1960 Riley 1.5 piston info

[Harris]

From: Shirley Meadows <[e-mail]>

Dear Sir/Madam.

I would be obliged if anyone could help with info re 1489 B series 1.5 engine from Riley 1.5. I am not a member of your club, nor is the engine to go back into a Riley, as the vehicle has been scrapped due to the body shell being well beyond repair. Therefore I understand if your club is reluctant to help.
The engine has been bought to help me rebuild my 1956 MG Magnette ZB engine.

However my query is as follows ;- The Riley engine has very little bore wear, and on removing pistons, after cleaning, I expected to see some indication of piston size, i.e possibly stamped “std” or +10 etc. There is no such marking. As well as having FRONT, which is expected, its stamped MOWOG, with a number 2 inside a diamond shape( which I take to be a piston fit ref), and the numbers G59(which could be a casting ref). Also the piston has a solid skirt, and my understanding was that this family of engines came from factory with split skirts.
Would it be possible for someone to confirm that this is a standard size piston, or any other info would be welcome.

Regards
Alan Meadows

Please reply to my email address above

[canuck]

For future reference I will respond here as well as to your email as requested.

Hello Alan,

First off keeping the pistons with the block and crankshaft is the preferred option. IMHO the Riley 1489 is a cut above the MG Z Magnette engine, (camshaft, cylinder head etc.) so this would be my preference. This is your car and of course you decide the best way forward to achieve your goal.

To my knowledge, and experience with various early and late B series BMC/BL engines the standard factory installed pistons would have been MOWOG brand.

MOWOG being a conglomerate, MO (Morris) WO (Wolseley) an G (MG). The MOWOG name appears cast into cylinder head, the block, stamped into the timing chain cover etc. be assured these are factory installed pistons.

The Riley piston as OE is a solid skirt 4 ring aluminium alloy, anodized piston. The oil control ring is a slotted scraper type and the gudgeon pin a clamped type.

The "2 inside the diamond" is a factory identification, used to match piston to bore. You should find "2 inside the diamond" on the deck of the block adjacent to the cylinder bore as well,

as below.

The oversize indication, (+0.010 etc.) would only appear if that were the case. Reinstall them as you removed them, keeping the piston matched to the bore, connecting rod and crankshaft journal. Honing of the bores to break the glaze and new piston rings are in order.

The two detail above lead me to believe you have a standard size piston & block to work with. This is a good thing.  

The proof of course is to measure, as with any engine rebuild being critically important. The engine bore in standard is 2.875" or 73.025mm.  

All the best

B 

[bobthescrapman]

Interestingly, the Club spares stock has a set of what is described as MGA 1500 Standard size pistons, and a set of plain liners for the same!