What motor do I have?
 

Hello from Iceland
I have a 911 motor from 1973 911T I have taken apart. My proplem is I am not sure what motor I have after I have mesured the cylender and head.
the head has the number 911.104.302.0R on it .
The ports messure is Int:29 mm Ex 33mm

The cylender bore is is 90 mm and KS854/2A writen on it
I have here the book: How to rebuild and modify Porshe 911 engines 1965-1989
And I can not find motor with that bore and then that head in that book.
It does not mach up with the model year or the port size
Can someone help me clear this for me.http://forums.pelicanparts.com/uploa...1612732741.jpg

90 mm is 2.7
The cylinder is KS so the piston should be too. There is a 5 digit casting number inside the piston to cross reference exactly what you have
There should be a stamping on the right side of the fan near the cam oil line 911/xx which will describe what was originally factory build.
Bruce

Looks like 2.4 heads, someone upgraded the P&Cs to 2.7 liter versions at some point - they're interchangeable between 2.4 and 2.7.

If it is originally a 1973 CIS motor, there should be a 911/91 stamped to the right of the fan housing.
http://forums.pelicanparts.com/uploa...1612998639.JPG

Wouldn't having exhaust ports larger than the intakes be a bit unlikely?

It may lead you to believe he has that reversed.
Here is a chart that seems to give specs, although I don't know how accurate.
http://forums.pelicanparts.com/uploa...1613236466.jpg

Nice chart.

I see that the 2.4Ts did have smaller intakes (probably because that seemed the easiest way for Porsche to dumb down that motor to fit the marketing scheme?), so what he measured as 29mm was probably 30, and these would be those T heads.

The chart has ??? for the ports for the '74 non-S, which was another of Porsche's misbegotten attempts at market differentiation. Anderson's book shows the cam was milder, the CR a bit lower, and the ports were 32/32, but the valve sizes were the same 46/40 as the S, so the question marks can be filled in

Ok so someone at some point upgraded the motor from 2.4 to 2.7. I need to buy new cylenders so the question is . is there any downside to keeping the 2.7 with 2.4 heads and everythings else on the motor from the 2.4 motor ? will I run into any problem doing that.
I have never seen or heard this motor run it was out of the car before I got it.