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mood's Avatar
 
Join Date: Jan 2002
Location: DAB Florida
Posts: 14
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4.5 vs 4.7 crankshaft

My "Euro" '82 4.7S engine is apart due water mixing with the oil and a big split in one cylinder. I have my replacement block ready for assembly but I noticed tiny rust flakes dribbling out of some of the crank oil holes. I wanted to use that crank to maintain the same rotating/reciprocating Assembly of my original engine. If I remove the crank oil gallery plugs to properly clean it, I won't be able to seal it again the same way as the factory, so the balance will be disturbed. I have another crank which is perfect, it was the only good part off a sweep-the-floor 4.7 engine that someone put together. That nice crank is stamped "4.5", so I assume it's off a 4.5 liter. Should I worry more about the imbalance caused by changing the gallery plugs on the 4.7 crank or about using a crank from another engine. I believe 4.5 cranks and 4.7 cranks are the same apart from the rod journal holes. Re-balancing the engine is not an option for me here.

The 4.5 crank is on the right.
Old 01-10-2007, 05:11 AM
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I would clean the 4.7 crank without removing the plugs. Just keep flushing with a solvent and oil until clean.
Using the other crank requires a re-balance.
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John V.
1990 928GT
1980 928 EuroS (GT2-S)
Old 01-11-2007, 05:25 AM
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What's the deal about balancing not an option?

You've obviously got the motor apart, so why not take the extra time (and not much extra expense) of having the whole assembly balanced and blueprinted, and then a very thorough cleaning of everything before assembly?

Anytime I've got one stripped that far, it's just good preventative maintenance (also good for more HP and longetivity) to do the above machine shop work.

The cleaning you can do yourself.......

I can assure you that when I build my 5.0/16V Euro top end hybrid, it will damn sure be balanced.

regards---rhjames
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Old 02-03-2007, 08:58 PM
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My guess is there aren't a lot of places to balance cranks in Kuwait......
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John V.
1990 928GT
1980 928 EuroS (GT2-S)
Old 02-04-2007, 02:28 AM
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Kuwait?!?!?

I should have noticed that, but what the heck. We've sent everything under the sun to those rich bastards, can't imagine there's not a machine shop to balance his stuff(?)

Who knows, maybe he can get the US Army to do it for him!

regards---rhjames
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Absence of Evidence, is not Evidence of Absence.

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Old 02-04-2007, 07:29 AM
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When I rebuilt my first 5.0 back in 2001, I spent $450 on "balancing" where all I reallly did was pay someone for their time to set it up & spin it, only to report back that it was already perfectly balanced. So, unless you've changed rods/pistons or crank, don't waste your $ even if you do find one. Mark
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Old 02-08-2007, 05:10 AM
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