Outer Limits 4x4 Board

Can someone tell me if a 3.9 timing cover off a 96 disco with the serpintine belt can be retro fitted to earlier 3.9/ 3.5's and therefore should also fit a 4.4 ?

I don't think there's any difference in the timing covers for all 3.9 & 3.5 engines.

It only changed to incorporate a rotary oil pump with the 4.0 and 4.6, AFAIK.

Yeah, i didnt think it would be different as guys fit 4.6's using thier original covers and gear.

I have been meaning to ask the same question.

I've been thinking about an item that requires a serpentine belt that increases horsepower.

Is not the crankshaft on an interim 3.9 with rotary pump longer to fit the gear to drive the oil pump? The interim front was on the 3.9 and 4.2 range Rovers and was introduced in January 1994. I do not know whether it was immediately on Discos but I reckon so. Have a look to see if there is an oil pump next to the oil filter!
All V8s are backward compatable but NOT the other way around.
IE you can fit the EARLIER timing case on a 4.6 block, but you have to use a spacer behind the crank pulley bolt.

The very early 3.9 serpentine front with a camshaft driven oil pump will fit.
Reagrds Philip A

Philip A wrote:Is not the crankshaft on an interim 3.9 with rotary pump longer to fit the gear to drive the oil pump? The interim front was on the 3.9 and 4.2 range Rovers and was introduced in January 1994. I do not know whether it was immediately on Discos but I reckon so. Have a look to see if there is an oil pump next to the oil filter!
All V8s are backward compatable but NOT the other way around.
IE you can fit the EARLIER timing case on a 4.6 block, but you have to use a spacer behind the crank pulley bolt.

The very early 3.9 serpentine front with a camshaft driven oil pump will fit.
Reagrds Philip A

So as all the V8 blocks are interchangeable, as long as i fit all the acc. from a 96 disco it should all work ? where is the rotary pump located?

G`day Nick ,

94 with a B suffiix in the engine number were i think the first of the longer crank engines . 37D00000B is a 94 Disco

96 will have the longer crank , so the timing cover won`t work on the 4.4 .

The pump for these sit inside the timing cover and the crank runs through the middle of it .

If you look inside the cover and there are any extra bits it won`t fit , well it will fit but there won`t be enough crank to fit the balancer .

Peter .

As Peter says, you need the crankshaft from a later engine as well.

You cannot fit a LATER timing case on an Earlier engine but you can fit an earlier timing case on a later engine.
The blocks are compatable, the crankshaft is different.
Regard s Philip A

Thanks Phil, will the harmonic balacers from these longer crank motors fit the short crank ? I wanted to fit the balancer and cover to use a single belt but since the cover is a no go, i may just use the balancer and get the right w/pump/ ps and alt pulley to suit. I need to replace my aircon pump anyway so a dunnydore one will do.

I do not know for sure as I have not tried it but I am pretty sure that the pulleys would be out of line as the water pump , alternator and power steer pulleys, (and aircon ) would be designed to line up with the crankshaft pulley on the longer crank.
I do not know how you could overcome this, maybe make a spacer between the harmonic balancer and the pulley?

Alternatively , there is an interim strange set up on 92s that has a multi groove pulley that drives the alternator only with a mulfti groove belt, but someone has reported a while ago that this whole setup is bogus, but if the intention is to drive a supercharger, maybe you could do something with that.
I too have toyed with the idea as those Toyota superchargers are cheap and probably could be run with a standard injection setup.
Regard s Philip A

G`day Philip ,

Ya Know , when i replaced the 3.5 with the 4.0 never gave the pulleys a thought but everything lined up as they should , which doesn`t make sense .

Just did a very quick measure with a tape measure so not acurate and the 2 blocks seem about the same length .

What i have on the Longer 4.0 crank is a timing gear another timing gear with the teeth removed , which is the same thickness as an oil pump gear and works as the spacer then the balancer .

The Shorter 3.5 crank had just the timing gear and the balancer .

All the belts and pulleys line up and i think you`ll agree , if told this i`d say , don`t think so .

My brains on overload just now so can`t make sense of it , when my brain feels a bit more flexable , i`ll investigate where the difference is as there must be one .

All the bestr , peter .

Peter,
I am pretty sure that you have the second spacer in front of the balancer, so that the washer bears onto the balancer and holds it tight against the timing gear. IE the longer crank sticks out the front more and the pulleys are aligned.
This is backwards compatability IE old front , new block and crank.

regards Philip A

Yes that`s right , thanks , said my brain wasn`t working properly .

In the mean time i have found as well as different pulleys there are also different balancers . The other balancer i have if fitted to the 4.0 would put the belts about 10mm out of alignment towards the block .

Should be another engine arriving tomorrow not sure if it has a balancer though .

Anyway thanks didn`t think i was that stupid .

All the best .

Philip A wrote:I too have toyed with the idea as those Toyota superchargers are cheap and probably could be run with a standard injection setup.
Regard s Philip A

If you mean the small superchargers fitted to corollas/sprinters (4AG) then this will be too small (inefficient).

The best bet is the Eaton M90. Good for up to 5L.
These are the ones fitted to the Commodore V6.
They cost around $2K second hand here, but from the states - sub $500.

No, I mean the slightly bigger ones fitted to 2 litre 6 cylinder Crown.
You would probably have little increase up high but from idle to say 3000RPM , I reckon they would add about 5Lbs and that is something like 40%.
In an auto they would make a BIG diifference, and seeing the air demand at high revs is probably not much more, the total air requirement of the engine would not be much more, and you could get away with the 14CUX and Unichip and maybe just add a slightly higher pressure regulator or bigger injectors.Its all about the area under the torque curve.
You could use your standard inlet manifold and MAF, and just fit it to blow through.

The packaging looks a bit problematic, as from the photos on ebay , they have to be placed upright as they have a sump, (by the oil filler), and that leaves the inlet duct on one side and the outlet on the other, so there may not be enough room between the motor and LH guard. There are bosses on the block on the LH lower front under the alternator, and that is where it could go, like the old York compressors used to.
BUT its a big project, and I am still stumped on how to drive it, as I already have 3 V belt sheaves on the crankshaft pulley. its a bit expensive to get the whole front off a later model and all the extras like compressor, alternator, waterpump etc.
So if anyone wants to be the pioneer and can do it at a reasonable price , I am all ears.

regards Philip A

I have fitted the 3.9 cover to my 4.4 block for a trial fit and its fits perfectly, only problem is the keyway on the crank is not long enough to engage the balancer but otherwise will work and the belt will line up with the waterpump pulley nicely. I will have to work out how possible it will be to extend the crank keyway and fit a longer woodruff key.

Well done Loanrangie. I have been watching this with interest to see how it would all line up. Glad it all worked out.

When fitting an earlier timing cover to a later block, I assume you can just make up a spacer for the crank from a some tube or aluminium block etc. Just measuring the difference between the two cranks should give the length needed?

G`day Nick ,

Don`t have a 4.4 crank to measure so don`t know if the nose is the same as a 3.5 .

They`re only rough figures .

3.5 crank that the gear and balancer run on = 70mm
Gear = 20mm..... times 2 for the pump gear = 40mm

Leaves 30mm for balancer to run on .

Balancer normally runs on 50mm .

Can`t see why 20mm couldn`t be taken off the balancer ( other than being a 1 off )

Don`t know for sure but i think to extend the key way the crank would need removing ( not sure if 4.0/4.6 have 2 keys , i could look in a parts thing if needed ) as you know it needs to be a very good fit for the key .


As i say they are very rough measurements and what ever clearence the balancer has on the crank nose would need to be maintained .

All the best , peter .

It wouldnt work to take 20mm off the balancer as the key doesnt protrude past the oil pump drive but the balancer does sit inline with the w/pump pulley and the crank sits about 1.5mm below the balancer bolt clamp point ( if that makes sense ?). So with a longer woodruff key to engage with the balancer keyway if would be perfect.

G`day Nick

Yea , i ment with the longer key .

I had a look in the parts thing and there are only 2 keys V8 rovers use .

90602025 is all up to the last short crank 3.9 .

ERR 2845 is long crank 3.9 and 4.0 and 4.6 .

Don`t give any dimentions of coarse .

A 4.4 must have a longer crank because instead of the 1.5 mm you have there should be 21.5mm unless something else is different ?

The 20 i was talking about was to get things as they were with the normal stuff .

All the best , peter .

When the balancer bolt is tightened the bal will be tight up against the oil pump drive which is then in front of the timing gear so if the key is longer on the long crank motors then its just re cut the keyway and bobs your auntie.

G`day Nick ,

Just got the Hammill Rover Book that Philip posted on Rangie/Disco .

Seems the key is longer for later engines .

The crank goes into a milling machine .

It works on any pre long nose as long as all the later bits and longer key are used .

Only other it says is remove pump drive from dissy shaft .

So your on the right track and bonus is that it says rotary oil pumps are 40% more betterer .

Say g`day to aunty bob for me .

Peter does it have dims for the longer key, would you think it was twice as long as the short ones?

G`day Nick ,

It has drawing but not to scale .

From the drawing the spacing at the rear of the keyway and surface the gear snugs on look to be the same spacing at the end of the crank .

Clearer maybe ? Keyway spacing same front and rear . Keys a bit shorter .

It has photos of crank nose and it looks like this .

I`d say somewhere around 1/3 longer .

According to the book the serpy belted short and long cranks use the same key .

It says that the short crank pulleys have more offset than the long crank pulleys only reason it gives is to clear the distributor .

It also isn`t very clear when discos went long nose but it seem it would only be on a late series 1 , series 2 all should be .

But it definatley says what your doing is doable .

I had a better look this arvo and i think will just get another keyway cut near the end of the crank and use either a standard crescent shaped key or maybe just a square keyway cut , either way the keyway in the balancer goes the full lenght so positioning of the new keyway is not critical - except to keep the timing marks in line.