Mercury Powerhead Swap

delta07d

Seaman Apprentice
Joined
Mar 28, 2012
Messages
32
If I swap a Mercury 1973 1500 powerhead with one from a 1977 which years specs should I use? According to the manual I have the only difference is in the timing 1973 has 6 btdc for the throttle pickup - primary, 1977 has 1-3 btdc.

Or does this statement cover this?

" All of them are speced different, but if the 1st pickup hits at 3-4 degrees BTDC advance - you win"

Thanks!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
Re: Mercury Powerhead Swap

A 1977 Merc 1500 Idle pickup timing is 4-6* BTDC. Not sure where you got your info....max advance is 21*BTDC. That outtake is likely from Clams Canino. It was general timing guidance.
 
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