153 CI to 250 CI swap

[italian]

I am considering doing an engine swap and am curious as to whether or not the new engine would bolt directly to the stern drive without modifications or replacement of the stern drive.<br /><br />I have a 1968 Sabrecraft Riviera with a 153 CI GM engine bolted to an OMC stern drive, I have considered rebuilding or replacing the 153 and noticed that I could replace the original engine with a 250 CI for about the same cost.<br /><br />Would anybody here know if the 250 would bolt into place on the stern drive without replacing it as well, or would I be better off sticking with the original setup?

 

[whywhyzed]

Re: 153 CI to 250 CI swap

you'd be better off with a 181 CI (3.0) as it is basically the same exact engine as the 153 but bored out and you'll be able to reuse all of your original components on it. As well, your mounts won't have to be modified. <br /><br />For all the redesigning and mounting headaches of The 6 cylinder, it will give you about 15 or 20HP more at the prop than would a 181, but that would be mostly offset by the added weight.<br /><br />If you use the 6 cylinder you might find yourself having to change drive ratios ($$$)...wheras with the 181 you could prob. just change props by 2" of pitch and keep your WOT rpm within the 4200-4600 range

 

[Bondo]

Re: 153 CI to 250 CI swap

Ayuh,.............<br /><br />IF you had a Running, in the boat, Complete I-6,.......<br />I think it would be a Fun Swap...............<br /><br />If you Don't have a Complete Donor,............. I Won't go Near It...........

 

[Lou C]

Re: 153 CI to 250 CI swap

And in addition to that the 250 six is a LONG engine, much longer than the 4 cyl you have now. is the engine compartment long enough for it to fit? I agree with the above idea, at least that minimizes the added work to make the conversion work for you. If you are looking to do something the OE manufacturer never did, there can be many headaches that no one can anticipate.

 

[italian]

Re: 153 CI to 250 CI swap

Thanks guys for the input, wouldn't it be possible to go ahead then and have the 153 bored out to add the horsepower closer to that of a 181?

 

[Bondo]

Re: 153 CI to 250 CI swap

Nope,......... It's a Different Casting,...... The Cylinder Walls Aren't Thick enough.........

 

[whywhyzed]

Re: 153 CI to 250 CI swap

oops, yeah.. I was generalizing on the engineering concept... the crank is balanced differently too....

 

[italian]

Re: 153 CI to 250 CI swap

Thanks fellas, really appreciate your help, a 181 might be in the works!