interference fit liner to block,rover v8?

twinpipes · Post by **twinpipes** » Fri Jan 03, 2014 11:30 am

Happy new year to all you petrol heads! Has any of you lot got any info with regard to the amount of interference fit of the liner to the block bore diameter of a 3.9 rover engine? I can work the thermal expansion rates out for the alloy block and cast iron liner,I just wanted to know the manufacturers specs on the amount of interference they use when building the engine or does anyone know what amount of interference a engine builder would use when using new liners in the process of reconditioning a used engine? Hope some of you can help with these queries,many thanks Twinpipes!!!

ChrisJC · Post by **ChrisJC** » Fri Jan 03, 2014 4:45 pm

http://landroverforums.com/forum/discov ... ide-57982/

suggests 3-4thou.

Chris.

twinpipes · Post by **twinpipes** » Fri Jan 03, 2014 6:11 pm

hiya Chris thanks for the post,I had already seen this post and the videos,I also read another post relating to des hammels book on the rover v8 and that mentions an interference fit of .007" so this is a bit confusing.I thought I would post the topic hoping to get advice from some reputable engine specialist of the rover V8.I will see if anyone else butts in.I have also watched a video of an engine rebuild,where they use liquid nitrogen to cool the liners before fitting them by hand into the block,then make sure they are fully home by hydraulic press,before decking the block.I think it was chessman engineering,but its the actual interference dimensions i am interested to know.Many thanks for the reply and happy new year,Twinpipes!!!

mgbv8 · Post by **mgbv8** » Fri Jan 03, 2014 9:03 pm

I havent seen the vid. But my engine guy drops my liners in liquid nitrogen and puts the block in an oven. The liners drop straight in and are then clamped in place for a 24 hour period in the workshop before the decks are skimmed.

ChrisJC · Post by **ChrisJC** » Fri Jan 03, 2014 10:00 pm

Sadly I suspect a factual answer will be hard to come by. Probably the best bet is to call up one of the liner manufacturers and try to blag an answer.....

Chris.

mgbv8 · Post by **mgbv8** » Fri Jan 03, 2014 10:04 pm

Try calling Chessman or Knight engine services for an answer?

DaveEFI · Post by **DaveEFI** » Sat Jan 04, 2014 12:05 am

ChrisJC wrote:Sadly I suspect a factual answer will be hard to come by. Probably the best bet is to call up one of the liner manufacturers and try to blag an answer.....

Chris.

There's nothing in the BL SD1 manual about replacing the liners. Nor about overbore sizes. Perhaps they expected the engines to last forever?

stevieturbo · Post by **stevieturbo** » Sat Jan 04, 2014 12:38 am

I sure as hell wouldnt be trying something like that myself !!!!

take it to someone who knows and has done hundreds if not thousands of them before !

DaveEFI · Post by **DaveEFI** » Sat Jan 04, 2014 9:19 am

True - but the BL manual gives details of fitting liners to the 6 cylinder engine. Which has an iron block not originally fitted with them.

ChrisJC · Post by **ChrisJC** » Sat Jan 04, 2014 9:36 am

DaveEFI wrote:
ChrisJC wrote:Sadly I suspect a factual answer will be hard to come by. Probably the best bet is to call up one of the liner manufacturers and try to blag an answer.....

Chris.
There's nothing in the BL SD1 manual about replacing the liners. Nor about overbore sizes. Perhaps they expected the engines to last forever?

Which is strange because the Haynes manual gives +10 and +20thou overbore data.

I suspect that there was never a need to reliner the 3.5 engines, it's only the 3.7" bore (i.e. 3.9litre+) engines that crack the blocks and need this fix!

Chris.

twinpipes · Post by **twinpipes** » Sat Jan 04, 2014 10:36 am

my thinking is that the 3 to 4 thou dimension mentioned earlier is not enough.The linear expansion for the alloy is 0.000023 per degree C and for the cast iron liner is 0.000015.So working the sums out for a 88 degree thermostat goes as follows.lets say the average alloy bore size is 3.850" X 0.000023 X 88 = 0.00779" so round it of to .008" The bores dimension is now 3.858" and for the liner, 3.854" (.004" larger)The sums are 3.854 X 0.000015 X 88 =0.00507 so round this of to .005" The liner outside diameter is now 3.859" the amount of interference now only stands at .001" not leaving much room for error on the amount of heat needed for the liner to become loose in the block.On a hot day stuck in traffic your block could reach 90 plus degrees C, also any slight tolerances on the liners or block even half a thou 0.0005" that is five tenths of a thou makes this even worse.It would have been nice to know how much of an interference fit that was used upon original assembly.There must be someone out their who knows the original spec and worked assembling these engines.My opinion is the difference should be at the least 0.005" thou and the 0.007" thou that Des Hammils book mentions is probably the top limit.Makes no wonder why this can be a problem on the rover V8,s what with worn tooling on the later engine machining,an the fact that the cast metal left upon making the bore diameter bigger to accept the larger capacity displacements and also the fact that the liners may not be fully home. Any other offerings welcomed many thanks Twinpipes!!! Hiya just looked at the post and put it right I did the dimentions for the liner the wrong way initially,anyway it all seems correct now,many thanks again Twinpipes!!!!