2.4 Race Engine or just Factory replacement

[Rexs-911T]

Pulled the 2.4L engine from my 1971-911T, It has always been a track car and just noticed the engine serial numb is not in the normal place and it is not the normal string of numbers. Bought this car last year, put 2.7L engine in it and getting ready to re-build the 2.4 and saw this. Any comments on what this might be..Factory replacement or race engine with this kind of serial#. BTW came with 46mm webers on it. Large for this motor but ran good over 5500RPM, crappy anything lower than 4500RPM. Note the normal location to the left for serial number is blank. The 911/51 indicates the 2.4L though

[kugelfischer]

911/51 is a standard 2.4 MFI T engine from a '72 or '73 car.
It looks like you have an unstamped case though. No serial number. Could have been a replacement case.

[RWebb]

degree the cams and look at the pistons to see what you have

cc the heads also

[Rexs-911T]

RW, might be a few weeks before I start tearing into it, will re-post once I get to look at the pistons, heads and CAMs

[TRE Cup]

sorry to be bearer of bad news, but the serial number was machined off ! You can clearly see the marks where the mill passed over it. Also the number area has sharp edges , which the factory never allowed out the door

A replacement case has no numbers on either the vertical tab, or the flat area adjacent to the chain housing.

the only reason someone did this is because it was stolen at some point in its life.

Rwebb is correct as you cannot assume anything from the type number on the block.

[Rexs-911T]

Sorry TRE....That is not a machined surface, being a machinist myself I know....What you see there is a rough casting is all. Picture does not do that surface justice. But definitely not machined off.

[TRE Cup]

Not to come off like an old fart, which i might be ;-) , BUT with all due respect- based on your picture that surface has been modified. It is NOT original as cast by Porsche

This is based on up close and personal working on this marque since 1974.

[tctnd]

Might be easier to sort out if you wipe the area down with acetone or carb spray (no abrasives) and post a nice clear pic.

regards,
Phil

[Rexs-911T]

My appologies TRE, cleaned up now and you are right, clearly ground. Hate to ask why they would do that, think I know the answer.

[daepp]

Don't the pros have some chemicals that will bring out the original numbers?