Author Topic: 331 Cylinder Bore Wear  (Read 2287 times)

Chris Arneson

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331 Cylinder Bore Wear
« on: January 03, 2005, 11:09:45 AM »
Hi all.

Over the Christmas break I disassembled a 1955 331CID engine and measured the bore wear.  I found that generally the cylinders were 0.002" over the nominal of 3.8125" except for at the very top were they measured about 0.006" over the nominal.  

I am wondering if anybody has experience to tell me if this minimal amount of wear justifies a complete overhaul or will the engine, if thoroughly cleaned and assembled with new gaskets, has more usable life left in it, and if so how much (admittedly a difficult question)?  

Maybe another way to go about the question is to ask if anybody is able to estimate the mileage based on the bore wear?  I bought the engine from somebody who knew nothing about the engine except they didnt want it.

I might be tempted to just assemble the engine and use it, since it will be several years before even 10K or 15K more miles will ever be asked of it.  Any thoughts from the crowd, experiences?

Chris

Jessie J.

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Re: 331 Cylinder Bore Wear
« Reply #1 on: January 04, 2005, 12:58:19 AM »
 The answer depends, some guys just cant tolerate the thought of not doing it right and could easily run up a $5000 re-build on an engine like this, heck Ive even seen em do it to engines that didnt -NEED- anything, but just because it was out of the car, "they might as well do-it-right", Cadillac owners as a group are generally not the types to accept any less than the best.
If you can get past that, the decision comes down to the actual condition of the cylinder walls and of the original pistons.
 Those old Cadillac engines are very strong, hard, durable and of a very high quality when compared to the SBC (soft-block-chevy) the engine that is most commonly rebuilt by replacing every moving part (because all were engineered to wear out together)
 Id check the ring lands carefully for wear (following the shop manuals recommendations) and if the clearances check out OK, hone the cylinders and install a set of new chrome rings.
 Looking at several considerations here, First, it is unlikely that a 1955 engine is going to be expected to rack up another 100,000 miles of everyday service.
 Secondly, internal parts like rings, pistons, bearings etc. are designed to be easily replaceable, whereas the cast-iron parts such as the block , crankshaft, rods, heads, are NLA and every machining operation unnecessarily performed on them ultimately reduces their service life.
 Third, is the economic consideration, little is ventured by a simple re-ring job, if the results are not deemed sufficiently satisfactory, a more major rebuild can be undertaken.(again, with the minimum amount of machine work that is actually required, i.e. overbore no more than is necessary to remove taper, DO NO machine work on the block, heads, connecting rods, or crank if within specs.)
                                  Jessie J.

Chris Arneson

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Re: 331 Cylinder Bore Wear
« Reply #2 on: January 05, 2005, 02:08:42 PM »
Thanks for the reply, this is the second such responce Ive gotten out of two attempts.  The other comes from a engine applications engineer at the company where I work.  We use i  He also has experience with restoration but not Cadillacs.

As mentioned, he suggested replacing things like rings, valve spings and even the lifters.  So that is my plan after measuring the rod and main bearings for wear and a good cleaning maybe even an acid dip.  Then finish with a bead hone and assemble.

I agree with your recomendations about not doing any machine work until required.  I feel the new oils of today will take good care of this engine and give me years of service.  I also feel that leaving things as original as possible is a testiment to the machine and its capabilities.  They tell a better story that way too.

Chris

Pat

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Re: 331 Cylinder Bore Wear
« Reply #3 on: January 05, 2005, 02:51:49 PM »
Chris,
Here is my take on the engine. I would take the block and have it honed on a sunnen cylinder machine. Have the machinist hone just to the point of taking the taper out of the bore, this will leave a straight cylinder wall for the rings to ride on (as well as a propper crosshatch) A ball hone will not straighten out the bore.
Chrome rings need a PERFECT cylinder wall to seat...good old fashioned (cheap) cast iron rings will seat quickly..moly filled cast rings will work too. If your piston ring lands are hooped you might find a machinist that can cut them and install spacers (not many shops do this anymore) in the old days they used to knurl the piston skirts to take up some of the slack in the bore...again..not done much any more.
Cheers, Pat