Main Bearing Oil Hole Alignment
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Main Bearing Oil Hole Alignment
Alright... Sorry to bother you guys again, but Main Oil Hole Alignment.
The middle hole in the saddle goes to the cam bearings. The one mostly covered up is the main feed line. I'm concerned by how much of it is covered by the bearing. Should I do a little (lot of) surgery? As it is, a 0.078" drill bit (#47) is the biggest that will fit through the passage. This main passage also has to feed the cam bearings through that slot. Yes, that is a restrictor in the cam bearing passage. I used them in my last engine. It measures 0.090", which seems like a joke, but the Dart block comes with bearings completely grooved on the outside, and THREE outlet holes. I stuck them in there in case it would have been a massive bleed.
Anyway, the bearings in the Dart 8.2 Sportsman block. Thoughts?
Thanks!
The middle hole in the saddle goes to the cam bearings. The one mostly covered up is the main feed line. I'm concerned by how much of it is covered by the bearing. Should I do a little (lot of) surgery? As it is, a 0.078" drill bit (#47) is the biggest that will fit through the passage. This main passage also has to feed the cam bearings through that slot. Yes, that is a restrictor in the cam bearing passage. I used them in my last engine. It measures 0.090", which seems like a joke, but the Dart block comes with bearings completely grooved on the outside, and THREE outlet holes. I stuck them in there in case it would have been a massive bleed.
Anyway, the bearings in the Dart 8.2 Sportsman block. Thoughts?
Thanks!
Re: Main Bearing Oil Hole Alignment
I always grind my oil passages over so they line up with the slots in the bearing shells, but it's more a matter of pride in workmanship than knowledge it does anything necessary.
I put restrictors to the cam bearings too, usually .062 or .078. You can just drill new, smaller holes in the cam bearings, but then you have to deburr them, and do it all over again next time you freshen the engine. I drill the set screws in batches and keep some on hand.
I put restrictors to the cam bearings too, usually .062 or .078. You can just drill new, smaller holes in the cam bearings, but then you have to deburr them, and do it all over again next time you freshen the engine. I drill the set screws in batches and keep some on hand.
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Re: Main Bearing Oil Hole Alignment
Is this the engine with the .002 main clearance you were troubled about? Concerning... yes. The slot in the bearing was designed for correct oil supply, no doubt. However, if it was me, I would elongate the slot to the end of the oil feed hole. Is it just the thrust, or do they all exhibit this?
Re: Main Bearing Oil Hole Alignment
Yea, I just checked... and for some reason, the center main bearing (thrust on a Ford) has a shorter slot than the rest of the bearings. I'll elongate this one, and the rest should be fine.BabyFinster wrote: ↑Mon Mar 30, 2020 7:06 pm Is this the engine with the .002 main clearance you were troubled about? Concerning... yes. The slot in the bearing was designed for correct oil supply, no doubt. However, if it was me, I would elongate the slot to the end of the oil feed hole. Is it just the thrust, or do they all exhibit this?
And, yes. This is the engine where I had 0.0020" bearing clearance... but smoothing the backs of the shells opened them right up.
Thanks!
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Re: Main Bearing Oil Hole Alignment
FYI
The cam bearings are grooved and the extra oil holes are to allow you to correctly clock the oil entry to the cam journal.
Only using the hole over the feed from the main can cause issues with high spring loads and prevent enough oil to the cam bearings.
I made a fixture to do cam bearings for fords before the grooved back bearings were available.
I am currently doing a 347 and had to machine and drill the HP durabond bearings customer supplied.
The cam bearings are grooved and the extra oil holes are to allow you to correctly clock the oil entry to the cam journal.
Only using the hole over the feed from the main can cause issues with high spring loads and prevent enough oil to the cam bearings.
I made a fixture to do cam bearings for fords before the grooved back bearings were available.
I am currently doing a 347 and had to machine and drill the HP durabond bearings customer supplied.
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Re: Main Bearing Oil Hole Alignment
ALL small block Fords are that way and there are millions of them out there just as they are.n2omike wrote: ↑Mon Mar 30, 2020 6:25 pm Alright... Sorry to bother you guys again, but Main Oil Hole Alignment.
The middle hole in the saddle goes to the cam bearings. The one mostly covered up is the main feed line. I'm concerned by how much of it is covered by the bearing. Should I do a little (lot of) surgery? As it is, a 0.078" drill bit (#47) is the biggest that will fit through the passage. This main passage also has to feed the cam bearings through that slot. Yes, that is a restrictor in the cam bearing passage. I used them in my last engine. It measures 0.090", which seems like a joke, but the Dart block comes with bearings completely grooved on the outside, and THREE outlet holes. I stuck them in there in case it would have been a massive bleed.
Anyway, the bearings in the Dart 8.2 Sportsman block. Thoughts?
Thanks!
However, Dart and many others use some kind of solution looking for a problem that is very rarely there ... a lot of builders of high bearing clearance or high RPM engines will will mark those center 3 main bearings at those block feed holes and use a 9/32" end mill in a bridgeport with the bearing in a mill-vice and open those bearings to a round hole. Then hand chamfer those bearings so there are no raised edges after machining.
Only the center 3 are usually done because those mains eventually feed 2 rod bearings while the end main bearings only feed one.
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Re: Main Bearing Oil Hole Alignment
If you look at a stock block you would see that the two oil holes are side by side and the main oil hole is pretty much parallel to the cam feed hole making this a none issue. For some reason dart moved it away from the cam feed hole and off to the side so when you put the upper bearing in, it blocks most of the main feed hole. I would say the bearing should be opened up personally.
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Re: Main Bearing Oil Hole Alignment
Here is a picture of a stock block so you can see what I am talking about. It’s drilled way different than your dart
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Re: Main Bearing Oil Hole Alignment
I can see how spreading those holes would make it stronger and less crack prone... but they should make a note of it! Starving off the center main like that is a recipe for problems!
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Re: Main Bearing Oil Hole Alignment
On my World Block, the holes are spread too. However, the solution they have come up With is a groove in the bearing housing to Connect them.
So even though the openings in the bearing do not cover both holes, the oil supply will be taken care off.
I just had to walk Down to thw bsement to check it out when I read this thread.....
So even though the openings in the bearing do not cover both holes, the oil supply will be taken care off.
I just had to walk Down to thw bsement to check it out when I read this thread.....
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Re: Main Bearing Oil Hole Alignment
The issue is with that oil hole in the Dart block not being correctly placed within that bearing housing bore, MAKING a problem.BLstangin wrote: ↑Mon Mar 30, 2020 11:52 pm If you look at a stock block you would see that the two oil holes are side by side and the main oil hole is pretty much parallel to the cam feed hole making this a none issue. For some reason dart moved it away from the cam feed hole and off to the side so when you put the upper bearing in, it blocks most of the main feed hole. I would say the bearing should be opened up personally.
In that situation, (most people don't have the resources to correctly modify the bearing), I would grind a chamfer on one side of that hole leading toward the center of that saddle about .200" deep at the hole; almost to where an O.E.M. feed is usually located.
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Re: Main Bearing Oil Hole Alignment
Thought I'd give an update:Walter R. Malik wrote: ↑Tue Mar 31, 2020 10:11 am The issue is with that oil hole in the Dart block not being correctly placed within that bearing housing bore, MAKING a problem.
In that situation, (most people don't have the resources to correctly modify the bearing), I would grind a chamfer on one side of that hole leading toward the center of that saddle about .200" deep at the hole; almost to where an O.E.M. feed is usually located.
I had a round needle/rat tail file that was about the same size as the slot, so I chucked it in a drill and elongated the hole until the majority of the oil passage in the dart block was uncovered. Now it looks like the rest of them, and should not be an issue. Don't know if this is the 'correct equipment' or not, but I think it will work.
I bought this block around 10 years ago. It is a Dart Sportsman, and came out before the SHP was available. I don't know if the SHP or current Sportsman/Iron Eagle blocks are like this, but anyone building a small block Ford with a Dart block should double check for this issue. The center main is the thrust on these engines. I don't know WHY it has a shorter oiling slot than the other four shells, but it does. Go figure.
Time to finally put this thing together! (until we run into something else) lol
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Re: Main Bearing Oil Hole Alignment
I for one, am interested in the outcome of your build. Please let us now how it turns out.n2omike wrote: ↑Thu Apr 02, 2020 10:41 amThought I'd give an update:Walter R. Malik wrote: ↑Tue Mar 31, 2020 10:11 am The issue is with that oil hole in the Dart block not being correctly placed within that bearing housing bore, MAKING a problem.
In that situation, (most people don't have the resources to correctly modify the bearing), I would grind a chamfer on one side of that hole leading toward the center of that saddle about .200" deep at the hole; almost to where an O.E.M. feed is usually located.
I had a round needle/rat tail file that was about the same size as the slot, so I chucked it in a drill and elongated the hole until the majority of the oil passage in the dart block was uncovered. Now it looks like the rest of them, and should not be an issue. Don't know if this is the 'correct equipment' or not, but I think it will work.
I bought this block around 10 years ago. It is a Dart Sportsman, and came out before the SHP was available. I don't know if the SHP or current Sportsman/Iron Eagle blocks are like this, but anyone building a small block Ford with a Dart block should double check for this issue. The center main is the thrust on these engines. I don't know WHY it has a shorter oiling slot than the other four shells, but it does. Go figure.
Time to finally put this thing together! (until we run into something else) lol
Re: Main Bearing Oil Hole Alignment
You and me, both! You wondering if it will blow up? lolBabyFinster wrote: ↑Thu Apr 02, 2020 11:06 pm
I for one, am interested in the outcome of your build. Please let us now how it turns out.
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