Thread: Leyland V8 Cam Timing

Does any one know if the cam timing set up of a leyland v8 is the same as a rover v8? I am running a 4.4 leyland terrier V8 ( essensially the same as a p76 just better ). Other than the block, crank, rods, spacer plates, and pushrods it is the same as my fathers 4.6 Rover V8, and doesn't perform any where near like the 4.6. The only work done to his engine that mine hasn't is the bottom end hasn't been balanced. I thought mine went well till driving his and am now dissapointed. Tim

Yes - I know this is likely a long dead thread, so normally I would just ignore it , but as I found it searching for something else, other people may find it too - so lets set a few things right.

For the record , I have a lot of experience with Terrier Trucks and Leyland P76's - both in V8 form. The Terrier's intended market was the smallest, cheapest and slowest of all the Leyland "G" cab trucks.

For simplicity and start of production - P76 V8 Blocks were initially cast in England as they share the same basic bolt patterns as the Rover V8 engine, "CastAlloy" in SA were contracted to take over production of the P76 V8 but Leyland were basically all but dead as Castalloy started delivering new blocks - creating a large surplus of new P76 V8's with nowhere to go. Eventually Leyland worked out they could run out the excess P76 V8's in the "new" Terrier Trucks.

All a Terrier V8 is - is a altered P76 V8. Mechanically the only difference in the actual engines (beyond the Rocker Covers being painted red) - is the lower compression pistons - Terriers having a greater dish in the top to create the lower compression.

P76's had a few different piston types for the car engines, only because the original pistons were found to crack and some had seating problems with the oil rings causing excessive oil burn and so they got some changes. Compression ratio remained the same on the higher comp P76 car engines, just the piston design was changed to improve the original oil and "skirt" cracking problem.

Every Terrier V8 and P76 V8 that I have ever taken apart - have the same part number on the crank and are made of the same material. Cranks were made in a few different places - including Repco making special castings so there are some different looking types and different balancing approaches also make them look different (Terriers were balanced for a different speed) - but 99% of all of the cranks are effectively the same boring P76 crank - unless you have an extremely rare (and very unlikely) Repco "test" one. Terriers were originally planned to have a forged steel crank and that what they told England they were going to do with the truck engines and some were even tested with them in England - and "forged steel cranks" are what is mentioned in the Australian truck advertising - but in truth - it never happened beyond the test engines, Terriers just used the standard P76 cranks as special "forged steel cranks" just were not necessary.

Terriers did not break cranks - people did trying to make them go faster.

Terriers were factory governed to a maximum of around 3900 RPM via a centrifugal rotor button and so they were also balanced for that RPM. The torque dropped off considerably in the low comp motor over that RPM anyway, so there wasn't much point in trying to rev it any harder. Because they were limited to that rpm - forged steel cranks were deemed unnecessary. Terrier's were designed for a top speed of 80klm (less if it was a heavy Terrier) - and they used an 5 speed non-overdrive gearbox .. so everyone immediately tried to make them go faster, where as Leyland wanted you to buy the more powerful "Boxer" truck running the larger Leyland "6-98" diesel engine, two speed diff and overdrive gearbox if you wanted to go faster with more weight.

Unfortunately the Terrier's governor could easily be removed by those "in the know" and a P76 rotor button put in its place allowing you to rev the motors much higher to around 5500 rpm - but at that RPM - the heavier low comp pistons, crank mounted cooling fan and the balancing became all wrong and the crank would break if you kept constantly pushing it that far. That's called intentionally using the motor beyond its design limit.

There are minor differences in bolt on bits and accessories like the Truck has a simpler single barrel carbie fitted to a std P76 manifold with a few less things drilled out and the Trucks have the temp sender in the LHS rear head welsh plug - instead of the top of the inlet manifold like a P76. Heads are just P76, one exhaust manifold doesn't have the "heat" pipe though it for the cars Auto choke and some of the "Red Rocker covers" - are literally just Blue P76 ones painted Red. The Terriers have a much deeper sump - it's a std P76 sump , cut and a extended piece hand welded in, with an extra hose connector added to the front RHS for the air compressor oil return - very boring.

Terriers use excess normal P76 V8 flywheels (same weight and all) - they even have the same part number cast into them as a P76 - but they are actually different to the P76 ones as the Terrier flywheel has 3 extra holes drilled in it to suit the "Chrysler E49" type "twin plate clutch" unit - the "twin plate" clutch adds significantly more weight to the whole assembly, not the flywheel and you just cannot realistically put a bigger flywheel on a P76 / Terrier V8. Terriers use P76 starter motors.

As for the higher comp but std P76 4.4 litre V8 - vrs the Rover 4.6 litre V8 performance -

I have done a proper dyno run on a P76 4.4 using all the Rover 4.6 gear - heads etc (it was replacing a blown 4.6) - but we were running an after market computer, not the factory Rover one (as it was too hard to wire up on the dyno) - The 4.4 / 4.6 hybrid V8 engine made slightly more power then Rover claims in the specs for the original 4.6 V8.

In short - the difference in performance on the P76 4.4 and Rover 4.6 blocks in not noticeable, and I have the paperwork (and video) to prove it .

Enjoy , Moth