36 replies to this topic

[racingbob]

just been playing with my ignition timing set it to 30 deg full advance

 

mg metro engine  new stage 3 head mg metro cam lucas electronic dizzy

 

does that sound about correct comp is a about 9.75 to 10.1

 

was showing 34 and thought a bit much

 

does ignition timing change over mileage or always the same once set

 

and if so does it normally show more retard or advance

 

 

 

 

[tiger99]

It changes. Wear of the timing gears, chain etc retards it generally but distributor shaft wear makes it fluctuate at random. Points, if you have them, suffer wear of the cam follower, which retards and increases dwell.

But these effects, except for the points, are very small on engines that are in good condition.

[ACDodd]

When you say change, do you mean physically change? Or the ignition advance requirement change?

Ac

[racingbob]

When you say change, do you mean physically change? Or the ignition advance requirement change?

Ac

general wear- example say after 10000 miles say was set to 30 but now showing different say 32 due to some king of wear

[lrostoke]

With a standard dizzy if setting for max advance its worth checking what degree of advance the cam in the dizzy is.

 

example if you set for 30 degrees max advance with an 8 degree cam , your static advance could be as high as 14 degrees which could give sluggish starting.

[ACDodd]

It does change with wear, usually retardation. If points it can advance.

Ac

[racingbob]

It does change with wear, usually retardation. If points it can advance.

Ac

thats interesting to know

 

after reading vizards book have set it to 32 deg at full advance till dyno

[carbon]

Total advance depends a lot on what fuel you're using. Is this with 95 or 99 octane?

[racingbob]

Total advance depends a lot on what fuel you're using. Is this with 95 or 99 octane?

its v power with  castrol valvemaster so yes about 99 all up

[Spider]

Good to see you about Bobby, following your surgury, trust all went well for you mate

 

 

Total advance depends a lot on what fuel you're using. Is this with 95 or 99 octane?

its v power with  castrol valvemaster so yes about 99 all up

 

 

The Total Advance needed will also depend on the Combustion Camber and how the flame front travels across / through it.  For standardish shapes, it's generally around the 28 - 32 range, but some of the more open ones can need more, but just depends on the shape. The RR really is the only place you'll find out.

 

Be aware too that some additives can reduce the Octane rating too.

[racingbob]

Good to see you about Bobby, following your surgury, trust all went well for you mate

 

 

Total advance depends a lot on what fuel you're using. Is this with 95 or 99 octane?

its v power with  castrol valvemaster so yes about 99 all up

 

 

The Total Advance needed will also depend on the Combustion Camber and how the flame front travels across / through it.  For standardish shapes, it's generally around the 28 - 32 range, but some of the more open ones can need more, but just depends on the shape. The RR really is the only place you'll find out.

 

Be aware too that some additives can reduce the Octane rating too.

hey Chris good to hear from you, surgery went ok was 5 hours still re-couperating

 

valvemaster has added 2 octane

[Trissy B]

Sorry if i'm hijacking the thread but I have just checked mine this morning and had 24 deg BTDC using a strobe at 1500 RPM. I've got a similar but not as good spec as racingbob - only the standard head for me.

 

The book says 12 deg. BTDC so I retarded it a bit to about that. Now seems a bit boggy at low revs...

 

Totally confused now!

[racingbob]

Sorry if i'm hijacking the thread but I have just checked mine this morning and had 24 deg BTDC using a strobe at 1500 RPM. I've got a similar but not as good spec as racingbob - only the standard head for me.

 

The book says 12 deg. BTDC so I retarded it a bit to about that. Now seems a bit boggy at low revs...

 

Totally confused now!

if your a bit concerned take it to a dyno like i am, but waiting for Slark to get  back off holiday

 

can you check it at 3500 - 4000 after reading vizards book i am happy at 32 deg until dyno

 

always mark the dizzy so you know where you are

[Trissy B]

Ok thanks - i've got vizard on the shelf so will give that section a read. Will check it at 3.5-k revs then too.

 

Cheers

[racingbob]

well i just checked mini again and shows about 32 full advance

 

but at 1500 revs vacuum off at the carb only shows 5