Thread: 3.5lt Classic CAM - WHAT TO DO?

Also the 1986 has a cracked B pillar so i have to end up with the 1988 model on the road.

All I can offer here is my experience with my well cared for 3.9 V8 that had done just over 307,000km pretty much entirely on LPG.

Head gaskets were toast, gas erosion on heads and deck, valve corrosion due to leaky gaskets, pistons and rings nearly perfect, cam so/so, lifters good, crank excellent but bearings very close to end of life. This engine had been spotlessly clean inside and always fed good oil. If you decide just to put a new cam in the 300k old engine you're still working on old components everywhere else. The '86 engine won't be too far behind on a 250k old bottom end. How long do you want to keep it?

As for cam choice, I think there's so much disinformation and self validation out there your choices are:

1) Talk to someone who has experience with many Rover rebuilds and cam replacements, the reason being nearly any new cam and lifters in an old engine (installed correctly) will feel better than clapped out gear. The DIY crew (such as myself!) will have limited experience with the general characteristics of various grinds and expected "normal" outcomes.

2) Go dead stock, worry less and enjoy the gain you should achieve just by replacing worn out stuff.

I spent a lot on new components for my 3.9 and went all out on the freshen up. I always liked the way the original engine drove all the way up to its last trip before the rebuild - adequate power on the highway and excellent bottom end for around town and noodling around in the bush. I didn't want to turn it into a freeway rocket only to find it was poop below 2,000 rpm. Mine is a manual and being able to make use of all gears from just off idle was important to me. The temptation was to try a different cam profile but in the end I went for a stock ERR5924 3.9 EFI cam driven by multi keyway Rollmaster duplex timing gear. I struck an interesting problem when degreeing in the cam - something was not correctly machined and I needed an indicated 4° advance to get stock timing from the cam. This was checked and rechecked to ensure I was not making a mistake, but 4° it was. Had it just been thrown together using indicated zero slots it would have been substantially retarded. There's always the chance that your rebuild engine with stage 1 cam isn't set to true zero!



Anyhow, just my thoughts...

Thanks MacMan,

I wasn't really sure what to do. I read in the range rover manual the "engine specifications" changed in 1987, i have no idea what that means. But thought i would possibly be better leaving that engine in there. But as you say, the rest of the engine is likely to need attention. I enjoy driving the manual but my old man thinks i'm crazy and should leave the auto in there.

I do not expect it to last forever and it is a second car and only gets driven for off road use, unless otherwise required.

I might pull the cover off and see what the timing is set to on the rebuilt engine, the thought never crossed my mind.

Is there a pro and cons for cam shafts in 3.5l EFI V8's on this forum yet? I know everyone you ask has different opinions. I don't have the option of going bigger engine unless someone wants to sell me a good one cheap.

I've heard the 3.9 cam in the 3.5 is a good combination. I'm after as much torque the 3.5 can provide for me on a budget. An R380 and an LT230 will be behind it, running 33 or maybe 35 inch tires.

My two cents worth,

If you are going to run 33 or 35 inch tyres the best combination to retain torque and off road performance would be to stick a standard cam back in it and change out the diff ring and pinion gears to 4.11 ratio.

You will loose more through the change in wheel size than you will by putting a stage one cam in it.

With 33's or 35's the 4.11's will make torque and gearing as close to the standard setup as you can get and to be honest a standard 3.5 - 5 speed combo with it's standard diameter wheels seems to have the right torque / gearing to tackle most off road work.

I tend to agree with you hear. But i've been wrong before and thought asking the opinion of others to be a wise thing to do. Apparently the 3.9 cam brings the torque curve in earlier.

I wonder what diff gears cost?

Originally Posted by CRR88

My two cents worth,

If you are going to run 33 or 35 inch tyres the best combination to retain torque and off road performance would be to stick a standard cam back in it and change out the diff ring and pinion gears to 4.11 ratio.

You will loose more through the change in wheel size than you will by putting a stage one cam in it.

With 33's or 35's the 4.11's will make torque and gearing as close to the standard setup as you can get and to be honest a standard 3.5 - 5 speed combo with it's standard diameter wheels seems to have the right torque / gearing to tackle most off road work.

Using my newly acquired (knocked it off from a mate) dial gauge I measured the valve lift on the valve side of the rockers tonight. They all measured 7-8mm. Approx. 0.28 - 0.32 inches I guess. Just an observation, it is difficult to find anywhere for a magnetic base to sit on an alloy car with an alloy V8.

Could someone with the knowledge of the standard cam in a 3.5lt EFI V8 please inform me what I should be measuring?

I could not find the cam lobe lift in the repair manual.