Gems vs Thor interchangeable parts.

Hi guys, bit of background.....

I've got a 4.0L in our D2 that is in need of a new engine (liners ) While im throwing money at the Disco I'll be upgrading to 4.6L

Was originally going to go with a short block from Turner and use my current heads. But since stripping mine down I've found the rockers are quite warn, one of which has lost its thrust pad totally and trashed the corresponding valve stem

Having priced up the seperate bits i now need to recon my heads, I've decided I might as well get a long engine instead of a short one.

Now for the reason for this thread.

I've located a used but low milage 4.6 Turner engine from a breaker, obviously it's a lot cheaper than a fresh engine. The only slight problem is that it's a Gems engine so I need to check if a mix and match will be possible.

1) Biggest one is obviously whether the blocks the same? Is there provision for the Bosch knock sensors on the gems block? I've read the crank sensor location is slightly different but can be modified, any info on this?

2) I assume the front cover would need to be swapped to Thor. Does the timing gear need changing too?

3) Rockers and shafts are they the same? Hopefully the low milage ones on the new engine will still be good to replace mine.

Obviously the inlet manifold needs swapping, and I'll be able to compare other parts while doing the rebuild. Just trying to get my head round which engine would be the better option - new or used.

Depends.

A cross-bolted block like we used from a late D1 had the bosses on the block for the knock sensors, 10-bolt heads should all be the same, flywheel sensor position is slightly different but can be modded to fit.

Ours was a genuine LR short engine and other than the flywheel pickup, everything else fitted, including the front timing cover, camshaft etc etc.

Still going, done nearly 90k miles on it now.

Peter

I've just had a top hat block (a '97 gems) put into my 2002 Thor.
Only difference in the block is the crank position sensor, needed cutting out & my thor sensor bolting in.
No difference between heads either (rocker gear etc).

The flywheel pickup housing is different but the mounting is the same, so you'll need a replacement housing EIQ100020.

It locates in the machined hole in the back of the engine casting and has a roll pin for accurate timing. It is then TIG welded in place with a small tack weld.

Peter

Thanks guys, just weighing up a third option.....

Are the cranks the same between Gems and Thor?

Or more to the point; when taking a Thor engine from 4ltr to 4.6ltr, can the "stroked" crank and rods come from a Gems engine?

My gut feeling is yes but just want to check.

JordanTD5 said:

Thanks guys, just weighing up a third option.....

Are the cranks the same between Gems and Thor?

Or more to the point; when taking a Thor engine from 4ltr to 4.6ltr, can the "stroked" crank and rods come from a Gems engine?

My gut feeling is yes but just want to check.

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Yep, crank & rods are the same Gems to Thor.
Mine has a 4.6 crank & con rods from a Gems but with 4.0 pistons to up the CR.

martynv8 said:

Mine has a 4.6 crank & con rods from a Gems but with 4.0 pistons to up the CR.

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Exactly what I want

My new plan is to get a bare top hat block from Turner and a cheap Gems 4.6 engine. Then mix and match with my Thor 4.0 engine to build up what I want.

Just deciding what cam to build it with, what are you running?

I'm running a Kent 180 from Turner.
Low end torque is a huge improvement. Not much to sing about at the top of the rev range but i've not really given it too much as it's only done 700 miles.

Found this on the bay?

Range rover 4.0 4.6 engine top hat liners | eBay

Yes, that's what prompted the start of this thread. I spoke to the guy and the two 4.6 lumps he's got are apparently quite low mileage, although the Turner invoice he sent me a picture of was dated Jan 2001.

Downside is that I'm in Ipswich (Suffolk) and he's in Aberystwyth. Means I can't see the engines running or even take the rockers off to have a peek at the general condition before buying.

That along with wanting a new cam and high compression is swaying me towards a fresh build, which would also come with a fresh warranty on the liners from Turner.

I guess Turners would be a logical approach. Be careful though, Turners often require many items to be replaced with the engine to validate warranty (rads, waterpumps, even heater matrix etc).
I practically got a new full engine in the end as the liner had taken a liking to my cylinder head so i got a new pair. I saved about a grand by getting the block, pistons, & crank etc from a guy selling on the bay. Just had to assemble the short engine before getting the engine swapped out from mine. Was a bit of a gamble but seems to have paid off.
How about V8Developments or ACR?

I have looked at the other engine suppliers and have mostly settled on Turner due to the amount of positive comments across multiple forums.

Tempted by ACR as their bare block is £250 less than Turner. Not nearly as much feedback, what I've found is all positive though which is reassuring. Guess I'll give them a call and see how much confidence they inspire over the phone.

We won't mention RPi

Turners do have a very good reputation, i bought most of my parts for the rebuild from them.
V8Developments will top hat liner your block for just under a grand, still considering getting my old block done & rebuilding mine....just what to do with it then?
RPI do a good job of spouting alot of BS.

martynv8 said:

RPI do a good job of spouting alot of BS.

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+1 on that!

Peter

Yes.

And if you went by some of the comments I've read you'd be forgiven for thinking their engines came in blue boxes. :lol:

What did it for me was when I was talking to a mate of mine who used to work at RPi. When I mentioned my issue he immediately said top hat blocks are s**t and coscast blocks are the only fix. He was gobsmacked when I pointed out that, since he left, coscast blocks have gone out of production and RPi are now happy to do top hats! :crazy:

Having said that, I'm still tempted to get the piper cam from them as it comes with new followers, timing gear and some of the gaskets I'll need for the build anyway.

Yep, RPI used to slate top hat liners saying only coscast were good until stocks ran out & now they sell top hats. I know a guy who has had quite a few engines from RPI in for repair. Mostly liner fails on coscast & also a few early cam failures.

2 points, Turners - none of the others. Second,dont forget to use a Thor cam sprocket.

martynv8 said:

...... also a few early cam failures.

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Any more info on this? Poor assembly or component failure? I'd be surprised if the cam itself from piper failed.

Also seperate from that, anyone know the difference between floppy and stiff timing chains? (Apart from the obvious :lol.

JordanTD5 said:

Any more info on this? Poor assembly or component failure? I'd be surprised if the cam itself from piper failed.

Also seperate from that, anyone know the difference between floppy and stiff timing chains? (Apart from the obvious :lol.

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It was definately the cam on one occasion but he does slate their assembly. I mentioned i was looking at the Piper kit for the rebuild when he mentioned it. In the end it was cheaper to get the parts seperately & getting the parts from Turners was assurance they were not cheap aftermarket.
I went for a stiff chain, don't ask why, just heard they were better.

Cheers,

I seem to be in exactly the same boat as you, just a few months behind :lol:

Ha, i took my time. Mine was tapping away with a loose liner for many months before it got too annoying. My original plan was to get a short engine from Turners or V8Dev but came across a bargain on the bay. At least this way i got to know the inner workings of the Rover V8 which is why i'm now tempted to fix & build up my old one, if only for satisfaction.