P76 Engine Rebuild & Specs

[enigmas]

I thought I'd provide a few details and pix about this engine and why I'm rebuilding a 1970's piece of technology rather than use a more common and easily available Rover V8 block.

Power and Torque Specs.

Leyland P76 4.4 litre
3.5 Bore x 3.5 Stroke.
9.0:1
192 BHP (143 KW) @ 4250 rpm
285 ftLbs (387 NM) @ 2500
Points Ignition/ WW2 Stromberg Carburettor (2 throats, Venturi Dia. 1.9”)

Rover V8 4.0 litre.
94mm Bore x 71mm Stroke.
8.2:1
177 BHP (132 KW) @ 4750 rpm
224 ftLbs (304 NM) @ 3000 rpm
EFI/GEMS ECU.

Rover V8 4.6 litre.
94mm Bore x 82mm Stroke.
8.35:1
210 BHP (157 KW) @ 4750 rpm
264 ftLbs (358 NM) @ 3000 rpm
EFI/GEMS ECU.

* It's interesting to see the high torque figure at a lower rpm than the Rover engines. This I believe is primarily due to the longer rods and consequent longer stroke.
I'm primarily interested in the lazy torque of these engines at a relatively low rpm. This engine suits the driving style and the auto box of a P5 very nicely.

[enigmas]

P76 Bare Engine Block Pix

Note
The centre thrust 'bearing saddle' has been rebuilt as a previous engine builder had shimmed the bearing shells leading to fretting of the block at this point.

Oil drain holes added for improved lube to the timing chain.

The block has been smoothed internally a bit to assist oil drain back to the sump.

Note only 10 tapped bolt holes on each bank for the cyl heads

Note the lack of an oil feed to the rocker gear. The casting is in place but is not drilled. The rocker gear is fed by hollow pushrods feeding oil up from the lifters.

NB.
The images below have been reinstated (05/05/21) due to a change in the ISP.
I trust that the images below are still pertinent to the topic and text.

[greg5599]

Hello,
I was looking at how the repair for the thrust bearing was fitted into your block. Can you give some info on who did that and how it was done? Is this custom or off the shelf?
Greg

[enigmas]

Greg the repair was done by a company called 'Crankshaft Rebuilders' in Blackburn (OZ, Victoria) They are an engine reconditioning business with an excellent reputation for quality work. It is custom work and was expensive. Initially they wanted me to find another block.

To repair the centre main thrust area of the block, material needed to be machined out to accept the custom (one off) saddle which itself was machined from a chunk of aluminium. They probably have a drawing for this component now. Once fitted the block was align bored to ensure everything was true.

[greg5599]

Will you be sleeving the block for larger capacity or leaving it as is?

Greg

[enigmas]

Hi Greg, no I won't be re-sleeving it for a larger bore as this only leads to problems. I do have a set of NOS .030" P76 pistons which will go into this motor. I also have 2 manifolds to choose from: one an EFI with a Gas Research carburettor, and the other a modified standard manifold with a Rover twin carb mount that has been modified and welded to fit utilizing SD1 twin Stromberg CD carbs with a manual choke.

The engine is being built for torque not high rpm and this is the forte of these engines. I rarely if ever need to rev (my current P76 engine) it beyond 3000 rpm for normal driving.

[enigmas]

Late Update:  P76 4.4 litre V8 Hybrid Engine.

Although this post was started in 2013, it was one of several mechanical/engineering projects that maintained my interest/focus over many years whilst I collected the required parts to finish it. This particular P76 V8 engine has also been modified to accept a ZF4HP22 automatic transmission from a Jaguar XJ40.

Below is a brief video of the engine as currently built up and being run on an engine test stand.

[johnwp5bcoupe]

Nice one Vince meticulous as usual