2.5 & 3.0 id confusion

[Bluestreak1]

I have read a couple of discussions on here about how to I'd which motor is which. One says 3.0 has harmonic balancer 2.5 does not. Have an 85 sea ray 2.5 according to the bore size. No balancer. Picked up another replacement engine that appears to have been rebuilt at some point. The tag on the back of the motor indicates 74 thru 77 2.5. It has what appears to be a balancer on the crank with the drive pulley. Any clarification would be appreciated.

 

[Bondo]

One says 3.0 has harmonic balancer 2.5 does not.

Ayuh,..... Welcome Aboard,..... Sounds like it's miss tagged,.....

 

[Bluestreak1]

Ayuh,..... Welcome Aboard,..... Sounds like it's miss tagged,.....

The appear to be factory tags/rivets

 

[Scott Danforth]

3.0 has balancer, 2.5 has pulley

3.0 says 3.0 or 181 on port side of block

2.5 says 153 on port side of the block

The 153 has 3.875" bore

The181/3.0 has 4" bore and a taller deck

 

[Bluestreak1]

3.0 has balancer, 2.5 has pulley

3.0 says 3.0 or 181 on port side of block

2.5 says 153 on port side of the block

The 153 has 3.875" bore

The181/3.0 has 4" bore and a taller deck

That's why I'm confused. 1 motor is tagged as 74 thru 77 2.5. But it has a balancer. Thev85 motor has the head off .so there's no doubt about that one. Are the cid # in the casting?

 

[Scott Danforth]

Are the cid # in the casting?

Yes, and the GM casting numbers are different

 

[Bluestreak1]

Yes, and the GM casting numbers are different

I'll go check that out. I hadn't noticed them.

 

[Bluestreak1]

So according to the RAstamped at the end of the number by the distributor, this is a 140hp 3.0. RA code was used from 74 thru 87.

 

[Bluestreak1]

So according to the RAstamped at the end of the number by the distributor, this is a 140hp 3.0. RA code was used from 74 thru 87.

My bad! The RA code was used up to 89 for 3.0s. Looks like maybe a variation in 87! Thanks for the input. Apparently the serial tag is in conflict with the code letters stamped on it.