Replace RR block with Std. Rotation block
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=47523
Printed Date: October-06-2024 at 8:25am
Topic: Replace RR block with Std. Rotation block
Posted By: robdubbleu
Subject: Replace RR block with Std. Rotation block
Date Posted: May-28-2019 at 4:09pm
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Hey folks, I've got my mid 70's engine at a machine shop for a rebuild. They told me the cylinders have already been bored 60-over and they don't recommend boring them any further, which they would need. My engine is reverse rotation, of course and has a 2-piece seal. I've found a new complete engine (minus the PCM marine stuff) from the mid 90's (non EFI). I believe that engine will be standard rotation (and probably a one-piece seal). I'd like to use that block (and crank, if necessary) but will have it re-built just so I know it's in tip-top shape. I'd like to basically have the new engine re-built in reverse rotation. What are my obstacles regarding the seal/crank/etc? I would consider keeping it standard rotation, but I've already got a new cam from Cam Research ready for it. TIA! *Edit: Incorrectly stated the cam was from Comp Cams. Fixed to say Cam Research* ------------- 1976 Ski Nautique (PCM 351) - Currently under major renovation: floor, carpet, interior, gel coat, engine overhaul - ALMOST DONE! |
Replies:
Posted By: woodyelc
Date Posted: May-28-2019 at 4:46pm
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The crankshaft on the late model is the same for both rotations the seal makes the difference. Use all you can off the RR motor so that the new one will turn the correct way. ------------- woodyelc |
Posted By: robdubbleu
Date Posted: May-28-2019 at 4:51pm
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So the old crankshaft will work in the new block? ------------- 1976 Ski Nautique (PCM 351) - Currently under major renovation: floor, carpet, interior, gel coat, engine overhaul - ALMOST DONE! |
Posted By: woodyelc
Date Posted: May-28-2019 at 4:58pm
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No use the crank that is in the late model just change the seal to a RR one piece. ------------- woodyelc |
Posted By: KENO
Date Posted: May-29-2019 at 8:51am
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If you're looking for a new one piece RR rear main seal here's a place that has them at a reasonable price https://www.alexsparts.com/rear-main-seal-marine-reverse-rotation-351w-viton-full-round-one-piece-main-seal/" rel="nofollow - link Or you can get one at SkiDim for a little more ................part number 1141 You can also get a smooth Timing cover seal for you RR engine at SkiDim ,,,,,,,,,,,,,,part number 1134 or get a Felpro 17795 at any auto parts store |
Posted By: Waterdog
Date Posted: May-30-2019 at 11:38am
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On a stock 351w engine the piston pin is 1/8 off set so the piston doesn't rock as much at the bottom of the bore. On a R/R engine the pistons are reversed on the rods for that. What I did was switch banks port & starboard. Lightly honed the cylinders and put it back together with new rings & bearings. Cam research Cam, Ported GT-40p heads, intake, 540 prop. Rune really, really well. ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: woodyelc
Date Posted: May-30-2019 at 2:40pm
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FYI the pistons are not reversed on FORD only on GM ------------- woodyelc |
Posted By: KENO
Date Posted: May-30-2019 at 3:00pm
I'll go along with that  I've had enough 302/351's apart both normal and reverse rotation to know that I've never seen the notches facing backwards on the pistons And the part number for the pistons are the same regardless of the rotation of the engine |
woodyelc wrote: