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Hi Everyone
This boat has been in my driveway for 3+ years. Its time to get wet.
Much of the structural work is done. The rest can wait.
I may have an opportunity to buy two recent, fuel injection, 5.7 mercruisers. These are standard rotation with one reversing transmission.
Does anyone know if they will fit?
If they do fit what alterations will be required?
Currently I have the standard merc 5.7 with velvet drive trani's.
Thanks

I assume these are for your 28.

What transmissions do the new engines have? Are they down angle and if so, how much.

Cliff

I've repowered 28's with the hurth 450 gears behind 5.7 MPI engines and they fit tight at the hatch on some models.

The tightest required removing the manufacturers plastic logo cover over the intake and grinding the hatch wood down to glass in a couple of places. I also had to slightly modify the throttle arm.

Basic fabrication.

Make sure the intake arrester hold down is water tight as water can run down the hatch pull and in some cases depending on boat angle run right over top the hold down and drip into the intake locking up the engine.

I've seen it happen.

They are the drop down tranis.
My 84 has the raised deck [alittle more head room in the engine compartment]
Hopefully it will fit but allitle adjustment is no problem.
Thanks about the water such a simple precaution to prevent such a big problem
Thanks

one more question is this set up a strong dependable unit or would a typical velvet drive easy to find and repair system be more dependable and cheaper to maintain?
Thanks again

I have the ZF45 8 degree down angles in mine and they fit no problem. I did have to raise the hatches though. It will all depend on the engine configuration that came in the boat as to how big the engine space is. Seems like lots of hatch clearance issues with these boats. I am running six cylinder diesels though so not a fair comparison.

The ZF Hurth 45 style gear is very reliable. The only issue or complaint I've had with this gear (63 gear also) is the stb gear(reverse rotation) can rattle at low rpm.

Nothing wrong with the gear though. The fix is usually a slight adjustment on the throttle set. Now on some MPI engines, the idle screw is fixed and the idle is controlled by the computer.

Easy way around that issue I've done in some cases without affecting throttle position sensor enough to create an issue is epoxy feeler gauge stock to the back of the throttle arm at the stop.

Doesn't take much to up the rpm 50 or so.

Depending on the exact model you are getting, some of the MPI systems have a fuel return back to the tank like a diesel or will recirculate it not using a fuel return line.

If you have the return line, don't plumb them together, run them seperatly back to the tank and do not use the extra hole in the pickup as the return.

Either use a t fitting in the fuel fill hose close to the tank as possible, better yet tap a new hole in the pickup plate.

If your engines recirculate, before they are put in, insulate any metal lines in the fuel system at the engine to prevent possible vapor lock issues.

Alot easier to do with the engines out than in.

I have had no problems with mine. I change the fluid and filter every winter. That equates to less than 100 hours per year for me. Never seen any shavings. I think the threshold for the 45 series is ballpark 350-360 torque which is about where my engines are. I will say that my boat will get on plane very fast. It does not seem to have that transition/plow where you have to get over the bow wake. I am using the 1.5 gear ratio if it helps you figure things out.

I was told these return fuel to the tank.
When I made my tank I added a tap to make it easy to suck out water or dirt I will use that for the return .

My trani is also a 1.52.

Thanks