A pair of Iron Dukes

[shaw520]

So,..I was painfully forced to sell my Searay 280 Sundancer,...it was a bitter breakup with the ex. I may NEVER find a boat that nice again and the blood, sweat, and tears that I put into it was unmatched.
Anyways,.. moving along,..Im in the process of locating another similar boat at an affordable price,... I came upon a 1986 Searay 270 Sundancer with twin 170 4 cyl Merc's. I know these have somewhat of a reputation for being UNDER POWERED,... and I wanted to get some opinions from boaters with any experience with these big cruisers with twin 4cyl. The current owner claims it will do 30 knot all day long and get better fuel mileage then the big 8cyl's. I personally have no need to do more then 30 knot and most times just putt along at hull speed... So any suggestions and opinions on the power set up is greatly appreciated.

 

[Scott Danforth]

those are Mercruiser 470's, not the 3.0's (the iron duke as you mentioned is a pontiac motor that was never in a marine application)

run, dont walk from the Mercruiser 470's. its a platypus motor. Mercruiser custom aluminum block, using Mercruiser custom crank that uses 4 pistons and rods from a ford 460, an iron head from the 460, a flywheel from the 250 cubic inch GM motor and a custom damper with an outboard charging system in it.

the heat exchanger is required because of the unsupported bores in an aluminum block with the iron head.

 

[ahicks]

From memory, the old 140 hp Mercruisers (and 120's?) were based on a 181" Chev II engine, known as the "Iron Duke". To my knowledge, they suffered only from a crappy oiling system to the top distributer bearing, where they had a lot of trouble. The bushing would wear, making it nearly impossible to set the points correctly. The 6cyl 165 Mercs had the same issue.

I loved the old 6's, but mixed memories regarding the 4's. Seemed like they had a lot of vibration.

 

[Scott Danforth]

the chevy II 153 cubic inch (4 cylinder version of the 230 inline six from the 196, 230, 250, 292 family) was not the iron duke. the iron duke is the 151 cubic inch pontiac motor which is a combination of half a pontiac V8 and their OHC in-line 6 parts with a new block. many iron dukes were used to power jeeps, however nothing to do with Chevy 4-cylinders. there are 6 bolts that are common, and that is it, not a single part other than the 6 bolts (valve cover bolts) are the same.

 

[shaw520]

I believe you are correct Scott,... Ive heard these are problematic engines and if memory serves me didnt they have an issue with coolant intrusion into the rear cylinder ? Kinda sad because the boat itself is in decent shape and the price point is even better ! I know a guy who has been nursing a 170 along for many years...they were quite common in late 80's

 

[shaw520]

this boat would be a good candidate for a Yanmar conversion,....but that would just push the price well beyond what the boat is worth

 

[Scott Danforth]

if the motor spacing is 34" you can upgrade to 4.3's when the 470's go if only 32", then your stuck with in-line motors

there are many things you can do to keep a 470 alive

it was a brilliant idea with a poor execution

My recommendations would be to talk the boat down as cheap as you can go, assuming you can turn wrenches
get a hull survey because 34 year old SeaRays have been known to have water intrusion

the things I would do with 470's if there was a killer deal on a boat and I had to live with them

• make sure the upgraded 4" HX is there
• make sure the upgraded exhaust elbow is there (or i would fabricate one)
• toss the iron head and replace it with an edelbrock aluminum head for a 460 (minimizes the head gasket issue)
• adjustable rocker conversion
• install a laser-cut bore girdle (spyder) to keep the bores stable (similar to what is done with supercharged porsche 928 motors - further minimizes the head gasket issue)
• use a davies craig electric water pump and eliminate the cam seal issue (would take some fabrication)
• upgrade to the 4-barrel if you only have the 2-barrel
• go with an alternator conversion - one motor gets an alternator, the other gets the PS pump
• convert the points to electronic ignition (Mallory, not pertronix)

or...., I would redo the transom and drop in a pair of V8's or a pair of 4 cylinder diesels and bravo drives.

 

[shaw520]

All very good info Scott and If I was that in love with the 470 it might be considered,...but buy the time I do that much investing I'll just spend the extra and get a boat with a pair of V-8's

 

[shaw520]

Here's an off the wall question Scott,.. Im shopping for a 25-30 ft cruiser in the late 80's to mid 90's era,..which brands are most likely to have dry stringers and transoms,... (ahhh,.. the million dollar question) LOL

 

[shaw520]

Update!,.. I didnt buy the 270 ,...I bought a 87' Sea Ray 300 Sundancer ,..5.7 Merc motors built in 2014 have 120 hrs on them,.. Onan Gen, A/C heat,.. ect,... only had it for a couple days now,.. still going through all the systems,..any experience with these old 300's,..by george they're a dime a dozen out there !

 

[shaw520]

[No message]

 

[JASinIL2006]

Nice looking boat!

 

[Scott Danforth]

Here's an off the wall question Scott,.. Im shopping for a 25-30 ft cruiser in the late 80's to mid 90's era,..which brands are most likely to have dry stringers and transoms,..

to that question.....None

unless the boat was stored from day one. manufacturing was shoddy across all brands with some being better than others.
Maybe look at Formula, Wellcraft or Hatteras

 

[shaw520]

Nice looking boat!

Thank you,..the decor is a bit dated,..but the bare bones are solid,.. Ive started with some vinyl wainscote.

 

[shaw520]

A bit of updating to the 3t00,... I know I should have started a new thread but since I already started here maybe one of the moderators will be kind enough to merge this with my other '87 Sea Ray 300' thread. So with my work in full swing its been hard to find time to work on her but here are some pictures of cabin updates. I replaced carpets,refrigerator, wall coverings,installed indirect lighting,..installed shower box,..installed a ProMariner 4 bank 4 phase charger,.caulked all railing supports and exterior hatches, treated all canvas with 303. Now,...one question before I upload pictures,...this boat did not come with an onboard waste holding tank,..instead it has a direct toilet to maceration going overboard,.... I dont use the head for anything but an occasional #1...but I want to make it legal to today standards,...can I just put a keyed switch on the macerator to make it conform to USCG standards? thank you