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Discussion Starter · #1 ·
I want to retard my ignition timing by turning my CAS a bit just to be safe until I can get it to a proper garage. I have seen a CAS turn all the way to the left, is that fully retarded or full advanced?

The car is basically a stage one. How much I have to turn my CAS down just to make sure it is a bit safer to use optimax?

Also, which direction to turn it? I think turning it toward the left retard the timing, and turning the CAS to the right advance it right? Not 100% sure.

A picture will help greatly as I am a bit confused when it comes to my left and right on a circle. :p
 

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hey jza - I'm a little confused here so basically If my ignition is at 15degrees (which it is now) and I turn the CAS clockwise a touch am I lowering the ignition to 14degrees? I thought it was anti clockwise?
 

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Right.

The engine rotation is clockwise : If you trun the CAS against that direction (anti-clockwise) you are advancing the timing (i.e. spark is coming sooner, before top dead center). If you turn the CAS in a clockwise direction that is delaying spark relative to TDC, in other words, retarding spark. So if you are at 15deg BTDC now, if you want 14drg BTDC you need to retard by 1 deg, you do this by turning the CAS in the direction of engine rotation, clockwise.
 

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Discussion Starter · #5 ·
since we are on this subject and I don't quite understand the process on the tread I read (not very good at maintance)

I know you want to be around 15 degree BDTC (what is BDTC?) for a GTR on UK fuel.

Question is, how do you figure out that you are 15 degree BDTC? I have heard the RB26 is 20 degree normal? and you got to do some math to get the 15 degree BDTC?

If someone can help me out here and give me the process to get it right, I'll most greatful. :bowdown1:
 

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you use a timing gun!

the notches on the crank denote 5 degrees

i have mine at 20degrees 980rpm, air con ON

no det whatsoever on 97/98/99 octane fuel but i inject a 10% methanol mix above 0.6bar through an aquamist syatem

BTDC

is

Before Top Dead Centre
 

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thanks TFS thats a great explanation :)
so basically If I wanted to retard it by 3 degrees I turn the CAS clockwise to make the spark occur later. I'm gonna get a timing light too and see how I get my head around that. read another thread and it seems quite straight forward :)
 

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yes its pretty easy with a HT lead..

yes turn clockwose about 1-3mm (use a gun to be sure!)
 

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There is a LT wire loop at the rear of the cylinder head that you use to check ign timing, a Snap-On light works well with the pickup left in the open position. There is other info on this procedure in the forum if you do a search.

...but 15deg is pretty retarded for the RB26, you will lose response and also the motor will run a bit hotter, too. For the lousy 91 octane (R+M/2) fuel we have here, I find 18deg to work OK as a compromise. Your fuel surely must be better than what we can get here in Calif so you should be able to run at least that much advance...
 

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I've just bought a timing light myself today - I've read that gtr's want to be at 20degrees and gtsts need 15 ideally. I'm not 100% on how the timing light works but If I get me car sorted out tonight with it I'll get a few pics up and let ppl know how it runs afterward. Speaking to Rod Bell and he said it should be sat at 15degrees on idle really - he was mentioning retarding it by 1degree to 14 but assumed I were using a timing light which I weren't at the time. Hopefully I'll have my shoddy ignition timing sorted out tonight :)

theres one question I do have tho - I have the powerFC in my car - if I'm using the timing light to check the static ignition timing (on warm idle) wont my pfc adjust the ignition all over the place? If thats the case how do I go about disconnecting this whilst I find out what the SIT is? I just want to get the car back to 15degrees SIT and I'm pretty sure its not at that value as I have to retard the ignition to 11 degrees (-4 in option7 on the pfc)
any thoughts on this are really appreciated - the car is running great but knocks on boost unless I retard to 11degrees - obviously all power is gone with that :(
 

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Disconnect the throttle position sensor first then set the timing to read what the PFC says. Then you can adjust ad-lib from the hand controller.
 

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thanks matey. I'm assuming disconnecting the tps sensor will prevent the pfc from adjusting my ignition on the fly as the engine runs?
also the hand controller never needed any adjusting when I had the old belt on - it sat comfortably at 15degrees and I'm pretty sure this is the static timing ignition that he set as yday he mentioned knocking it back a degree to see how it goes.
I was getting max knock counts of 12-15 on mental hoofing and that was with a dodgy cambelt so chances are it should be smoother once I match the timing to the 15degrees the pfc shows :)
thanks mate - cant wait to leave work hahaha!

erk just thought on - is the tps sensor plug the brown one above the block at the front just in front of that metal pipe beneath the strut bar? (see image below)
if so as you can see on mine it aint even got anything plugged in!!
 

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but the plug underneath it has, follow the small loom which goes into the bottom of the sensor.
 

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thanks Martin.
well I made the adjustment last night but I didn't disconnect this sensor. I basically used the timing light and when I shone it at the crank I found out the car was sat at 25degrees?!!?! way out!! Anyhow I turned off engine, adjusted cas clockwise ..10 degrees ..adjusted the cas anti clockwise and it was sat nicely at 15degrees.
took the car out and it was far far smoother - no knock and got the car up to 0.6bar with very little knock (16being the highest and that was crapola gear change). However wet roads and lots of rain stopped me really trying it out but it seems promising and its good to know I can get a whiff of boost from the car now!

however my idle was at 800rpm which was adjusted from the stock 650rpm (car kept stalling so we upp'd the idle & made changes to fuel cut off points (hasn't stalled since then.)
I'm gonna knock down the ignition to a stock 650rpm using the pfc tonight then disconnect the throttle position sensor then I'll see the true ignition degree on the crank - from there I should hopefully be able to get the car back to how it was - heres hoping :)
 

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There is a LT wire loop at the rear of the cylinder head that you use to check ign timing, a Snap-On light works well with the pickup left in the open position. There is other info on this procedure in the forum if you do a search.

...but 15deg is pretty retarded for the RB26, you will lose response and also the motor will run a bit hotter, too. For the lousy 91 octane (R+M/2) fuel we have here, I find 18deg to work OK as a compromise. Your fuel surely must be better than what we can get here in Calif so you should be able to run at least that much advance...
inject methanol on boost, 10% would bring you to almost 100ron ;)
 

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update..

reet got the car home last night after work - nice n warmed up so made most of that and the dry weather:

-disconnected the throttle sensor plug - car immediately starting idling at 950rpm +/-50rpm ...bit high that :eek: The PFC would always adjust it back down to 800rpm but I thought I'd save it the extra work
-Adjusted the idle screw on the AAC valve and brought it back down to 800rpms. plugged throttle sensor plug back in - hey presto no adjustment from the PFC :)
(on a side note obviously the rpms were up n down but they stayed in the 750-850rpm range at all times after this)

-after that I used the PFC to bring the ignition down to 650rpm - let the car idle for a moment or two and find its feet
-using the timing light I noticed that the ignition was a little bit advanced (even tho it was dead on 15degrees last night but that was at 800rpms) - probably sat at about 17degrees.
- whilst engine was running at 650rpm I very carefully loosened off the CAS - like my knuckles but the fan had no qualms about letting me know which was the tougher of us... numerous times!
-made a tiny adjustment (we're talking 1mm!!) anti clockwise to advance the ignition a touch and checked the markings again with the timing gun. Bang on 15degrees hoot!
-made the most of the dry weather and took it up the road - car knock levels seem to safely sit well on the ground on bimbling 30-50mph speeds and when I used my right foot and went through the gears going through all the rev range I didn't see a knock count above 20. still seemed a little high for me so I adjusted the ignition to -1 degree on the PFC and tried again - didn't see anything above a knock of 12 hurray!

-worth mentioning here that Rod Bell suggested that the signal given to the timing gun is always delayed a touch and he suggested adjusting the CAS then driving it to find my way back to my original knock levels. However since the fitment of the cambelt and other bits + full fluids change I think its unlikely I'm gonna see the knock levels in the same way i used to - they appear quite a big rockier prob due to much more responsive engine vibration or something - the good thing is they're staying nice n low now so I'll see how it goes on.

hoofed it to work like a loony and its awesome - not a peek from the engine too - rather chuffed with myself hehe :squintdan

I'll get some pics taken over the wkend (ie: at a time when I can take em whilst its light!!) and fill out this reply a little more
 
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