Retarding CAM timing

[drexchan]

If I retard the CAM timing for let say 4 degrees, do I need to advance the ignition timing for 4 degrees? Please enlighten.

 

[CcL]

why wanna retard cam timing?
get sluggish off the line performance wor...

 

[flamefox850]

i assume u are retarding SOHC cam right ? then if the distributor attach to cam..of cos u need to advance ur ign timing at least 4deg to compensate 4deg retard of cam timing

*from what i know, retarding cam timing on sohc will ensure powerband to go upper rpm range

 

[drexchan]

flamfox,

*from what i know, retarding cam timing on sohc will ensure powerband to go upper rpm range

That's what I intended.

I have a same thinking coz the distributor is attached to the CAM. BUt someone selling the adjustable cam pully say no need.... I just want to reconfirm. Siemens-VDO is not that friendly. Needs a PDT2000 to advance the ignition timing.

 

[drexchan]

I am now starting to doubt on the seller's professionalism.

 

[flamefox850]

u can feel the hp going towards high rpm la. dun worry..just try it. u've got nothing to lose. trust me

 

[mengz]

does the ecu auto adjust the ignition timing? like for my car no distributor, my fren told me that the ecu will auto adjust to the retarded cam timing, no need use MUT or PDT2000 wor. issit true?? anyone can clarify this?

 

[drexchan]

retarding yes. when the ECU sense knock. But advancing (as in my case), I afraid that a PDT2000 is required. But somehow, the SC guys (that I asked) don't know how to do it.

 

[cyborgsabah]

the ecu will retard the ignition timing when its sense knock but it only retard as low as your base ignition timing, and vice versa when its sense less or no knock, it will advance your timing... so becareful when advancing your ignition timing dun advance so high as the ecu will not be able to retard the timing to a safe level...

 

[boyzone]

how about DOHC one ?? is it same adjustment ?? for my 4G91, there is no have knocing sensor, can it retard itself ??

 

[Noskid]

hmm..... ....how abt car like 4g15(carb)...how 2 retard the cam timing??
me noob here la....^^"

 

[drexchan]

so.. please forgive my ignorance, but can you confirm that the ECU automatically advances the timing as well? In what circumstances? If you say when it doesn't sense any knock.. then I suppose the timing is variable based on the feedback of the knock sensor. Correct? If an adjustable cam pulley is used and the cam timing is retarded, the ECU will automatically advance it to harvess the max performance out of it?

 

[mengz]

okies...i've just spoken to my mechanic which told me that there's no such thing as retard cam timing 4 degrees means must advance ignition timing 4 degrees, or vice versa. the amount is not fixed, thats why need to go for dyno tuning to get the best results. the best is to get a piggyback or ems which allows u to adjust ur ignition timing on various rpm lvls.

come to think of it, retard/advance cam timing to X degree's and advancing/retarding X degree's on the ignition timing, won't it cancel out the effect? its just like 0 degree on cam timing and 0 degree on ignition timing? logically la :P

 

[drexchan]

not logic IMHO, how can one equalize ignition timing (spark)and camshaft timing (intake and exhaust valves)?

Lets start looking at the changes on the camshaft, distributor relative to the crankcase when we adjust (let say, retard) the cam timing.

We focus on SOHC, where the distributor is attached to the CAM. First, imagine that you are standing on the cam pulley side.

The camshaft rotates anti-clockwise right?

So, when the CAM timing is retarded for x degrees (pulley rotates anti-clockwise), the CAM will rotate clockwise for x degrees relative to the pulley, and 2x degrees relative to the crankshaft.

Remember that the distributor plate will also rotate clockwise relative to the crankshaft for the same 2x degrees, and that's retarding the ignition timing.

In short:

retarding cam pulley timing -> retarding ignition timing.
advancing cam pulley timing -> advancing ignition timing.

So, on my SOHC, I need to advance the ignition timing back to the base timing as it has been retarded, relatively.

If the ECU is able to advance the timing to harves the max out of it, to what extend?

Correct me if i am wrong.

 

[cyborgsabah]

so.. please forgive my ignorance, but can you confirm that the ECU automatically advances the timing as well? In what circumstances? If you say when it doesn't sense any knock.. then I suppose the timing is variable based on the feedback of the knock sensor. Correct? If an adjustable cam pulley is used and the cam timing is retarded, the ECU will automatically advance it to harvess the max performance out of it?

yes.. in most EFI engine, the ignition timing are variable.... thats why other than fuel maping you got ignition timing maping too....

 

[flamefox850]

not logic IMHO, how can one equalize ignition timing (spark)and camshaft timing (intake and exhaust valves)?

Lets start looking at the changes on the camshaft, distributor relative to the crankcase when we adjust (let say, retard) the cam timing.

We focus on SOHC, where the distributor is attached to the CAM. First, imagine that you are standing on the cam pulley side.

The camshaft rotates anti-clockwise right?

So, when the CAM timing is retarded for x degrees (pulley rotates anti-clockwise), the CAM will rotate clockwise for x degrees relative to the pulley, and 2x degrees relative to the crankshaft.

Remember that the distributor plate will also rotate clockwise relative to the crankshaft for the same 2x degrees, and that's retarding the ignition timing.

In short:

retarding cam pulley timing -> retarding ignition timing.
advancing cam pulley timing -> advancing ignition timing.

So, on my SOHC, I need to advance the ignition timing back to the base timing as it has been retarded, relatively.

If the ECU is able to advance the timing to harves the max out of it, to what extend?

Correct me if i am wrong.

yerp..u r correct dude. adjusting the cam pulley timing will adjust ignition timing also on SOHC engine as the distributor also attached to camshaft.

but....yeah the ecu have auto-advance and auto-retard feature. normally it will advance timing when sense less boost or got vacuum as 'it' dun want the engine die when idle and got more umpphh when using a little high gear on low rpm. and it will auto-retard when sensing more boost coming (if turbo)

that's why i only using bigger injectors and set -ve setting on my safc, my engine got horrible knock even though i never touch my distributor at that time. this is cause by the ecu sees less boost with the -ve setting at safc.

and yes, dyno tune, knock sensor tuning and wide band tuning is a must when u want more power and more safe ride. but for poor guy like me...what to do...adjust secukup rasa only la hehehe