12 G 1505 crank

[woodypup59]

Just pulling a 1275 engine apart and can see the crank has 12 G 1505 moulded in the forging. The conrods seem to have very big caps too. No pictures a t m. Can't see any cam markings apart from a pink (?) dot.

Googling suggests the following.

12G1505* - 1275cc - Non-S, EN16T with 1.75" dia. big ends
* 12G1683 - 1275cc - 12G1505 forging, non-S, EN16T with 1.75" dia. big ends, Tuftrided

So its a steel crank with large big ends.

Does that and the hefty big ends mean its a bit racy ?

I'm not very familiar with this large bore stuff so forgive the scant details.

[GraemeC]

Standard A-series 1275 crank (non-S) as used in 1275GT, ADO16 1300 etc.
Has fillet radii on big-ends meaning it can be stroked and then used with 1.625” rods

[65MK1S]

My 12G1505 (AEG623) crank has 2.00" mains and 1.625 rods

[Spider]

Might need a photo here so we all can be 100% sure.

My lists show this crank was fitted in 2 styles. 1 was fitted to the early 1300 series of engines up to about 68-ish (and I'm guessing this is what you have) and the other to the later Cooper S in Tuftrided form.

As 65MKIS suggested, I have the Mains lists at 2.00" and the Big Ends at 1.625".

It would have the 1275 Midget type Con Rods.

[65MK1S]

Yep, my rods are AEG521's

[GraemeC]

If it was an AEG623 it would be stamped as such wouldn’t it?

[65MK1S]

Crank1.jpg

Yeah, mine's stamped AEG623 right over the top of the 12G1505

[woodypup59]

I will get some photos tomorrow and hopefully look at the hefty con rods.

[Thorp]

As GraemeC has already stated, this sounds like a standard 1300 Crank.
The 12g1505 forging was also machined (and stamped up) for other applications, with the 1.625” journals as above and also there was a tuftrided version of it used in the 1300gt. This has the 12g1505 ground off and 12G1817 stamped over the top in the same way as the Crank above.

[251 ENG]

The mk3 cooper s crank AEG 623 is made out of a 1505 forging , just machined differently to the srd 1300 crank .
Differences are
Cooper s big ends
BMC cross drilling
Cooper s centre main thrust width

It is then tuftrided

There are also crankshaft shafts modified from other forgings used in early ADO 16,s fitted with 1300 engines with cooper s rods
But that's a hole other story

[woodypup59]

Heres a picture of the crank with markings and the ( to me anyway ) hefty big end cap.

Is this a standard non-S 1275 bottom end ?

All comments welcome.

[Thorp]

Yes, standard non S bottom end. That type of rod is perfectly serviceable, but heavy.

[Spider]

This is what it is;-

Standard A-series 1275 crank (non-S) as used in 1275GT, ADO16 1300 etc.
Has fillet radii on big-ends meaning it can be stroked and then used with 1.625” rods

and I've updated my own list !

The Rods on them are OK but can be lightened a long way. Depending on what you're doing with the engine, you may wish to consider tracking down some A+ Rods for it.

[Costafortune]

Early transverse 1275's as fitted to VdP 1100's as an option from 1965 used an EN16T crank with S rods and journals. I think a few had the proper S crank.