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+--- Thread: Would like Camshaft Specs (/showthread.php?tid=1547)
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RE: Would like Camshaft Specs - Ian Williams - 09-08-2018
I am not sure the Nippy data is correct, I have three of them and unless I have made a massive error the inlet opens at TDC. I believe that there were slightly different timings for the Speedy cam and possibly that explains the discrepancy in your figures and my measurements Charles?? I would also be interested to know the missing timings from your table.
RE: Would like Camshaft Specs - Chris KC - 09-08-2018
(08-08-2018, 10:01 PM)Charles P Wrote: I can't remember quite where this came from - possibly Dave Armstrong
I'd be interested in the data on the 9C cam Robert
Thanks for posting this interesting info Charles.
I presume the timings shown correspond with 'standard' cam followers for each model concerned? (touring cars were all 3/8" radius I believe but unsure about the sports models).
RE: Would like Camshaft Specs - Colin Reed - 09-08-2018
(09-08-2018, 07:21 AM)Ian Williams Wrote: I am not sure the Nippy data is correct, I have three of them and unless I have made a massive error the inlet opens at TDC. I believe that there were slightly different timings for the Speedy cam and possibly that explains the discrepancy in your figures and my measurements Charles?? I would also be interested to know the missing timings from your table.
Hi Ian,
What are your nippy cam specs.
RE: Would like Camshaft Specs - Charles P - 09-08-2018
(09-08-2018, 07:21 AM)Ian Williams Wrote: I am not sure the Nippy data is correct, I have three of them and unless I have made a massive error the inlet opens at TDC. I believe that there were slightly different timings for the Speedy cam and possibly that explains the discrepancy in your figures and my measurements Charles?? I would also be interested to know the missing timings from your table.
Ian
These are merely what I was given - I have no idea who made them or how accurate they may be.
And yes, over a reasonable production period, like the 65/Nippy, I'd expect cam specs to change.
Charles
RE: Would like Camshaft Specs - Robert Foreman - 09-08-2018
The 9C141 camshaft gives a lift of 0.255" on the inlet and 0.251" on the exhaust.
Bearing in mind that the pattern camshaft was bent and Kent Cams selected the best lobes to take their profiles from .
Hope this is of help
RE: Would like Camshaft Specs - Ian Williams - 09-08-2018
On my Nippy cams I have made note of inlet opening at TDC closing 60 ABDC, exhaust open 45 ABDC and closing 24 ATDC, lift 3/8". I have also seen published another set of figures which differ slightly from Charles and mine, possibly originating will Bill Sheehan, sorry if thats wrong Bill but it would be interesting to hear from you when you read this. I wonder if the answer is that there are actually three Nippy profiles, two bearing splash fed, two bearing pressure fed and three bearing. I have a three bearing cam and two of the earlier types, not sure if they are from splash or pressure fed engines, I will re measure them all and report back.
I raced for a while with a Nippy cam in my special, however found very worthwhile gains to be had with a good re-profiled cam, I say good because I have come across some pretty average grinds out there. I am no expert when it comes cam profiles, I measure them by performance on the track, I have heard a number of pet theories over the years but I tend to listen to the one or two people with proven track records of reliable grinds.
RE: Would like Camshaft Specs - Colin Reed - 09-08-2018
HI Ian,
On those Figures you have 24 degree overlap and a lob phase angle of 110.25 cam degrees
thanks
Colin
PS Duration In 240 Degrees
Ex 249
RE: Would like Camshaft Specs - Speedex750 - 10-08-2018
Hi,
Charles's chart did come from me, it was on the Speedex site at one time. As warned then there do seem to be a few sets of figures around for the standard profile and all the figures, with unknown provenance, are quoted with potential measuring, setting up, wear and accuracy errors. I suspect, and I've no evidence to support this, that the profiles are probably a simple and symmetric as the Bruce White dimensions suggest and then the check on set up accuracy is that the maximum inlet lift ATDC figure should be the same as the phase angle - probably at or near 110 degrees ATDC. Different figures for the sports cams may be just other discrepancies rather than a different profile.
A CAD package should be able to predict the specs of the standard profiles from Bruce White's geometry if that's what you're after.
Hope of interest, Dave.