Good deal on V8 camshafts but help me choose one

What do you want to achieve? your running out of puff in high revs, you have restrictions/ timing issues, you can't create a mountain of torque without ci, but you can alter cam timing, but you want to continually drop your timing cover to alter cam timing? its an askful task

Have you had a dial o0n your existing camshaft? you need to workout whether its worn itself, talking to a cam grinder is likely the ultimat way, but you need to know, ci, style of aspiration, vehicle wieght, ratio's, comp. ratio etc

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Originally Posted by Hardchina

Thought about going solid?

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No. I will staying with hydraulic lifters.

Just found some info that suggests the 3.9 efi cam is the same as the 3.5 carb cam (which one?) but the whole cam has 2 degrees more advance.

More cam advance tends to the shift the torque peak downwards.........

I can understand why there are different views on this topic.

The following are the factory cam specs for the high and low comp carb engines as taken from my workshop manual.


Compression ratio. 9.35: 1

Valve timing Inlet/ Exhaust
Opens ........................... 30" B.T.D.C. /68" B.B.D.C.
Closes ................ 75" A.B .D. C./ 37" A.T.D.C.
Duration . 285" /285”
Valve peak 112.5" A.T.D.C. /105.5" B.T.D.C.



Compression ratio 8.13: 1

Valve timing Inlet / Exhaust
Opens ......................... 36" B.T.D.C./ 74" B.B.D.C.
Closes ................ 64" A.B .D. C./ 26" A.T.D.C.
Duration . 280" / 280”
Valve peak 99" A.T.D.C./ 119" B.T.D.C.

Comments on the differences between these would be informative and appreciated.

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Originally Posted by rovercare

What do you want to achieve? your running out of puff in high revs, you have restrictions/ timing issues, you can't create a mountain of torque without ci, but you can alter cam timing, but you want to continually drop your timing cover to alter cam timing? its an askful task

Have you had a dial o0n your existing camshaft? you need to workout whether its worn itself, talking to a cam grinder is likely the ultimat way, but you need to know, ci, style of aspiration, vehicle wieght, ratio's, comp. ratio etc

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I dont want to overly complicate the decision (too late I know).

I just want the factory cam which will maximise off-idle and low - mid range torque with reasonable power up to about 4000 rpm and a torque peak around 2500 rpm. I am restricting the choice to the 4 factory cams because I can get a good deal on the whole package (lifters, gear, chain, gaskets etc). Yes I'm tight.


Its a toss up now between the low comp carb cam (pre emission?) and the 3.9 efi cam (because of potentially more total advance).

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Originally Posted by rovercare

:eek:

You wanna have to make adjustments, solid valvetrain is for high HP engines, to extract every last digit:D

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Pfft, adjust once or twice a year, a solid grind can be done for any engine tune, although i'm not sure how much more low down torque it would enable from a mild / stock (solid equevilent) grind, but it would be more :). A solid lifter does not need the gradual initial ramps a hydroulic lifter does = better, more effective cam profile, higher lift in the first initial degrees = more power / torque, more effiency.
Good luck finding an off the shelf grind or some one who would care enough to actually go there.

At least with a solid you'd know when the cam is wearing :).

But yeah. i'd never go solid - just thought i'd put it out there

Quote:

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Originally Posted by mark2

I dont want to overly complicate the decision (too late I know).

I just want the factory cam which will maximise off-idle and low - mid range torque with reasonable power up to about 4000 rpm and a torque peak around 2500 rpm. I am restricting the choice to the 4 factory cams because I can get a good deal on the whole package (lifters, gear, chain, gaskets etc). Yes I'm tight.


Its a toss up now between the low comp carb cam (pre emission?) and the 3.9 efi cam (because of potentially more total advance).

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My vote,

thor grind cam + thor manifold + 5 x fork lift bottles in the boot for the extra range or go the just go the full efi conversion route.

Quote:

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Originally Posted by Hardchina

Pfft, adjust once or twice a year, a solid grind can be done for any engine tune, although i'm not sure how much more low down torque it would enable from a mild / stock (solid equevilent) grind, but it would be more :). A solid lifter does not need the gradual initial ramps a hydroulic lifter does = better, more effective cam profile, higher lift in the first initial degrees = more power / torque, more effiency.
Good luck finding an off the shelf grind or some one who would care enough to actually go there.

At least with a solid you'd know when the cam is wearing :).

But yeah. i'd never go solid - just thought i'd put it out there

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No arguements on your info, but in reality, not many people bother with valvetrain adjustments until a noticeable lack in performance:D

Quote:

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Originally Posted by mark2

The following are the factory cam specs for the high and low comp carb engines as taken from my workshop manual.


Compression ratio. 9.35: 1

Valve timing Inlet/ Exhaust
Opens ........................... 30" B.T.D.C. /68" B.B.D.C.
Closes ................ 75" A.B .D. C./ 37" A.T.D.C.
Duration . 285" /285”
Valve peak 112.5" A.T.D.C. /105.5" B.T.D.C.



Compression ratio 8.13: 1

Valve timing Inlet / Exhaust
Opens ......................... 36" B.T.D.C./ 74" B.B.D.C.
Closes ................ 64" A.B .D. C./ 26" A.T.D.C.
Duration . 280" / 280”
Valve peak 99" A.T.D.C./ 119" B.T.D.C.

Comments on the differences between these would be informative and appreciated.

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3.9ltr EFI 8.13:1 & 9.35:1 both use the same cam .

As Above

32 BTDC....70 BBDC
73 ABDC....35 ATDC
285.................285
104 ATDC..114 BTDC

I`ll watch with interest .

Hey if you want the ULTIMATE cam go for one that uses solid roller lifters & cam. Best of both worlds. Torque & Power .You world probable have to get a cam grinder to do a special grind for Rover V8 (not cheap).
Second best are hydrolic roller cams & lifters
More food for thought.
Not sure if there are roller lifters for Rover V8

great timing for me on this thread.

I have just converted my 1976 Range Rover, standard at 8.25:1 comp, to an electronic distributor and have made a small cock up in that I have managed to strip the drive gear off the cam. Oil pump gear shaft issue which is now fixed- I shortened it a bit more.

However I am going to do the cam while I have got it apart. I too can get a good price on a range of standard cams my quandary was which cam? I wouldn't mind sacrificing a little bit of low down torque for even more on road power but not too much, I still want an easy to drive car that idles and pulls well. This is NOT an off roader. I have a Defender for that.

From past experience with Range Rovers is the standard low comp cam is good. Loads of low down grunt and went really well on the open road. High comp engines are ok but never had the zing. They also produce less bhp on paper (125 vs 130, both at 5000rpm) but a little more torque. (190 vs 185, both at 2500rpm). I assume that a raising the comp of a 8.25:1 motor would yield more power than the genuine high comp motor and I like the power range of the early motor any way, so that was my plan. To re-use a low comp engine spec cam.

But where does the efi cam fit in and how does it go in an early low comp stromberg fed 3.5 as compared to the standard range of cams? It seems to bear more similarity to the early cam than the later high comp cam but with more exhaust lift. At least thats what I make of it. I really have very little idea on how to decipher these things.

And what about an SD1 or P6 cam? I can get those too!

Stef