3400-3100 engine swap

Can some tell me what is the difference is in the 2 3400 engines in the alero.I have a 1999 alero with a 3400, can i put a 1998 malibu 3100 in the 1999 alero.I notice in the chevy parts book that the camshaft is the same part # on the 3100 an 3400 for 1999.I realize that the pcm will have to adapt to the new 3100 engine.Also does anyone know why the camshafts break so often in the 3400 engines.I dont seam to see this problem with the 3100 engines.Is this early model camshaft better.

The 3400 camshaft is hollow. It usually breaks as a result of siezure, e.g. coolant getting into the engine oil,usually as a result of leaking intake
gasket(s).

As for the 3100 fitting in the 3400 engine bay, they are essentially the same engines, so in theory it should work. The VCM would need to be recalirbrated as the 3100 is technically a smaller engine.

I personally would find a 3.4 and do the exchange, much less of a hassle in the long run.

Can some tell me what is the difference is in the 2 3400 engines in the alero.

Welcome to AF.

What do mean by 2 3400 engines in the Alero?

The same LA1 VIN "E" 3400 V6 is found in '99-'04 Alero. Just a bigger displacement version of the LG8 3100. However, there are two different variants of the GM 3100 V6. You have the earlier VIN "M" ('99 and under) and the later VIN "J" versions of the 3100 which was introduced in certain GM cars in the 2000 model year. So keep this in mind if you decide to use the 3100 which I would not recommend.

sorry,thats what i meant,what are the differences between the 2 3100 vin m and vin j and which one would be more compatible with my 3400,there are no 3400 engines with reasonable price/mileage at the salvage yards but there several low mileage 3100 for half the price,i also have a 2001 grand am that needs a 3400 ram air motor and the 3100 would work there too i hope,i was told by the salvage yard guys that they have heard of the swap but didn't know anything about which intake,exhaust,egr,injectors,etc that should be used,i have replaced a couple 3100 engines and i know they look similar but have no idea on interchangeability thanks in advance for all your help,you guys are great,i've gotten lots of help in the last year from reading other threads,best site i've ever found