mounting diffrence between 5.7 blocks?

[UberSquid]

I recently purchased a 1984 22' sea sprite cuddy for a song because the PO locked up the motor. It has an OMC 800 outdrive and a 5.7 motor. I've pulled the out drive and will be pulling the motor this weekend. I have a couple of options on new motors to drop in and plan on buying a used motor on Friday.

My question is, do all of the chevy 350/5.7 blocks mount the same way or do I need to be looking for a block that is of the same vintage. I'm assuming that any year motor will drop into the front and rear mounts but after working on a friends 160 mercruiser and finding that not all blocks would fit his mounts I started to wonder. I've done a search and not found any useful reference.

Thank you in advance

Jeremiah

 

[cr2k]

Re: mounting diffrence between 5.7 blocks?

Not so much the block mounting but the crankshaft bolt holes. Your old engine is probably a 2 piece main seal engine and you will need to replace with same.

Car engines are not good replacements either. I have been told that a truck engine is a little better. You should change the core plugs to brass, especially the ones behind the flywheel that would require engine pull to replace.

Do NOT use and automotive carb, fuel pump or electrical parts. Use the marine parts off your old engine. These are certified for the explosive environment that can be present with an enclosed marine engine house.

 

[UberSquid]

Re: mounting diffrence between 5.7 blocks?

What I plan on doing is taking a truck motor and throwing most of it out, keeping the block and reciprocating assembly. All the marine components from my motor go on the new one and I'll run it gently for the rest of the season while I build up a new motor based on my old block. (If it's usable!) Then this winter I'll swap the motors back out, finish the custom work I want to do and be ready for spring.

The boat is solid and I'm going to set it up for great lakes fishing but this year I plan on keeping it on the reservoir by my house as a way to escape from the wife and office

I've done a lot of reading and know what auto components to avoid, I just couldn't find any reference to the mounts. That answers my question, I'll make sure and check before I buy anything.

 

[LAC_STS]

Re: mounting diffrence between 5.7 blocks?

I just replaced a 2 Pc seal 5.7 with a 1 pc.

Bolted up fine. Had to get a new flywheel and coupler and that's it.

 

[UberSquid]

Re: mounting diffrence between 5.7 blocks?

Was it n OMC 800? Where did you get the coupler? What is the difference in the fly wheel?

 

[LAC_STS]

Re: mounting diffrence between 5.7 blocks?

Was it n OMC 800? Where did you get the coupler? What is the difference in the fly wheel?

It was an omc cobra.

The old 2 Pc engine had a 3 1/2" bolt pattern flywheel. The 1 Pc has a 3" bolt pattern flywheel.

Since the coupler bolts to the flywheel you need a new one for the new bolt pattern flywheel.


I got the coupler at a local place that was a little more expensive because I wanted it faste because I had the engine out and wanted the new one in.

I boats had the coupler I needed for $189. The flywheel was $110 at napa