A friend asked me about the correct engine timing for his 1.6, 8 valve motor with a carb. I don´t have the Vitara FSM, but I figgered that the value would be the same as the 1.3 carbed Samurai, which is 10* BTDC @ 800 rpm.

However, after asking me, my friend "decided" to take a look in his fawking owner´s manual and found that the Vitara motor timing is 8* BTDC.

So why the difference?? The only thing I could think of would be the difference in stroke. Would this be it?? If so, why??

TIA

I would say the tail pipe emmissions - you would think that earlier timing would allow more complete combustion, but perhaps they are deliberatly allowing a bit of HC into the catalyst - it requires a certain amount to burn and stay hot, otherwise it passes too much NOx. Perhaps other settings leaned out the mixture too much, and this was a fix.
My best guess.


deepmud

Ignition timing depends alot on the cam that your using.
Timing doesn't know the difference in stroke.
The valves opening and shutting control when ignition should occur. Other factors are minimal.

I have never touched the timing on my 1.3 it runs too good to worry about it.

Other motors I always timed by ear, get it running and keep advancing it until you get spark knock or the starter bucking when you start it hot. Then retard it slightly.

Trial and error. adjust drive sdjust drive until you get optimum performance.

You should have timing advance turned off when adjusting timing, whether by ear or timing light. The old school method I was taught was adjust to 18" of vacuum at idle, with vaccum advance removed from the distributer. I am not sure how that would work with F.I., though.
deepmud

Hey Silver... Is yours set at 10* or is it set at something different?
Iv'e had problem running mine @ 10* as we are suppose to.

I have never checked it on my 1.3.
It runs too good.
If I think about this week, I'll put a light on it.
I'll be out most of the week shooting and cutting up deer.
I usually shoot 3 Dad shoots 2 or 3, and my friends usually bring theirs over for me to process.

Busy week.

my 1.3 runs fine with 10BTDC but1.6 8v with 1.3 carb likes 3or4 BTDC at most, pings like crazy with anymore lead...............:D