The rod ratio is as you've correctly guessed, something like 1.7 and above
is desirable. The std. P76 motor has a stroke of 3.5" and a rod length of
6.25" this gives a ratio of 1.78. The higher the ratio number, the longer
the piston 'pauses' at TDC and BDC. This has benefits for the combustion
process, but I can't remember the details.
I guess I was thinking that if you put the P76 crank into the Rover block
you'll have to use shorter rods, unless you change the pistons. Has anyone
else out there done this?
-----Original Message-----
From: dkern@napanet.net [mailto:dkern@napanet.net]
Sent: Thursday, 4 February 1999 15:34
To: Simon Sparrow
Subject: RE: P76 Crankshaft
Thanks for your thoughts. I have the Hardcastle book but there are no
"details" therein. He even does not say whether anyone has done it before.
Have to admit, I'm not exactly sure what "rod ratio" is. Is it anything
like rod length divided by stroke length? What is the significance and
what are desirable numbers?
I suspect an RPI 4.6 block would way out of my price range. I have heard
of RPI but am not yet familiar with any of their products.
Thanks again,
Dave
>Don't know about a source, but people have done this before. See David
>Hardcastle's book 'Tuning Rover V8 Engines' for details.
>
>The only problem I could see is that your rod ratio (which seems to have
>become a key measurement recently) might not be so good with the smaller
>block.
>
>Having said that, its a lot easier to find stuff for the Rover engine
(water
>pumps, starter motors, inlet manifolds) than the P76, so if you can create
>an engine based on this, it'll be less hassle in the long run.
>
>What about an RPI engineering 4.6 short block?
>
>-----Original Message-----
>From: dkern@napanet.net [mailto:dkern@napanet.net]
>Sent: Wednesday, 3 February 1999 17:25
>To: buick-rover-v8@autox.team.net
>Subject: P76 Crankshaft
>
>
>2/2/99
>
>
> Does anyone know of a source for a Leyland P76 crankshaft? Any
>idea of cost? It may be a hair-brained scheme, but I want to use it in a
>3.9 liter (241 c.i.) Rover block with whatever combination of pistons and
>rods is possible. I do know the main bearings are 2.5" instead of 2.3". I
>want to use Buick 300 heads because of bigger valves and larger combustion
>chambers (54 cc instead of Rover's normal 36 cc). Also, I have the Buick
>300 heads but no Rover heads. I do, however, have several Buick 215 heads
>with 37cc combustion chambers. I would like to achieve about 8.5 : 1
>compression ratio so I could use ordinary fuel. I'm probably nuts but what
>else is new?
>
> TIA
>
>Dave Kernberger
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