How Fast Should She GO

[flyingd]

I was curious what the best cruising speed and top speed I could expect out of a 1969 18' cheiftain with the 120 mercruiser in it.

How much better would it go if I had the 140 in it.

 

[Watermann]

So do you have a Chief? Pictures of it would be good! I would say your looking at low 30's for the 120.

If your wanting to upgrade from the cast iron lump, take a look at my Chief's re-power and restoration project.
.

 

[elkhunter338]

I get 28 mph wot @ 4600 rpms with a newer 140, cruise @ 20ish @ around 3,500 rpms. I would anticipate similar results with a 18' and a 120hp.
I wish I had twin 70hp outboards. My 140 manifold just broke and left me with no boat for my vacation. Home to fix it.

 

[airshot]

I have a 22' Islander with the 140 hp, top speed is 34mph (gps) and typ cruise is 3200-3300 rpm at 22-24 mph depending on wind and wave conditions. Your 18
with the 120 should be pretty close to those numbers

 

[Catfishcabin]

My 18ft chief with the 120 tops out at 32-34mph

 

[jbcurt00]

Catfish, please take note of when a topic was last posted to. Its been nearly 3rs, well past the 90days inactivity guideline.

 

[Catfishcabin]

Catfish, please take note of when a topic was last posted to. Its been nearly 3rs, well past the 90days inactivity guideline.

Sorry about that I must have used the search feature and didn't realize the date