Nice boat, bad motor

#1 08-23-2005, 04:56 PM

I am getting out of airplanes, and trying to go fishing! Problem is, it seems like boats aren't any cheaper. The '79 V-20 I just bought lasted about 1 1/2 runs, then the engine ( Mercruiser 470) failed. It will not idle or accelerate. Peaks out at 2800-3000 RPM, then decelerates and dies. After playing with it for several days, #3 cylinder lost all compression (cause unknow at this point) I am told that parts for this engine are difficult to get, so rather than fighing it, I am thinking of putting in a new I/O unit. Any comments on the parts situation, and mayby someone in the Biloxi, MS area who knows how to work on these antiques?

#2 08-23-2005, 07:30 PM

IMO, ditch the I/O and mount a bracket and outboard of some sort.

Who made the engine? It might be easier to get a long block than you think (std Chevy or Ford or whatever was used at the time). Or, perhaps tie a new Mercruiser to the old outdrive.

Franco · #3 08-23-2005, 10:13 PM

The Merc 470 is half a bigblock ford engine - peculiar to merc only. there are several posts on the net about it. I'd have to agree that if your willing to repower, spend the money and plug the hole, hang a bracket and outboard and enjoy the extra space and full transom

Skools Out · #4 08-24-2005, 12:34 AM

hey if i can put twin 225's just drop an I/O big block in the boat a 454 or 502 Chevy and bravo Merc outdrive

Franco · #5 08-24-2005, 01:46 AM

Hey, If your heart is set on an I/O - I have a freshly rebuilt 225 h.p GM 5.0 ( less than 10 hours on the motor) litre and a Volvo Penta outdrive I'll pull outta my boat and I'll hang a bracket!!!!

reelapeelin · #6 08-24-2005, 08:12 AM

Flyer, if I were in your shoes, I'd swap boats w/ Franco or CAN your I/O and hang a bracket/outboard on that full transom...if you've been flyin', I KNOW you appreciate RELIABILITY...shame you got into boatin' w/a problem motor...hope it doesn't turn you away... ;) ;D...

Curious...what size fuel tank in your '79?...

greateastern · #7 09-02-2005, 12:00 PM

Screw the brackett. :o I have a 470 mercrusier on a stepv20. The 470 is the best motor out there mercrusier ever made there are some updates to the motor that are really easy to install that makes this motor crank in open water. I just had mine completely rebuilt for $2,500. it is stonger then ever. the 470 or 170 are great on gas and at $4.00 plus a gallon I'm fishing Block Island from Montauk NY on a 1/4 tank of gas. "Rebuilt it" find some one that knows the engine. If you like I can give you a number of the shop that did mine in Riverhead NY.

P.S. Brackett= $3,000 to $5,000
150 to 200hp outboard= $15,000 to $20,000
470 Rebuilt= $2,500.00

You do the math.
470 Fresh water cooled dady likey. ;)

Franco · #8 09-02-2005, 12:38 PM

CHECK HIM OUT FLYER, THE MAN HAS EXPERIENCE!!!!!
HE SOUNDS LIKE HE KNOWS OF WHAT HE SPEAKS!

jaysea · #9 09-02-2005, 02:02 PM

hi,im runin a 470 merc,runs great,only has 350hrs very dependable ,there are pleanty of parts used on ebay under mercruser 470,ive been kicken around the bracket thing ,when the time comes to repower,my marine mecanic says to leave it i/o *before going bracket, he also said to take the boat to a fiberglass man an have the transom beefed up if going to go bracket, sounded like good advise id put in a v6 fi nextime 200hp

jaysea · #10 09-02-2005, 02:13 PM

ha ,not to knock any body with an out board powered boat,if mine came with an out board id repower with the same,just happened that i bought my boat from a friend and i/o it is ,so i/o it will stay,