Thread: 81 RR 3.5 Carb to 4.0 Carb conversion

The problem with these blocks (and 3.9/4.6's for that matter) is that the ali between the cylinders in the block is very very thin. In fact when this thin web of ali cracks it lets the liner move abit, which in turn leaks coolant. It's been said by others on this forum that any 4.0 or 4.6 thats been cooked/overheated will have this problem.The history of your block sounds like it could even be another victum. You can overcome it by 'top hatting' the new liners, but this will cost about 2k.

Whatever I have read about slipped liners says that if one has gone the others are not far behind.
You should get the lot done with top hats, as the heartbreak of continually pulling the engine out and down would be far greater than the initial cost of a full job.
Regards Philip A

we did the same conversion on my 18 yr old 110 ute.
we got hold of a 4.0L cross bolted short motor for a special price, got some heads, timing cover and sump of an old 3.5 that had been sitting out in the rain for 3 yrs since my mate put a chev 350 in his rangie.
had the heads done and put a stage 1 cam shaft in it from Bruce Davis performance landys in sydney.
one of my mechanic mates put it together for me for a bottle of scotland's finest, but the camshaft sprocket had two timing marks on it, one was for a reason i can't remember, but you guessed it, he lined up the wrong one and when we got it going, we bent every inlet pushrod.
off came the heads the next weekend, got 'em fixed and put them back on.
couldn't get it going after this, so tilt trayed it up to my mate's work (land rover dealer) where one of the better mechanics had it going like new in about half an hour.
to the untrained eye it looks exactly like a 3.5, but goes much better and is very torquey. rego was no problem.
i used the original carbys from the 3.5. they are well within spec and work fine.

Thanks for the replies thus far. I would like to keep this thread going, I will be sure to update on my progress.

PhillipA - Having never rebuilt and engine before this going to be big learning experience for me. That is why I got the cheap block, and the reason I am putting it in the old 81 I have. If it all turn pear shape, and I end up slipping liners at every service interval I will count my loses and walk away vastly more experienced. I hope to use what I learn to build something a bit better for the 89RR I have, that would be when I would spend the 2000 to set up the block.

I also see that you suggest you don't need to use the thrust plate on the front of the cam. That is good to know, I suppose it will come down to price. If I can get a decent cam that will allow a thrust plate I will use it.

I also read that it will require a crankshaft spacer, so the pulley bolt can pull tight, these appear easy to come by though.

Secondly it also appears that on the left hand rear of the block there is a hole for a crank shaft angle sensor, (opposite where the starter motor mounts) this will need a blanking plate. Has any sourced one of these?

Does anyone know if I will require a Engineer Certificate for the 3.5 to 4.0 xbolt engine swap?