1969 Starcraft holiday 3.0 mercruiser - Possible swap to 4.3

[Scott Danforth]

The pistons are the same, but the cylinder head substitutes to a later cylinder head 936-5325 is the original and 936-5544 is the replacement number.. The original likely has smaller chambers and thus higher compression, but without knowing the casting number of both, it's speculation.

Same 9.3 compression ratio.......... The higher octane was required due to the ignition timing. Argue if you want, the 140hp rating was a crank rating, which in 1986 became 130 ot 135 depending who sold it

 

[Scott Danforth]

My 2300 pound (from mfg specification) fiberglass 17 footer would run somewhere near 36 MPH at 4800 RPM with the 3.0L. With the 4.3L runs right at 48 MPH at 4800 running the only prop I ever tried, a 4 blade aluminum purchased as a ski/board puller. Never tried to see what top end would be with a prop designed for that function. Of course the 4.3L weighs in right about 200# more than the 3.0L, putting dry weight of the boat now nearer 2500 pounds.

As far as I know, the only thing changed about 3.0L HP ratings over the years, from what I could see from parts lists and reading up, is how rated horsepower went from flywheel to prop rating, reducing stated values by 8-12% depending on applications. This occurred by US trade agreement in 1983, signing on to Internation Council of Marine Industry Associations Standard No. 28-83 (ICOMIA 28-83).

Exactly........ Nuff said

 

[GA_Boater]

Since you asked here about a 4.3 and started a new thread with the same question, both have been combined. You'll get the same answers with less confusion on our side and your side. Tried to change the title to reflect the 4.3 addition.

 

[Bow4game]

Sorry I just now figured out how to search the forums. I think I can manage finding the info now haha. Thank you all.

 

[Bow4game]

I had a few question on my Starcraft. I seen a pic where some star crafts had wood under the gunnels, like under the aluminum side rails. i don’t believe mine has any. Should it? Also what thickness and size should the aluminum angle be that runs along the floor that the side panels fasten to? The kick panels I think is what they are called. Not doing a restoration just making a nice reliable fishing boat. Also what’s the recommended thickness for floors and the kick panels? I noticed the kick panels are kinda structural to keep cracks away. Thank you for your input.

 

[Bondo]

I seen a pic where some star crafts had wood under the gunnels, like under the aluminum side rails. i don’t believe mine has any. Should it?

Ayuh,..... It ain't really necessary, unless yer mountin' "Stuff" there,.....

Also what thickness and size should the aluminum angle be that runs along the floor that the side panels fasten to?

My ole Islander, those were as the hull, .065" thick, probably 1, 1/4, or 1, 1/2", angles,......

Also what’s the recommended thickness for floors and the kick panels? I noticed the kick panels are kinda structural to keep cracks away.

1/2" works pretty darn good,.....

Just don't use P/T wood,.....
The salts in the wood eats the aluminum of yer boat,.....

 

[Bow4game]

Great thank, you very much.