Standard cam duration

[MechaT]

Anyone know the duration of the standard 1.3 SR cam? The Haynes manual only states the lift.

[Stuart]

id guess its something like 230-250degrees

based on the fact taht looking at the 1.4 carb cam as approx 240-260ish

ive not measured the std cambs, but thats what i reconed when i looekd at them after having measured others

[S_Gault]

this is one of those things that drives me nuts..

you cant possibly say what duration any cam is without quoting the check height you are working at.

This is also the reason why you cant compare Piper with Kent without re-measuring them both on the same clearance.

I do quite a lot of cam polar plots for competition cams and this is one thing i come accross all the time.

Steven

[Stuart]

ive not personally plotted a nova camshaft, but i have done it on quite a few k-series ones.

and also other people plotted other cams, so in the vaugest possible sense i got a "feel" for how it looks.

I know that in Advance Engine Technology (book that is) i lists loads of differing cam types etc so that no one profile can just be looked at and have its details summarised.

but also in the same thoughts looking at a Kent/piper where your told the duration and then looking at a standard one, then you can make a "best" guess. also the power of the standard lump would give clues as to the basic duration.

not accurate, but to be fair if your just intrested then accuracy isnt vital.

[S_Gault]

fair point..

Heres where i come from thou- When building competition engines I have to measure each cam as 2 of the same grind often dont measure up the same.

There is one particular engine I deal with a lot that i have to buy 10 cams to get one that works as the grinding is so crap

Steven

[Stuart]

yeah, from the point of view for high performance engine building you obv want to measure up so that you have the best cam for the job etc.

:)

but in the general game of "whats the standard duration" a well educated guess is cool.

[S_Gault]

yea.. just me having a rant!


Steven