2.5 or 2.7

[GuyM]

sorry if this seems like a real muppet question, but i've had a hunt round a few of the forums and not found the answer so far.

is there any (external) way to tell if my lump is a 2.5 or a 2.7? Usual thing...chap i bought it off thought it might be a 2.7....but no paperwork to back it up!...i wasn't too worried either way as the car stacked up fine.

is there a stamp on the block anywhere or is everything that distinguishes it inside?

sorry if this is a dumb question!

cheers

[chip-3door]

Mcdonalds straw down the spark plug hole mate!

Wind the engine to TDC, sit the straw onto the piston, mark it, then again at BDC, mark it again, the distance between the two marks is the stroke of the engine.

[Conan]

Mcdonalds straw down the spark plug hole mate!

Wind the engine to TDC, sit the straw onto the piston, mark it, then again at BDC, mark it again, the distance between the two marks is the stroke of the engine.

Awesome tip!

[Ziggy]

If it's an alpina engine, it'll be marked on the block & head with C2 27 (or equiv).

If it's based on an ETA lump it'll be marked 27 6E B on the same part of the block as the engine number :



(credit to Iain T!)

& if it's based on a 2.5, then the only way you're gonna know is like Chip said

[chip-3door]

The mcdonalds straw test is one i invented years ago for telling the difference between 1.0 and 1.1 mini engines, LOL


sounds like a total bodge, but due to the fact there is a few mm diffence in strokes its more than accurate enough to tell if its a 2.5 or 2.7 crank, you obviously woulnt want to use it to accurately measure the stroke of a custom crank of course, as its not accurate enough, but for getting you "in the right ballpark" its fine, honestly!

As above though, it wont help if its a bigger bore motor, only if its an ETA crank swap

[kidsinister]

Try looking at the numbers cast into the head (behind the manifold); if I'm not mistaken, a 2.5 head will end with "882" and 2.7s use a different head, probably a "732".

Apologies if I'm talking out my arse - someone will be along in a moment to correct me.

[chu346]

Try looking at the numbers cast into the head (behind the manifold); if I'm not mistaken, a 2.5 head will end with "882" and 2.7s use a different head, probably a "732".

Apologies if I'm talking out my arse - someone will be along in a moment to correct me.

That would be 883 and 731 or even 200, and a 2.7 could be built with either one of these heads.

[Simon13]

200 head was used on e21 M60's only, it's either a 731 or 885

[kidsinister]

Ah, I see you spotted my deliberate mistakes...

[GuyM]

thanks for all your replies. i'll have a look at the weekend in the daylight and will give the straw test a go too.

[chu346]

200 head was used on e21 M60's only, it's either a 731 or 885

My car and Temple's car has a 200 head.

[Simon13]

200 head was used on e21 M60's only, it's either a 731 or 885

My car and Temple's car has a 200 head.

unlucky then! tis the worst head to use!

quote totalbmw "forget the 200 head"

[chu346]

I know

But that's why i've just bought a 731 head to get ported. The 200 was just for the short term till I get the cash to get the 731 head sorted.

[GuyM]

had a go at the straw test...could not get it to work accurately so still not sure.
could not find engine numbers on the block......it's very grimey.....to be honest not even too sure where i'm meant to be looking ....i know, i know this is probably really simple to some people...but not me!
did however come accross this weird casting lump (about the size of a 10p piece) between the front two cylinders/spark plugs.
the photos are a bit poor but basically all it has on it is 2.5 and below it 2.7
does that mean anything or have "......they've all got that mate...."?

[Kos]

had a go at the straw test...could not get it to work accurately so still not sure.
could not find engine numbers on the block......it's very grimey.....to be honest not even too sure where i'm meant to be looking ....i know, i know this is probably really simple to some people...but not me!
did however come accross this weird casting lump (about the size of a 10p piece) between the front two cylinders/spark plugs.
the photos are a bit poor but basically all it has on it is 2.5 and below it 2.7
does that mean anything or have "......they've all got that mate...."?

all late m20 325i heads have that

[telski789]

mine just says 2.5....

[bigun]

put the car on the rolling this will sort it

[bigun]

road lol