The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Tone on 13.11. 2010 10:17

Title: which camshaft
Post by: Tone on 13.11. 2010 10:17

Hi Guys, I was wondering if you can tell which cam I have in my 58' swinging arm A10. I ask this because nothing else is standard on it, it's got a alley rocket head, 389-46 carb(60/63 A10SR). I have the head off and putting the pushrods in I have marked there travel, now I know its not very acurate but it's 1/4", 6.5mm "lift" I need to know as i'm not sure if I time it at 3/8" or 11/32"? cheers Tony.

Title: Re: which camshaft
Post by: Tone on 13.11. 2010 10:26

I forgot to ask any ideas on valve clearance with this set up, cheers Tony.

Title: Re: which camshaft
Post by: dpaddock on 13.11. 2010 16:02

Camshaft lifts range from .302" to .365". Perhaps you should remeasure.
Unless you have good gasoline, I suggest the 11/32" BTC timing.
Valve clearances at .010" inlet and .012" exhaust should do it.

David

Title: Re: which camshaft
Post by: muskrat on 13.11. 2010 19:51

G'day Tony,
                    the lift is measured at the valves, as the rockers are not 1 to 1 ratio.
Use a degree disc on the crank to see when the valves open and close. I haven't got my book in front of me at the moment to give you the figures but it will be around. Inlet opens 42 deg before TDC and closes 50? after BDC, Exhaust opens 40? before BDC and closes 50? after TDC. Once you have that info you can compare to the book.
Cheers

Title: Re: which camshaft
Post by: trevinoz on 13.11. 2010 21:02

Tony,
            If you go back and have a look at Orabanda's dyno tests, you will find that 5/16" is the ideal advance.
You will need to identify the cam for the correct clearances.
Trev.