engine swap help needed

[jere1972]

have a 91 mercruiser Bravo1 7.4l, Motor just blew lots of blue smoke, can't rotate the crankshaft, looking at a Merc horizon 7.4 V-drive, don't know what a V-drive is assuming has some kind of transmission, my Question is what is a horizon motor?, what is a V-drive?, can I use my bell housing and New coupler that I just installed last year on my 91 7.4, and use the Horizon motor on my Bravo setup?

 

[Bt Doctur]

Re: engine swap help needed

most likely but you might have to change the flywheel and starter or use your starter and flywheel . The reason is most inboards use a "aft entry" starter.It mounts to the "bell housing" not the engine. It is just the opposite rotation of the engine. The ring gear is in a slightly different location.
A V drive is what the name implys. power from the engine goes thu a V shaped gearbox then to the propeller shafting on a inboard.
Horizon motors to me mean their fresh water cooled motors
typical V drive for a inboard Hurth Marine V Drive Gear | eBay

 

[jere1972]

Re: engine swap help needed

Thanks for the insight, kinda made some of the pics I looked at make sense! I was thinking there may need to be a flywheel change along with the housing, my coupler and starter are brand new, it would really be nice if I could use my starter, coupler, flywheel and housing, don't know if they are bolt for bolt

any idea on HP from a 2000 7.4 horizon, I understood my old engine to be 300hp @ prop shaft,

 

[Bondo]

Re: engine swap help needed

Thanks for the insight, kinda made some of the pics I looked at make sense! I was thinking there may need to be a flywheel change along with the housing, my coupler and starter are brand new, it would really be nice if I could use my starter, coupler, flywheel and housing, don't know if they are bolt for bolt

any idea on HP from a 2000 7.4 horizon, I understood my old engine to be 300hp @ prop shaft,

Ayuh,... It oughta be a direct swap, No issues there,...

Both motors are 'bout 330 hp,...

 

[jere1972]

Re: engine swap help needed

was hoping for a easy change, the guy selling the engine stated the horizon was 380hp, not certain if true, seems these engines are all over the place hp wise! depending on year, generation Clymer book states for my year 300hp, but like Bondo stated I was also told 330, maybe thats a 7.4 Mag??, also found a 7.4 Gen5 (Marine Power), guy claims to only have 200 hrs, has 4bl carb, claims this engine to be 340hp, $400 more then the Horizon but he will put new OEM Merc manifolds and include A harness adapter to be drop in ready, so now comes the decision the Horizon is MPI, closed cooled with 350hrs but needs some parts swapped around but other wise Very well maintained, the Marine power will have brand new manifolds but reusing my SS risers & be rigged bravo drop in ready with 150 less hrs and also has closed cooling,
any preference over MPI and Carbed motors, Carbed seems easier to maintain maybe more reliable, would the MPI yield a better fuel economy and or performance

 

[HT32BSX115]

Re: engine swap help needed

any preference over MPI and Carbed motors, Carbed seems easier to maintain maybe more reliable, would the MPI yield a better fuel economy and or performance

I would have went with an EFI engine if I could have found one! They're VERY reliable!

 

[tazrig]

Re: engine swap help needed

I would have went with an EFI engine if I could have found one! They're VERY reliable!

+1^^^ Fuel injection is just better all the way around. MPI's are much more fuel efficient then carbed. Easier starting. Smoother power. Really no comparison.

 

[jere1972]

Re: engine swap help needed

Went and looked at 2 Engines one carbed and one MPI both looked in worse shape then mine, my engine is rebuild-able so thats the option I took, pulled her this past Saturday and dropped her off at the builders shop, said 10 days and she'll be better then new,, he did mention to me that in the big block, I should run Diesel oil 15w-40w, it contains Phosphates and is better for the motor that is what he is filing her with, any truth to this???

 

[bajaunderground]

Re: engine swap help needed

Went and looked at 2 Engines one carbed and one MPI both looked in worse shape then mine, my engine is rebuild-able so thats the option I took, pulled her this past Saturday and dropped her off at the builders shop, said 10 days and she'll be better then new,, he did mention to me that in the big block, I should run Diesel oil 15w-40w, it contains Phosphates and is better for the motor that is what he is filing her with, any truth to this???

Prolly worth less than $.02...

Make sure whatever oil you decide (I have no opinion on diesel oil viscosity and/or phosphates?) but I do know that it should contain a zinc additive, at least for break-in period!, otherwise, go with what oil is recommended by your engine manufacturer?

 

[Walt T]

Re: engine swap help needed

Wow, Phosphates. Is the guy old or maybe also an aircraft mechanic? Jeez don't overthink oil. Just use good name brand oil whatever weight is recommended by Merc. Don't let your head get full of other peoples nonsense. You'll end up like me all twitchy and with a real nose for BS