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.
Yes...it's smaller diameter, but it has small holes around the out side if I remember right. It's about $14 I think...When you say Diamond coated wheel, do you mean a cut-off wheel?
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.
If this new part can't break....what old part will??
Found a Dremel chain saw sharpener bit that worked great. Did all 8 with one stone.
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Looks good!
Bare Tub Restoring 69 BBB Javelin SST 390 Go/Mod Pak
Frame Off Restoring 82 Wagoneer with 401 MPEFI transplant
"First rule of government funding; Why build one when you can build two at twice the price!"
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.
If this new part can't break....what old part will??
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.
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
1979 Jeep CJ-7 401 AMC, GMC 6-71 Blower 10% overdrive, Bugcatcher with electronic fuel injection and a little N2O for fun, all self built. (this supercharger stuff is easy)
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.
Let's explore this a little further.Originally Posted by Blown7
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?
Bare Tub Restoring 69 BBB Javelin SST 390 Go/Mod Pak
Frame Off Restoring 82 Wagoneer with 401 MPEFI transplant
"First rule of government funding; Why build one when you can build two at twice the price!"
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
1979 Jeep CJ-7 401 AMC, GMC 6-71 Blower 10% overdrive, Bugcatcher with electronic fuel injection and a little N2O for fun, all self built. (this supercharger stuff is easy)
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