Inliners International Forums General Discussion Vortec 4200 Marinizing a Vortec 4200

The goal here is not to produce tons of HP for the strip but rather to create a reliable engine for a continous duty application. This will likely mean derating the output to make sure the cooling system can carry away all the excess heat from running the engine continuously under load @ 3000 R.P.M.

The first hurdle to jump across will be to source a vapour proof starter for it.

Does anyone know if the starter from the Vortec SB 350 or other common marinized GM 4,6 or 8 cylinder engine will bolt straight on?

The second hurdle will be to adapt the bellhousing to SB chevy bolt pattern to connect it stern drive. Is there something on the market today that will accomplish this?

The third hurdle will be to actually manage the ignition, fuel delivery and variable exhaust camshaft timing. I think the first two can be done with something like SDS EF4 system as I would want to have easy way to manage ignition advance curve to keep detonation under control. I'm not yet sure how to control valve timing. How does factory manage this aspect of engine?

The fourth hurdle will be to provide closed cooling system and water cooled exhaust manifold. I can source raw water pump and heat exchanger easily. Since cylinder head is of a crossflow design, having a stainless steel tubular water cooled exhaust manifold fabbed shouldn't be too difficult.

Finally, most marinized engines use stainless steel gaskets. Can I have a cylinder head gasket made up from this material at a reasonable cost?

You are probably asking why I want to do this? My boat already has twin inline chevy 250's and v-6's or v-8's won't fit. It's getting harder and harder to find parts for my old Mercruisers and I would enjoy the benefits of better fuel economy from a modern fuel injected engine.

I welcome all of your suggestions for this project.

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The second hurdle will be to adapt the bellhousing to SB chevy bolt pattern to connect it stern drive. Is there something on the market today that will accomplish this?

I do not know of any adapters that are commercially available, that said the dowel pin spacing is the same as a SBC. Folkd that race this engine redrill scatter sheilds.


The third hurdle will be to actually manage the ignition, fuel delivery and variable exhaust camshaft timing. I think the first two can be done with something like SDS EF4 system as I would want to have easy way to manage ignition advance curve to keep detonation under control. I'm not yet sure how to control valve timing. How does factory manage this aspect of engine?

I'd suggest you run the GM electronics with the mods needed. Westers garage can do this for you. This way you get the full benefit of knock detection and cam control.

The fourth hurdle will be to provide closed cooling system and water cooled exhaust manifold. I can source raw water pump and heat exchanger easily. Since cylinder head is of a crossflow design, having a stainless steel tubular water cooled exhaust manifold fabbed shouldn't be too difficult.

Finally, most marinized engines use stainless steel gaskets. Can I have a cylinder head gasket made up from this material at a reasonable cost?

I think the stock head gasket is S/S. If your running a closed loop cooling system - run antifreeze - then you don't need to mess with the head gasket.