tuning a series diesel engine

[Phil Hancock]

90BHP @ 4500rpm & 132lb/ft @ 1500rpm.

[secondjeremy]

So little more torque than the 4 cylinder which I think is sometimes quoted at 124 lb ft.

[lexi]

Yes but six cyl petrol is smoothest delivery you can get........smoother than v8 in theory. and lots smoother than 200tdi.

Tony has Salsbury axle anyway?

[Julian]

Yes but six cyl petrol is smoothest delivery you can get........

Gas turbine is better!

[ejparrott]

Second vote for 2wd with a TDi, and I run 3.54 diffs with 10-spline half shafts, I've yet to do any damage attributed to the TDi.

[FridgeFreezer]

Mine used to be a six, they are very sweet engines and sound lovely, just a bit rare so not as cheap to fix as the I4 or V8, and sit somewhere in between on the power/mpg stakes. Much like the 4cyl, I suspect a lot of extra power could be gotten from a 6 with a more modern fuel & ignition setup without stressing it.

[tacr2man]

I have often thought the six would benefit from a turbo, as its a very long stroke small bore engine so not the best for revving JMHO

[Julian]

Just to add a little to this thread.

My series 3 Diesel was a little sluggish and fairly smokey for the first several hundred yards after a cold start. But that was how I thought things should be as I specifically went for a Diesel because of its crapness! Anyhow, one day when I had a few spare minutes I slackened the pump mounting bolts and advanced it up by about 2 degrees. (=4 degrees at the crank) Well, bsugger me the engine is now so much more lively and willing - at least another 7 or 8 bhp at a guess and after starting up in the cold the production of blue/white exhaust smoke has been seriously curtailed!

It is a little noisier now - a little more harshness to the engine note, but given the cacophony of other sounds from the machine it's no big deal!

Julian.

[Snagger]

If the fuel injection is a little retarded, it results in blueish white smoke when cold and a reduction in performance, but it also makes starting much easier. Advancing the injection a little to much gives significant black smoke on full throttle, a harsh engine note (a bit of a bark), lessened performance, higher running temperatures under load and more difficult starting. The timing should be set that you get just a little black smoke at full throttle and just a trace of harshness when going from low rpm to full throttle under drive (ie not in neeutral with the bonnet up!). Slack in the timing chain or skew gear and drive on 10Js causes a lot of timing trouble, so check the condition of those parts if you are having any inconsistent behaviour or trouble setting accurate timing.

[Snagger]

I've never driven a 2.6 - my only experience of one was a friend's 109 twenty years ago, and his was plagued with reliability issues. I'm under the impression that they're more temperamental than the 4cyls, especially the cooling system, but hat once correctly set up, they're a great drive.

As far as improving their perfomance is concerned, I've heard of the use of different manifolds and carbs, and possibly a different cam shaft, from another application of the same base engine. The name Westlake rings a bell.

[Tanuki]

The six is a lovely smooth engine indeed - and it sounds good under load too.I've seen a 109 fitted with the twin-carb "Weslake"-head 3-litre out of a Rover P5; you can't do this swap on a RHD car though as the rearmost carb wants to live in the same space as the pedal-box/steering-column.--Tanuki

As far as improving their perfomance is concerned, I've heard of the use of different manifolds and carbs, and possibly a different cam shaft, from another application of the same base engine.  The name Westlake rings a bell.

[Julian]

Another way to gain about 1BHP: Take the standard 4 bladed fan and grind two blades off at the hub.

As I didn't know if I'd get any cooling problems I purchased a fan off the ebay to experiment with, reasoning that if the experimentation was a failure I could swiftly stick the old fan back on. The fan that arrived was a slightly smaller diameter than that fitted, but nevertheless I set to with the grinderette and loped off two blades. I can report that I have absolutely no bothers with cooling, the hottest day so far has been 22C. I guessed that stationary in traffic would be the worst case so left it running after a good blast while I drank a cup of tea and the temp stayed rock steady 1/2 scale deflection.

I didn't want to fit an electric fan, probably a better alternative, as I don't like adding extra complication.

Julian.

[FridgeFreezer]

I find the worst case is working hard in low box, ticking over is not so bad but doing donuts in low 2nd makes the fans come on full speed

[larna86]

I've got the Rover P5 3lt engine with Weslake head in my S1 86inch. Admittly it's a tight squeeze but possible. It's used off road a fair bit and with the original gearbox I've broken one half shaft only.

When set up well it's very very smooth and will idle at 600rpm easily.

Just my two pence worth

[Julian]

Yes i suppose working hard in low box is the worst case, especially if you make the engine 'lug' at low revs as the fan will only be turning slowly.

I don't really do that, as I just pull a trailer on the roads as a worst case and 1st in high box is enough to climb a 1 in 1

I beginning to wonder now that i've got all this new found power by advancing the pump timing if I could try some 10 spline Range Rover diffs, maybe just do the rear one first and see how it goes..... What do you think SWB 2 1/4 Diesel already fitted with Fairey OD, am I asking too much?

Julian.

[ejparrott]

If you've got 205's I'd go for it, otherwise I wouldn't, not until you've fitted a TDi anyway.

[Julian]

Tyres are 7.50 by 16

How does that compare with 205's?

Julian.

[ian_s]

if i remember rightly a 7.50x16 tire is about 10% taller than the 205x16

[Gremlin]

Use the gearing calculator, IMO 3.5 diffs on a series diesel is a no no....

[ejparrott]

Big tyres, them's for a 109 or optional on an 88....don't bother swapping diffs until you fitted a TDi.

[Julian]

Ok thanks. I'll leave it as it is. One of the reasons I was condidering taller diffs is because I suspect the rear diff on mine is fairly worn. It makes no noise but there's a lot of 'lash' in the propshaft when you compare it to the front diff.

Julian.

[Snagger]

Ok thanks. I'll leave it as it is. One of the reasons I was condidering taller diffs is because I suspect the rear diff on mine is fairly worn. It makes no noise but there's a lot of 'lash' in the propshaft when you compare it to the front diff.

Julian.

Swap the diffs over then! The front diff doesn't wear much because it spends most of its time idling, with the road wheels turning it and the only resistance the prop UJs and 4wd front casing's bearings and oil. The rear is driving all the time, though, so gets the most wear.

3.54 diffs are too tall for a 10J (2.25 nad) or 12J (2.5 nad), as you'll never have enough torque to reach cruising speed and even pulling out at a junction would become difficult. An overdrive is far better, allowing you to cruise at lower rpm, saving fuel but also making a more comfortable drive. With a 2.5, my 109 would do 60mph on level road (with no significant headwind) with the OD engaged, and that's with a big roof rack and bullbar with lots of spot lights, a spare on the bonnet and four mudflaps, all creating a lot of drag. The 10J should manage the same on a "clean" Series vehicle without bother.

[Julian]

Swap the diffs over then! The front diff doesn't wear much because it spends most of its time idling, with the road wheels turning it and the only resistance the prop UJs and 4wd front casing's bearings and oil. The rear is driving all the time, though, so gets the most wear.

.

That's a brilliant idea,- It'll be a job for the winter probably after I've done the gearbox. Total cost = two new gaskets :-)

My front axle has probably done next to nothing as it has FWH fitted. And (I guess) the crown wheel & pinion mostly works on the backside of the teeth as it's going backwards....

When I remove the rear axle I will look into reducing the 'lash' in the thing - the pinion engagement probably needs tightening up at a guess?

Julian.

[Snagger]

When I remove the rear axle I will look into reducing the 'lash' in the thing - the pinion engagement probably needs tightening up at a guess?

Julian.

Yep, but it's slightly trickier than it seems - you have to move the pinion in a little as well as moving the crown wheel towards the pinion to keep the mesh points the same. If you just move the crown wheel across (by adjustingt he diff carrier bearings), then thegears will mesh slightly diffently and could howl. However, like you said, there won't be much wear on the back sides of the teeth, which will become the driving side as it moves to the front axle,and there won't be much torque applied at high speed (because that's normally in 2wd), so setting it up like a new axle should work well enough.

[Julian]

Big tyres, them's for a 109 or optional on an 88....don't bother swapping diffs until you fitted a TDi.

Yesterday I went for a long run. 45-50mph is the sorts of speeds that I do when the road allows and I was noticing that I spent a fair amount of time in 4th overdirve with my foot on the boards. (light soot from the exhaust that you can see from the door mirror.) I decided that I was kidding myself thinking that the engine would be happy with Rover diffs, well it might now and again on a nice level road with a following wind but anything but the ideal is going to see constant gear changing and fiddling with the OD lever.

Best leave it as nature intended!

Julian.