Oil Squirter Notches in Rod Bearings

[1980_Cj7]

Well, finally picked up the new rod bearings from the machine shop and started making the oil squirter notches in them.

I used a fine stone in the Dremel tool, which worked well, but it only lasted thru one test notch on an old bearing, and one new bearing. Need to pick up a handful of stones tomorrow. Chamfered the edge with a fine round needle file to finish it off. I have an extra rod here to use to locate where the notches need to be.

Question for you guys, is there some kind of protective coating on new bearings? After I got done making the notch, I sprayed a little brake cleaner on the bearing to wipe it off good, and it seems like it took a "coating" off where I first started wiping the bearing surface. I quit right away, but the part I wiped is noticeably smoother and slicker than the part I didn't.

[Blown7]

Yes, the bearing is coated with either babbit, lead, or Aluminum or some other soft material only maybe a couple thousanths thick at most over a Copper back.

Jeff

[1980_Cj7]

But brake cleaner wouldn't take that off would it? This seems more like a primer or some sprayed on film to maybe protect the actual surface. It feels kinda rough textured. Where I wiped isn't showing the copper layer, it just feels much smoother and has a slightly different appearance. In other words you can see a line where I wiped and didn't wipe.

By the way, they are Clevite 77 bearings.

[hotratz]

Heres a link to the Clevite page. Clevite (http://www.engineparts.com/p_performance_bearings.asp) The text in the page does mention "coating"
At the bottom of the page there is a "Ask Clevite" tab you can click on and ask technical questions.

[jeep_man_401]

Just go out and buy the Diamond coated wheel :t: for the Dremel. It doesn't leave nearly as much dust, cuts really easy (kinda fast) and will last through all your bearings and piston rings (made a end gap tool using the dremel also) and more.

Wipe the bearing using a dry lint free tissue. Like on used for cleaning glass. and vola...you'll be done in no time!!

Any coating will be left on them...

I would guess...assuming its a grayish looking coating on (mine had the same thing) that it is some sort of dry lub for the "first start" to help protect the bearing.

Also to save you headach...throw that lub in a tube they send with the cam and get a good moly based PASTE for the cam and lifter as it won't drip off while sitting...Summit can help there!

P.S. my bearing also had small "lines" on them when I installed them the final time an they worked fine. The lines were from the crank grinders bore mik....I made them use a bore mik on the mains to get the crank clearance to what I gave them the spec for and not some 30 year old spec for a stock rebuild. #-o Now you know the shop did good work because there is the proof that they checked!

it's in the details... :lo1l: :?

[1980_Cj7]

Heres a link to the Clevite page. Clevite (http://www.engineparts.com/p_performance_bearings.asp) The text in the page does mention "coating"
At the bottom of the page there is a "Ask Clevite" tab you can click on and ask technical questions.

Duh, why didn't I think of that, I use the technical assistance lines all the time. Anyway, I followed your advice and got an UNBELIEVABLY fast response from Clevite, like within 5 minutes. I gave them the specific bearing numbers I was working with. I know some bearings come coated, but I didn't think that was what the case was here. Here's what they said:

"There's a real thin flash coating on a stock bearing to keep it from oxidizing on the shelf. You're wiping off that coating. As long as you're not using an abrasive, you'll be OK."

So, my suspicions were confirmed. Think I'll follow jeep_man_401's advice for the rest of the bearings. Thanks for the help guys. I learned something new today.

[hotratz]

Heres a link to the Clevite page. Clevite (http://www.engineparts.com/p_performance_bearings.asp) The text in the page does mention "coating"
At the bottom of the page there is a "Ask Clevite" tab you can click on and ask technical questions.

Here's what they said:

"There's a real thin flash coating on a stock bearing to keep it from oxidizing on the shelf. You're wiping off that coating. As long as you're not using an abrasive, you'll be OK."



When I rebuilt my first engine as a 16 yr. old pimple faced teen I was being schooled by an old motor head guy of the times. When we installed the bearings he told me they came coated from the manufacturer as a protectant during break-in period. He said if this were strickly a race track engine he would take 00 steel wool and wipe the coating off before installation. Not suggesting anybody should do this but this was over thirty years ago so it goes to show these coatings have been a manufacturing practice for a long time.

[1980_Cj7]

Well, brake cleaner obviously works too, and without the risk of scratching.

Seems like that coating would affect clearances in fitting the bearings, unless it's factored in. Either that or it's so thin that it's inconsequential.

I'm wondering if the oil ultimately removes it, or it just wears off, or what.

[1980_Cj7]

Just go out and buy the Diamond coated wheel :t: for the Dremel. It doesn't leave nearly as much dust, cuts really easy (kinda fast) and will last through all your bearings and piston rings (made a end gap tool using the dremel also) and more.



When you say Diamond coated wheel, do you mean a cut-off wheel?

I was thinking about using something like that rather than the cylindrical stone I started with. The notch in the rod is actually "V" shaped. What I was doing so far was using the stone to grind a semi-circular notch down into one bearing half from the seam line where the bearing halves meet. I was thinking with the cut-off wheel, I could angle two straight cuts to come together and make a "V" to match the rod.

[82Waggy]

A half circle notch is what the bearings used to have. Sounds like a lot of extra trouble to match the V in the rod.

[1980_Cj7]

Agree. I'm not necessarily looking to match the "V" in the rods, on the contrary, I'm just looking for the quickest and easiest way to notch these bearings without spending a fortune on Dremel bits. Want to get these bearings done and back to the shop so I'm not holding up progress on our engine while they're finally working on it.

[jeep_man_401]

When you say Diamond coated wheel, do you mean a cut-off wheel?

Yes...it's smaller diameter, but it has small holes around the out side if I remember right. It's about $14 I think...

As far as the coating I would wipe the back of the bearing clean just before installing them...steel on steel tranfers heat better...anything between the two slows down the heat transfer.

[1980_Cj7]

Found a Dremel chain saw sharpener bit that worked great. Did all 8 with one stone.

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/Rod_Bearings_002.jpg

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/Rod_Bearings_005.jpg

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/Rod_Bearings_008.jpg
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[82Waggy]

Looks good!

[jeep_man_401]

Looks like factory! How hot did the bearing get though?

Funny thing I have a chain saw and a Dremel...but I still use a hand file. #-o

[1980_Cj7]

I was conscious of and careful of not getting the bearing too hot. I had my bare fingers right close to where I was grinding and never let it get too hot to hold.

Now, I just hope all the rods are machined the same. I used one that won't be used in the engine, and used the same rod to fit all the bearings. Notice how the bearing is off-center side to side? That is due to the placement of the pocket in the rod that the little tab on the bearing fits into. If the notches vary on the other rods, or from one rod to another, well....

I don't think it will be any problem if the notches I made in the bearings don't line up exactly with the "V" notch in the rod though, as there will still be plenty of opening for the oil to find its way thru.

[Blown7]

Not to sound negative, but I think you may bleed off too much oil from the connecting rod journal with that big of a groove. The squirter hole only lines up with the oiling hole on the crankshaft under pressure once every revolution. Connecting rod width is controlled so that the oil stayes on the journal long enough to act as a barrier for high loads and heat disappation. Usually the width is kept within .003 thousanths to control the bleed.
I think your looking to save the pistons and bores

(which I think is counter productive and yes I remember your last problems)

at the expense of the connecting rod bearings and crankshaft.

You have to remember your connecting rod only gets oil every 360 degrees of crankshaft rotation, unless you have a cross drilled crank.
Just my two cents FWIW.


Jeff

[1980_Cj7]

Yeah, I was thinking about that too. But, didn't AMC design the engines to have squirter holes in the bearings?

Our rod bearings didn't look so hot after only 300 miles on the last rebuild, and there were no holes in the bearings. But, seeing some of the other mistakes the machine shop made, I don't know how good of a job they did on the crank and bearings, so I don't know what might have been the cause.

[82Waggy]

Not to sound negative, but I think you may bleed off too much oil from the connecting rod journal with that big of a groove. The squirter hole only lines up with the oiling hole on the crankshaft under pressure once every revolution. Connecting rod width is controlled so that the oil stayes on the journal long enough to act as a barrier for high loads and heat disappation. Usually the width is kept within .003 thousanths to control the bleed.
I think your looking to save the pistons and bores (which I think is counter productive and yes I remember your last problems) at the expense of the connecting rod bearings and crankshaft.

You have to remember your connecting rod only gets oil every 360 degrees of crankshaft rotation, unless you have a cross drilled crank.
Just my two cents FWIW.

Jeff

Let's explore this a little further.

If you look at the timing of the oil flow through the rod journal passages on a standard crank (not cross-drilled) with half groove main bearings, the rod passages are fed oil through only 180 degrees crank rotation - and it looks to me that the timing of this oil flow relative to the power stroke is random at each journal.

I don't think these squirters are actually applying oil directly to the bores at all, rather, they simply add more total windage. Well, leakage past the edges of the rod bearings ought to do this job sufficiently.

My machine shop gurus suggest that the rod squirters are not necessary with todays oils and in fact may lead to excessive oil consumption by overwashing the bores. It does seem to me that not allowing flow through the squirters would help maintain film strength on the rod bearings, especially if they are not getting oil pressure through the full 360 degrees of rotation.

I am still torn on the full groove main bearing idea, simply because of my observation on two high time engines that had them and they did not seem to be worn excessively.

I do not however fully understand the dynamics of 180 degree rod journal oiling. As I said the timing of this seems random to me from one rod journal to the next - some start oiling just after combustion and some long after (maybe it does not matter). It does however seem obvious that full groove bearings or cross-drilled cranks would be feeding the rod journals at all times, and I cannot imagine why that would be a bad idea since it does seem as though the rod bearings suffer the most.

What say you?

[Blown7]

Well with a full groove bearing you more than half the bearings load carring capability. I don't have the formulas in front of me but for example if the main is one inch wide and the load capacity is say 2000 lbs with a full groove bearing the bearing capabilty will be less than 1000 lbs.
Of course the diameter of the journal is figured in the formula as is the viscosity and ability of the breakdown of the oil film, clearance is figured by the speed of the bearing and heat rise of
theoil entering and leaving the bearing.

With the pressures my bearings have seen on the dyno I wouldn't even think of using full grooved mains.

My vote is stick with the half grooves.


Jeff

[Blown7]

Yeah, I was thinking about that too. But, didn't AMC design the engines to have squirter holes in the bearings?

Our rod bearings didn't look so hot after only 300 miles on the last rebuild, and there were no holes in the bearings. But, seeing some of the other mistakes the machine shop made, I don't know how good of a job they did on the crank and bearings, so I don't know what might have been the cause.

Squirter holes are a carryover from the 1950's when engine designers thought the extra oil was necessary on the bores. since the 1970's engine designers have found then to be unnecessary. I don't have them and my bores are just like new.

Have you posted any pics of the old bearings?


Jeff

[1980_Cj7]

Jeff, no, I never got any pics of the old bearings. I don't know if the new shop saved them for me or not. I'll ask when I take these new ones back tomorrow. I know they didn't look that great to me, and the new shop concurred. There was no copper showing or anything, but they were showing uneven wear/shining spots. I think it was to one side if I recall. I'll try to get them and post some pics.

Now you have me wondering if I should go with the squirter holes or not. I could always just eat the cost of the set I modded, and put ones in without the holes. The new shop didn't feel they were needed either. Decisions, decisions.

[jeep_man_401]

I know they didn't look that great to me, and the new shop concurred. There was no copper showing or anything, but they were showing uneven wear/shining spots. I think it was to one side if I recall. I'll try to get them and post some pics.

Isn't uneven or wear on one side signs of a not correctly seated bearing and/or bent rod?

If the engine won't see a ton of HP or turn super high I wouldn't worry about the bearing holes. It still has to go through the little squirt hole. I think maybe some more study is needed on this.

I would suppose the rods for the stroker motors don't have the squirt hole. What was the cause of the old bearings going? Did they have the squirt hole?

[Blown7]

There was no copper showing or anything, but they were showing uneven wear/shining spots. I think it was to one side if I recall. I'll try to get them and post some pics.

Usually shiny areas to one side is indicative of oil overheating problems. If the shine is to the connecting rod to connecting rod side, it indicates not enough rod to rod clearance. If it is to the cheek side there is not enough radius in the crank throw.

Jeff

[Blown7]

Not to sound negative, but I think you may bleed off too much oil from the connecting rod journal with that big of a groove. The squirter hole only lines up with the oiling hole on the crankshaft under pressure once every revolution. Connecting rod width is controlled so that the oil stayes on the journal long enough to act as a barrier for high loads and heat disappation. Usually the width is kept within .003 thousanths to control the bleed.
I think your looking to save the pistons and bores (which I think is counter productive and yes I remember your last problems) at the expense of the connecting rod bearings and crankshaft.

You have to remember your connecting rod only gets oil every 360 degrees of crankshaft rotation, unless you have a cross drilled crank.
Just my two cents FWIW.

Jeff

Let's explore this a little further.

If you look at the timing of the oil flow through the rod journal passages on a standard crank (not cross-drilled) with half groove main bearings, the rod passages are fed oil through only 180 degrees crank rotation - and it looks to me that the timing of this oil flow relative to the power stroke is random at each journal.

I don't think these squirters are actually applying oil directly to the bores at all, rather, they simply add more total windage. Well, leakage past the edges of the rod bearings ought to do this job sufficiently.

My machine shop gurus suggest that the rod squirters are not necessary with todays oils and in fact may lead to excessive oil consumption by overwashing the bores. It does seem to me that not allowing flow through the squirters would help maintain film strength on the rod bearings, especially if they are not getting oil pressure through the full 360 degrees of rotation.

I am still torn on the full groove main bearing idea, simply because of my observation on two high time engines that had them and they did not seem to be worn excessively.

I do not however fully understand the dynamics of 180 degree rod journal oiling. As I said the timing of this seems random to me from one rod journal to the next - some start oiling just after combustion and some long after (maybe it does not matter). It does however seem obvious that full groove bearings or cross-drilled cranks would be feeding the rod journals at all times, and I cannot imagine why that would be a bad idea since it does seem as though the rod bearings suffer the most.

What say you?

Found the formulas it's under Journal Bearing Lubrication analysis in the Machinerys Handbook.

First find l/d ratio= length of bearing including shaft deflection and misalignment (should be maintained below .0003 thousands per inch of length.
Bearing pressure PSI = Pb= W divided by Kd
Oil Temperature rise thru bearing try to keep under 20 degrees F
Sleeve bearing pressure for a auto engine between 500-700 PSI for the mains
800-1500 for a diesel
Torque parameter vs. Eccentricity Ratio for a stock 401
l/d ratio is 1.375 = 3.6 torque parameter
Then flow factor of oil=q

Much more things involved and you have to do your own figures but add hydrodynamic action plus the highest RPM of the engine to find the bearing speed in FPM.


To make a long story short, in my case I need to run SAE 50 oil at 6000RPM with .0032 Main clearance to take the hit of Nitrous with non full groove bearings without overloading the bearing.

Jeff

[1980_Cj7]

I just got a picture in my head of Albert Einstein at a chalk board...trying to figure out if he should use oil squirters in his 401! :happy6:

I had the rod bearings bagged and numbered which rod they came off of, when I took the engine to the new machine shop, but I don't know if they kept them like that...or kept them at all for that matter. I'll ask tonite, and try to retrieve them.

The other thing I was thinking, is that although the hole in the bearing looks pretty big, look at the path the oil has to take from there. The "V" in the rod is smaller, then the groove around the rod bolt is even smaller yet. So, the path necks down noticeably.

I'm gonna talk to the machine shop tonite and see what they think. I also need to ask them how much experience they have with AMC's though. You'd think there wouldn't be that much difference from one brand of engine to another, as they all operate basically the same, but I'm really starting to wonder.

[1980_Cj7]

Well, just returned from the machine shop. After a lengthy discussion with a man with a lot of experience that I highly respect , I decided NOT to use the bearings with the squirter holes. He told me, as have some of you, that it was old technology that has been gotten away from. He said he's watched engines running with no oil pans (I forget what he said was hooked up to them) and said you wouldn't believe the amount of oil flying everywhere. So, for the sake of not wanting to take any oil away from the rod bearings, I told him to just put bearings in without the holes.

Anybody in the market for a good buy on a set of brand new "custom" .020 over rod bearings with oil squirter holes??? I'll make you a real good deal.

I told him to make this to be the best engine he's ever built, becuz I ain't doin this again! I almost wish I'd never heard of a 401, but hopefully, soon, when we have it back in the Jeep and are almost keeping up with Fuzz, we'll forget about all this. Heck, if it was easy, everybody would have one, right?

[82Waggy]

I told him to make this to be the best engine he's ever built, becuz I ain't doin this again! I almost wish I'd never heard of a 401, but hopefully, soon, when we have it back in the Jeep and are almost keeping up with Fuzz, we'll forget about all this. Heck, if it was easy, everybody would have one, right?

These issues you have been having are not unique to the 401, or any AMC for that matter. Bad machinists are everywhere.

Last summer my buddy had a set of 351 Cleveland heads rebuilt, blueprinted the whole motor. They did not hone the new bronze valve guides for sufficient stem clearance. During cam break in at 2000rpm an exhaust valve seized, bent pushrods and valve stems, filled the engine with bronze dust, and stuck two valves open. Can you say" DO OVER"!

Tore it all back down, cleaned it out, new bearings again, reworked the valve guides, new gasket set again, more dollars. Been running great ever since (for a Cleveland anyway). We put KB pistons in it by the way.

Never time to do it right. Always time to do it over.

[seth gordon]

The oil squirt holes are thought to put some oil on the cylinder bore and also some on the cam lobes; how efficient or important this oiling system is could be argued. What is known is that factory cranks must have the oil holes radiused & chamfered. The use of full groove bearings is definitely not recommended. At one time, Randall engineering recommended that the main journals be grooved. Currently, cross-drilling the crank is the general method for avoiding oil starvation.

Seth