Debate about auto vs marine engines

[prinler]

I call all these websites looking for answers while im looking for a new block for my 3.8L V6 229. I found a reman 229 for $1900 longblock... or $450 out of a running car.

Half the people i ask tell me i can leave the motor as is. bolt on the manafolds, intake, pully's and it will work fine for my boat.... Then the other half tell me i need to change the cam and bearings and crank out of my current marine motor. even possible the pistons and maybe heads?

I know i need new freeze plugs, gaskets but what else? Whos right!?! pulling out the little hairs i have left lol

 

[mylesm260]

Re: Debate about auto vs marine engines

I can't speak specifically for the 3.8, but me (and many others) are running automotive (truck vortec) 4.3's in our boats with no problems.

Might I sugest renaming you're post to:

"does anyone have any experience marineizing an automotive 3.8"

Very important, try to get the specs for you're doner vehicle. You need to know a couple things:

#1. How much peak torque and at what RPMS
#2. How much peak HP and at what RPMS.

If you're getting peak HP @ anything higher than 4800 RPMS or so, and peak torque any anything about 2800 or so, then your cam is no good for a boat.

This is why truck cams work so well in boats, because like boats, trucks need a lot of bottom end "grunt"

3.8's were used in some performance applications, so they likely came with much hotter cams, that if put in a boat would give you no bottom end, and would result in:

-Possible water intrusion
-No "hole shot"
-Not being able to reach max RPMS

 

[Lancer23]

Re: Debate about auto vs marine engines

Well, I can't speak for your engine/manufacturer combination, but have become intimately familiar with the "Chris Craft" engine in my Lancer over the last few weeks. In fact, I'm in the process of rebuilding it.
Let me quote the Chris Craft manual...
"Note: Since the cylinder block assemblies (included fitted pistons, ring assemblies, and bearings) are not stocked by Chris Craft, they must be ordered from Chevrolet. The following changes will have to be made to the cylinder block assembly as supplied by Chevrolet to make it suitable for marine use: Replace 8 steel cup plugs 1-5/8in with 8 Chris Craft 16.74-10001 brass cup plug and replace two 1/4" pipe drain plugs with Chris Craft 16.53-10155 brass plugs."
Sure enough, the block, intake, heads, cam, crank, pistons, etc, etc are all standard GM car parts and bear standard GM part numbers.
Everything on the OUTSIDE is marine parts... starter, alternator, fuel pump, fuel lines, carb, flame arrestor, oil pan, exhaust manifolds, etc.
Again, can't speak for your setup, but my world famous Chris Craft motor is a plain ol' Chevy at heart.

 

[gadget73]

Re: Debate about auto vs marine engines

Most marine engines are nothing more than modified car engines. The freeze plugs and gaskets are the bulk of it, but the cam specs make up the rest. If you've got the right gaskets and plugs, and the cam is suitable (or just a correct spec replacement for the marine motor) then it should run fine. I wouldn't worry about moving over the rotating assembly, its probably not different, or not enough different to matter. Just make sure your flywheel bolts up.

 

[180shabah]

Re: Debate about auto vs marine engines

Not a 3.8 expert, but wasn't it available in both even fire and odd fire configurations? You will need to match your current setup so that you can reuse your distributor.

Or, why not take the opportunity to install a 4.3?

 

[kennys0900]

Re: Debate about auto vs marine engines

I just bought a 4.3 Vortec and was wondering what parts are better on the vortec motor that I shouldn't swap over from my orignial mercruiser 4.3 motor. I have heard that the vortec heads and cam is better or just as good as the boats original 4.3? Is that correct then just change freeze plugs, water pump and head haskets? Also I am not sure how much this matters but the boat and original motor is a 93 model and not sure about the year on Vortec motor but it's full fuel injected not throttle body injected.

Edit: After reading a little more about this to use the vortec heads I need a different intake manifold? What manifold do I need?. My original 4.3 was a 4bbl motor.

 

[mylesm260]

Re: Debate about auto vs marine engines

I Don't know much about marine intake's (as I'm running an automotive intake,) but I think you should be able to find an intake manifold that will work with the vortec heads and you're existing carb.

Also, the vortec heads work best with the vortec pistons, so leave them together.

And *MY* experience is that the vortec cam works great in a boat, lots of bottom end and top end (and stock peak HP is @ 4400 rpms)

 

[180shabah]

Re: Debate about auto vs marine engines

Kenny, you need to start a new thread.