Second attempt(thread didn't post 1st time)

starsnstripers

Lieutenant
Joined
Nov 30, 2007
Messages
1,330
I have reworked my transom in my 1972 SS215 Slickcraft 21.5' to take a Mercruiser instead of the OMC stringer it once had. I Have the transom assy. plate,gimble, and 1.50:1 drive from a V8. I was going to put a 305 or a 350 in it, BUT! I found a boat today i can buy reasonable with a good 4.3 eng. and Cobra drive. (1) Can i use the OMC manifolds to hook up to my Merc exhaust Y tube? or do i need Mec manifolds?(2) The 4.3 is a Gm It is a 1.50:1 eng correct? (3) Since i already did my transom over I probably wouldn't use the whole Cobra set up, Opinions?
 

starsnstripers

Lieutenant
Joined
Nov 30, 2007
Messages
1,330
Re: Second attempt(thread didn't post 1st time)

Also Will the V8 Merc exhaust tube be ok to use with the 4.3? thanks
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,241
Re: Second attempt(thread didn't post 1st time)

Nope,... You can't put an OMC dressed motor, on a Merc. transom assembley...
The OMC exhaust is a different diameter,....
And, That's just the 1st Problem you'll run into...

4.3s use a 1.84:1 or 1.65:1 ratios,... 1.5:1 is for V8s...
 

starsnstripers

Lieutenant
Joined
Nov 30, 2007
Messages
1,330
Re: Second attempt(thread didn't post 1st time)

thanks Bondo, so i can use the motor, i'd just need manifolds and outdrive. will the 4.3 with Merc. manifolds work on my V8 exhaust Y tube?
 

starsnstripers

Lieutenant
Joined
Nov 30, 2007
Messages
1,330
Re: Second attempt(thread didn't post 1st time)

Well what about putting the whole drive setup in my boat, 4.3 W/ OMC Cobra Drive? I'd have to redo the transom, But saves me from getting a drive and manifolds. What would you do? thanks
 

starsnstripers

Lieutenant
Joined
Nov 30, 2007
Messages
1,330
Re: Second attempt(thread didn't post 1st time)

Whats the Horse Power on an 86 4.3? 170ish?
 

haulnazz15

Captain
Joined
Mar 9, 2009
Messages
3,720
Re: Second attempt(thread didn't post 1st time)

Just go find a 5.7L V8 to go with the equipment you already have. You wouldn't be happy with a 21' boat and a v6 anyhow. I wouldn't put a single OMC item on my boat if I were you. The outdrive and transom/exhaust stuff is more expensive than finding a used 350 marine motor.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,241
Re: Second attempt(thread didn't post 1st time)

will the 4.3 with Merc. manifolds work on my V8 exhaust Y tube?
Ayuh,..
Whats the Horse Power on an 86 4.3? 170ish?
Ayuh,.. with a 2bbl... about 200+ with a 4bbl...
Well what about putting the whole drive setup in my boat, 4.3 W/ OMC Cobra Drive? I'd have to redo the transom,
Ayuh,... I think I'd rather Shoot myself 1st.... But whatever Trips your trigger...
The Transom hole is the Same as the Merc...
Just go find a 5.7L V8 to go with the equipment you already have.

Ayuh,.... Amen....
SBCs are a dime a Dozen,....
A Hundred dollar junkyard pickup truck motor with brass coreplugs will put you on the water,+ give you somethin' to Work with....
Brand New GM Goodwrench motors are still only $1500. or Less...
Nevermind,... I see you don't have the motor's Dressings....
Are you finding your parts along the coast, or inland,..??
You need to find a frozen split SBC Dressed as a Merc,+ a $100. 350 motor with brass coreplugs...
Then you'll only need Manifolds...
 

starsnstripers

Lieutenant
Joined
Nov 30, 2007
Messages
1,330
Re: Second attempt(thread didn't post 1st time)

I think i'll get the 4.3 and get manifolds and a 1.84:1 drive. I think that motor will be more efficient and plenty of oomph! I had a 160 hp L-6 in my last years boat same thing SS-215 Slickcraft and it went just fine. An extra 15hp and better fuel effiency than a straight 6 and a V8, i'll be a happy boater.
 
Last edited:
Top