How it is with oil filler cap side?

[Wladek]

Hi,
so, today i decided to made a new set of spark wires for my not rebuilt yet engine.
I was measuring lengths of wires directly on engine and decided to see on internet what lengths have other people. At that moment i noticed (never noticed that before) that some valve covers have oil filler on the side closer to firewall and other on the side closer to radiator. At first i thought maybe it's just engine type differences (CS vs CSI, carburetor/intake manifold/air filter location etc.) but no, according to google photo's both of types had oil fillers also in different locations.
On mine 72' engine and the second spare 75' i have oil filler closer to firewall (both genuine D-jetronic engines).
Any suggestions about the difference? Replaced/spare valve covers? Target market difference? Production years difference? Or maybe something else?

 

[Honolulu]

I thought carbed engines had the oil filler hole forward, injected engines closer to the firewall. AFAIK they're interchangeable, so any engine could have had its cover swapped.

 

[HB Chris]

No expert here but early M30 valve covers all had filler in front, CS and CSi. When the b34/35 style air box came along it blocked access so filler was moved to rear. The second pic is from a later model, it has the flat boss on upper/rear of valve cover. There are several different styles too, some are thicker where the studs come through and some have bolts/bosses on upper side facing intake system.

 

[Wladek]

I thought carbed engines had the oil filler hole forward, injected engines closer to the firewall. AFAIK they're interchangeable, so any engine could have had its cover swapped.

It make sense.
I think some covers where replaced with defective early type cylinder heads as hole sets.

No expert here but early M30 valve covers all had filler in front, CS and CSi. When the b34/35 style air box came along it blocked access so filler was moved to rear. The second pic is from a later model, it has the flat boss on upper/rear of valve cover. There are several different styles too, some are thicker where the studs come through and some have bolts/bosses on upper side facing intake system.

First photo - block from 72' cylinder head 78', second photo block 75' cylinder head 78' or 79 don't remember exactly.

 

[Wladek]

No expert here but early M30 valve covers all had filler in front, CS and CSi. When the b34/35 style air box came along it blocked access so filler was moved to rear. The second pic is from a later model, it has the flat boss on upper/rear of valve cover. There are several different styles too, some are thicker where the studs come through and some have bolts/bosses on upper side facing intake system.

You are probably right.
Watched at my photo's collection of about 50 different injected 72-75' e9 (most CSI and some CSL) - about 70% of them have valve cover with oil filler closer to radiator.

 

[Wladek]

Today take off cover (engine from first photo) - underneath 74' was written.

 

[HB Chris]

Probably from an e12 530i from 1974.