Camshaft Specs?

[DarrenRGD]

Anyone know the camshaft specs of the 4.2, 4.5 and RR engines, please?

[DarrenRGD]

I need timings and lift figures if possible

[a1rak]

As far as I know I have not seen any published can timing figures. The cam timing on the AJP is not done it the traditional way with a timing gauge. There are lots of threads on here explaining how it is achieved and it is also in the engine build manual.Hope this helps

[DarrenRGD]

Is there any aftermarket cams or will fitting a 4.5 cam to a 4.2?

[bionicjim]

Tuscan challenge cams are the way to go
Massive lift and duration/over lap
Or you could have some one of profiled
Give dave at RND a call

[DarrenRGD]

Thanks

[bionicjim]

Can spec from blue prints as follows
270deg of duration on the inlet and outlet
With a lift of 0.540 thaw of lift in and out
Minus the tapet
Race cams inlet lift 0.590 the exhaust is the same as standerd cams
Valves are 45mm inlet and 37mm outlet

[bionicjim]

Hope this helps

[DarrenRGD]

bionicjim said:

Hope this helps

Brill thanks, don't suppose you have the timings of the inlet/ exhaust cams eg no of degrees btdc?

[bionicjim]

No mate to some degree the cam timing can be your own choice
As to when and wear you whant the power to be cuming in but this must be within a small window I will see if I can get the correct info for you

[Tanguero]

DarrenRGD said:

bionicjim said:

Hope this helps

Brill thanks, don't suppose you have the timings of the inlet/ exhaust cams eg no of degrees btdc?

If you are wanting to set your cam timing on the engine, the instructions are all in the Engine section of the workshop manual. http://www.thetvrsite.com/cerbera/workshop-manuals
Most indies recommend setting at equal lift on overlap at TDC, rather than the given figure though.

[DarrenRGD]

Tanguero said:

If you are wanting to set your cam timing on the engine, the instructions are all in the Engine section of the workshop manual. http://www.thetvrsite.com/cerbera/workshop-manuals
Most indies recommend setting at equal lift on overlap at TDC, rather than the given figure though.

I had already looked through the workshop manuals and didnt see where to setup the cam timing, only to go off the scribed marks, which is quite different. there should be a figure that no1 inlet is at full lift BTDC, measured in degrees off the crank

[Tanguero]

DarrenRGD said:

Tanguero said:

If you are wanting to set your cam timing on the engine, the instructions are all in the Engine section of the workshop manual. http://www.thetvrsite.com/cerbera/workshop-manuals
Most indies recommend setting at equal lift on overlap at TDC, rather than the given figure though.

I had already looked through the workshop manuals and didnt see where to setup the cam timing, only to go off the scribed marks, which is quite different. there should be a figure that no1 inlet is at full lift BTDC, measured in degrees off the crank

That is not how it is done on an AJP. The workshop manual does give step by step instructions in the "Tappets" part of the "Engine" section, but the general principle is that you set the front piston to TDC on the compression stroke and adjust the cam so that the cam followers are either level (equal lift on overlap) or at the specified height difference (1.5mm) from the exhaust on overlap on the rear cylinder of the same bank. That sets the correct cam timing without any angle measurement at the crank.

Edited by Tanguero on Tuesday 23 October 09:26

[DarrenRGD]

Tanguero said:

That is not how it is done on an AJP. The workshop manual does give step by step instructions in the "Tappets" part of the "Engine" section, but the general principle is that you set the front piston to TDC on the compression stroke and adjust the cam so that the cam followers are either level (equal lift on overlap) or at the specified height difference from the exhaust on overlap on the rear cylinder of the same bank. That sets the correct cam timing without any angle measurement at the crank.

Edited by Tanguero on Monday 22 October 21:12

After reading what you have put and re-reading the manual, i now "get" what you are saying. Surely someone has come up with a more accurate way of measuring the cam timing, as putting the lobes level at TDC or 1.5mm difference at TDC, is a) not very accurate and b) a big difference between book settings and indie settings. that must be 20 odd degrees of difference? thats certainly one way of ruining the performance of the engine!

[Tanguero]

It is plenty accurate! You can set TDC to within a few of minutes of arc readily enough and measuring the relative heights of the followers with a dial gauge will give you an accuracy under a thou or so.

The difference between equal lift and 1.5mm difference at that point on the cam lobe is only a couple of degrees. The slots in the cam pulley limit the adjustment to < 10 degrees anyway and it is considerably less than that amount of adjustment. Don't forget that one cam is raising and the other lowering so its only 0.75mm on each follower.

I believe that this method is considerably more accurate than the traditional method of using a degree wheel on the crankshaft.

Anyway, that is how it is done on the AJP by everyone.

[DarrenRGD]

Tanguero said:

It is plenty accurate! You can set TDC to within a few of minutes of arc readily enough and measuring the relative heights of the followers with a dial gauge will give you an accuracy under a thou or so.

The difference between equal lift and 1.5mm difference at that point on the cam lobe is only a couple of degrees. The slots in the cam pulley limit the adjustment to < 10 degrees anyway and it is considerably less than that amount of adjustment. Don't forget that one cam is raising and the other lowering so its only 0.75mm on each follower.

I believe that this method is considerably more accurate than the traditional method of using a degree wheel on the crankshaft.

Anyway, that is how it is done on the AJP by everyone.

Firstly, thanks for your replies, it's helping me understand some of the quirks!

I've not had chance to get hands on with the AJP yet, so i'm just in the process of revising before the winter strip. I suppose i'm just used to the traditional timing wheel etc setup, i didnt realise that the pulley is slotted, a bit like a vernier pulley?
whats the effect of having level lobes compared with the book figures?

[Tanguero]

DarrenRGD said:

Firstly, thanks for your replies, it's helping me understand some of the quirks!

I've not had chance to get hands on with the AJP yet, so i'm just in the process of revising before the winter strip. I suppose i'm just used to the traditional timing wheel etc setup, i didnt realise that the pulley is slotted, a bit like a vernier pulley?
whats the effect of having level lobes compared with the book figures?

Nothing so sophisticated as a vernier - just plain slots.

Equal lift on overlap gives a steadier idle and at least hypothetical shifts the torque curve downwards a little.

These threads may be of interest if you are considering valve clearance/timing on the AJP

http://www.pistonheads.com/gassing/topic.asp?h=0&a...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...