Marine Block, Auto Block
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=6370
Printed Date: January-17-2025 at 5:51pm
Topic: Marine Block, Auto Block
Posted By: Thephantomkaw
Subject: Marine Block, Auto Block
Date Posted: April-19-2007 at 10:41am
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Hey guys. I was just wondering what the differences are in a Chysler 318 Marine block, and a auto 318. Other than the cooling system/bolt on's of course. I am talking about the internals. Can you use a auto block, and use all of the marine bolt-on's? Thanks! ------------- ~Michael~ |
Replies:
Posted By: JoeinNY
Date Posted: April-19-2007 at 10:56am
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By block do you mean the block casting or are you talking about the short block including rotating assembly. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Thephantomkaw
Date Posted: April-19-2007 at 11:54am
Sorry I didn't specify... I was talking about the whole short block(including assembly). ------------- ~Michael~ |
JoeinNY wrote:Posted By: David F
Date Posted: April-19-2007 at 12:08pm
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Yes, if the rotation is the same. Casting plugs should be changed from steel to brass/copper (what ever is marine).
All (most?) marine engines start out as auto engines (Unless reverse rotation and then each manufacturer is a bit different on what is marine specific). ------------- |
Posted By: TRBenj
Date Posted: April-19-2007 at 12:37pm
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Isnt piston-cylinder wall clearance larger on a marine motor? ------------- |
Posted By: backfoot100
Date Posted: April-20-2007 at 10:06am
I haven't heard this Tim. Don't forged pistons require a little extra clearance? I don't think the clearances are any different than in a auto unless the pistons that you use require the extra clearance. At least that's the info that I've read in my Chevy marine books that I've got. Maybe Blue Oval's are different. I know that my engine has forged factory pistons which may be the norm for marine engines which would then require the extra clearance? |
Posted By: JoeinNY
Date Posted: April-20-2007 at 10:55am
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Marine piston to wall clearance should be higher. Forged pistion to wall clearance even higher. In general you should follow the piston manufacturers recommendation unless they do not have a specific marine recommendation if that is the case I would minimally shoot for the higher side of the tolerance range. You also need to go with a slightly higher ring end gap typically as well. In general the low end of the marine gap tolerance and the high end of automotive overlap so its more than possible that an appropriate automotive clearanced block will work.
Reasons that I have heard sighted for the differences include the extended full load operating conditions a boat sees compared to automotive apps, and the possibility in a boat of the thermostat opening up and allowing cold lake water into the engine where the the cylinder could shrink much quicker than the piston. Either way people do scuff new engines and lock up rings when they push the low ends of the automotive tolerances. Now beyond that legend has it that chrysler produced some of the most marine of the marine versions. I have heard of more corrosion resistant alloys in the block all the way up to different cooling passages in intakes. If in doubt search it out on here it has been discussed by those who know... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: TRBenj
Date Posted: April-20-2007 at 10:58am
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The 2 threads Im thinking of are
http://correctcraftfan.com/forum/forum_posts.asp?TID=363 - Here and http://correctcraftfan.com/forum/forum_posts.asp?TID=2843 - Here AWhite70 seems to have had some good experience on the subject. I believe Alan also verified the special marine clearances with his machine shop when having his rebuild done. ------------- |
Posted By: 64 Skier
Date Posted: April-20-2007 at 11:46am
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Marine engine piston to cylinder wall clearance is 040. For an auto its 025.
That auto short block might be OK for cruising, but if your pulling slalom at 3200 to 3600 rpm it may lock up on you. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: Thephantomkaw
Date Posted: April-20-2007 at 11:49am
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Thanks.. guys. Also.. Do I have to use a marine carb/intake? ------------- ~Michael~ |
Posted By: TRBenj
Date Posted: April-20-2007 at 12:16pm
Carb, yes- its a safety issue. Intake, maybe. The marine Chryslers had a unique cooling setup. ReidP has shared the info here before. An aftermarket auto manifold can be used, but the cooling system requires some degree of modification. ------------- |
Posted By: eric lavine
Date Posted: April-20-2007 at 4:35pm
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I know on chevy's there will be a number casted in near the flywheel and from memory ive seen 010 which means there is more nickel or some other metal for strength, but the marine pistons are fitted differently and anymore all you see are roller cams in marine engines. ------------- "the things you own will start to own you" |
Posted By: Rick
Date Posted: April-23-2007 at 7:56pm
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I had my 66 Barracuda's 318 M Rebuilt and bored .60 over as it had sea water in it for a year. After boring we found the cylinders still pitted. We got a salvage 318 and rebuilt it from there As long as the rotation is right and therefore the seals. You should be OK. It now had about 300 hours on it without a problem. If you need a 67-70 318LM block there is a Speed Shop in El Cajon with one ready to go bored 60 over as they did one and then found out they had the wrong block ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=250&yrstart=1996&yrend=2000%20" rel="nofollow - 2000 Ski |