5.7 GM Marine Repower Options?

[prohan007]

In SoCal and it's time to repower. I'm looking for advice on the best way to proceed.
New GM Marine Longblock Crate Engine or remanufactured marine longblock or take to a machine shop to be rebuilt. I have twin (circa 2000) VP 5.7L GSi engines.

I have spent many hours researching different engine suppliers, reman outfits, and machine shops. It seems that most have bad reviews about quality, warranty, poor customer service after the sale, or all of the above. I don't mind paying for good quality, just looking for a reputable company, builder, or machine shop to deal with, any advice would be appreciated. I plan to remove and install the motors myself.

 

[docmirror]

I'm getting ready to rebuild my Ford 460. And, honestly all I'm subbing out is the basic machining. Bore cyl, deck the block, and clean it. From there, I'm doing all the asm myself. I had the heads done by a shop and I had to take them back. They ground out a passage in the exh too far and exposed a water jacket. Forgot one inner spring on a valve and a couple of the valve seals were not pushed all the way down on the stem retainer. I complained bitterly but all they did was fix what they already screwed up.

So, taking a set of pistons and rings to the shop so they can do the bore properly, and tell them exactly what to take off the decks, and that's it. From there, it's all my show. New cam bearings, crank bearings, rod bearings, etc.

If you find a good machine shop stick with them, cuz I have no hope of decent quality work anymore.

 

[prohan007]

Thanks, DocMirror, I appreciate you taking the time to reply.

 

[Scott Danforth]

first, unless your motors have high hours (and I mean over 5000), not sure why you would need to rebuild unless the boat sits in water and the exhaust manifolds failed.

however assuming the motors are worn. take to your local machine shop. line-hone the mains, deck the block, bore out to the smallest size you can. put new slugs and rings, redo the heads and you are out maybe $1800 per engine.

now assuming you completely toasted both motors. you can build a 350 or a 377 for exactly the same price with new parts. only slighly cheaper than the 377 crate motors, however with much better rotating assemblies and cams

 

[cptbill]

What is the reason for repowering?

 

[prohan007]

I'm repowering because I had a riser gasket fail back in September (while in the water) and the SB engine got saltwater intrusion. Additionally, back in 2007, things got tough financially and I let the boat sit for 6 years without running the engines. Some of the cylinders have mild pitting from rust.

 

[docmirror]

I'm repowering because I had a riser gasket fail back in September (while in the water) and the SB engine got saltwater intrusion. Additionally, back in 2007, things got tough financially and I let the boat sit for 6 years without running the engines. Some of the cylinders have mild pitting from rust.

Based on this, I'd just look into a re-bore, and check the condition of all the rotating asms. Marine engines are like little race engines with quality materials. Aside from pistons and rings, likely a lot of the rest of the engine is seaworthy. For the engine that was sitting take a good look at the cam lobes. If you see any kind of pitting there, plan for a cam and lifter renew, but that is based on exam.

Get your hyperutectic pistons and a good set of rings to the shop, they will bore and hone to your pistons. If you have never used plastigauge read up on it and use it for the crank and rod journals. Better to go with the materials that you've had than replace with potential China junk.

One more thing. Hunt around for US made gaskets. Felpro does NOT make gaskets in the US anymore. There are a couple places that make them in the US, but you need to ask specifically. I use this place, and they are very good to deal with. All gaskets made in US;

www.americangasket.biz

 

[Scott Danforth]

I'm repowering because I had a riser gasket fail back in September (while in the water) and the SB engine got saltwater intrusion. Additionally, back in 2007, things got tough financially and I let the boat sit for 6 years without running the engines. Some of the cylinders have mild pitting from rust.

Lack of maintenance is what kills the motors

I would talk to your local automotive machine shop.

Line hone the mains, deck the block, LCQ pistons, +.001 on the normal bore, and you may need new heads $800/pair.

 

[BRICH1260]

If you choose to replace the engines, I had a good experience with Michiganmotorz when I replaced mine. You might check out their website for prices and availability.

 

[Scott06]

In SoCal and it's time to repower. I'm looking for advice on the best way to proceed.
New GM Marine Longblock Crate Engine or remanufactured marine longblock or take to a machine shop to be rebuilt. I have twin (circa 2000) VP 5.7L GSi engines.

I have spent many hours researching different engine suppliers, reman outfits, and machine shops. It seems that most have bad reviews about quality, warranty, poor customer service after the sale, or all of the above. I don't mind paying for good quality, just looking for a reputable company, builder, or machine shop to deal with, any advice would be appreciated. I plan to remove and install the motors myself.

If you can do the work yourself, spend the money to get new base engines (long blocks) i went through the same exercise as you seven years ago. Bought a extended base engine from Michigan Motorz ( carb intake distributor) has worked flawlessly for seven seasons. Glad a went this route.
of course pricing was more favorable back then …

one nice thing MM would give a one year warranty even if installed by owner vs marine mechanic. Never needed it but may warranties didn’t cover such situations

 

[cptbill]

The 5.7 GSI long blocks I put in my 330 Cabrio came from Marines for less .com, all the gaskets where included and they sell Barr manifolds and risers