The V8 Owners Forum -

Does anyone have a copy of David Hardcastle's 'Tuning Rover V8 Engines?

I found an interesting titbit that lets me ID when my engine was made a little more and would love some confirmation.

http://www.trevor-turner.co.uk/Build19.htm

Bottom of the page, in the december 31st comment:

I have resolved the compression ratio issue by reading more carefully the books that I've got on the shelf. David Hardcastle's excellent 'Tuning Rover V8 Engines' states that ".....although in 1974 the Rover P6B engine had the compression ratio dropped to 9.25:1 (from 10.5:1 - Ed.) with a change of piston". Oh well, that clears that up then.

So if such is the case, my engine, a 451xxxxx series 9.25:1 engine with double springs and small valves would be a '74 or later engine, but pre '76 when that number series finished.

I'd love to know whether there's anything more in the book on the compression changes!

Hello kiwi303,

I have a copy of that book.

I also own a 1974 Rover 3500, whcih was originally fitted with a 10.5 : 1 CR engine.

A friend who also owns a 1974 Rover 3500 has the 9.25 : 1 CR engine.

Off the top of my head, the only difference between the two engines, save for the pistons is in the SU carburettor needles. Both engines have different needles.

Transmissions are different along with some subtle interior changes.

I am pleased to assist in any way I can.

Ron.

Oh just remembered, distributors fitted to both engines were also different.

Ron.

so if the book is right, then your engine would be slightly earlier than your friends.

so it sounds like the same rods are used, I've found a rebuild kit with +.020 +.030 and +.060 pistons which they say are 9.35:1, I was wondering if they would change a 9:25 to 9.35 or if it was the rod length that changed between engines and fitting them to my existing rods would mean the compression would stay at 9.25

If it's just a piston change, then that means the same rods plus the new overbore pistons will give me .1 more compression. that's a plus.


Different engines do it differently and there are still the new landie heads with their different cc chamber to take into account with this build

I'm learning something new about the rover V8 each week if not quite each day

That is correct,..my engine is slightly earlier.

The connecting rods for the P6B engines along with all the 3.5, 3.9 and 4.2 litre engines right through till the end of production remained unchanged.

For these engines, only the pistons changed to vary the compression.

If you fit the later 10 bolt heads with their 28cc combustion chambers and use the composite gaskets, then the CR will be the same as using 14 bolt heads which have 36cc combustion chambers with pressed metal gaskets.

Ron.

so... the 10 bolts would be the HRC 2210 heads? The heads I'm looking to get are ERC 0216 heads, either a pair of carb landie heads or a pair of EFI Rangie heads.

The 10 bolt heads on my 4.6 have the casting number HRC 2479.

Ron.

You mentioned overbore sizes of +20 +30 and +60thou, don't know if that was a typo but you cannot bore the liners in excess of 1.mm or 39thou as the integrity of the liner would be severely reduced.

The normal overbore is 20thou and i would advise you to go with that.

Do you know what pistons these are as the max available in the UK is +20thou unless you use a piston from another engine and then it gets complicated.

Compression ratio is always determined by the size of the piston bowl, the later heads have 28cc. chambers but these are used with the thicker composite 39thou gaskets and larger bowls in the pistons, these pistons do not fit the earlier rods.

Kevin.

Kevin.

Kevin

go to www.staparts.co.nz scroll down the page to the long list of parts in the smaller font, that will take you to a search page, choose by make and engine code, select rover and then the 3500 carb or 3500 efi. sorry, got the two smaller sizes .010 too small, it should be 030, 040, 060 not 020 030 060.

the piston options are at the top of the page. the link title says:

PISTON SET ROVER 3500 9.35:1 LEYLAND P76 2mm 2mm 4.76MM OIL PIN 22.22MM X 72.6MM DISHED TOP 88.9mm BORE

I note they say both 3500 and Leyland P76, as I understand it the P76 engine is taller than a stock 3500 block with stock 3500 width bores but longer stroke 3.5x3.5 rather than 3.5x2.8, and P76 pistons can switch into a rover 3500 without alteration.


the part number to the left says: PS22507 030

the two sizes under that are respectively PS22507 040 PS22507 060


further down under piston rings the .060 bore size is 90.4mm: Ring Set 90.4mm 2mm 2mm 4.75mm oil V8 Rover 3.5 Ford 221 V8

Very strange, do you know where these pistons are sourced or the manufacturer

I have never seen +030 or +040 let alone .060 which you could not use as you would need to bore out almost half the liner quickness.

Most engines would not need more than the first oversize which as mentioned is +.020 thou.

Just noticed that the ring size for their quoted + .060 is 90.4mm. which is
+.5mm over standard which = +.020 thou. curiouser and curiouser!

Kevin.

Hang on, isn't standard bore 3.500, which is 88.9mm? that would make the +.060 1.5mm larger than standard, not .5mm larger. How thick is the liner? since the rover is a dry liner not a wet liner, shouldn't the liner thickness not really matter so much so long as the liner is intact and not cut through to the underlying aluminium of the block?

they have a .020 ring set, which is listed as 89.4mm, which IS .5mm over the 88.9 they list as the STD ring size.

It's Sunday here now, but I think I'll ring them tomorrow (monday) and ask them a few questions. I want to know what is in their "Conversion set, 1967 1976) anyway.

Well I rung them, the pistons are a non-hypereutectic cast aluminium alloy, so should be good for a fairly brisk engine, as while not as solid as forged, they won't be as brittle as hypereutectic pistons.

The manufacturer is a company called riteweight or rightweight, it's about 205 for the piston+pin set and 55 for the rings, so roughly $260 to re-piston the engine, 91 quid at the current exchange rate. I spoke to an engine place in town and they charge $230 to re-bore and hone a V8 block. so just under $500NZD, or 180 quid for the job.

add $160 to regrind and true the crankshaft and $53 for new white metal main bearings and $35 for rod bearings, that's another $248 or 87 quid.



Running a set of vernier calipers over the bores and pistons however, they don't seem out of spec or worn, I think a flexhone on a drill to give a quick hone and then a new STD ring set would do the job. and be cheaper. Running the same vernier calipers over the crank journals also shows them to be within the specs I've found online. So I may be able to simply replace the bearings and be good.

kiwi303 wrote:Hang on, isn't standard bore 3.500, which is 88.9mm? that would make the +.060 1.5mm larger than standard, not .5mm larger. How thick is the liner? since the rover is a dry liner not a wet liner, shouldn't the liner thickness not really matter so much so long as the liner is intact and not cut through to the underlying aluminium of the block?

Of course, a +.060" rebore is only taking 0.030" of metal off the liner (0.75mm), since the oversize refers to the bore diameter, not the radius! I would have thought it would be OK, considering they are dry liners as you say.

Jeff