Variable Cam Timing

[ITA124]

Hi All,

Got a set of adjustable cam wheels and mounted them to the factory timing setting.

Double checked the cam shims. Had to change all the exhaust shims by about 0.002" due to a thinner cam box gasket

ACE124 and I ran the cams out and with 0.5mm running clearance measured,
Inlet Cam 9.9mm lift 280deg
EX cam 9.55mm lift 266deg

An open question
How much overlap?
What deg would you start the Ex open BBDC?
What deg would you start the Inlet open BTDC?

Or a link to website?

I have run the profile out in Autocad. The overlap is arbitrary. Is this also correct? or do I need to subtract a value (90, 180, ?)

[majicwrench]

Does the cam not have specs with it?? It has been 20+ years since I last did this kind of thing, but cams came with specs back then.

[So Cal Mark]

you should have opening and closing figures based on the centerline

[engineerted]

If these are stock Fiat cams, then the full lift of the cams should be at 110 degrees ATDC intake and and 110 degress ABDC exhaust. When using adjustable cam pullies you need to find the actual full lift of the cam and mark them. See Guy Croft link for some more info. http://guy-croft.com/viewtopic.php?f=1&t=14


Ted

[guycroft]

Have to correct your typo there Ted

"If these are stock Fiat cams, then the full lift of the cams should be at 110 degrees ATDC intake and and 110 degrees ABDC exhaust"

110 degrees ABDC exhaust should read 110 degrees BTDC

G

[engineerted]

Thanks Guy for the correction, yes it should be BTDC.

Ted