Uprated cam data
Discussion
GasMunkey said:
All you need to know is that's a really tasty cam, make sure you got the ptv clearance and enjoy
FYI that's a fairy large cam, don't except a smooth idle or much power under 3k but after that she will scream
Hi Alex, how poor is the tickover?, as i cant get mine smooth, and it pulls really well mid range.FYI that's a fairy large cam, don't except a smooth idle or much power under 3k but after that she will scream
I'm not sure if it has an uprated cam or just a really worn one.
Cheers
Jamie
My old cam was a similar size
I'm not sure if this link will work but you can hear mine 'lope' like a yank drag racing muscle car
http://youtu.be/3nf10BnS6jU
I'm not sure if this link will work but you can hear mine 'lope' like a yank drag racing muscle car
http://youtu.be/3nf10BnS6jU
chrisdurham said:
Hi guys. Ive found the info on the crower cam that I have, but the numbers dont mean anything to me lol. Can somebody give me a summary of what they mean?
Yeah that's chunky alright. Triple valve springs!When degreeing it in the salient settings are on that black and grey wheel diagram.
Black ring is intake valve. Grey ring is exhaust valve...so it reads
I/O = Intake opens: Intake valve starts to open at 10 degrees before top dead centre (10.0 BTDC) and reading around clockwise stays open until 38 degrees after bottom dead centre (38.0 ABDC)
With the exhaust valve it's the same deal - it starts opening (E.O) at 49.9 degrees BBDC and stays open until 5 degrees ATDC.
This gives an overlap of 15 degrees (time when both intake and exhaust valves are open and it's this that (I think) gives you lumpy idle on hairy cams - as the last bits of the exhaust gasses can contaminate incoming fuel charge
If you have a known good TDC mark then you can see if it's miles out just by looking at when the tappets on the relevant valve start to move by eye but you'll really need a pointer and a degree wheel to measure it exactly.
HTH
Ryan
Edited by debaron on Sunday 13th January 11:28
debaron said:
...
I/O = Intake opens: Intake valve starts to open at 10 degrees before top dead centre (10.0 BTDC) and reading around clockwise stays open until 38 degrees after bottom dead centre (38.0 ABDC)
With the exhaust valve it's the same deal - it starts opening (E.O) at 49.9 degrees BBDC and stays open until 5 degrees ATDC.
I don't think you can class ~ 1.25mm (0.05") follower lift as 'starts to open', that's actually over 2mm at the valve stem tip (ie valve open 2mm!) - it's been off the seat for a long long time.I/O = Intake opens: Intake valve starts to open at 10 degrees before top dead centre (10.0 BTDC) and reading around clockwise stays open until 38 degrees after bottom dead centre (38.0 ABDC)
With the exhaust valve it's the same deal - it starts opening (E.O) at 49.9 degrees BBDC and stays open until 5 degrees ATDC.
spend said:
I don't think you can class ~ 1.25mm (0.05") follower lift as 'starts to open', that's actually over 2mm at the valve stem tip (ie valve open 2mm!) - it's been off the seat for a long long time.
Aha - so that's what the 50 thou lift is all about? I presume they do that because it's easier to measure?Anyway I stand corrected!
So are we saying then that at the degree values shown on the wheel that the valves will be 50 thou x 1.6 off their seats?
debaron said:
Aha - so that's what the 50 thou lift is all about? I presume they do that because it's easier to measure?
Anyway I stand corrected!
So are we saying then that at the degree values shown on the wheel that the valves will be 50 thou x 1.6 off their seats?
Yes.Anyway I stand corrected!
So are we saying then that at the degree values shown on the wheel that the valves will be 50 thou x 1.6 off their seats?
Thats how americans generally measure their cams, it's printed quite clearly on the spec sheets as well
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