Main Bearing Oil Hole Alignment

[n2omike]

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!

[dwilliams]

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.

[BabyFinster]

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?

[n2omike]

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?

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.

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!

[BabyFinster]

Glad you are at ease, Cheers!

[ProPower engines]

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.

[Walter R. Malik]

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!

ALL small block Fords are that way and there are millions of them out there just as they are.
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.

[BLstangin]

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.

[BLstangin]

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

[n2omike]

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!

[Caprimaniac]

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.....

[Walter R. Malik]

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.

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.

[n2omike]

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.

Thought I'd give an update:

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

[BabyFinster]

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.

Thought I'd give an update:

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

I for one, am interested in the outcome of your build. Please let us now how it turns out.

[n2omike]

I for one, am interested in the outcome of your build. Please let us now how it turns out.

You and me, both! You wondering if it will blow up? lol

Engine is a 8.2" deck height 363.
249/258 0.700"/0.690" 110 LSA solid roller
Ported Super Victor
Trick Flow 225 High Ports
Mahle flat tops 11:1 (pump gas)
Scat crank, Oliver Rods

Will be going in my 1966 mustang with a toploader 4-speed and 4.33 rear and 200 hp nitrous plate.
With a flat tappet, pump gas 306 with TW heads it went 6.26 @ 109 in the 1/8 and 9.87 @ 136 in the 1/4.
It's a pump gas street car that goes to the track 2-3 times/yr. At the track, drain the pump gas, add C12 and turn on the bottle valve.

First car. Had it since age 15, and I'm 52 now! It's gone from a 14, 13, 12, 11, 10, and finally a 9 second ride. Car served sole daily driver duties into the mid 10 second zone.

I'd like to dyno the 363, and see what it's worth.

Thanks for the interest.