8 replies to this topic

[pierres]

mini 998 standard engine plus rc40 1.75" exhaust
need to do the timing at the weekend
Haynes say 8deg at 1500rpm vacuum tube disconnected and blocked
Have heard some people use 10deg at 1000rpm vacuum tube disconnected and blocked
does this work out the same or not ??

[dklawson]

See the thread linked below:

http://www.theminifo...92-timing-help/

 

Specs published 30 to 40 years ago for a "new" engine with the then common fuel will have little bearing on what is currently correct for your engine.  Published timing specs should be considered a starting point, not the end goal.

[pierres]

See the thread linked below:
http://www.theminifo...92-timing-help/
 
Specs published 30 to 40 years ago for a "new" engine with the then common fuel will have little bearing on what is currently correct for your engine.  Published timing specs should be considered a starting point, not the end goal.

Thanks for that but how do I add a 32 BTDC mark to the pulley as I only have the basic timing light
So what is the difference between 8 and 10deg settings please don't say 2deg

Edited by pierres, 18 November 2015 - 02:52 PM.

[CityEPete]

You need an advanced timing light, you then set the light to 32 and time the car to 0 degrees on the pulley,one with a digital tachometer is with having so you don't need to keep looking inside the car and it will be more accurate.

[dklawson]

If you only have a basic light you have to add the 32 degree mark to your front pulley.  You can do this with a little math.

 

Get a dress maker's measuring tape (they are cloth, not metal).  Clean the front pulley where the timing mark is... all the way around.  Wrap the tape around the pulley and get as accurate a measurement as you can for the pulley circumference.  Write that down.  Now multiply that measurement by 32 and divide by 360.  Write that number down.  The number you just calculated is the distance between the existing zero (TDC) mark on the pulley to where the 32 degree mark needs to be made.  Use your tape again to accurately locate the 32 degree mark on the pulley.  Make a punch mark there and fill the mark with white paint.

 

Time the engine as listed in the other link, lining up the zero pointer with the 32 degree mark on the pulley with the engine running at 4k RPM.  If after your load test drive you determine you need to retard the timing, do that at idle.  Start the engine and let it idle to temperature.  Do not adjust the engine speed.  Use your simple timing light to determine where the timing is now.  Write that down.  From wherever the timing is... retard the timing 2 degrees and write that value down.  Do the test drive again to confirm there is no knocking and pinging. Repeat as necessary until no pinging/knocking is heard.  When you are happy, make one last measurement of the timing.  Write the timing figure and RPM down for future reference.  Those are the values you can use again in future tune ups.  You have determined the max advance for your engine with its unique build / condition and the quality of fuel you are using.

[pierres]

Thanks for all the replies

[KernowCooper]

Engine to engine you may find that your not able to run 32degs maximum advance on unleaded

[dklawson]

Which is why you load test the engine by doing something like accelerate uphill in too high a gear listening for knocks and pings.  If bad noises are heard, you retard the timing in 2 degree steps until the engine is happy.

[CityEPete]

The whole process it's much easier and more accurate/repeatable with a proper tuning light with a tacho and advance setting. Best tool I've purchased in the last few years.