Leyland 4.4 crank in Rover 3.9

Eric78 · Post by **Eric78** » Sat Dec 19, 2015 7:56 am

Hi, I'm just wondering if the Leyland P76 or Terrier crankshafts will fit a 3.9 block with any amount of ease? Would it be any easier to use a Buick 300 crankshaft instead?

Being from Australia Leyland cranks are somewhat easy to get, just wondering what the level of compatibility is.

kiwicar · Post by **kiwicar** » Sun Dec 20, 2015 8:52 am

Hi
From what I have read both cranks will drop in, as I am sure you are aware you will need a combination of rods and pistons that will enable you to keep the pistons in the bores (at both ends). You really want to keep most of the reduction in deck height in the piston compression height as the rod/stroke ratio will be less than ideal. you may need to look at chevy 305 pistons and a 36 thou overbore to find a piston with the right compression height.
best regards
Mike

Darkspeed · Post by **Darkspeed** » Sun Dec 20, 2015 5:10 pm

Will need the mains turning down or the block line bored. The mains are 2.5"

There is quite a bit about it in the Hardcastle Tuning book and how they were used to create 5.0L engines.

Triumph-V8 · Post by **Triumph-V8** » Wed Dec 23, 2015 5:13 pm

I prepared engines with the Real Steel crank, the Terrier crank and with the
Buick Riviera crank. The last had about 98mm stroke if I remember right
and I had it combined with the 5.85" Chevy rods.

They all create some problems clearing the engine block and the oil pan.
The Riviera crank was difficult to balance internally. All cranks need
rebalancing what is quite a lot of work. I created my own bobweights
and have my own balancing equipment.

Also grinding down the mains from 3" to 2.5" is not easy because the oil
bore moves outward with the smaller mains. It needs some engineering to
meet the oil guide in the main bearing shell. The Terrier also needed some
grinding down but not that much to let the oil feed move outward.

I also have two modified Terrier blocks with 94mm bore.
Their advantage is that the block height is bigger to employ longer liners
and longer rods. Disadvantage is that inlet manifolds have to be custom
made like the valley gasket.

Major problem with the Riviera crank was the rear that needed machining to
accept the Rover flywheel. Also the diametre for the seal is different and I
made an adaptorflange to accept a proper sealing ring.

All in all I stepped back to the 89mm crank with 97mm bore.
That can be used with 6" Chevy rods and performs well.

Greg55_99 · Post by **Greg55_99** » Mon Dec 28, 2015 2:45 pm

When you refer to the "Buick Riviera" crank, are you talking about the 3.85" stroke crank out of the Buick 350 V8? If so, how did you fit that into a Rover block? Or, did you fit that into the P76 block?

Greg

Triumph-V8 · Post by **Triumph-V8** » Tue Dec 29, 2015 1:17 am

It is the 3.85 crank with 3" mains.
Do not remember but I think it was the 340 and there
are some differences, one fits the other one not.

The main steps had been to cut the mains to 2.5"
cut the rear end and drill the holes for flywheel
took the extralight 5.85" Chevy rods
and forged pistons from KB from a Chevy stroker kit.

That crank was externally balanced but with additional plates
welded to he counterweights and the light rods and pistons
it worked internally balanced.

Block was a 4.6 block with flanged liners in 97mm.
Oilway had to be grinded to allow the crank to rotate
and the oil pan needed space at the front to clear.

Greg55_99 · Post by **Greg55_99** » Tue Dec 29, 2015 3:43 pm

This is quite interesting. Did the engine last? With that much stroke the piston is pretty far down in the hole. What heads did you use? Can you give some more details of this engine?

Greg