Outer Limits 4x4 Board

G'dday Mates,
i need some advise on how to go about my V8 problem.
I've a 3.5 RR and blew a piston recently.
So i went out to buy a 1996 3.9 Disco half cut to drop into my RR.
But after dropping the engine into the car it didnt sound good and there was water in the cylinder.
The mechcanic took out the head and the head was F!@# with the valves !@#.

So my question is what's the difference in bore x stroke of the 3.5 and 3.9?
The next million dollar question is the 3.5 cylinder head interchangable on to the 3.9?
Are they any difference in head dimensions, valves inlet/ outlet, ports, compression ratio and etc?

Oh by the way the 2 engines are high comp engines.
Is there any other forums or someone who are into Rover V8s who good knowledge on this engine i can ask advise from?
Thanks in advance.
Best Regards.

G'day, whilst I haven't tried bolting the earlier heads on to a later model engine I have seen plenty of threads over the other 47 pages where people have done it successfully.

But I will say if you're going to the trouble of pulling engines in and out then you will need to get the heads serviced at least.

What made the original engine blow? They don't usually 'blow pistons' or throw rods. Unless you barbecue them or run 'em out of oil.........

Suggest you want to find the cause of the death of the old engine as well. Could be a malfunctioning injector, etc..

The previous 3.5 engine went was due to fueling as a result of slip shod workmanship on the mechanic when replacing the injector hoses. Hence fuel delivery to the injectors was being suffocated and hence cost the piston to fry.
Hence i bought a 3.9 2nd engine. Unfortunatly that came with a fecked cylinder head.
So now i'm wondering if i can plonk the cylinder heads from the 3.5 on to the 3.9 block?

I've got 3.5 heads on a 4.6 block. The pistons have a concave crown, high compression engines use pistons with a different crown to change compression ratio, not a different head.

Thanks for the response.
My current intention is to drop in cylinder head ERC 0216( 3.5 EFi) on to a 3.9 block (1996 Discovery). Will it be a direct bold on? Will there be any issues to address or modification required?

By fitting the cylinder head will it raise the compression?

Another thing does anyone know the size of the valves on the HRC2210 (3.9 head post 93)? I've the 3.5 specs but cant find the 3.9 cylinder head specs. How about the combustion chamber?
Also is there any difference between the 3.5 and 3.9's intake manifold/ plenum? Preferrably bolt on which manifold on my engine?

Hey Peter R,
thanks for the reply.
How do i find out what and where is the engine prefix? The best i can say is it's from a 1996 Series I facelifted Discovery.
I've to check the gasket from the 3.9 Discovery. But i believe it's a composite as it's hard to flex as compared to a normal gasket.
The 3.9 heads from the Disco that's kaput has 10 bolts.

My intention is to drop my old 3.5 Range Rover 1989 High Comp cylinder head on to the block of the 3.9 1996 Discovery.

Oh btw are the valves from the 3.9 interchangable with the 3.5 head?
Best Regards
Victor

G`day Victor , the engine number is on the lefthand side at the top of the block , just below where the head mates up , in the centre between cylinders number three and five , near the dip stick . Just the first two numbers and the letter would help .

I'll check on this.

Composite 3.9 gaskets are thick and black normally , tin gaskets are thin in comparison and will have at least some parts that will still look like metal .

The 3.9 gasket are compostie, while the old 3.5 is metal. When i get the mechanic to fix back the head which gasket, top overhaul kit should i use? The 3.9 composite gasket kit or the old 3.5 kit?

If you can put the 3.5 and 3.9 heads side by side , where the 3.5 has the outer row of bolts , closest to the sparkplugs , do the 3.9 heads have the same amount of metal in the same area but no holes ?

Correct, the 3.9 heads looks very similiar to the 3.5 but no holes.

Is the 3.9 block crossbolted ? If you look just above the sump on the side of the block is there a row of 4 bolt heads along each side . If there they are about 50mm above the sump gasket and spaced at about 150mm .

Yup.

The valves should interchange but i won`t know for sure till you get back .

Looks like the valves are interchangable as my mech measured it and they seem to fit nicely.

Another thing is that after with the piston slamming the valve into the head on my 3.9 i suspect that the conrod is bent but i would not know until my mech drops the engine. Can the bent 3.9 conrod be replaced with the old 3.5 conrod as i believe the stroke is the same.
Thanks again.
Best Regards
Victor