Cyl head gas flowing and other questions.

Hello,

It's my first post on here for a while since getting rid of my 2a, should be getting hold of a series 3 soon.

I've heard of a few people gas flowing the head on a 2.25 petrol, will this give me any improvement on power/mpg?

And could anybody give me an idea of the original thickness of steel as used on the chassis and bulkhead?

Also, does anybody make an LED tail, sidelight and indicator kit for the series?

Thanks, i've missed my landy.

I've got the stage 2.1 9:1 head and hi-torque cam from ACR and later a Weber DMTL Carb for a 90 and they made a big difference.

When I first got the motor someone had put 3.54 diffs on and it struggled on the hills round here even after I'd fettled the original carb.

I couldn't really tell you which part made the biggest difference as I did them head and cams at the same time but if I was doing the same again I think I'd give the flowed head a miss. Once you have the 9:1 compression and the hi-torque cam you can run 3.54 diffs and an overdrive and you won't be revving the arse off it so you're kind of losing the benefit of the flowed head I suspect.

When I first changed the head+cam I instantly got a faster car but was still running a Weber 34ICH, it was quicker and used a bit less juice (I think I was getting about 17mpg - not bad for round here with all the hills). I later got hold of a defender manifold set and upgraded to a Weber 32/34 - needed a bit of fettling to convert to a cable throttle but only took a couple of hours in the end. I now get 20-21mpg round here and knocking 30 on long 50-60mph runs.

The main gain that matters is the increase in low-down torque requiring fewer gear changes and leading to a more relaxed drive, a bonus off road too it will pick up from crawling at idle nicely now where it would have struggled or stalled before.

I've now swapped back to 3.54 diffs plus an overdrive. It will cruise up hills now in 4th (same ratio as 4+overdrive) at 40-50mph which would have required 3rd and a headache before and much nicer to drive.

I don't understand why more people don't fit the DMTL carb as a first upgrade the progressive twin barrel setup really suits a Landrover with really nice smooth control over crawling on the first skinny barrel and enough flow for foot-down...

Top speed ? had it up to 100 on the continent, pant ****tingly scary though so won't be doing that again in a hurry. That said it will sit at 80 on motorway all day until you come to a steep hill but it will manage on all the steep ones between here and Glasgow without having to fall below 65...

A ton in a 2.25 series!!!!! I got 77mph with just the weber carb and 7:1 head.

So how different is the manifold? And is it needed for the dmtl carb?

dominicbeesley said:

I've got the stage 2.1 9:1 head and hi-torque cam from ACR and later a Weber DMTL Carb for a 90 and they made a big difference.

When I first got the motor someone had put 3.54 diffs on and it struggled on the hills round here even after I'd fettled the original carb.

I couldn't really tell you which part made the biggest difference as I did them head and cams at the same time but if I was doing the same again I think I'd give the flowed head a miss. Once you have the 9:1 compression and the hi-torque cam you can run 3.54 diffs and an overdrive and you won't be revving the arse off it so you're kind of losing the benefit of the flowed head I suspect.

When I first changed the head+cam I instantly got a faster car but was still running a Weber 34ICH, it was quicker and used a bit less juice (I think I was getting about 17mpg - not bad for round here with all the hills). I later got hold of a defender manifold set and upgraded to a Weber 32/34 - needed a bit of fettling to convert to a cable throttle but only took a couple of hours in the end. I now get 20-21mpg round here and knocking 30 on long 50-60mph runs.

The main gain that matters is the increase in low-down torque requiring fewer gear changes and leading to a more relaxed drive, a bonus off road too it will pick up from crawling at idle nicely now where it would have struggled or stalled before.

I've now swapped back to 3.54 diffs plus an overdrive. It will cruise up hills now in 4th (same ratio as 4+overdrive) at 40-50mph which would have required 3rd and a headache before and much nicer to drive.

I don't understand why more people don't fit the DMTL carb as a first upgrade the progressive twin barrel setup really suits a Landrover with really nice smooth control over crawling on the first skinny barrel and enough flow for foot-down...

Top speed ? had it up to 100 on the continent, pant ****tingly scary though so won't be doing that again in a hurry. That said it will sit at 80 on motorway all day until you come to a steep hill but it will manage on all the steep ones between here and Glasgow without having to fall below 65...

Click to expand...

I've got very little idea of what any of that means when it comes to the real world of fitting.......But I suspect I should find out.

Running on a Zenith atm and off road it hunts on a steep downgrade and stalls going up....which int ideal

HG, If you got 77mph without an overdrive then you were really going some! Even with that is pushing it I don't like to go that fast without overdrive and 3.54 diffs - both add about 30% to the original top speed of 60-65.

The manifold is an easy-ish swap. It bolts straight on and looks almost identical. The difference is the hole on the top for the carb is bigger and square instead of round to allow the double-barrels to mate. The exhaust one is also different where it mates to the inlet and so needs to swap which is a pain as you then need to adapt the exhaust...the 90 exhaust flange is a wider diameter. I just cut and shut a 90 exhaust downpipe onto a series one with a mig welder.

The other, possibly easier, carb option is ACR's SU conversion. That would no doubt run like a dream but I'm not sure of the efficiency. The only experience I had with SUs in the past was that they ran rich but that could have been poor set-up.

BB, sounds like your carb is in proper need of a service! Could be the big O-ring between the two halves is leaking?

Fitting the stuff from head and cam from ACR requires a fair bit of time and patience:
Radiator and preferably driver's wing off - I didn't take wing off and spent extra time ****ing around getting the distributor skew-gear back - shouldn't take long, except like me you'll probably end up having to fix the radiator panel, mounting brackets, captive bolts etc etc

Then undo all the plumbing to the top of the engine and remove distributor, manifolds etc

Whip rockers off, inspect and replace any very worn ones but only if they're very worn, replacement ones, even OEM can be a bit rubbish I've found, if they're just a bit flatted it might be better to dress them with a file if its not a lot of material?

Whip head off and send it to Roland at ACR for the swap. (don't forget the oil feed pipe at the back).

Have a look at pistons, not how much play, how scratched the bores are, consider doing rings then think sod it the compression was ok!

Take front off engine and remove timing chain and water pump, inspect all the timing chain bits and replace knackered stuff - a bit of wear probably doesn't matter but probably worth getting a new chain while you're in there.

The cam then needs to come out, take the inspection plates off, pull all the tappets and guides and consider replacing - I did mine but should probably have left them as one of the new ones failed after about 10k, remove skew gear from

Setting the new cam up is the most difficult part, there are instructions from ACR but you need a pair of dial test indicators. First find TDC and find it EXACTLY you want to be within a smallish fraction of a degree. I made up a pointer and circle that I nipped up onto the front pulley (I also realigned my timing marker while I was at it but it needs to be more accurate than that). It's easy enough to find, rest the DTI on the top of the piston and find its highest point. Then check either side of TDC by taking bearings either side (say 1/2mm down and 1mm down) and take the average of those - this is to try and counter any play in the little end or big end that might be affect the exact TDC you want to know where the crank is not necessarily the piston which might have a dead spot.

Then you set up the cam, this is a case of getting the #1 and #2 tappets to "rock" at exactly TDC, with both DTIs one on each you should get identical lift on them both. To set this up you will need to mess around with the chain position and the big cog on the end of the cam. The big sprocket goes onto the cam with a keyway which can sit in one of 6 positions each gives a slight offset.

That all takes an hour or two of farting around but it is worth getting the cam timed in properly. I'm half tempted to have an play with mine seeing what happens if you advance or retard it a degree, one should give more at top speed the other a bit more at low down grunt. However, where Roland advises certainly seems to work well.

While you're doing all this you also have to get the skew gear back in - this can be a pain as you need to drop it down a hole and line up notch for the screw that holds it in place, plus you have to get it up so that the keyway is pointing at the right point when the engine is at TDC plus you have to make sure its at #1 TDC and one turn round from where the valves are rocking or your distributor will be out by 180 degrees and you'll either have to swap all the wires round or have the dissy on backwards. This took me ages as I'd not removed the wing - in the end after nearly giving up I rigged up a web cam and computer so I could watch one hole while poking the other! With that set up I had it sorted in no time.

Then its a case of put everything back together, torque it all up nicely, do the tappets and see if it still runs!

When I did mine it took a good few evenings all in but a lot of that was horsing around with fixing dodgy body work, wiring and plumbing. The most involved bit if you're not technically minded or a bit cack handed is setting up the cam but is by no means difficult, just requires a bit of thought and patience.

I really enjoyed the whole process of doing mine and am really happy with the results. I'm still toying with the idea of doing it all again on the 109 but then again I may give it a 3.5 rover engine....

D

meant to mention also that I swapped the first idle jet in the new Weber Carb for 1 size smaller, it run a bit too rich on progression and that saved a couple of mpg without upsetting performance.

DMTL more expensive than 34ich and requires a throttle cable which can end up being a bodge or achieved with a 90/110 pedal. So extra cost on top. But yes if you've had all the fancy work done to the head then you may want an upgrade. Some people use a small SU with an elbow to let it sit at the correct angle (45 degree ish I guess like on rv8). But ditching the oil bath filter makes it less original and maybe noisier, if that's a concern. If you can get hold of a 2.5 petrol engine that would probably be cheaper and would come with a DMTL already fitted! Grab the throttle pedal at the same time if its from a wrecked 90 etc.. 2.5 looks pretty much same as a 5 bearing 2.25 too.

Steel used for bulkhead repair (footwells etc..) is usually 1.2mm, not sure what they were originally?

DMTL vs 34ICH paid for itself by saving 47 Gallons of fuel around £300 for new GENUINE carb, ebay manifolds and 90 downpipe.

I'm pretty sure (I haven't got my notes here) that the DTML ( with smaller idle jet) improved mpg by about 4-5, so taking 3.5mpg as a conservative estimate: I work out it pays for itself after about £5,300 miles. Just in terms of fuel - don't forget it goes faster and smoother too.

Other stuff I've done for an odd mpg:

- freewheeling hubs : it feels faster but not much noticeable mpg improvement, I suspect it aids acceleration a bit not having to spin up the front axle.
- kenlowe fan: I got about 1-2mpg maybe after fitting that, more in the winter as it means the engine is up to temp earlier and so you can give it less choke for less time
- 9:1 head : means you can use regular unleaded and so save on expensive additives, I seem to recall that the cam and head together gave a about 4 mpg extra

I did keep pretty good records of mpg but not sure where the older ones are now, new ones are on spreadsheet. However, keeping good accurate records doesn't tell everything as it can't take into account that I now tend drive quite a bit faster as more power and torque are available. If I drove at the speeds that were possible when top speed was about 60 and it took 10 minutes to get there I'd probably save another few mpg!

The cable was not quite a bodge. I just welded up a small bracket that sits on the bulkhead and connects the cable to the original linkage arm (one hole drilled in it IIRC). I can get photos if anyone's interested.

D

Seem to recall reading 2.5 cam gave better performance when fitted to 2.25 and if fitted with 2.5 head allowed you to use unleaded with no adverse effect.
May have been under the influence so not 100% sure.
I would be interested to know if anyone has info on how to gas flow head, is it worth grinding manifold casting to aline with head etc?