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41 60 special 346 engine need cylinder ring help

Started by mr41cadillac, June 06, 2013, 03:57:45 PM

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mr41cadillac

I have my 346 on engine stand and need advice on rings to buy. I don't have a micrometer.  what exactly do I need to measure the in side of cylinders and where can I buy a reasonably priced one from. I cant seem to find anyone around here who has one .  thanks john

Jay Friedman

#1
You need what are called "telescoping gauges" and a "dial caliper".  Instead of a dial caliper, you could also use micrometer big enough to measure the bore.  For example if the the bore is between 3 and 4 inches, you'll need a 3"-4" micrometer.  I think you can buy these measuring tools from Harbor Freight or Northern Tools.

You'll have to measure the bore at several places from top to bottom and at several positions; that is, from the 9 o'clock and 3 o'clock position and the noon and 6 o'clock positions.  See your shop manual.  If you've never done this sort of thing before, I'd consult a professional.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Paul Phillips

John
This may be time to consider taking the block to a machine shop. Your measurements will tell you, but it will be a surprise if the wear on all cylinders is the same top to bottom and rotationally in the bore, much less from one cylinder to the next. If you see variation, then machining is the best choice. The shop can do a consistent bore to the 'worst' of any cylinder, so you can buy the right pistons and rings as a +0.x0 set.  In todays world, you can't easily source individual piston/ring sets for individual cylinders.

Also be sure to carefully inspect for cracks in the bore and between the bore and valve seats. It is not uncommon to see cracked cylinders in the engines. A good shop can fix those as well, usually by stitch welding.

Paul
Paul Phillips CLC#27214
1941 60 Special (6019S)
1949 60 Special (6069X)
1937 Packard Super 8 Convertible Victoria
1910 Oakland Model 24 Runabout

pauldridge

The rings, of course, are of specific size to go with the pistons.  There should be negligible wear on the piston bodies themselves, so you could measure the piston diameter (much, much easier and more precise than trying to measure bore diameter), then consult the manual to determine if you've got standard or oversize pistons.  In fact, many of the pistons are marked with their size on the face, you might be able to clean one off and read it.

Please note that the pistons are specifically constructed with a taper, so it is important where you take your measurements.. the manual should shed light on this, especially the tank overhaul manual, which is much more detailed than the "factory' one, and available free online, just search this forum.

I just recently overhauled my 346.  As I recall, the nominal piston diameter is measured just below the lower ring, but don't quote me on this.
Phil
Phil Auldridge
Austin, TX
1940 60S as well as MGA, Stingray, '39 Ford Coupe, BMW 3.0 CS, '59 Jaguar, '51 Hudson Hornet, '64 and '70 Mercedes roadsters, and Nash-Healey LeMans Coupe
[img]http://www.auldridge.org/images/hdricon.jpg[/img]

mr41cadillac

thanks all the block from the 41 cad is going to the machine shop this week. the man there said he can check and do whats necessary but does nor re  assemble. if you have any advice I would appreciate it. he is really good at this. when iget it back im assuming I can reassemble it myself. any tips ?  thanks john

Dave Shepherd

If you have never assembled an engine before you need a good general manual and the Cad manual, there is way too much to consider to deal with in this forum.

Jay Friedman

If it were me, I'd get someone who has done it before to show you how to do it the first time.  Though the shop manual will explain it all, there's lots of stuff to remember and little tricks and details that only experience can teach you.  Keep in mind that if you get it all back together and the engine installed in the car, if you put the connecting rods in backwards or installed the rings incorrectly or lots of other variables you'll have problems and will have to do all that work all over again. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."