1.7 and 2.0 O series compatibility. Replacement or replacement parts

[MarinaCoupe]

Yes that’s right. ‘High compression’ pistons for the Marina, Italy, Ambo, SD1 are all 9:1, so not super high. “Low compression” pistons are 8:1. You’ll get a little more performance if you use high compression pistons. The low compression pistons were used so the the likes of Royal Mail could use their own depot based 2 Star fuel pumps (88 RON).

Assuming that you’ll be using garage fuel, then ‘basic’ E10 is about 93/95 RON, so the “High Compression” pistons will be fine. When it comes to set the engine up, just use timing settings from one of the saloon cars.

[sherpa]

as ive now got a pair of 2 litre O series crankshafts, im thinking converting my sherpa 1700 to 2 litre, do they sound very different to the 1700 engine? do high and low compression pistons alter the sound of the engine?
Having driven my sherpa pick up years with the low compression 1700 in, i would like to keep that same sound it makes, its what i consider the sherpa sound if that makes sense . i have no experience with a 2 litre version, never driven one never heard one.
after taking this new old stock poorly stored princess short engine to bits one piston has a bit of the skirt broke out so that ones scrap for starters, found a pair of genuine sherpa low compression 2 litre pistons on ebay, just a shame it wasnt a set of 4.
ive put the other boxed 2 litre crankshaft on ebay now and the 2 litre engine block after a very thorough clean up

[david painter]

I personally wouldn't bother with low compression pistons, as the fuel is more than capable of running on a HC engine, all be it you may have to retard the ignition a couple of degrees if it pinks. I converted a Transit Pinto I once had from LC to HC don't recall it sounding any different. Very much improved the van. Once worked for a chap that sold ex post office and BT vans as a front ( Turned out to be a MI6 Agent but that's another story) A lot of those vans were restricted mainly be making the throttles only open by about 1/3. If you are looking for pistons try FW Thorntons in Telford they have been in the piston/engine parts game since the early 1900's. A lot of their stock is bought from closed down dealerships etc and can best be described as Aladin's Cave
Dave

[david painter]

BMC O Series Engine Pistons NOS Hepolite Sherpa 200 230 250 2550 CR 8:1 +.030" dont look very expensive to me

ebay listing dosent mention 1.7 or 2.0 but 30 thou rebore your problem is solved as you have both 1.7 and 2.0 cranks
Dave