New engine. To build or buy

[rkf63k10]

I'm in the process of buying a short bock from Rapido Marine or buying all the parts I need and building it myself. Problem is, is that I really don't know what kind of reputation and engine quality Rapido Marine has. It's going to cost about the same either way I go. What do you guys recommend? BTW it's a 350 merc.

 

[Scott Danforth]

depends, what kind of relationship do you have with your local machine shop?

Nothing wrong with Rapido's product. its been discussed here in depth. use the search function.

I myself would build it, and I would build a 383 stroker with a scat/KB rotating assembly and vortec heads

 

[harleyman1975]

If It was me I would build it myself then I would know exactly what I had and I would balance the reciprocating mass to maximize engine life. I would also source out a forged crank and have the block magnafluxed. I would source out a good set of vortec heads and polish the ports and install stainless steel valves...But that is just me...Do it right the first time.

 

[rkf63k10]

I was leaning to building it myself also. I bought the boat last year only to find out the block was cracked. It has a good rotating assembly. I have a brand new set of Vortec heads and manifold also. I'm on a pretty tight budget right now so I'm buying a new block and putting the old rotating assembly in it. The pistons are standard size. (4.00 bore) crank is in great condition also. Later on I will upgrade, but for now I just want to get it on the water,

 

[Scott Danforth]

you cant re-use pistons, so no way to re-use your existing rotating assembly in a new block, and it costs more to recondition a set of rods than buying new forged rods. having a crank ground is almost the same price as a new crank.

that being said, if your on a budget, pull a running 350 out of a truck at a you-pull-it, change the head gaskets and core plugs, go boating while you build the motor you want.

 

[MBAKER]

I just went through this a few years ago. Replaced a 5.0 with 5.7 and built one locally. Money was comparable to getting a mass reman or even new GM but like previous poster said we were able to balance it and stick in some better pieces here and there at the same time. In the end we got a better than new engine for same price, don't regret it at all. If you have the ability to build it or have a good machine shop close that would likely get my vote.

I haven't looked at Rapido prices but if I were you I would look at Marine Power and look into getting a brand new GM engine. Last I looked they were around 3K I think, and these are brand new never run GM engines just like the new boats come with. This takes quality of the remanufacturer out of the equation and you get same quality as new boat owner would.

 

[rkf63k10]

I can get a short block from Rapido for $1550 shipped. I can build one for a little less than 2 grand with parts from Summit racing. I think I'd rather go with all new parts, even the block, and build it myself. I was just thinking that if Rapido built a quality engine and a lot of you guys have used them I would go that route just to get it going again, but I really need to slow down and go over the whole boat and and fix it up the right way. This is a project boat anyway. 1990 Checkmate Maxxum 229. Good looking boat, but it needs some TLC. I appreciate all the help!

 

[MBAKER]

One thing to keep in mind on your '90 is the fuel pump, electric or block mounted? If you have a block mounted pump make sure any new block you get has the hole drilled for it. Some of the newer GM blocks do not.

That's more reasonable than I thought for short block. You can also get a brand new 350 shortblock from GM for around $2000 and put your heads, cam and tin work on it. As mentioined, advantage to building one is you can have the bottom end balanced, you can square deck and align hone the block, and upgrade heads if you want. On the other hand the Vortec 350 is pretty solid in stock form anyway and will run a long time if taken care of. I wouldn't go crazy upgrading parts unless you plan on making some major changes later on, the stock parts are pretty solid as is. When I did mine I was switching from 5.0 to 5.7 so I needed the bottom end anyway. Unless your previous engine suffered some damage I wouldn't be afraid of using your crank if they check out, and even the rods if you get them reworked and put new bolts in. One thing I would suggest since the newer blocks will already be set up for it, would be to look into getting a stock roller cam setup. Its worth it in my opinion for the extra power especially with Vortecs. The stock marine cam is pretty easy to come by too, its not big but runs out pretty good.

One thing I wish I had considered more is making it a 383 while I was at it. Wouldn't have cost anymore at the time but I was concerned about the drive since we do a lot of skiing and hard takeoffs. It probably would have been fine though looking back. We dyno'd it to break it in and even with stock cam it still made 350HP, nice increase over a sickly 305 at the time.

 

[rkf63k10]

Ok so here's the plan. Going with a new block, new rotating assembly with eagle crank, rods and pistons. I have new Vortec heads that I'm going to do a little porting on to open them up a little more. I haven't decided on a cam yet. This is a budget build. All I'm looking for is a great running, reliable engine.

 

[MBAKER]

With budget build in mind.... since you are starting with a 350 already I would just have the crank polished or ground if necessary, and R/R the rods, then get new pistons to hang on them. Prob save a few hundred over new. No need to overthink things really, its just a stock rebuild.