUATOR".

This brings me to my redo... "The Seat Of The Pants Performance Evaluator", and there has to be one in/on every vehicle being tested, or the testing isn't possible. This sounds like myrth and merriment, but, it is as serious as a full blown heart attack, you cannot get the input, evaluation and testing the SOTPPE gives, on a fixed mounted parts evaluator.

There are a couple of sayings, one with a '(fill in the blank)' that fits almost everything ever thought of. First, What is a (fill in the blank)...If YOU can't have fun with it? The second is just a statement... "Be ALERT... and, pay attention. Why? Because we need more 'LERTS' whom pay attention".
 
#37 ·
Thanks to everyone’s input, I appreciate the feedback from all who commented , it helps learning. I am now wondering that what put my timing way out ? This all happened when I changed all my plugs to correct reach plugs, the originals were ‘short’ in the vortec heads, it began to run different and rich,and pinged on throttle, this is when I re-did timing by drive/feel. This is when I checked 28* @idle. I have now got it back to 18-20* with the dizzy rotated more retarded, CW. It is further rotated that original position with wrong plugs. I haven’t test drived yet as weather is bad but idles sound good and restarts first go. Funny though Checking total timing at 2500+rpm, I didnt over rev it, was @55* and didn’t look like changing?? Slowly getting on top of it. 👍👍
 
#38 ·
At 2500 RPM you want to be at 30-35 degrees of timing "all in" (read with vacuum advance plugged). Your timing at that point is vase + mechanical as VA has gone away.

Generally, with VA distributor, your base (without VA) is 8-12 degrees and with VA at idle if your VA provides 8-12 degrees also you should be 20-24 degrees of timing at idle. If VA adds more than 12 degrees advance, back off base timing accordingly....or control VA limit which is another conversation but an important one relative to ideal timing

And yes, the Butt-O-Meter is a valuable tool if one has a calibrated one;)
 
#39 · (Edited)
I’ve not read the entire thread here, so I apologize if the has been covered.

Considering all the confusion and oddities on this, you might want to test for true TDC and insure it is (or get it) marked correctly on your damper. Then make sure your timing marker is in the correct position to monitor the reading accurately.

Just a thought from where I sit 😜

YMMV.
 
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denholden
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