Vector/Inline 150 Power

Hey Randy,

I just picked up a cherry 76 Vector with a 150 In-line on it. Trim and tilt factory for that year separate pump and cylinders. I cannot remember the stock gear ratio for that year but I will be installing a 1500XS lower unit with low water pick-ups and I believe the 2:1 gear ratio. ? is where do I start with the prop shaft height and with what prop. I know you have been asked this. I plan on rebuilding this motor this winter with boyeson reeds, Wiseco Low dome pistons and some mild porting on the exhaust side with a V-6 Aluminum flywheel with a custom rapair stator. I would like to see 6500-7000 RPM with this motor. I know that detonation is a problem for these motors. In the past we just backed the timing off a couple degrees and removed the exhaust tube and drilled some 1/2" holes in the housing to let them breath a little as well as a size bigger jet in the top carb. with steel on steel needles and seats.  I will be registering as a member as soon as I get the baby in top shape. Can you install solid mounts in this motor have you ever made any or will your current one's work.

David Scott


Don't go porting up the block if you plan on the low dome pistons. The thing will make LESS power and not have any bottom end. Leave the high dome pistons in set the timing up and buy some race gas (high octane) to mix 50-50 with your pump gas. This is way less expensive and the only way you will see the performance you are looking for: the 150 inline had high-wide ports already.




Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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