10 replies to this topic

[Neildanks]

I have purchased a mini sport camshaft kit and a vernier timing chain setup, i am using a timing disc setup to set the camshaft to crank timing as in the A series video mini builder.

Now he sets his vernier timing chain to get 107 and 1/4 degrees but this differs to every cam i understand.

How do find this figure. I have set to 108 degrees at the moment and do not want to carry on my build until i am sure this is correct.

When i contact mini sports for this information all i get thrown back at me is the figures below

24-64/59-29

these figures do not mean a thing to me, i think these are figures which relate to distributer timing.

Can anyone explain how i find the figure in degrees as in the DVD A Series 1380 Build

I hope people can understand what ive tried to explain please help.

[Neildanks]

The cam is also the same as the St 731 Leyland one i have found out if this will help amswer my question

[samsfern]

found some info in my minisport catalogue for you, ca3 -road/rally - 2500 to 7000rpm - 268 degree duration - valve lift is 0.320" - valve clearence is 0.016" - full lift ATDC is 110 degrees.

[Pigeonto]

I believe it works like this inlet duration is 24/64.Add them=88, add 180(deg)=268, halve that=134,subtract the 24=110deg

[Neildanks]

Looks like i got to adjust a little bit more then how close does it have to be does 1/2 a degree really make that much differance

[Neildanks]

And if thats how its worked out whats the 59-29 part mean just so i understand
i'm begining to think i'm on countdown LOL

[samsfern]

people normally say, anything within 2 degree for a road car, and 1 degree for a race engine. I always try to get as close as possible, as thats where the cam will perform best. May as well get it as close as possible whilst the engines out the car.

[Neildanks]

people normally say, anything within 2 degree for a road car, and 1 degree for a race engine. I always try to get as close as possible, as thats where the cam will perform best. May as well get it as close as possible whilst the engines out the car.

Thanks for that advice, why could,nt mini sport just put on there website with the other information about the cam the degrees ( 110 ) as well as the other figures

[Pigeonto]

And if thats how its worked out whats the 59-29 part mean just so i understand
i'm begining to think i'm on countdown LOL

Inlet opens 24 degrees before TDC and closes 64deg after Bottom dead centre.. Exhaust opens 59 deg before bottom (at the end of the power stroke) and stays open all the way up the exhaust stroke until 29 deg after TDC at which point the inlet has already opened a bit (since 24 degrees before TDC)both valves open a bit , called valve overlap

[Neildanks]

And if thats how its worked out whats the 59-29 part mean just so i understand
i'm begining to think i'm on countdown LOL

Inlet opens 24 degrees before TDC and closes 64deg after Bottom dead centre.. Exhaust opens 59 deg before bottom (at the end of the power stroke) and stays open all the way up the exhaust stroke until 29 deg after TDC at which point the inlet has already opened a bit (since 24 degrees before TDC)both valves open a bit , called valve overlap

so when i set to 110degrees this will mean that the valve openings will be correct then i assume

[Cooperman]

I normally set to 2 degrees advanced from recommended, i.e. 106 degs for a 108 deg required setting. Then as the timing chain stretches most during the first 2000 to 3000 miles, it will self-retard by the time 3000 miles has been done and give the optimum setting for the longest time. You won't actually notice any difference to performance unless it over about 4 degs out in practice, but it's nice to know it is correct.