Engine Building 101

[Bill E Bob]

Well, I have the rings on the pistons (after checking end gaps), the
crank in the block, and the pistons in the holes. Have checked main
and rod bearings with plastigauge as the book says and all are within
specs EXCEPT #2 rod bearing. The plastigauge (across the face of
the bearing and journal from front of engine to back) reads from
almost no clearance at the front to spec at the back. The crank
however spins with no binding other than the new pistons. My next
move would be..... Sure would hate to spin a new bearing--
kinda' offputting

Sorry, no pics (Diiaall uuuppp) plus dimbulb here hasn't yet learned
how (I'm talkin' downloading from camera to PC--much less tryin' to
upload)

Thanks Large
Bill

[D.Nickerson]

Well, I have the rings on the pistons (after checking end gaps), the
crank in the block, and the pistons in the holes. Have checked main
and rod bearings with plastigauge as the book says and all are within
specs EXCEPT #2 rod bearing. The plastigauge (across the face of
the bearing and journal from front of engine to back) reads from
almost no clearance at the front to spec at the back. The crank
however spins with no binding other than the new pistons. My next
move would be..... :?: Sure would hate to spin a new bearing--
kinda' offputting :shock:

Sorry, no pics (Diiaall uuuppp) plus dimbulb here hasn't yet learned
how (I'm talkin' downloading from camera to PC--much less tryin' to
upload)

Thanks Large
Bill

Bill, I was never a Plasti-gauge man. What I always do is install all caps and bearings without the crank. Then I mic the crank, then I use an inside mic to check the bearings. Then I can switch bearings around to get within the range I want, kinda like blueprinting.

Yours, though, sounds like you have a taper. Here's what I would do:

First check the thickness of that bearing with veneers or mic to see if it's the bearing that is tapered. If it is that, call manufacture and get another one.

Was the crank cut? If it was, check the crank for the taper. If your crank is good, I'd say the taper is in the rod. See if you can find a buddy with an inside mic and have him check the journal. If it is the rod, it can easily be honed by an engine machine shop. I take it you are doing this rebuild for resoration and not engine failure? If no engine failure, I'd leave it go. It lasted this long with no problem. Rod clearances are less than the mains anyway.

Let us know how you made out. Doug

Let me know how you make out.
Doug

[Gary Dotson]

You might have had a slight bind at the wrist pin holding the small end of the rod off center. Make sure the wrist pin is free & well lubricated & try the plastigage again. I too prefer the mic method, but I realize the average hobbyist might not have these tools available.

[Eugene]

Remove #2 piston. Remove the inserts and check the rod and cap bearing mating surface for any debris or damage. Reassemble outside the engine. Using a micrometer check the diameter in 4 to 6 different places, 2 or 3 just inside each end of the hole and the center.

And another thougt. Manufacturing defect in the insert. You might put the inserts from #2 in another conecting rod to see if the problem moves.

[Bill E Bob]

Welll, I Ahh...might have been a bit premature (story of my life) in
my frantic plea for help. Removed the #2 rod cap, wiped down the
rod, cap and inserts. Inspected same. I then noted some shine on
the leading edge of the lower bearing half and also on the trailing
side of the upper bearing half. Sooo, the neuron fired and I vaguely
remembered from the Willer "Book of Knowledge" that the early
year bearing caps weren't indexed and had a habit of twisting and
binding. I measured the crank journal (within specs). (BTW the crank
had been ground 10-10) So I retried the plastigauge, but this time
tapping the rod cap gently to the rear as it was being torqued. Bingo
0.002 across the journal and bearing faces. Relubed the bearing halves
and retorqued while GENTLY tapping rod cap to the rear.
BIG SIGH OF RELIEF

Thanks Large to all who offered great advise. Sometimes its the simple
things.

Bill

[Lurker Carl]

I was curious about the final outcome. Nice job! Thanks for the update.

[BigBill]

I still use plastic gage too.

On one my mechanic jobs at a dealer back in the 70's I had a head mechanic throw a pile of bearing boxes on my bench when i was rebuilding a Rambler 232 6 cylinder engine. I asked him if he was sure all the bearings were the correct size being out of the main box? He said yes there the correct ones. I then asked him for plastic gage and he said we don't use that here what do you think this is a machine shop? He snapped on me.....

So i went to work and assembled everything. While it felt kind of tight i figured he was right and the parts were the correct size.

Hint: I used extra permatex on the oil pan gasket after all we don't want a customers car comming back with an oil leak right?

I was about to start it up for the first time and it was 5pm on a friday afternoon so it was time to go home for the weekend. And the head mechanic took over the job since he got overtime on friday and saturday too...

When i came in on monday he asked me why i put so much permatex on the pan gasket. I told him i didn't want to have any comebacks with oil leaks. He then said what a time he had getting the pan off. I then said why did you pull the pan? He said the engine was too tight and the main thrust bearing was the wrong size. I told him that using plastic gage could of found that problem out ahead of time. He didn't talk with me for a while......

My point is we can never becareful enough, check and double check to make sure its right the first time. And don't trust the markings on the box too for they can be wrong too. Its up to us to make it right.

Remember to moly up the cylinder walls, piston skirts, lifters, cam, bearings too. I like to use a soft rag to burnish it in on the cylinders. The very first startup is the worst time for any wear to occur. I also like to use an external oil pump driven by a 1/2" drill to pump up the oil system before it starts too. I did this on all my engines but not on the cubs yet. I even did this on the gravely tractors too till i seen oil squirting on the front PTO then i knew the system was pumped up and primed.

[geibes]

...i was rebuilding a Rambler 232 6 cylinder engine...

Well there's your first problem.....

Just kidding, the AMC 232 and 258 engines are awesome! Just not sure the Rambler was worth it...

[D.Nickerson]

Glad you got it figured out. Doug

[BigBill]

...i was rebuilding a Rambler 232 6 cylinder engine...

Well there's your first problem.....

Just kidding, the AMC 232 and 258 engines are awesome! Just not sure the Rambler was worth it...

The older ramblers started out as 199's and the same block design was in the last of the 4.0 jeeps and i think that puts it at the longest running inline 6 cylinder designs? I think?

Those old mid 60's to 70's ramblers were the best much like the subaru's/toyota's of today they never quit if you took care of them.

[Rick Spivey]

Yep, those engines were nearly indestructible. My daughter's Jeep Grand Cherokee still sports one of those 4.0's. Not a great towing vehicle, but gets decent mileage, runs smooth, and only needs oil changes.

[John *.?-!.* cub owner]

My wife had a 70 Hornet 6 cylinder. engien was the only thing in the car that didn't give trouble. It is probably still running someplace, minus the car.