4.2 cam in a 3.9?

Post by Andrew Cleland
Still trying to sort out a new cam for my 110 3.9i after the Britpart
near-disaster. I see Rimmer's have genuine LR 4.2L cams for £95, which is
a bit of a deal. Has anyone any experience of running one of these in a
3.9? So far as I know, it should fit fine, it's just a case of whether the
grind is different and if it is, is it any good in a 3.9?

Why not ask Rimmers, they are probably as knowledgeable as anyone on rover
V8's

Andrew Cleland

2009-02-11 11:13:58 UTC

Post by Andrew Cleland
Still trying to sort out a new cam for my 110 3.9i after the Britpart
near-disaster. I see Rimmer's have genuine LR 4.2L cams for £95, which
is a bit of a deal. Has anyone any experience of running one of these
in a 3.9? So far as I know, it should fit fine, it's just a case of
whether the grind is different and if it is, is it any good in a 3.9?

Why not ask Rimmers, they are probably as knowledgeable as anyone on
rover V8's

Could do I s'pose - just tend to trust 3rd parties more ;-)

AC.

Andrew Cleland

2009-02-11 12:21:04 UTC

Post by Andrew Cleland
Still trying to sort out a new cam for my 110 3.9i after the Britpart
near-disaster. I see Rimmer's have genuine LR 4.2L cams for £95, which
is a bit of a deal. Has anyone any experience of running one of these
in a 3.9? So far as I know, it should fit fine, it's just a case of
whether the grind is different and if it is, is it any good in a 3.9?

Why not ask Rimmers, they are probably as knowledgeable as anyone on
rover V8's

Spoke to Rimmers - they say "it may work in other engines, but
Land Rover only sold it for the 4.2" - which is perfectly correct but
not a huge lot of help.

Is there anywhere I can find specifications for the standard Rover cams?
I've got both David Hardcastle's and Des Hammill's books on the RV8 but
neither give much info on factory cams.

AndyC.

Badger

2009-02-11 13:29:53 UTC

Post by Andrew Cleland
Still trying to sort out a new cam for my 110 3.9i after the Britpart
near-disaster. I see Rimmer's have genuine LR 4.2L cams for £95, which
is a bit of a deal. Has anyone any experience of running one of these in
a 3.9? So far as I know, it should fit fine, it's just a case of whether
the grind is different and if it is, is it any good in a 3.9?

Why not ask Rimmers, they are probably as knowledgeable as anyone on
rover V8's

Spoke to Rimmers - they say "it may work in other engines, but
Land Rover only sold it for the 4.2" - which is perfectly correct but not
a huge lot of help.
Is there anywhere I can find specifications for the standard Rover cams?
I've got both David Hardcastle's and Des Hammill's books on the RV8 but
neither give much info on factory cams.

I rebuild RV8 engines, and I've been wondering the same thing myself for
quite some time now. Rover never, to my knowledge, published the valve
timing figures for the 4.2 cam, but I know it IS different to the 3.9
timing. I'm still trying to find the timings after 4 years....!
Badger.

Andrew Cleland

2009-02-11 14:06:28 UTC

Post by Andrew Cleland
Still trying to sort out a new cam for my 110 3.9i after the Britpart
near-disaster. I see Rimmer's have genuine LR 4.2L cams for £95, which
is a bit of a deal. Has anyone any experience of running one of these in
a 3.9? So far as I know, it should fit fine, it's just a case of whether
the grind is different and if it is, is it any good in a 3.9?

Why not ask Rimmers, they are probably as knowledgeable as anyone on
rover V8's

Spoke to Rimmers - they say "it may work in other engines, but
Land Rover only sold it for the 4.2" - which is perfectly correct but not
a huge lot of help.
Is there anywhere I can find specifications for the standard Rover cams?
I've got both David Hardcastle's and Des Hammill's books on the RV8 but
neither give much info on factory cams.

So it's not just me being useless then! ;-)

I'm almost tempted to buy one (£95 for a genuine cam isn't bad) and then
I suppose calipers, a dial gauge and a degree wheel should be able to
get the numbers. Do you have the numbers for a 3.9 we could compare it with?

From memory the 4.2 is a longer stroke but the same bore as the 3.9, (I
think) that shouldn't effect the valve/piston clearances unless the cam
is higher lift, which I doubt...

Andrew.

Badger

2009-02-11 15:47:16 UTC

Post by Andrew Cleland
So it's not just me being useless then! ;-)
I'm almost tempted to buy one (£95 for a genuine cam isn't bad) and then I
suppose calipers, a dial gauge and a degree wheel should be able to get
the numbers. Do you have the numbers for a 3.9 we could compare it with?
From memory the 4.2 is a longer stroke but the same bore as the 3.9, (I
think) that shouldn't effect the valve/piston clearances unless the cam is
higher lift, which I doubt...

Yep, longer stroke. 3.9 figures are:-
IO - 32 btdc
IC - 73 abdc
EO - 70 bbdc
EC - 35 atdc
Duration - 285 degrees
Inlet peak - 104 atdc
Exh peak - 246 atdc
Lobe centres - 109 degrees
Lift - 0.39"/0.40"

3.9 cam is basically the same cam as the rover SD1 3.5, but dialled in 2
degrees advanced!
3.9 cam - ERR5924
4.2 cam - ERR5925
Badger.

Andrew Cleland

2009-02-11 18:24:13 UTC

Yep, longer stroke. 3.9 figures are:-
IO - 32 btdc
IC - 73 abdc
EO - 70 bbdc
EC - 35 atdc
Duration - 285 degrees
Inlet peak - 104 atdc
Exh peak - 246 atdc
Lobe centres - 109 degrees
Lift - 0.39"/0.40"
3.9 cam is basically the same cam as the rover SD1 3.5, but dialled in 2
degrees advanced!
3.9 cam - ERR5924
4.2 cam - ERR5925
Badger.

Righto, I've ordered a 4.2 cam from Rimmer's - I'm half-expecting a call
to say it's no longer available, but we'll see. Hopefully it'll arrive
for the weekend and I'll get it setup on some vee blocks and do some
measuring.

Andrew.

Andrew Cleland

2009-02-18 08:32:32 UTC

Post by Andrew Cleland
So it's not just me being useless then! ;-)
I'm almost tempted to buy one (£95 for a genuine cam isn't bad) and
then I suppose calipers, a dial gauge and a degree wheel should be
able to get the numbers. Do you have the numbers for a 3.9 we could
compare it with?
From memory the 4.2 is a longer stroke but the same bore as the 3.9,
(I think) that shouldn't effect the valve/piston clearances unless
the cam is higher lift, which I doubt...

Yep, longer stroke. 3.9 figures are:-
IO - 32 btdc
IC - 73 abdc
EO - 70 bbdc
EC - 35 atdc
Duration - 285 degrees
Inlet peak - 104 atdc
Exh peak - 246 atdc
Lobe centres - 109 degrees
Lift - 0.39"/0.40"
3.9 cam is basically the same cam as the rover SD1 3.5, but dialled in
2 degrees advanced!
3.9 cam - ERR5924
4.2 cam - ERR5925
Badger.

Got the cam and it looks very nice indeed. Unfortunately we've had a
slight issue with the kitchen waste coming apart under the floor, so I'm
having to replace the kitchen floor at the moment, which takes priority
over measuring camshafts! Hopefully by the weekend...

AC.

SimonJ

2009-02-18 18:31:11 UTC

Post by Andrew Cleland
Got the cam and it looks very nice indeed. Unfortunately we've had a
slight issue with the kitchen waste coming apart under the floor, so I'm
having to replace the kitchen floor at the moment, which takes priority
over measuring camshafts! Hopefully by the weekend...

You need to get your priorities right mate! the kitchen floor can wait!

Nige

2009-02-19 00:06:25 UTC

You need to get your priorities right mate! the kitchen floor can wait!

Exactically.

--
Nige,

Range Rover Td6 Vogue
BMW K1200S
BMW F800GS
Honda VTR1000F
Discovery II Td5 Auto (coming soon)

Andrew Cleland

2009-02-19 08:06:12 UTC

Post by Nige

You need to get your priorities right mate! the kitchen floor can wait!

Exactically.

Y'all haven't met my wife have ya? ;-)

I think if I started on the cam now, it would very swiftly find itself
somewhere the sun don't shine - and that would hurt, quite a lot...

William Tasso

2009-02-19 02:37:56 UTC

Post by Andrew Cleland
Got the cam and it looks very nice indeed. Unfortunately we've had a
slight issue with the kitchen waste coming apart under the floor, so
I'm having to replace the kitchen floor at the moment, which takes
priority over measuring camshafts! Hopefully by the weekend...

You need to get your priorities right mate! the kitchen floor can wait!

yeah? not if you need the flat surface for fixing the Land Rover.

--
William Tasso

Land Rover - 110 V8
Discovery - V8

Andrew Cleland

2009-04-10 21:18:26 UTC

Yep, longer stroke. 3.9 figures are:-
IO - 32 btdc
IC - 73 abdc
EO - 70 bbdc
EC - 35 atdc
Duration - 285 degrees
Inlet peak - 104 atdc
Exh peak - 246 atdc
Lobe centres - 109 degrees
Lift - 0.39"/0.40"
3.9 cam is basically the same cam as the rover SD1 3.5, but dialled in 2
degrees advanced!
3.9 cam - ERR5924
4.2 cam - ERR5925
Badger.

Righto, finally got around to doing something with the 4.2 cam. I fitted
it this morning and measured it using a dial-gauge on the inlet and
exhaust tappets for cylinder 1 and a degree wheel on the crank nose.

I can say with a fair degree of confidence that the lift is the same as
the 3.5 and 3.9 cams at 0.4" (at the valve) and that lobe seperation is
slightly greater than the 3.9 cam at 112.5 degrees.

With less confidence as I only measured lift at every 10 degree of
crankshaft rotation, which in retrospect was a little too coarse, the
duration seems to be slightly longer at somewhere around 300-305
degrees, the inlet opening and closing later than the 3.9 and the
exhaust opening a bit earlier and closing a bit later. I'm not
super-confident about these numbers as I say, and I'm a little surprised
that the duration for inlet and exhaust are different - I wouldn't
expect Rover to have been that clever with the cam design.

The details are available in an Excel spreadsheet at
http://miro.pet.cam.ac.uk/~ajc219/land-rover/42cam.xls

Anyhow, I've installed the cam in the normal position (no advance) and
hopefully will get the engine running over Easter weekend - I'll be sure
to let you know if it idles (or goes...) like a top-fuel dragster!

Cheers,

AndyC.

Pantelis Giamarellos

2009-04-14 07:40:40 UTC

Andy Hi,

I seem to remember that the 4.2 engine was initially developed by JE
Engineering.
When the LSE was considered by LR as an upgrade to the existing RaRo Classic
model range the factory has bought the manufacturing and design rights from
JEE.

This must be a good explanation on why the camshaft is different from the
3.9 one (but then again if memory serves me right the 3.9 cam is also
different from the 3.5 and this was an LR "in-house" designed job.

Take care
Pantelis

Post by Andrew Cleland
So it's not just me being useless then! ;-)
I'm almost tempted to buy one (£95 for a genuine cam isn't bad) and then
I suppose calipers, a dial gauge and a degree wheel should be able to
get the numbers. Do you have the numbers for a 3.9 we could compare it with?
From memory the 4.2 is a longer stroke but the same bore as the 3.9, (I
think) that shouldn't effect the valve/piston clearances unless the cam
is higher lift, which I doubt...

Yep, longer stroke. 3.9 figures are:-
IO - 32 btdc
IC - 73 abdc
EO - 70 bbdc
EC - 35 atdc
Duration - 285 degrees
Inlet peak - 104 atdc
Exh peak - 246 atdc
Lobe centres - 109 degrees
Lift - 0.39"/0.40"
3.9 cam is basically the same cam as the rover SD1 3.5, but dialled in 2
degrees advanced!
3.9 cam - ERR5924
4.2 cam - ERR5925
Badger.

Righto, finally got around to doing something with the 4.2 cam. I fitted
it this morning and measured it using a dial-gauge on the inlet and
exhaust tappets for cylinder 1 and a degree wheel on the crank nose.
I can say with a fair degree of confidence that the lift is the same as
the 3.5 and 3.9 cams at 0.4" (at the valve) and that lobe seperation is
slightly greater than the 3.9 cam at 112.5 degrees.
With less confidence as I only measured lift at every 10 degree of
crankshaft rotation, which in retrospect was a little too coarse, the
duration seems to be slightly longer at somewhere around 300-305 degrees,
the inlet opening and closing later than the 3.9 and the exhaust opening a
bit earlier and closing a bit later. I'm not super-confident about these
numbers as I say, and I'm a little surprised that the duration for inlet
and exhaust are different - I wouldn't expect Rover to have been that
clever with the cam design.
The details are available in an Excel spreadsheet at
http://miro.pet.cam.ac.uk/~ajc219/land-rover/42cam.xls
Anyhow, I've installed the cam in the normal position (no advance) and
hopefully will get the engine running over Easter weekend - I'll be sure
to let you know if it idles (or goes...) like a top-fuel dragster!
Cheers,
AndyC.

Andrew Cleland

2009-04-14 19:15:31 UTC