Thanks to all those that replied to my earlier query about using a super a connecting rod in a super c engine. They look exactly the same with the main part number. I measured the extra length at the top above the wrist pin hole and it is 3/16" longer. Would this be a balance problem if I used it? Thanks....
- Thread starter Normie
- Start date
Janicholson
Well-known Member
If they weigh within 2 to 3 grams of the others no issue. if heavier, grind the lump some. jim
Steve@Advance
Well-known Member
That is there for the purpose of balancing. The factory machines some off to correct the weight. There is probably a boss on the bottom of the cap for the same reason.
Balancing an engine is an in depth procedure I can't begin to understand or replicate.
But as slow as these old engines turn, it will have minimal effect if it is a little different from the others.
Balancing an engine is an in depth procedure I can't begin to understand or replicate.
But as slow as these old engines turn, it will have minimal effect if it is a little different from the others.
jimg.allentown
Well-known Member
The extra length could cause clearance problems as well as balance problems.
After you put it together with an odd connecting rod, you will be back on this forum asking why your engine runs rough, vibrates, or just blew up.
Do it once and do it right.
Or, if you prefer, do it right or do it over.
After you put it together with an odd connecting rod, you will be back on this forum asking why your engine runs rough, vibrates, or just blew up.
Do it once and do it right.
Or, if you prefer, do it right or do it over.
dr sportster
Well-known Member
Yes -- all rods must be the same.
jimg.allentown
Well-known Member
I posted a comment earlier. After some thought, I want to add to it.
First problem I see is the extra length. That would change the swept area of the piston. The piston would come up higher in the block and would not go as low in the block. The problem there is that is the top of the piston comes up ABOVE deck height, it might hit the head. Potential damage is the rod might get bent, the piston might be damaged, and there could be potential damage to the crankshaft.
Second problem is balance. A different connecting rod could change the compression ratio of that cylinder. It would also change the reciprocating weight of that one cylinder. How much of a problem could it be? Think about this. 1500 or 2000 RPM might seem slow for an engine, but at 1500 rpm, the piston is going up and down 25 times per second. compare that to something like a paint shaker that goes so much slower yet needs to be bolted to the table because it shakes so bad.
Third problem is potentially dimensions. You have several to consider. The diameter of the piston end. Since wristpins are fitted to within a few 10,000ths of an inch, is it correct? How about the crankshaft end? Inside diameter and width come into play here. It only takes .001" to make the difference between a quiet and properly lubricated bearing and a noisy or oil starved bearing that will lock up shortly.
Lastly, why not just get the RIGHT rod for the engine or have the old (and presumably damaged) one reconditioned? If you are that tight on funds, perhaps you should not be rebuilding an engine.
One final note. If you ask enough people and ask often enough, you will eventually get the answer that you seek. That does NOT make it the RIGHT answer. Just the one you want to hear.
First problem I see is the extra length. That would change the swept area of the piston. The piston would come up higher in the block and would not go as low in the block. The problem there is that is the top of the piston comes up ABOVE deck height, it might hit the head. Potential damage is the rod might get bent, the piston might be damaged, and there could be potential damage to the crankshaft.
Second problem is balance. A different connecting rod could change the compression ratio of that cylinder. It would also change the reciprocating weight of that one cylinder. How much of a problem could it be? Think about this. 1500 or 2000 RPM might seem slow for an engine, but at 1500 rpm, the piston is going up and down 25 times per second. compare that to something like a paint shaker that goes so much slower yet needs to be bolted to the table because it shakes so bad.
Third problem is potentially dimensions. You have several to consider. The diameter of the piston end. Since wristpins are fitted to within a few 10,000ths of an inch, is it correct? How about the crankshaft end? Inside diameter and width come into play here. It only takes .001" to make the difference between a quiet and properly lubricated bearing and a noisy or oil starved bearing that will lock up shortly.
Lastly, why not just get the RIGHT rod for the engine or have the old (and presumably damaged) one reconditioned? If you are that tight on funds, perhaps you should not be rebuilding an engine.
One final note. If you ask enough people and ask often enough, you will eventually get the answer that you seek. That does NOT make it the RIGHT answer. Just the one you want to hear.
wore out
Well-known Member
According to the FIAT on-line parts lookup the Super A and Super C engines take the same connecting rod, 30926DFXA. It may be possible that one of the engines had different connecting rods swapped in at some time in the past, or has a replacement engine.
If you read closely, the O.P. is talking about extra metal ABOVE the connecting rod. I take it to mean one rod has an extra metal protrusion similar to the rod in this photo:
<img src = "https://i.imgur.com/VQtzpBK.jpg">
If that is the case, and the center-to-center length between the bores is the same, the rod will works just fine in his low speed engine, or the extra metal could be ground off.
Previously, I advised him to take the rods to an automotive machine shop and have the center-to-center length checked,to do a quality repair the rods need to be checked anyway.
Doesn't seem like he liked that advice.
If you read closely, the O.P. is talking about extra metal ABOVE the connecting rod. I take it to mean one rod has an extra metal protrusion similar to the rod in this photo:
<img src = "https://i.imgur.com/VQtzpBK.jpg">
If that is the case, and the center-to-center length between the bores is the same, the rod will works just fine in his low speed engine, or the extra metal could be ground off.
Previously, I advised him to take the rods to an automotive machine shop and have the center-to-center length checked,to do a quality repair the rods need to be checked anyway.
Doesn't seem like he liked that advice.
Janicholson
Well-known Member
If you weigh the rods,and they are 2 to 3 grams different run it. If heavier, grind the projection till they are close. Jim
Similar threads
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.
Copyright © 1997-2024 Yesterday's Tractor Co.
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy