Replacing A connecting rod in place

Step-down said:
If the rod isn’t bent , hoping the small end of the rod is Acceptable
Remove shim from rod cap
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As long as the bearing is not damaged, you can remove any shims and/or file a couple thousands off the rod cap to snug it up. I recommend about.001" at a time.
If the wrist pin is the problem, I would replace/check the piston also.
 
If I was going to do this, I thought I would just mic the crank, and if it was still mostly round, buy a rebabbitted rod the right size, and install it. Wouldn’t that work?
 
I have done complete bottom-end bearing jobs (crank and rods) on both a BMW M6 and a VW GTI...all done from the bottom with the oil pan off. (Plastigauge is a God-send.) I used a popsicle stick to push the old bearings out and new bearings in. That might be a problem with babbited bearings, of course. :)


The question at hand is about replacing the whole rod. Others have already commented that it has been done from the bottom. My take is this: Since the Model A is just a flathead design, what's the big deal with popping the head off? There's no retiming of the camshaft or anything like that to deal with. Just pull the piston out the top and be done with it. The only problem with these "engine still in the car" rebuilds is that the crank/cam isn't removed and checked for wear and you can't align bore the block...but in the world of stock 40 horsepower four-bangers it should be no big deal.

All the bearing surfaces on the crank can be inspected and everything can still be "Plastigauged" so I don't see the downside. If you are dealing with a relatively tight, well running engine there should really be no real need for align boring and all that other stuff. If you are feeling REALLY randy one could even hone the cylinders and put in new piston rings...just make sure to really wash out the engine with a good solvent so there is no metal flake on the crank and such.


Just my 2-cents...
 
emf said:
You may find it easier to remove the entire piston/rod assembly through the bottom. I had a Studebaker that had a bad rod and I removed the piston with the rod through the bottom. I had to rotate the crank a little at a time to get the piston around and out. Once the rod was re-poured, I merely reinstalled the piston and rod and all was well.


Frank
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HOUDINI would have been GOOD at changing PISTONS/RODS---LOL
Bill W.
 
I found really good information on rod adjustment on the model T sites. I shaved rod caps (no shims left) when the engine was in the car and eliminated all of the play apart from #2 where the crank was out of round by about .002. Still found a happy medium. It worked well. If the rings and valves hadn't been completely worn out, I would have run in like it was. It did stop the rod knock and ran well for another 2k miles before I did valves guides and rings. I did replace the rods at that time.IF you pull the head and go through the top you run the risk of the rings breaking on the ridge. One new rod may put things out of balance as they are supposed to be a matched set. If its a bandaid, I would go through the bottom just like you want, but shim/shave the rod cap instead of replacement unless you find missing Babbitt.
 
If you have a crank that is .002 out of round you will end up with .004 clearance in the end. It will last for awhile but sooner or later you will have trouble.
 
Hoovercw said:
I found really good information on rod adjustment on the model T sites. I shaved rod caps (no shims left) when the engine was in the car and eliminated all of the play apart from #2 where the crank was out of round by about .002. Still found a happy medium. It worked well. If the rings and valves hadn't been completely worn out, I would have run in like it was. It did stop the rod knock and ran well for another 2k miles before I did valves guides and rings. I did replace the rods at that time.IF you pull the head and go through the top you run the risk of the rings breaking on the ridge. One new rod may put things out of balance as they are supposed to be a matched set. If its a bandaid, I would go through the bottom just like you want, but shim/shave the rod cap instead of replacement unless you find missing Babbitt.
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"rings breaking on the ridge"??! That's what ridge reamers are for. If you don't have one, go to your nearest AutoZone and rent one free!
Also, you're apt to break a ring land against that ridge, and need a whole new piston, not just a ring!
 
I think the point was he is looking for a bandaid to get running and if you remove the piston through the top then yes, a ridge reamer is in order. something he is trying to avoid.
 
George Miller said:
Most likely the engine needs a complete rebuild. All the rods rings pistons valves had traveled the same distance. So unless some thing happened to just that rod the rest are not far behind. Like I said it is always best to do it right.
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George. I totally agree . Trying to patch at best won’t produce good results in the end. I don’t like to ad this bit By his own admittance he was lazy and trying to fix it an easy way. The easy way would be to remove the head. For the rod properly, light hone on cylinder if needed and replace as needed.

Agree the engine probably needs much more.
Larry
 
Again I will say, I was not really thinking about doing this. I was just curious, because of the roadside experience described in Steinbeck’s book. I’ve pulled the head on my A before because of a blown head gasket, and I know how easy it is.
 
I like ASAPGUY’z story about his Grandfather getting his T back on the road with a piece of leather cut out of a boot. You do what you have to do, sometimes.

I will get my A fixed right, like it certainly deserves, when I get around to it. The main thing is that I am enjoying having it, and playing with it. I also enjoy all the banter from you guys on this site, although I’m not as serious about it as maybe I should be.
 
truesdaleg said:
I like ASAPGUY’z story about his Grandfather getting his T back on the road with a piece of leather cut out of a boot. You do what you have to do, sometimes.

I will get my A fixed right, like it certainly deserves, when I get around to it. The main thing is that I am enjoying having it, and playing with it. I also enjoy all the banter from you guys on this site, although I’m not as serious about it as maybe I should be.
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"You're not as serious about it as you should be"? Stay that way! Have fun! Continue to enjoy it! You don't need the original air in the tires nor the original water in the radiator to have an acceptable car.
 
40 Deluxe said:
"You're not as serious about it as you should be"? Stay that way! Have fun! Continue to enjoy it! You don't need the original air in the tires nor the original water in the radiator to have an acceptable car.
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Very well said! After all, these are just cars, and for most of us, just big boy fun...
 
FWIW, many years ago I helped a friend re-ring the engine in his English car, don't remember what make it was. The big end of the rod was too big to go up through the cylinder. We had to pull the rod/piston assembly up and take the wrist pins out to separate the rod from the piston and then drop the rod out the bottom.
 
It's yours, no matter what... I would hate to post some of the on the fly band aids we did on our cars in the 60's. I believe that it may have been the chemicals in our systems that helped us be so creative.
Enjoy the adventure. Chap
 
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