Mercruiser 3.0

What is the difference in a 3.0 135 horse and 3.0 140 horse other than 5 horse power?

Re: Mercruiser 3.0

The 135HP GM 4cyl marine engine has more HP than the 140HP GM 4cyl marine engine....

Re: Mercruiser 3.0

... because the 135HP engine is rated at the prop and the 140HP engine is rated at the crank

Re: Mercruiser 3.0

fishrdan said:

... because the 135HP engine is rated at the prop and the 140HP engine is rated at the crank

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Can I replace the 135 with a 140?

Re: Mercruiser 3.0

It depends if the years are close enough as there were several changes through out the years, flywheel, rear mount, coupler, manifold, riser, carb, wiring harness, etc, etc.

Probably not going to be plug-n-play going from a 135 to a 140

Re: Mercruiser 3.0

fishrdan said:

It depends if the years are close enough as there were several changes through out the years, flywheel, rear mount, coupler, manifold, riser, carb, wiring harness, etc, etc.

Probably not going to be plug-n-play going from a 135 to a 140

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Sounds like could be costly. Can I reuse anything off of my 135. It has a cracked block with milk shake oil.

Re: Mercruiser 3.0

What year engines are we talking about? If they are close enough then you may be able to do a straight swap of long motor...

Re: Mercruiser 3.0

achris said:

What year engines are we talking about? If they are close enough then you may be able to do a straight swap of long motor...

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Mine is a 93 i am assuming the one we are working with is 2 years different in either direction.

Re: Mercruiser 3.0

Same block used from 1990 to 1995... Your call...

Re: Mercruiser 3.0

achris said:

Same block used from 1990 to 1995... Your call...

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Excuse me pardon me, but the 3.0 block hasn't changed from 1968 to current apart from the rear main seal. There were some slight carb and jetting changes along the way, but the block is that same block now as it was in the late 60's apart from a 2 piece vs 1 piece rear main seal. The heads changed from larger to smaller ports to increase velocity and make it a "Vortec" marketing scheme. HEI was added when the head and rear main seal change came around in 91. Flywheel size change from 12-3/4" to 14" in 1992-ish.

The breaks go 1968 - 1990/91 and then 1990/1991 - current. This is why when you go to buy a new or reman engine from any supplier, they only have two types.. 1968-91 or 91-current. You can't buy any other type.

http://www.perfprotech.com/store/catalog/Boat-Long-Block-Engines-30L-4-Cylinder,5972.aspx

Here you can see the head types and conversion kits for pre and post 91 motors. Note the port size changes.

http://www.flagshipengine.com/catalogpages/23/page23.htm

If you're going to go the new route which I highly recommend, I would steer you to having your mechanic or someone with a shop hookup call Flagship Marine Engines. They're a GM crate engine dealer and have the 3.0LX motors which you have for $1750 with no core charge which is way cheaper than you'll find anywhere else. They are dealer only so unless you state when calling that you're a marine mechanic, they won't quote you prices. For ordering, they get sticky and will want a tax ID and business license faxed in showing that you're specifically a marine mechanic. I had a friend use his..