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Discussion Starter #41
Your engine block has oil "galleys" that are passageways for the pressurized oil to pass through. There are diagrams on the internet that show the galleys in a 351W block. One of the lengthwise galleys ends right behind the distributor and there is a plug in the block to hold the oil in the galley. Some people drill a small hole in this plug to allow oil to spray out onto the distributor and cam gears.
Thanks, do you happen to know where people would drill this hole?

We have examined the gear on the cam, luckily for us it does not appear to be damaged.

We have removed the gear from the distributor shaft and we will be buying the MSD 85834 steel gear.
761631
 

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The factory oil galley plugs are pressed in expansion cup plugs just like a freeze plug in the side of the block. Most people remove those press-in plugs, tap the holes and use screw-in plugs to replace them. You can drill a .030" hole in the screw-in plug that goes behind the distributor.
 

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Discussion Starter #43


The factory oil galley plugs are pressed in expansion cup plugs just like a freeze plug in the side of the block. Most people remove those press-in plugs, tap the holes and use screw-in plugs to replace them. You can drill a .030" hole in the screw-in plug that goes behind the distributor.
Thanks! Might look into this. But based on your previous answer, would I be correct when I say that the cam gear and distributor gear are not supposed to be oiled by default hence people are making drill holes themselves?
 

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Well they get oiled by the oil sloshing/slinging around in block. Not the best, but adequate. Early motors had an “oil slinger“ disc on the crank Gear of timing set to address this. Sometimes it is overlooked in rebuild. I don’t believe they were used in roller motors, which I believe you to have?
so that is why this mod is used, motors without a slinger can benefit. I am not an expert here. Going off memory...which has been known to fail. Others will correct my errors or clarify my points.
 
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Not as old as I thought!...sorry I edited while you were quoting
 

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Thanks, do you happen to know where people would drill this hole?

We have examined the gear on the cam, luckily for us it does not appear to be damaged.

We have removed the gear from the distributor shaft and we will be buying the MSD 85834 steel gear.
View attachment 761631

The MSD gear should come with instructions on where to install it, I used them just a month or so ago when I installed my Comp gear on my 5.0 distributor. Its a very small window to hit of about .010" so make sure you have some calipers handy.
 

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A measure of old gear from top of gear to bottom of distributor. Put new gear at same distance. Drill new hole in gear and shaft. Don’t try to reuse old hole. Use a good roll pin, and measure it again for correctness. Use good calipers for exact measurements
 

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Discussion Starter #49
Thanks for the clear explainations guys! Really helps a lot understanding what's going on inside there. Tomorrow we will remove the oil pan so fingers crossed that the iron shards are in there :).

To be continued
 

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When this happened to my buddy, we never found any metal chunks. He did not have broken teeth on the gears, but they were worn to the point of being “sharp as knives” nothing in pan, and only minor scarring on gearotor in oil pump. Replaced pump,upgraded to moly shaft, converted to duraspark distributor for 1985 GT 5SPEED. PROBLEM SOLVED.
 

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Steve, NO, that would NOT be correct, the factory plugs have a hole that drizzles oil onto the gear. I don't know how one would drill a hole that small, I always purchased the plugs that already had the hole drilled. I put one behind the dizzy, and another on the other lifter gallery. These plugs also help to let air out of the oil system if there is any in there. Many people who do their own engine at home do not realize that they need the spacial drilled plugs in these locations. Chewed up dizzy gears are the result. Frequently gets blamed on HV oilpump, even though the pumps aren't causing this problem, lack of knowledge is the cause of problem. Who assembled the engine you have ? Do they know about the plugs ? LSG
 

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Steve, NO, that would NOT be correct, the factory plugs have a hole that drizzles oil onto the gear. I don't know how one would drill a hole that small, I always purchased the plugs that already had the hole drilled. I put one behind the dizzy, and another on the other lifter gallery. These plugs also help to let air out of the oil system if there is any in there. Many people who do their own engine at home do not realize that they need the spacial drilled plugs in these locations. Chewed up dizzy gears are the result. Frequently gets blamed on HV oilpump, even though the pumps aren't causing this problem, lack of knowledge is the cause of problem. Who assembled the engine you have ? Do they know about the plugs ? LSG
Interesting. I have drilled the hole in screw in plugs before, but I have never seen a factory engine with a hole in the press fit oil galley plugs.

Set up your new gear to the following document:
 

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It's a popular mod but I have never seen one come that way from the factory. Drilling it is actually very easy, but in my opinion. The amount of oil flowing around my home made primer tool tells me the gear is getting plenty of oil.
 

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Steve, to me, fussing around with a drill is silly when you have a box of plugs with the hole already drilled. I think they're 50 cents each. I've seen hundreds of HV pumps installed in engines over the last thirtyfive years. Never seen an HV pump eat a distributor gear. Not even once. But I HAVE seen dozens of engines from other shops, and by individuals, that used a solid plug, and had problems. So why use a solid plug behind distributor and timing gears ? And if you take apart an older factory engine, you'll find the plug behind the distributor is not just a normal push in. LSG
 

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Discussion Starter #59
Steve, to me, fussing around with a drill is silly when you have a box of plugs with the hole already drilled. I think they're 50 cents each. I've seen hundreds of HV pumps installed in engines over the last thirtyfive years. Never seen an HV pump eat a distributor gear. Not even once. But I HAVE seen dozens of engines from other shops, and by individuals, that used a solid plug, and had problems. So why use a solid plug behind distributor and timing gears ? And if you take apart an older factory engine, you'll find the plug behind the distributor is not just a normal push in. LSG
LSG, Thank you for the heads up. How can I tell whether I have a plug with a hole installed? Does that require me to take the engine out and inspect it or is there another way?

Thanks.
 

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Steve, if you get a long hex drive and spin the oil pump with a drill, counterclockwise, IIRC, you'll be able to look into the hole where the distributor fits and see oil shooting out from the hole. LSG
 
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