Mercruiser 170 to 470 Conversion

I've got a 1986 Four Winns Horizon that come with a Mercruiser 170. The engine threw a rod a couple years ago and I pulled it with the intentions of swapping the top end over to the 470. I've already ran into a problem and didnt know if anyone had an awnser and advice of more isses to come.

My problem is with the flywheel and coupler. It appears the crank for the 170 uses bolts to secure the flywheel allowing clearance for the coupler. While the 470 has studs that pertrude from the shaft not allowing the coupler from he 170 to fit. Is there anyway that I can just heat up and remove the studs allowing me to secure the 170 flywheel to the 470 crankshaft?

-Jake

PS. are there any other major issues I should look out for?

Re: Mercruiser 170 to 470 Conversion

Ayuh,... The studs are just screwed into the crankshaft,...

Unscrew 'em...

Cinch up a pair of double nuts on 'em, 'n turn 'em out on the bottom nut...

Re: Mercruiser 170 to 470 Conversion

No 3.7 expert here - were there any real differences in the 170, 470, 480????

Re: Mercruiser 170 to 470 Conversion

Thanks guys I'll try heating them up with a double nut and unscrew them. I thought this was going to be more of head ache.

-Jake

Re: Mercruiser 170 to 470 Conversion

180shabah said:

No 3.7 expert here - were there any real differences in the 170, 470, 480????

Click to expand...

OK there are several designations 470, 165, 170, 180, 190, 485, and 488. Sometimes it is also called a 3.7 L. They are all basically the same IL4 engines. Some of the early (1982 and earlier) 470's have different exhaust systems. The 180, 190 and 488 are 4 bbl. versions. All of the 224/IL4 engines listed here are "470" type engines: http://www.mercruiserparts.com/selectModels3.asp?type_id=4 . Know nothing about a 480. That should confuse you.