4.2 cam specs

[paul c]

Been searching for the cam specs for a 4.2 cam, as I am using one in my 4.6 for my 110 with an interim cover, su carbs and distributor and finally found a post with them so tomorrows job is to check the cam timing. As found on Rangerovers.net

From RAVE

4.0 litre P38
Valve timing Inlet Exhaust
Opens 28°BTDC .......... 66°BBDC
Closes 77°ABDC .......... 39°ATDC

4.6 litre P38
Valve Timing Inlet Exhaust
Up to 99MY
Opens 14°BTDC ........... 64°BBDC
Closes 70°ABDC ........... 20°ATDC
From 99MY
Opens 28°BTDC ........... 72°BBDC
Closes 64°ABDC ........... 20°ATDC

3.9 Classic
Valve Timing Inlet Exhaust
Opens 32°BTDC ........... 70°BBDC
Closes 73°ABDC ........... 35°ATDC
Duration 285° ................. 285°
Valve peak 104°ATDC .......... 114°BTDC

4.2 Classic
Valve Timing Inlet Exhaust
Opens 28°BTDC .......... 72°BBDC
Closes 64°ABDC .......... 20°ATDC
Duration 272° ................ 272°
Valve peak 108°ATDC ........ 116°BTDC

[paul c]

The 4.2 cam I bought several years ago came in a eurospares box with err5925 on it, but it doesn't match up with any of the specs from the rave post, inlet centerline at 117 and exhaust at 113, so I am waiting on another err5925 to arrive. The duration figures from rave are at about 1thou lift on this cam.

[rich112]

I'd be interested to know this too!

I have this cam in my 4.6 that needs replacing. No idea what it is though.

It has the dizzy drive on, so might be a stock 4.2 cam?

[paul c]

The new one has just cleared customs so should be here by the end of the week so I can pull this one out and compare them.

[rich112]

The new one has just cleared customs so should be here by the end of the week so I can pull this one out and compare them.

Great!

[paul c]

Both cams have green paint markings the same.
I seem to be getting the same figures with both, inlet opens 14 BTDC closes 84 ABDC exhaust opens 63 BBDC closes 29 ATDC
278 duration inlet with 117 ATDC peak, 272 exhaust with 113 BTDC peak
Neither match the supposed figures from Rave.
Not sure whether to buy a Cloyes timing set and advance it 4 degrees or stick with it as it is.

[MGB V8 Turbo]

I thought this may be helpful, based on the timing information given above:

The 4.2 cam has an Overlap of 48.00 degrees.
Intake Duration is 272.00 degrees.
The Exhaust Duration is 272.00 degrees.
Lobe Separation Angle is 112.00 degrees.
The Inlet Cam has an Installed Centerline of 108.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 116.00 degrees BTDC.

3.9 EFI cam has an Overlap of 67.00 degrees.
Intake Duration of 285.00 degrees.
The Exhaust Duration is 285.00 degrees.
Lobe Separation Angle is 109.00 degrees.
The Inlet Cam has an Installed Centerline of 110.50 degrees ATDC.
The exhaust cam has an Installed Centerline of 107.50 degrees BTDC.

I am looking at the 4.2 cam for a single rear mount turbo installation. Looks like a very good turbo cam to me for what I want, which is low speed torque.

[paul c]

The specs from LR don't seem to match the cams that are actually supplied though, the measurements taken from both cams that I was supplied as 4.2 cams are in my post above, the intake duration I measured was 278 degrees not 272. I am hoping to get my 4.6 running soon after I get home at Easter.

[SuperV8]

There is no mention of lift in any of the OE spec's above.
There are many performance aftermarket cams available for the Rover V8 with many different specs - why not just pick one which matches your requirements?

edit#
seems the OE cams are 1/3 the price of 'performance' cams - so guess that's a reason to use an OE cam if it meets your spec requirement! Still missing the lift data though?

[paul c]

Did read somewhere that all the factory rover cams had the same lift, I haven't checked it out for myself though so can't confirm if it is true.
At the time I bought the first 4.2 cam I was going to build a 4.2 engine and it was available and at a good price. When I decided to go to a 4.6 I found that they were commonly swapping to 4.2 cams in the 4.6 engines in the NAS defenders to keep the original EFI and distributor etc when their 3.9s needed upgrading. I had been going to use the 14CUX myself before deciding to keep with SUs.