Ask questions about webinar lessons here. To see the Previous Webinars for a complete list of archives tuning webinars.
Was going to degree my BC cams this weekend. I have noticed the cam card that came with my cams (BC 264 for a 3sgte) are different to the cam card online under the same part number.
My cam card that came with the cams state the following at .050" lift:
Intake -2 ATDC 38 ABDC
Exhaust 46 BBDC -10 BTDC
On their the website it states:
Intake 2 BTDC 34 ABDC
Exhaust 42 BBDC 6 BTDC
In this case what would be the best thing to do? Should I be using the website or the cam card that came with the cams?
I'd be contacting BC directly and ask for clarification as that's a very confusing situation you've got going on!
Does the website state where they measured it?
WTF? Did you get it sorted out OK?
The only point that is the same is the intake opening - all other points and the durations* are different... are you sure that was the right card that came with the camshafts and/or that you were supplied the correct ones? Either way, as Andre said, needs to be fixed by the supplier.
*If the durations were the same, but timing was slightly different, might have been due to them being interchangeable for several different engine spec's - eg, displacements, torque/power range and whether NA or forced induction.
Tfear - measurement point (lift) where they were to be measured is irrelevant as that is on both leading and trailing flanks and the timing is to the lobe centreline which is the midpoint* between them.
*That said, there are some specialist camshafts that have an asymmetric design with different profiles for the leading and trailing flanks - but they are rare and will have more detailed timing details.
Actually Gord it's not uncommon for performance cam grinds to have some degree of asymmetry. That's why it's preferable to time the cam based on the opening and closing points rather than using the common method of finding a point each side of peak lift and using that to find the centreline. Depending on your cam grind and the point you choose to reference, this can result in a timing inaccuracy of a few degrees quite easily.
Ah, good to know - something I should be more aware of nowadays, especially as it does make sense where a finger, or rocker, type follower is used as the geometric ratio may be quite different on each flank.
Check the exact part number or serial number you received vs the part number on the website. It's possible they sent you the wrong thing, or there is a typo on the website. The intake cam duration is the same but the exhaust cam duration isn't.