Thread: 2.6 Engine Improvements

Hi Bacicat
I'm very pleased to see that you are determined to stick with the 6 cyl 2.6
There seems to be a lot of negative thought regarding these engines, it makes you wonder how many of the knockers have had actual experience with them. They have a reputation for burning exhaust valves, due mainly I think to incorrect maintenance. It is imperative that the (exhaust) valve clearances are reset (correctly) every 20,000km. With normal wear the clearances tend to decrease and so they don't sound like there is a problem, that is, the tappets remain quiet. If the clearance is decreased the vale spends less time on the valve seat, and time the valve spends shut is when most of the heat within the valve is dissipated, so less clearance means overheating of the valve. I know that adjusting the exhaust clearances is not a simple task, but the way we use our vehicles 20,000k's can take years to accumulate, so even if it needs to be done annually it's no big deal.
Another factor to consider here is that the standard exhaust manifold tends to retain some pressure at the end furthest from the outlet, which is why valves on cylinders 5 and 6 seem to be the ones that suffer from burning. Fitting a free flowing set of headers or extractors virtually eliminates valve problems, providing the engine is kept in tune.
The inlet manifold is cast integrally with the cylinder head and has water passages running all the way under the inlet ports and directly behind where the carby bolts on. This is to heat the ports and aid vaporisation of the fuel particles in extreme cold weather conditions and prevent carburetter icing. Machining the inlet manifold off and replacing with a bolt-on type would be a nightmare. Rover addressed this with the Weslake type head on the later sedans and NADA spec Land Rovers. If you wish to have a look at a Weslake head or a 2.6 sectioned head I have one.
The UK engines used a shim steel head gasket which increased the compression ratio.
In my experience the 2.6 responds very nicely to a few simple mods.
1. The inlet tract porting is very restrictive and easily improved
2. The exhaust ports are restrictive and easily improved.
3. The valve timing can be advanced to improve mid-range torque (set exhaust peak at 108 deg BTDC.
4. Increase compression ratio to 9.0:1. This requires grinding the top of the block .030" (0.75mm) and fitting a steel head gasket.
5. Fit an electronic ignition system.
6. Fit exhaust headers or extractors and a free flow system.
7. Fit a large free flow air intake and filter.
This should give you around 120 bhp and 5000 usable rpm along with approximately 160 ft/lb torque at 2000 rpm.
If you stick with the carby you may need to reprofile the needle to prevent leaning out at higher rpm.
With my Series 3 I regularly get 20 plus mpg sitting on 100kph and about 17 mpg sitting on 120 kph.
Adding a 3 litre crank and rods will give another 20 bhp, providing you use the larger 2 inch SU.
You are welcome to come and have a look when you have time.
Also, I have a pressy for Cam.....



Also some photos of porting. Appologies for image quality.


Original exhaust port


Modified exhaust port


Original inlet port looking through valve opening


Modified inlet port looking through valve opening


Original exhaust port looking through valve opening


Modified exhaust port looking through valve opening


Original inlet opening behind carby


Modified inlet opening behind carby

Hope you find this long winded reply useful.
Look forward to catching up with you again.
Cookey

Great write up Cookey - thanks heaps. I'm certain to be asking plenty of questions from you once I start on the engine. I'm getting itchy fingers now - I really want to get stuck into it, but I have the chassis, front and rear axles, brakes and gearbox to do before I start on it.

So hopefully in a few months depending on how dedicated Cam is with the chassis cleaning he has just started.. So far so good though - he's out there now with the grinder and a wire wheel going for it.

I started chassis cleaning on my Defender 6x6 with a wire wheel and angle grinder, after what seemed like months of weekends I still couldn't get into the corners and the finish just looked ugly.

It was then I took the chassis to be chemically stripped, even though it was over a grand I'm glad i did it because it revealed invasive rust under the bump rubber brackets. If I hadn't done that I may have never found it and ended up with much more significant repairs.

I did seriously consider getting the chassis dipped, but it is in extremely good condition - I mean no rust anywhere - rear crossmember - perfect, dumb irons - like new. A bit of surface rust where the paint has come off, but a lot of the chassis comes up like new with a quick scrub with warm water and a scotchy. Once it's clean, the surface rust is being treated with rust converter, then primed and top coated. About 1/4 of it is done now, and once the front section is done, it's plain sailing down the back end. I give us another week and the chassis will be cleaned and painted. I do have to weld a few things back on - the front fuel tank bracket is U/S and I have to make 2 up so I can mount the passenger side tank. The outrigger on the LHS back crossmember is bent - think it was backed into a tree or something, so have to fabricate that too.

Only other bit is the main crossmember under the flywheel housing which looks like a pretzel. The Ho Hars have a good one that's heading my way soon, so I'll stitch that in when it arroives and that's it done!

Easy when you type it out like this....

I'm sure Cam will post pics in the rebuild thread once its looking the part.

My problem is that the previous owner (and importer) dismantled the vehicle and had the chassis sand blasted, then painted it with ferrous oxide paint (enamel) and finished off in chassis black (acryllic) he then died and I bought the vehicle still dissassembled. The problem was the acryllic was coming off in patches and stuck on in others. I couldn't risk blasting it again so that left me with the chemical option.

A coil sprung 6X6 is such a large chassis! The rear axle is at 150", so the whole thing at least two 88" chassis.

That's a LOT of chassis...

You didn't comment on the grille for Cam.

Cookey

Originally Posted by cookey

You didn't comment on the grille for Cam.

Cookey

Oops - sorry . We really appreciate the offer but we had just bought one on ebay - from another member here last week - it turned up yesterday.

Again, really appreciate the offer.

Cam is looking forward to a road trip up there to meet you and look at everything you do.. I can't wait to be bolting on the disk brake conversion to the series 3.