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Ive got an old like 72 or so 3 cylinder 49 ci powerhead kicking around and am considering trying to port it myself as i got it for next to nothing. Are the cylinders coated on the old ones? They dont look like steel and dont have over spray from any nik. The blocks in decent shape if i can hone it. Anyways the exhaust port has two bridges in it, so three smaller ports. So my thought on that side is to widen the outer two ports and raise all three, then open up the transfers a bit as well. Is this a do able procedure for a novice in the porting department?

best way to port 49 ( and i was told this by a reputable engine builder) is to throw it in the scrap pile it came from and get a 56er..

Lol i know the 56 is a better option and is more then likely the direction im heading in but would love to see what it would do. It would literally cost me a set of rings, gaskets and getting it honed to get it up and running so for that is it really worth passing on?

probably not worth modding.. and really probably not worth building if its not going to be what you want..

,, i think there are some parts of the 49 you can use on a 56 i have no idea what those parts are.. others will chime in..

Yeah i hear ya but at the same time i cant really sell it for anything the way it sits either haha. I was going to be using it more for a learning resource. The 56 probably wont happen until later this year and Figured the 49 should be cheap enough to fill in a few month void in the early summer. As a running powerhead it must be worth more then the cost of rings and gaskets, no?

some of the 75hp were 49 cu in blocks with the 2 bridges at an angle.
you cant oil those bridges though due to them being at an angle.

personally I would just rebuild it and use it as stock unless your going to be spending a lot of money.

if you get it revving too high the bridges in the exhaust ports melt and break up.
loads of them around with cracked and missing bridges, but there is also a lot of old strong motors still kicking ass when beefed up
a touch.

just put new rings, a hone and new gaskets and enjoy a summer with it.
then when the time comes its a sellable engine.

is this a shortshaft mid-section with manual gears too ? and what size is the gearbox.
or is this long with electric shift ?
a photo would show what it is.
if its a small gearbox and mid then its a part of a race package for the future.
you probably have the lightened flywheel and good exhaust system on that engine.
but if its electric shift then just put it back as normal and sell it on to someone who wants it on a classic boat.

and no those were not coated with anything special, just plain steel bores.

There is lots of early 70s OMC 49 stuff out there. There were some 71 to 73 new old stock power heads selling for $150. There is no demand for them because they all have the longer cranks for the early ignition. If you have good old style ignition, I would get one of those power heads or get a complete motor. I purchased a complete 65 hp 1973 for $120.00 just for the lighter flywheel. The motor was in good shape and I sold it off as a parts motor.
If your going to do the one you have. I would just rebuild it stock. It will not have any resale value unless your very lucky in finding the right buyer. The best 49 block is a 1976 in my view.

Its a 15" motor with the old style manual shift case, also have a 15" omc surf 60 thats electroshift. The manual shift motor will be turned into a hustler for the delta we got off of a member on here. So based of the exhaust ports having the bridges its an early 75 hp 49ci block? Someone took off the serial number tag off of the swivel, are the blocks stamped like merc? Which is the early ignition? I know the surf 60 is cdi ignition, believe the other one is too. Did the older ones have points?

so its a 15 inch mid, I dont suppose you know if its the 1.86 ratio or 2.42.
either way the mid being short is good if you want a fast motor at some stage.
but just rebuild as a normal every day engine and it will give plenty of fun and last a long time.

save all your big bucks for when making a go fast 56 engine. (thats if you want a 56 ).