Change Cam ?

[MR JONES]

How much more accelleration am I likely to get by fitting a Piper 270 cam.
I am running a 3.5 rover engine with webber 500 carbs and am told I can expect
an extra 20 to 25 bhp by going up one cam, without to much extra surgery.
I would have to pay to have the work done, as engines are not my field, so
will the end result justify the expence? Any advice appreciated.

[maxGD059]

Cheers

Richard
(It'll only be a 5 minute job)

[maxGD059]

Oops managed to post a blank ? how

Hi there
The quickest way to get more power is to change your cam. However as the rest of your engine is fairly standard ( ie heads & capacity) Then dont expect too much from the change. You may get 20bhp at 6000rpm but who uses revs like that very often on the road? In addition you will probably notice a drop in bottom end power. Most engine tuners will tell you that changes to an engine must be balanced & as the heads in the Rover are quite restrictive then if they remain unported then you will not realise the full potential of your webber/cam change
Hardcastle's book on tuning is quite useful on this topic

Cheers

Richard
(It'll only be a 5 minute job)

[robert]

>You may get 20bhp at 6000rpm but
>who uses revs like that very often on the road?

Errm, me. :7 :7 :7

Robert
Forum Admin

http://www.cobraclub.com/flags/UK.gif

[kdavies3]

Hmmm me too or at least I will when I'm run in.
Have you ever driven a Honda S2000? Max power is at 7500 rpm. }>

Kev Davies

[maxGD059]

I thought you weren't supposed to be posting at the moment? If I'd known then my comments would have been modified to....
'Who apart from Rob uses revs like that very often?'!!!!

Cheers

Richard
(It'll only be a 5 minute job)

[DrFelch]

What diff are you running ?

[MR JONES]

I'm using a 3.38/1, I had a 3.93/1 before but first gear was unusable and no top end

[PeteV]

Depends on what state of tune the engine is already in.

Rover V8s eat camshats for breakfast & if you're running on say, a cam thats seen 100k-odd then chances are its lobes are flat as pancakes. You should always change the lifters too when doing a cam swap or else you risk major trouble later on. Haven't looked at the spec of the Piper 270 for a while but IIRC its very similar to the Real Steel Hurricane but just a tad hotter. In other words a mild 'fast road' cam. You should definitely notice the difference but don't expect to be blown away by just a cam swap. Rover V8 heads are very restrictive in standard form & you can get some pretty impressive gains from fairly simple 'porting' using nothing more than a Dremel & a copule of carbide burrs (watch that swarfe though !)

Final note is that its probably not too easy to get the cam out of a V8 Sumo without at least dropping the propshaft & lowering the back of the 'box so that the cam can clear the rad. Still got my Crane 218 sat in the box as I haven't yet got round to making time to 'do it properly' - recon that I should really check vavle-to-piston clearances rather than just bolt it in & hope since my engine is such a mixture of bits (4.6 block / SD1 heads with larger valves etc.)

Pete.

[maxGD059]

Pete
You simply must change your cam this winter as your heads & capacity are well up to it. I changed to a 218/220 this year & the pull thru' the rev range is tremendous. Like you, my block is bored out but it isn't stroked hence only 4.0 litres. Heads are done & valves standard size but waisted to improve flow. You won't regret the effort

Cheers

Richard
(It'll only be a 5 minute job)