discovery 2 v8 4.0ltre or 3.9

guinness · Dec 27, 2009

hi can any one help.
can i fit my 4.oltr heads on a 3.9 and do i have to change any thing else as i have availble a 3.9 which i was thinking of transfaring.
after my last thread it was confirmed that the 3.9 is the same engine as the 4.o ltre.
also will my thor type manifold alternator pumps etc transfare.
many thanks.

listerdiesel · Dec 27, 2009

I think I mentioned this before, but here goes:

10-bolt heads will go onto any 10-bolt block.

The block for a THOR engine has the flywheel pickup in a slightly different place to the GEMS engine, other than that you can build a THOR top onto a GEMS bottom end. We have done it and it works.

The 4.0 and 3.9 designations are only sales chatter, they are both 3950cc engines, and only one piston is listed for both engines. They kept up the different labels so that the THOR engine was always the 4.0 and the GEMS was the 3.9.

Peter

guinness · Dec 28, 2009

hi peter how does the ignition sensor work on the fly wheel and how far away from the flywheel must it be to work.
will now decide to rebuild the 3.9 and then swap over once its finished.
how hard is it to split from the gear box once all the bolts are removed from the bell housing

thanks

Beast o Bodmin · Dec 28, 2009

There are differences in some as the 4.0 has a cross bolted bottom end.This is a stronger engine as a result.

guinness · Dec 28, 2009

would this make a differnce as i have to change the block as i think its cracked.

vougese39 · Dec 29, 2009

i would rebuild the 4.0 as the crank sensor has a cast opening in the block to allow the sensor to be in correct alignement to the flywheel and for the cost building the 4.0 would be the same as the 3.9 plus the top hat linners

The Mad Hat Man · Dec 29, 2009

why would anyone rebuild one of these lumps without top-hatting it?

discovery 2 v8 4.0ltre or 3.9

guinness

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