2 replies to this topic

[ceegee]

I have a very low mileage 998 that I have just fitted a Swiftune SW5 Cam, Mini Spares stage 1 tuning kit, light weight duplex timing gear and very lightly modded, skimmed, cylinder head (mostly just to clean/smooth things up) with standard valves. I was wondering whether anyone out there has experience of tuning this sort of set up and what would be the optimum ignition timing to get it running nicely? Any other words of wisdom on this topic would also be appreciated.

Thanks

[Jupitus]

I have a very low mileage 998 that I have just fitted a Swiftune SW5 Cam, Mini Spares stage 1 tuning kit, light weight duplex timing gear and very lightly modded, skimmed, cylinder head (mostly just to clean/smooth things up) with standard valves. I was wondering whether anyone out there has experience of tuning this sort of set up and what would be the optimum ignition timing to get it running nicely? Any other words of wisdom on this topic would also be appreciated.

Thanks

What I would do is get on the phone to Swiftune, give them the details you gave us, and ask them what they would recommend

[dklawson]

Actually... the best answer to your question is to suggest the following which I seem to post every month or so. Perhaps a FAQ is in order.

Idle your engine until warm then stop it, disconnect and plug the vacuum advance line.
Restart the engine and use the idle screws to bring the engine speed up to 4000 RPM.
With the engine running at speed, set the dynamic timing to about 32 BTDC.
Tighten the dizzy back down, reconnect the vacuum advance line, and reset the idle speed.
Test drive the car putting it under load accelerating uphill in a higher than normal gear.
(For a hill you'd normally take in 3rd gear, use 4th and accelerate)
Listen for knocking and pinging. If any is heard, retard the timing in 2 degree steps followed by another test drive and adjustment until the pinging/knocking goes away.
(This retarding of the timing can be done at idle based on the advance you see at idle RPM... just make 2 degree steps down from where you are each time).

When no more knocking or pinging is heard you have the MAXIMUM advance your engine can tolerate for its condition and the fuel you use. You can record this idle speed advance value and use it in the future tune-ups without using the 4000 RPM adjustment. Remember, if you switch to lower grade gas and as deposits build in your engine the pinging may return and you'll need to retard the timing more until it goes away.

Swiftune can make arbitrary recommendations but setting the max advance as I describe above gives you the most you can tolerate for your engine's unique situation.