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Old 03-15-2005, 11:17 AM
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martini martini is offline
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Boat: Mastercraft, Prostar, 1984, PCM 351, 1:1
Location: Austin, TX
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Engine refresh/rebuild success!

This might be long and it's been slow around here lately, so here goes.

A couple of years ago I bought a remanufactured marine long block from a good source to repower my 84(pics have been posted of it here before). The engine itself was fine and has worked very good for 100 hours, however a mistake I stupidly made prevented 3 of the cylinders from sealing properly. Essentially it overheated on break in, good for the cam, not so good for the piston rings.

Long story short, I installed the raw water pump on backwards, so instead of pulling water in, it was pushing water back out. Once I installed the pump, the right way, the temperature came down and it seemed to settle in. It made good power, but I was consistently oil fouling 3 plugs over the course of a season. I knew what the problem was and I knew I would have to fix it eventually, so I decided to go ahead and bite the bullet this off season and tear it apart, rehone the cylinders and re-ring the pistons. I figured I would replace all the bearings as well too, since I would be in there anyway.

Once I got the engine apart and could see what had happened, it basically confirmed what I had originally feared. Glazed cylinder walls, caused from overheating. I checked out the bearing surfaces and they a looked brand new! That was great news! The block is essentially at the end of it's serviceable life as told by the overbore at 4.060, which is fine on a 351. I knew the deglazing wouldn't take too much material, if any, and I was going to use a good set of Sealed Power file fit rings to fit them to each cylinder perfectly. By the way, the cylinders had almost no taper to them what so ever, even more good news! So the honing began. The cross hatch pattern was not as difficult to master as I thought it was going to be with the honing stones. Actually very easy and fast. It was nice when I was done to see the cylinders look brand new.

I figured since I had it apart, I would also put a set of GT-40 heads and some nice FRPP roller rockers from my 94 Cobra on it I had lying around. Took the heads to a machine shop to clean and inspect, valve job, mounting holes drilled to accept 1/2" head bolts and brass freeze plugs installed. The heads checked out, so all was good.

Once I had everything I needed, I cleaned the block completely and set out to reassembled everything. I checked tolerances as directed, checked tolerances as directed some more and o yeah, did I mention checked tolerances? It really isn't that hard to do if you have the right tools, measuring instruments and most important of all, PATIENCE! I took about a month to completely assemble it, working on it a few hours a week. No stress was my motto when going about it. I had plenty of time and a warm garage to work.

You don't know how happy I was when I laid all the new bearing inserts, lubed and torqued everything down, that it spun very freely and smoothly. So, flash forward to the moment I go to turn the key last weekend to see if all my hard work paid off. It fired right up, no leaks, no overheating, oil pressure was over 40 psi at start up and would rise and fall with engine rpm! The hotest it got was about 160. I did a few happy jumps and shut her down after about 15 minutes. I won't be able to give it a true test until I can get her out on the lake, but I think it should be fine.

It sounds very different now too, which was a very nice side effect to this project. It is very racey sounding and it revs very easily. Sounds mean. I didn't have time to tune it, set timing or anything. That will be the next thing that I will do.

All in all, I would do it all over again and it was fun performing everything on my own. I learned alot and I think I am going to rebuild that 94 Cobra motor I have and turn it into a marine engine as well. Possibly sell it. We will see. Anyone in the market for a 302!

If you want to ask me questions about things I did not include or you want to know about, just ask. I'll try to answer your questions as best I can. I'll post pictures of my build from start to finish as soon as I can get them off my camera.

Long time lurker, recent poster. Have a great day!
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Old 03-15-2005, 11:30 AM
jimmer2880 jimmer2880 is offline
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I'm glad everything worked out for you. Thank goodness that you were able to have "no stress" time to do everything right. Sounds like you did a good job.
If one day you're asked:
" How did you spend your time here on Earth?"
Will you say:
"I kept a crabgrass free lawn"
It's time to SKI.
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Old 03-15-2005, 11:39 AM
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east tx skier east tx skier is offline
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Boat: 1998 Ski Nautique
Location: End of my rope.
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Sorry Brian, but Martini may have just gotten by you on the winter projects.

Great job. Keep us posted on your lake test.
Previous: 1993 Prostar 205

Red 1998 Ski Nautique, PCM GT40, 310 hp, , Acme 4 blade, Perfect Pass SG/Zbox.


Be kind. Have fun.
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Old 03-15-2005, 11:46 AM
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BriEOD BriEOD is offline
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Boat: 2000 MasterCraft ProStar 205 DD
Location: Severn River, MD
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Great work, hope it runs fine in the water.
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Old 03-15-2005, 12:00 PM
martini's Avatar
martini martini is offline
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Boat: Mastercraft, Prostar, 1984, PCM 351, 1:1
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I forgot to list the components installed and specs. 351w overbored .060, GT-40 heads, 1.60 FRPP roller rockers, stock intake, MSD coil, electronic ignition, 1" inch carb spacer(to prevent heat soak and it works), Edelbrock marine carb, all fuel lines plumbed with AN fittings and hoses, adjustable fuel pressure regulator and fuel pressure gauge(Edelbrocks are finicky about PSI). And a newly aqcuired Acme prop.
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Old 03-15-2005, 12:14 PM
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G-man G-man is offline
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Boat: SN 196 previous 93 stars&stripes 190 red
Location: TX
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you'll love the acme prop!!!!!!
06 AWSA Approved Towboat
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Old 03-15-2005, 12:47 PM
Lance Lance is offline
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Boat: 1987 Prostar 190 PowerSlot, 2004 22' Bennington Pontoon 90 HP Mercury 4-stroke
Location: Burke, VA
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Very impressive. Sounds like a good learning experience. I would enjoy doing something similar but I don't have any excuse to take mine apart since everything works well. Guess I shouldn't complain too much about that!

I have heard so much about the GT40 heads that that alone might be a good project. Probably not for awhile though.
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Old 03-15-2005, 12:58 PM
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jayderwin1 jayderwin1 is offline
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Boat: MasterCraft, ProStar 190, 1986, 351.
Location: Nashville, TN
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that is love and dedication. how long did it take to do the whole project?
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Old 03-15-2005, 01:04 PM
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rem_pss308 rem_pss308 is offline
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Boat: 1999 X-Star 330 HP
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Anyone know if the aluminum GT-40 heads would be ok to put on the boat motor?

Jegs has them for about $100.00 cheaper than SKIDIM.com
"Let me not pray to be sheltered from dangers, but to be fearless when facing them."

1999 X-star, 330 LTR, Zero FLex tower.
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Old 03-15-2005, 01:35 PM
Ski-A-Rees Ski-A-Rees is offline
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Thats great. I just bought my boat and the starter had died from having a leaky water pump. Had the starter rebuilt and a new water pump and everything was great! This weekend I took it out to find that at the end of one of the risers has a leak in the rubber tubeing towards the end of the boat. Well I didn't think it was that bad so I keep the bilge pump on and off I went. Came back to the ramp in line with all the other club boats after the show to put it back on the trailer. Made the mistake of turning her off to go get my car. Big Mistake!!! It wouldn't start!!! Found out the I still had enough water for the fly wheel to pick up water and kill my brand new starter. So I had to pull the boat on the trailer which made me so mad. I havn't taken it apart yet myself to see if I can get it to work or have it rebuilt again! Sad Day!!!
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