Is it a 3.9 or not??

big col · Oct 27, 2008

Hello every one, i'm new to the forum and have bought a rover v8 engine, it's eventualy going in my transit van, i bought it as a 3.9 but it doesn't say 3.9 on top of the plenum chamber. So is it a 3.9 or not? Any advice greatly appreciated,Cheers Big col.

ian c2 · Oct 27, 2008

im sure someone will have expertise to tell you from the engine number or such ...

but in the meantime , you could measure the crank with a measuring stick down a sparkplug hole .
(i think the difference between the two will be the stroke)

9

RoverDave · Oct 27, 2008

Hi Big col,
Its simple, what is your engine number ? I can tell you what size engine you have!

Dave

big col · Oct 28, 2008

the guy that sold it to me said it didn't hane a number because the block was changed during a re-build. So no number, sorry. He also said it had a tvr hi-lift cam fitted too, and new lifters and timing gear. Which makes sence to me so i had no reason to doubt him. I wanted a 3.9 because they have top hat liners and are more robust. ( no pourosity issues with the liners), any info would be good. Cheers, big col.

ian c2 · Oct 28, 2008

if you have no reason to doubt him , why this thread ??

anyway , you can measure from tdc to bdc through the sparkplug hole .

eightinavee · Oct 29, 2008

big col said:
the guy that sold it to me said it didn't hane a number because the block was changed during a re-build. So no number, sorry. He also said it had a tvr hi-lift cam fitted too, and new lifters and timing gear. Which makes sence to me so i had no reason to doubt him. I wanted a 3.9 because they have top hat liners and are more robust. ( no pourosity issues with the liners), any info would be good. Cheers, big col.

If you want reliability you need a 3.5,any of the bigger bore engines can suffer problems with loose liners/cracked blocks.If the engine you bought was cheap you can be fairly sure it wont have had stepped liners fitted - its an aftermarket mod and is quite expensive.

ian c2 · Oct 29, 2008

hey col
this isnt going to help you , but following eightinavee's post , i googled .....
got you this off the rpi website .

3.5.=89.5mm bore Std 3.5 crank
3.9.=94mm bore Std 3.5 stroke crank
4.2.=94mm (3.9 bore ) plus and 4.2 longer stroke crank
4.0 is the same capacity as 3.9 but uses later big journal crank and is cross bolted
4.6. + 94mm bore ( As per - 3.9 & 4.0) but uses later big journal (long stroke) crank and is also cross bolted as is the 4.0.

Is it a 3.9 or not??

big col

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