cam timing
time for an update!
I took my stock cam gears off and fitted some shiny adjustable ones.
After installing the cam gears, initially set to zero, the car drove slightly differently.
Slightly rougher idle, maybe a touch more low end torque.
So I suspect zero on my adjustable gears is slightly different to the stock cam gears.
To find out how much, you can find exact TDC and zero the cam gears.
However I used the slightly less scientific method of finding out how much my ignition timing was out, and what exhaust cam adjustment was needed to get it back in again.
Using this method I think my cam gears give about
+1deg advance when set to zero.
I'll figure it out exactly at some point and edit the results to give accurate numbers.
So now I tried some settings.
The first few settings I tried were just with the car stationary, checking how it revved and idled, so I could quickly try lots of different settings and get a feeling for what different cam timings do.
The results were really not what I expected.
.
.
I left the exhaust cam at close to zero and tried adjusting the intake cam first.
intake
5deg advance
really lopey idle.
sounded awesome, but getting it to idle happily at
<1200rpm would be tricky! ran alright once it had some revs.
5deg retard
very nice idle.
revs good, throttle response good.
10deg retard
still nice idle, maybe even nicer! still good revs and response.
My cam gears maxed out at 12 degrees, so I set them back to 10 and moved on to the exhaust cam.
Also I should add that I was a little confused at this point, because my results were the opposite of what I was expecting! Also I double checked my cam timing and it's correct; I'm not a tooth out.
exhaust
After each exhaust cam adjustment I reset the ignition timing to 10degBTDC each time.
5deg advance
idle a bit rougher, felt boggy and revved up kinda slow when I blipped the throttle.
5deg retard
idled nice, revved up quick again.
I could get it to idle at
~800rpm to set the ignition timing, which is normally quite tricky.
I couldn't try any more, because I was running out of adjustment on the dizzy.
So, I left it like that.
I have a super sweet idle, low rpm driving is fine, and the power comes in 6000-8000rpm, and there's more power than before.
In fact I have to watch the tacho because it really doesn't drop off at all! So I'm running intake
-10, exhaust
-5, which with my cam gears zeroed I think is probably
-9,-4.
I think I might back off the intake retard a bit at some point, but I'll probably just drive it round like this for a while.