Cam shaft

[kriss5154]

Hi All

Promise last stupid question, have 1996 Chim 37000 miles what should I look out for if cam shaft is failing.

[caduceus]

BHP & torque figures. What is it producing?
Cam lobe discolouration. Rounded lobes. Followers with a concave surface or halo rings.
If you're going to change the cam, change the followers and springs too. But this is another topic completely

[Steve_D]

The RV8 is very good at hiding a duff cam. They rarely make any noise because the hydraulic lifters take up the wear. I have removed cams that have had multiple lobes worn until they were almost completely round but the engine sounded really sweet.

Only sure way to know is visual inspection either by removing the inlet manifold or the sump.

You could remove the rocker shafts and measure the lift of each pushrod but you need to be very careful that you don't dislodge a pushrod which can then drop down inside the engine. If you are going to use this method then I would suggest taking all the pushrods out (keeping them in order) then just use one rod to measure each cam lobe lift having tied a piece of string to is so it can't drop in. Note when removing pushrods do not lift then straight out but first push the top over to one side. if you lift the oil in the top of the lifter can give enough suction to raise the lifter out of its housing. It will then fall into the engine with a sickening clatter. This method is very time consuming so a garage are unlikely to do it. Taking off the inlet you are already part way through the job of replacing the cam.

Steve

[Engineer1949]

as already stated the rover engine runs perfectly happily with worn cam lobes etc. in fact tickover low down may even be better due to the lack of valve opening effectively turning it into a mild cam but when the engine really needs to breath i.e. full throttle openings and near on max revs it will show up with low bhp readings dont go by tvr published figures they where allways ambitious to say the least so only proper way is to remove and inspect.


john

[Tony91]

When the cam had worn on my old Griff it ran fine up to 4500/ 5000 rpm then it would run rough under load.
Normal driving was fine.

[Chimp871]

I had 5mm difference across my lobes after 55k and didn't even know until I measured lift

On stealth cam now, it's not night and day but is better. 280bhp on a 450 which is TVR's original claim back in the day.

[JonathanT]

Tony91 said:

When the cam had worn on my old Griff it ran fine up to 4500/ 5000 rpm then it would run rough under load.
Normal driving was fine.

and to not help matters, when mine was worn it felt sluggish and sounded a bit chuffy under 3000rpm but then picked up ok after that. This was when one of the lobes was round enough that the exhaust gases burnt a hole through the valve due to insufficient lift.