The V8 Owners Forum -

I'm hoping Andreas can add more specific information on how this was done. I didn't want to pollute the P76 thread.

Greg

Yes, will do.
What do you want to know?

Anyway it will not become a race engine but a
strong puller just from idle because stroke is
very long and rod length is limited creating
high acceleration and max speed on the piston.

I had it in use with a 260 degree ISKY hydraulic cam.

The piston was similar to this
http://www.summitracing.com/int/parts/u ... /overview/

The combustion chamber was grinded into the head as much as possible.

You are right, the liners had been pretty short and that was the reason
that I stopped that project. I got a flanged liner block and although we
discussed my project and my needs a "normal" length liner was fitted and
there was some space for a longer liner to go deeper into the block.
So the piston was pulled out of the liner at BDC up to the gudgeon pin.
The liner could easily be more than 5mm longer than this solution and
that in my opinion would be very healthy.

So I decided to make some tests but than removed the engine before
something could fail.

Right now I will have to make a decision to have custom made flanged liners
in a 4.6 block or continue with my P76 block an fiddle with the custom EFI
inlet manifold and more width at the exhausts that make trouble in my
engine compartment.

Just remember that there was some difference between 340 and 350
engine. Maybe it was the crank, if so I have the 340 crank with same stroke. If they are the same please forget that detail.

Some pictures, they tell more than words!

First is the front of the crank. Note how the oil hole moves due
to grinding mains down from 3" to 2.5"



Same problem with the mains in the middle



And the 5.85" rods with the KB forged pistons:



And the machined rear, additional counter weight can be seen, too

These are my pics from some years ago. I never went anywhere with this project as you have:

http://forum.britishv8.org/read.php?6,29211,page=4

Greg

The P76 is the better block for that purpose.
Looks quite good but there remains the problem with the manifold.

Did you rebalance the crank? It is externally balanced
what leaves the problem that pulley and flywheel are
imbalanced and are different to the Rover parts?

Seems the problems moved elsewhere
but did not solve themselves......

Cast iron is no option for the block, its much too heavy
although it would be reliable and work out of the box.
Than it would be a Buick engine, no longer a Rover.

Since my original intent was to stroke a P76 block with a Buick 350 crank I'll tell you some things I later found out.

The P76 block main bearings are unique to that engine. The main size is 2.5495" which is slightly larger than the Buick 300 and V6 size of 2.4999". the P76 main bearings are also slightly narrower than the Buick main bearing so when the crank was cut down on the mains to P76 size and the oil holes moved over, it's tricky to get the P76 bearings to cover that. The wider Buick bearings would have been a better solution. With a bit of line boring, the Buick 300 and V6 bearings can easily fit the Rover block but not the P76 block without major money being spent (or block shims being fabricated).

I have two P76 blocks available and both of them are poorly cast and have obvious core shift. The only benefit from this much stroke is to combine it with a larger bore. The blocks I have would probably be seriously weakened if the 3.5" liners were removed and the block bored oversize for 3.7" liners. There is also scoring on the inside of the lifter bores and those would require boring and sleeving.

The original P76 maincaps are quite loose in the registers. My thoughts were to replace the P76 maincaps with taller Buick 300, aftermarket Buick V6 or Buick Supercharged V6 crossbolted maincaps (which fit quite well and tighter). However, the biggest problem I found had to do with overall block strength. I was told by several gents from Australia that the P76 block is prone to cracking down the middle of the lifter valley when more power is applied. I saw a website of a group of F5000 vintage race car builders that Tig welded bracing across the valley to solve that problem. Even after that a block girdle was required. That's a LOT of work.

After all of that the only thing I found that could easily be done is to use stock Buick 350 6.387" capscrew type rods with the Buick 350 crank. My plan was to also use an aftermarket Buick 300 stroker flywheel on the 350. I didn't want to get into making complicated rebalancing or shaving the counterweights on the crank.

As for the intake manifold. There is the Wilpower 4 barrel single plane intake from Australia available for the P76.

Anyway, since the Chevy LSX engines came out, most of this went out the window. The Chevy engines are light years better than the P76. Also, the TA Rover big valve heads are now available but when the costs are added up, it put an end to this idea.

Greg

Could the crank modification be applied to the 4.6 blocks? They are already cross-bolted mains and able to support larger bores.

I have no idea why any would worry about using a 40 yo engine that the P76 4.4 engine is. It wasn't a great engine when new and is worse now.

It did not handle revs and engine failures were common.

If you want a larger "Rover" engine go a variant of the 4.0/4.6 engines.

Garry

Greg55_99 wrote: My plan was to also use an aftermarket Buick 300 stroker flywheel on the 350. I didn't want to get into making complicated rebalancing or shaving the counterweights on the crank.

Interesting report and how far you already have been.
You can be happy that you did not finish.
My crank was externally balanced what means all of the counterweight
did not fit into the crankcase and rest was put on the flywheel.

The Buick 300 is internally blanced and from that you would have created
a nice jumping engine that walks around like a wrong filled washing machine.

I have two P76 with 94mm bore but never stripped to look inside.
They have been a gift and as my TR6 is a bit small I will run in trouble
with the more spreaded heads. As you said, at some point it is better to
look at another type of engine.

unstable load wrote:Could the crank modification be applied to the 4.6 blocks? They are already cross-bolted mains and able to support larger bores.

If you look at my pictures you can see a 5.7 litre engine based on the
4.6 cross bolt with flanged liners. It has the maximum bore somewhat
above 96mm and a 98mm stroke with the Buick 340 crank.

garrycol wrote:I have no idea why any would worry about using a 40 yo engine that the P76 4.4 engine is. It wasn't a great engine when new and is worse now.

A bottle ship can be built easily without the bottle
It is the challenge and it is the ROVER that especially
attracts me to investigate in silly projects.

Anyway, during that testing I found that a lot of problems can be cured with
other parts, maybe from different engines and the result is a nice
performing engine that was built in GB.

I am hesitating to swap to the small block Chevy although I already have
some parts of that engine in use in the ROVER.

Its main attraction comes from ist weight and its size and its use as
an major upgrade in many British cars. What would be Morgan without the Rover?
The TVR also were preferred for their V8s, like Marcos, Ginetta, MGBGT and many others......

Hi Andreas,
When you said the counter weights on the crank did not fit the crankcase I wondered about that. Are we talking about the same crankshaft here? The crank I used came out of a 1972 Buick 350 engine. When I cut down the mains to P76 size and placed it into the block, ALL of the counter weights cleared the inside of the crankcase. Some grinding would be required when the rods were fitted at the front of the crankcase and on the oil feed hole and galley. That was all that I found necessary to make it fit. If you look at the link I posted with the pics I hope you can see that the crank, once cut down, actually turns freely in the Rover block with no obstructions. There is also a small counterweight on the end of the crank where the flywheel bolts on. The Buick 300 crank does not have that. In looking at your crank, it doesn't look like mine at all. Was it machined off or are we discussing the same crank here?

Here's a thread on another board from a gent that cut down a Buick 350 crank to 2.5" on the mains to fit into a Buick 300 block. He's posted a pic showing no welding required on the conterweights.

http://www.mgexp.com/phorum/read.php?40,2598435,page=8

Greg

Sorry I am German and will explain what I mean:
The crank is the original Buick crank like it should be and fits
into the crankcase. The problem was solved in the factory to
make it fit. They did so by not fitting the whole required counterweight
to the crank. So it fits but is not balanced properly yet.

The rest of the counterweight is positioned outside at pulley and
flywheel because all the free space inside in the crankcase is already used.

If you do not fit the correct flywheel some of the required counterweight
is missing and the engine becomes a terrible shaker.....

So you have two alternatives to get the big stroke crank run:

If you keep the heavy stock rods and pistons there is no chance
to get the correct counterweights into the crankcase.

If you go for extralight rods and pistons only a little bit of counterweights
is missing on the Buick crank, that can be welded to the counterweights
to make this system work without the special flywheel and pulley.

The problem with internally/externally balanced cranks did not meet
us, the Rover engine users, because all other cranks for our engine
are internally balanced and do not need that special flywheel and pulley.

By the way: The V8 has the disadvantage that every change in
rod and piston weight requieres rebalance of the crank!