Mercruiser 165 cracked, looking to replace with chevy i6 250

Tripler

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Hello, i am new to forums, i have a 1977 glastron ssv-189 with a mercruiser 165 that is cracked in the block just below the heads under the manifold. i have found a chevy in line 6 250 that has good compression and was running when pulled from a c10 van. i am looking for input on what and how i need to go about putting the running engine in the boat, what i need to change and what i do not need to change. any help is greatly appreciated.
 

Scott Danforth

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Take truck motor and strip to block an heads. Replace core plugs with brass. Replace head gasket with marine.

Transfer everything else from boat motor over to truck motor

Go boating
 

Scott Danforth

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no, you leave the pistons, crank, etc in the motor. just replace the head gasket with marine, core plugs with brass or stainless

you want the marine water pump, all accessories, rotating electrics and ignition from the marine motor.

maybe a new timing set. swap cam if you want, however the truck cam will be close enough to the marine cam
 

Bondo

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i have found a chevy in line 6 250 that has good compression and was running when pulled from a c10 van. i am looking for input on what and how i need to go about putting the running engine in the boat, what i need to change and what i do not need to change.

Ayuh,.... Strip it down to the Long Block configuration,... then bolt on all the marine accessories,...

The "Gotcha" ya might run into is,...
Many truck, 'n car motors don't have the spot for the forward starboard side motor mount holes,....
Fortunately, there Is a work-a-round you can build,....
 

kenny nunez

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Also look closely at the location of the timing marks on the truck engine and make sure they are in the same location as the marine engine. You may have to swap the timing cover and re use the harmonic balancer. Seal the head bolt threads with #2 Permatex.
 

Tripler

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Thanks for all the info. I am all done with my knee surgeries and am ready to tackle the beast. One question on the soft plugs, why do I need to replace if I am running in fresh water lakes? Just curious. Any help is always appreciated.
 

Bt Doctur

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Do you mean 165 as the GM inline 6 cylinder motor and your replacing it with a GM 250 cu inch motor aka 160/165
 

Scott06

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The soft plugs are steel and will rust out even in fresh water hence using brass plugs. Factory Head gasket will corrode also if used in anything but antifreeze. Everything else cam bearings etc are the same vs truck engine you have.

Take note of what bondo said about front motor mount not all truck engines have the boss on left hand side for motor mount. You can fab up a mount I'm sure someone here can show you how it's done I feel need be
 

Bt Doctur

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make sure the front motor mount flange is on the replacement motor
 

Tripler

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Getting ready to start the transfer and order parts, can I use the old head bolts or do I NEED new ones?
 

prlwng

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Get new head bolts. The cost is less than having to redo it again for improperly torqued bolts.
 

Bondo

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Ayuh,.... I Don't, but I guess you can if ya wish,....
 

Scott Danforth

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the head bolts are NOT TTY bolts like newer motors so you can re-use them until they wear out.
 

Tripler

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hello again, well i got the motor in the boat finally stripped down. i have looked at a lot of the bolts and all looked good. i am getting ready to start the tear down of the truck engine. Kenny, when you say seal the bolts with #2 permatex, you are talking the threads right. I am open to any other hints that might help. the motor in the boat has a plastic block between the cast iron block and the motor mount on the front alternatore side. the otherside on the new block has the 2 bolt holes for the mount. it is sure nice to be able to ask people questions. thanks again.
 

Silvertip

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And when you install the head, make sure you understand how to adjust the lifters. You don't just crank down the rocker arm nuts. There is a definite adjustment procedure. It is covered over and over in these forums. The reason you need to use a sealant on the head bolt threads is because the bolt holes in the block go into the water jacket. No sealant means water can get past the threads and into the oil. Head to your local library and grab a Chevy CAR service manual for your vintage engine. The six cylinder engine will be covered in detail. It is the marine stuff external to the engine that won't be covered in that manual. Otherwise, buy a service manual for your power plant.
 

Tripler

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all the mounting ears look to be there. i have a doc appt with the wife at noon will dig into it more tonight. i picked up some black hi temp gasket sealant for the oil pan from orileys. that should work for the head bolts right. also i am very mechanical with vehicles but working on boats is new for me. i really appreciate all the help. thank you.
 
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