Thread: new 3.9 block

Originally Posted by milld

Hi,

I've got an opportunity to buy a near brand new 3.9 high compression long motor. As my current 3.9 motor liner has slipped I've been told that the liners don't slip as easy on the later 3.9 because the liners are pinched in. Is this true? Are the latest blocks better manufactured?

I want to go ahead but I'm scared about reliability

Cheers

Steve

Steve, No differences I'm afraid. The only way to remove this issue is to fit a top hat liner block. The liners only move usually because the block develops a crack behind the liner and releases its grip.

A Hi comp engine would be a good idea though, makes them pretty responsive and quite efficient, especiially if you intend to fit LPG one day.

JC

Originally Posted by milld

Hi,

I've got an opportunity to buy a near brand new 3.9 high compression long motor. As my current 3.9 motor liner has slipped I've been told that the liners don't slip as easy on the later 3.9 because the liners are pinched in. Is this true? Are the latest blocks better manufactured?

I want to go ahead but I'm scared about reliability

Cheers

Steve

Hi Steve,

Have you had a look at this blog JE Robison Service — the blog as mentioned by Pedro in: http://www.aulro.com/afvb/discovery-...ml#post1381095?

It certainly looks like they will not slip, but reading the full article there seems to be an argument for going with top hat liners anyway. Personally, if I had a 3.9 out of the car I would be installing top hat liners, along with new cam shaft, bearings etc.

Ron

Yes there is a difference albeit all RV8 blocks produced between 1988 and 2005 are nearly identical irrespective of capacity.

Blocks post 94 have a far stronger bottom end. This is done by more side ribbing and incorporated provision for cross bolting main bearing caps . They are also distinguishable by having 10 head bolts (tapped and used) not 14 compared to the pre 94 block. However it wasn’t until 4 and 4.6 litre engines where each cap was 4 bolted (2 vertical and 2 cross). The 4 and 4.6 litre engines also have main end big end bearing journals about 5mm larger in diameter so 3.9 and 4.0 l bottom ends are not interchangeable. The other difference is a “shoulder” was machined at the base of each bore to stop liner slippage.

You can see this “shoulder” in the picture in the JE Robison blog above of the block they sawed in half. A fix prior to this block modification was to pin the bottom of the liner however I question the sense of that when it is cracked block not a slipped liner which is the root cause of the problem

It sounds as though the block you can get has such a “shoulder” however I suspect it has been set up for a 4.0 or 4.6 litre engine and if so, will not take a 3.9 bottom end. You need to find out exactly what vintage it is (block is stamped)

However I would not touch a dedicated 4.0 litre block in a rebuild for love or money unless it was T hatted. The reason being LR ultrasonic block testiing had 4 litre engines getting blocks with the thinnest wall thickness between liner and water gallery and the 4.6’s getting the thicker ones. I have read that it is thought over 2/3 of 4 litre RV8’s are now cracked.

The only way to prevent coolant loss via crack and up around the top of the liner into combustion chamber is by using T hat or flange liners. The good news is once done it is better than new.

I would also use studs and nuts instead of stretch head bolts as there seems to be some correlation between tensioning action and crack locations in relation to head bolt holes, albeit I find it strange JE Robison make no mention of this fix.

Originally Posted by cockie55

Yes there is a difference albeit all RV8 blocks produced between 1988 and 2005 are nearly identical irrespective of capacity.

Blocks post 94 have a far stronger bottom end. This is done by more side ribbing and incorporated provision for cross bolting main bearing caps . They are also distinguishable by having 10 head bolts (tapped and used) not 14 compared to the pre 94 block. However it wasn’t until 4 and 4.6 litre engines where each cap was 4 bolted (2 vertical and 2 cross). The 4 and 4.6 litre engines also have main end big end bearing journals about 5mm larger in diameter so 3.9 and 4.0 l bottom ends are not interchangeable. The other difference is a “shoulder” was machined at the base of each bore to stop liner slippage.

You can see this “shoulder” in the picture in the JE Robison blog above of the block they sawed in half. A fix prior to this block modification was to pin the bottom of the liner however I question the sense of that when it is cracked block not a slipped liner which is the root cause of the problem

It sounds as though the block you can get has such a “shoulder” however I suspect it has been set up for a 4.0 or 4.6 litre engine and if so, will not take a 3.9 bottom end. You need to find out exactly what vintage it is (block is stamped)

However I would not touch a dedicated 4.0 litre block in a rebuild for love or money unless it was T hatted. The reason being LR ultrasonic block testiing had 4 litre engines getting blocks with the thinnest wall thickness between liner and water gallery and the 4.6’s getting the thicker ones. I have read that it is thought over 2/3 of 4 litre RV8’s are now cracked.

The only way to prevent coolant loss via crack and up around the top of the liner into combustion chamber is by using T hat or flange liners. The good news is once done it is better than new.

I would also use studs and nuts instead of stretch head bolts as there seems to be some correlation between tensioning action and crack locations in relation to head bolt holes, albeit I find it strange JE Robison make no mention of this fix.

Agreed, but as regards liner issues, no difference IMO. And yes, use of studs is a good idea, and pinning liners is really of no use.

JC

JC

Just noticed you have a new long motor not just offered a new block. Is it factory (where has it been hiding???) or a new build by someone?? If it is a D2 block my thoughts stand unless you could get it ultrasounded. If it is a factory post 94 D1 block build snap it up and maybe think about finishing off cross bolting.

Don't know if it's 100% relevant, but if anyone is looking for a brand new block for a 3.9, they have a couple on Landrover Classic Parts.

$1100++ but a reasonable price to pay for a factory warranted part?

wow sheerluck!!!,

that sounds awesome!!!! I thought they were around 3k - 4k alone. Maybe I should buy one and put my heads + new cam, pistons etc on it.

Originally Posted by cockie55

Just noticed you have a new long motor not just offered a new block. Is it factory (where has it been hiding???) or a new build by someone?? If it is a D2 block my thoughts stand unless you could get it ultrasounded. If it is a factory post 94 D1 block build snap it up and maybe think about finishing off cross bolting.

it's done just 8000km only and is as new. I need to ask a few more questions but it's going for $2950. If I told you where it is..... I would then have to kill you lol!!!