Merc in-line 6 shaft and lower options??

**ct20sutphen** · 03-21-2021, 11:12 AM

I’m looking for info on parts interchange w the merc inline 6. Mine is a 25 inch lower w spacer but a solid shaft not an extension. Wondering what lowers will fit from what engines.
Need to get this thing down to at least a 20 without the spacer or even a 15
also shaft interchange would be helpful.

**Dave S** · 03-21-2021, 12:36 PM

I have 20 inch lowers......Check your PMs.....

**ct20sutphen** · 03-22-2021, 12:54 PM

Still would be good to have the interchange info posted for people w these engines . If any has the info.

**25two.stroke** · 03-22-2021, 05:18 PM

All inline 6 lowers will bolt up. Driveshafts and such are not interchangeable between the I-6 and V-6 motors nor are the prop shafts and or shifting mechanisms or gears. Any of the I6 lowers will bolt to each other though.

**merc paul** · 06-07-2021, 05:29 AM

Are there any inline 6 powerheads that will bolt straight onto a 850xs

**Dave S** · 06-07-2021, 06:11 AM

Any of the 1973 L6 and newer Mercs will bolt up. The only thing you should do is change the tunner......the L4 uses a different type.

**Tin Man 2** · 06-07-2021, 06:29 AM

Is the tunner a misprint? I’ve got a couple i6 power heads and an 800 lower, are they compatible? Thank You for any advice.

**Dave S** · 06-07-2021, 09:20 AM

Depends on year......1966..1972 Exhaust housings.....not real tunna style.......1973 had 2 big exaust holes under the PH......Merc 800.... depends on year.

**faztbullet** · 06-07-2021, 07:58 PM

I6 are 2:1 ratios and I4 are 2:3:1

**starviper10** · 06-11-2021, 08:13 AM

Originally Posted by 25two.stroke

All inline 6 lowers will bolt up. Driveshafts and such are not interchangeable between the I-6 and V-6 motors nor are the prop shafts and or shifting mechanisms or gears. Any of the I6 lowers will bolt to each other though.

Is it just a spline difference between I6 and V6 driveshafts? I thought I've seen some guys running sportmasters under I6 powerheads, perhaps they had an I6 spline cut and welded onto their V6 lower? I believe the V6 lower bolt patterns are the same as I6 right?
Thanks

**merc1250bayliner** · 06-11-2021, 12:48 PM

No it's not. Nothing lines up between v6 and l6. I've tried.

**Bodhi** · 06-11-2021, 02:40 PM

Originally Posted by starviper10

Is it just a spline difference between I6 and V6 driveshafts? I thought I've seen some guys running sportmasters under I6 powerheads, perhaps they had an I6 spline cut and welded onto their V6 lower? I believe the V6 lower bolt patterns are the same as I6 right?
Thanks

Might have just been a coned lower you saw , as mentioned above v6 won't be compatible with inline stuff

**1954bmw** · 06-11-2021, 04:04 PM

Hey Starviper, how is your MX14 coming??

**starviper10** · 06-14-2021, 07:55 AM

Originally Posted by Bodhi

Might have just been a coned lower you saw , as mentioned above v6 won't be compatible with inline stuff

Thinking back on this now, that might've been a 12" mid inline that I saw. So it likely had a V6 adapter plate instead of a inline 6. Thanks for the correction there, good to know

Originally Posted by 1954bmw

Hey Starviper, how is your MX14 coming??

Still in pieces in need of gel repair and finish, along with complete blasting and painting of the merc.