230 con rods

[David Pollock]

Thanks Go,   I am going to give this a try.  On this particular set of rods, the upper part is fully reversible (in the manufacturing process) in that it has an oil sqirt and shell lock on both sides. The caps are numbered 1-6 and after being fitted to a particular rod  are not interchangeable, yet they have a great deal of extra material which could be safely removed if the extra weight is found to be on the big end. The rods are not drilled at the top for the pin bushing  oil, even though the bushing itself is. So there is a safe place to remove weight at the top.  Also, there is considerable variation in the big end nuts that have been used over the years, and it may be possible to add/delete weight there too.  I am familiar with the process of balancing each end using vee blocks and knife edges etc, so with a bit of perseverence I think I can manage this.  My other problem  (or solution thereof) is that the six piston pins vary in weight as they are not a matched set. ( someone lost the set that accompanied the new pistons)    Thanks , all , for taking an interest.  dp

[Go Fleiter]

David, the rods should have an I - beam cross section, so most of the torque is taken at the margins of the rods. Try to find the point on which the lightest rod of one offset set stays in balance like a beam scale. Than try Plymouth?s hint with with boring or carving little spots out of the shaft of 2 others of the same set. Take from both sides. Do until You may reach the same weight plus nearest equilibrium balance point as the reference rod. . Than try with the opposite offset set. My machine people do so. "White hair" help a lot as they have good judgement and experience and konw where and how much to take off! good luck! Go

[David Pollock]

Thanks  Todd and Plymouths for the benefit of your experience here.  I have "static " balanced engines with good results but this particular engine is being assembled with parts from many different sources so I wanted to have it dynamically balanced. (new pistons, nos crankshaft , etc.)  I think I can bring these rods into balance with a bit of effort, but as the shop rejected these rods, I hoped to find a set which was a little closer.

The "short" engines do have offset rods so mixing them around is a bit more challenging than with the Chrysler/Desoto blocks.    I am going to try another machine shop before doing anything radical. I will look for someone with hair as grey as mine.  I want to build  a really smooth runner to replace  the 230 which I currently have in my 50 Ply. It has  9 to 1 compression and runs really strong but it  has a spray welded crankshaft which worries me and for whatever reason is not as smooth as it ought to be.

Years ago, I balanced an engine by trial and error by adding and deleting bolts and washers around the outer ring of bolts on the flywheel.  It worked really well, but this was more of a stop-gap measure to cover up some internal problem with the crankshaft itself.   dp

[TodFitch]

...(snip)...These engines don't rev very high and I doubt you'll ever rev much over 2500 even in 1st gear...(snip)...? ? ? ?

Max brake horsepower (BHP) on all the Chrysler L-6 engines I am familiar with is at 3600 RPM, I have seen a Chrysler engineering BHP curve that goes to 4000 RPM. And my car is geared so that it is turning over about 3600 RPM at 65 MPH and it cruises comfortably at 55 to 60 MPH (2800 to 3200 RPM).

So even if you are running a newer car than mine with, say a 4:11 rear end, you will spending lots of time with the engine over 2500 RPM. So I think you ought to worry about matching the factory specifications on balance for your engine parts.

That said, many years ago I purchased a set of new pistons for my car and the weight variation was far in excess of factory specifications. I was unsure of my ability to safely remove material from the heavier pistons without compromising their structural integrity. So I installed them as follows:

Cylinder	Weight from mean (arbitrary units)
1	0
2	-1
3	+2
4	-2
5	+1
6	0

This worked well as the #3 and #4 pistons are on the same throw of the crank and #2 and #5 are also on the same throw. I ended up with a smooth running engine.

However the original post was about rods. And rods are offset and so do not interchange as easily as pistons so I don't know if this "shade tree mechanic" technique would work for that case. And it may be that you have to worry about where the excess weight on a rod is (near big end or little end) which is not a consideration on pistons....

[David Pollock]

My machine shop suggested I find another set of connecting rods for a 230 I want to have balanced. The set I have apparently? has over 50 grams variation even though they all came out of the same engine.
Plymouth from mid 54 to 59, trucks, powerwagons and Dodge cars all used this engine in the USA but they are rare here in Canada. (3 1/4 bore X 4 5/8 stroke)? ?A? 49 parts book gives? part #? 954376 for rods 1,3,&5 and 954377 for 2,4 & 6? for the Dodge engine? although the rods I have carry part # 1554530? (later model perhaps)? I also need a matched set of six piston pins for the 3 1/4 pistons. Good used is ok? . (mine went missing somehow)? In hopes that someone out there can help.......? dp