CAMSHAFT TIMING

The Rover 2.6 is a bit unusual compared with more modern engines with the peak at low rpm.
With the 3.5 the peak is around 2500 already so you might not want to take it much higher.
Lowering the torque peak speed on an engine like the 3.5 could give an apparent increase in torque at lower rpm?
I fitted a "towing" cam to an '82 RR I once had which lowered the peak and worked well for towing a heavy trailer but there was not much torque available over 3000. It was a bit disappointing for normal road driving.
I guess it depends what you want to do with it, the std cam timing is a reasonable compromise for a RR.
Terry

Hi Blokes,
Oooops, and Doh,
I was wrong, I checked up on what the scribes say about Advance and Retarding the cam timing and they say that Advancing the timing shifts the power torque curve down the rev range and the other way obviously when retarding it, so apologies to all who may have been a bit confused about my comment when agreeing with Rover-56.
Anyway I still have not got those specs that I need.
Regards:-
Patrick M.

OK , tuning Rover V8 engins gives camshaft as

30/75/68/37

But no lift figures.
This is given as used in P6B,SD1 ,TR8,and Rover Vitesse so is probably for non emission RR.

OK how to power tune Rover V8s gives lift as0.39in/9.9MM in all cases

Regards PhilipA
BTW my understanding is that 3.9 injection cam is a 3.5 injection cam with 5degrees advance.
You may find that a non emission cam performs as well as all 3.5 injection and 3.9 cams were `emission cams.

Quote:

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Originally Posted by rover-56

Well, Rick's experience doesn't match mine.
I have often advanced the camshaft 2-3 deg on various engines to move the torque peak up a bit.
Most recently when I rebuilt the S3 2.6 I advanced the camshaft 3 deg. (took a whole day of fiddling) and the difference is very noticeable, you can hear and feel it. The std timing puts the torque peak at 1500rpm (where Rover says it is)
Advancing 3 deg. puts it at2200, and you can feel and hear it in the exhaust note on hills.
Also advancing gives you a bit of insurance for when the chain and sprockets wear a bit, the timing comes back closer to std.
Terry

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Quote:

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Originally Posted by rick130

Funny, every race engine we built (Ford 1600) where the stock cam was forced on us by regs (Ford GT cam) we'd retard the cam timing, the more retarded, the more it moved the torque peak up the rev range.
Might depend on lobe centres


Road engines I've always run at stock timing.

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not surprising,

what needs to be watched is the initial cam profiling, theres a range of degrees a certain amount of overlap and lift can be tweaked around in to good effect, depending on a few other engine factors what effect shifting the cam timing on stock lobes has will vary, Rover engines have all followed a more or less "British" style build of being setup to run at lower speeds so the cams and runners are set up to provide the torque down low, Advancing the cam timing gets things happening earlier on and so restricts engine performance at the low end but at the higher end when fluid velocity becomes more effective you gain it back at the overlap. the downside of this is fuel consumption goes up, not quite the British ethos in automotive design called for at the time.

the americans on the other hand tend to go about it the otherway happy to have faster revving engines with bigger fuel consumptions. so unsurprisingly with their cams optimised for this with different overlap timings and lifts they react differently to the British standard form.

Hi Blokes,
WOW, thanks heaps, I am really happy with your responses and it is comforting to know everyone has contributed with something positive.
Regards:-
Patrick M.