Full Timing Oilng with Harlan Sharp needle bearing rockers

[Ian Robinson]

Want to convert to full time oiling to get rid of the potential #4 main and 6 & 7 rod bearing failures. Have Harlan Sharp rockers for my 500" low deck build but I know needle bearing rockers flow/pass more oil and require restrictors , be nice not to have to spend a year trying our different sizes.
Considered installing a restrictor in the stock oil feed at the block surface but would rather get rid of the problem, since I've experienced this with my and my friends big blocks.

Plan to run lines to the rear of thre rocker shafts from the main gallery at the back of the block.

 

[lewtot184]

the stock rocker shaft oiling isn't full time oiling. it's restricted thru the camshaft's #4 bearing journal oil passages. hooking up lines from the back of the block to the heads/rocker shafts (like indy heads) will be full time oiling.

 

[IQ52]

Just run the clocked #4 cam journal. As long as you don't have a full groove in the number 4 cam bearing or a full groove around the number 4 cam journal you shouldn't have excess oil at the Harland Sharp rockers. I've run 451-500 strokers with Harland Sharp rockers to 7,600 rpm with no oil starvation to #4 main and 6/7 rods using a 4qt oil pan, 3/8 pickup and high volume oil pump.

You can also make 1/4" diameter 3/8" long restrictors w/ various size holes (generally .040" as .060" has always been more than enough) and drop them into the oil passage that comes through the head underneath the rocker shaft stand. The rocker shaft hold-down bolt or stud keeps it in place.

But of course, as always, do whatever make you happy.

 

[Ian Robinson]

lewtot184

I realise that the stock rocker oiling is fed thru the holes in the cam at #4 once every camshaft revolution and this feed drops the flow and pressure to #4 main and 6 & 7 rod bearing as Andy Finkbeiner states in his book he's even witnessed this failure with an engine on a dyno with 70 lbs. oil pressure. I rebuilt a 440 six pak years ago that had these bearing gone, and I've been in cars that had this happen after an extended high speed run. I want to run the rocker feed thru the rear threaded end of the Harlan Sharp shaft from the main oil gallery at the rear of the block but after checking into this on the internet I find a lot of talk about the needle bearings flowing too much oil and dropping the feed oil pressure.

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My first move was to install restrictors in the block feed as you suggest but I would rather remove this problem by converting to full time oiling off the rear of the block and was hoping someone had already done this with the Harlan Sharps and had a heads up on what size they had found worked.

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My first move was to install restrictors in the block feed as you suggest but I would rather remove this problem by converting to full time oiling off the rear of the block and was hoping someone had already done this with the Harlan Sharps and had a heads up on what size they had found worked.

 

[IQ52]

This is a 600HP pump gas small block but you can do the same thing to a big block. Rotate the cam bearing so that it oils the cam journal but blocks the oil through the block to the rockers. I think I ended up just redrilling a hole to feed the cam journal. Then you can run off the lifter oil galley to the passages up the block to the heads and rocker arms. The brass fitting screwed into the rocker arm oil passage is drilled and tapped for air bleed jets and I believe we finally settled on a .040-045 jet. The lifter galleys receive oil after the main's oil galley.

So...........I guess my answer would be that a .045" hole to each rocker shaft should provide enough oil.

 

[lewtot184]

if you look carefully at the #4 cam bearing you will notice that the rocker shaft feed holes don't perfectly line up with the oil passage in the block. this is by design, another restriction. only about .150"-.160" of the bearing hole is exposed to the oil passage. the oil passage is larger, .281", because of the manufactures production design. using larger drills reduces drill breakage in fast production. i talked to an engineer one time who stated he wasn't allowed to design a passage any smaller than .250". this was done specifically to reduce tool breakage and enhance production. people look at that passage in the block and think that it's full flow, it's not. the real issue is the firing order at the #4 main. all rollerized bearings are oil bleeders and actually require less lube. full time oiling from the back of the block may require some restriction.

 

[Ian Robinson]

Thanks for the info,I suppose you could run the supply out thru the rear valley wall and connect to the fittings there. The only down side I can see is that you would have to remove the heads to change the restictor size , otherwise nice set up.

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Hey thats some interesting info about the hole locations, and the comment about the firing order.

 

[Ian Robinson]

if you look carefully at the #4 cam bearing you will notice that the rocker shaft feed holes don't perfectly line up with the oil passage in the block. this is by design, another restriction. only about .150"-.160" of the bearing hole is exposed to the oil passage. the oil passage is larger, .281", because of the manufactures production design. using larger drills reduces drill breakage in fast production. i talked to an engineer one time who stated he wasn't allowed to design a passage any smaller than .250". this was done specifically to reduce tool breakage and enhance production. people look at that passage in the block and think that it's full flow, it's not. the real issue is the firing order at the #4 main. all rollerized bearings are oil bleeders and actually require less lube. full time oiling from the back of the block may require some restriction.

Forgot to mention I was talking to a guy in Texas, big time drag cars, big time HP, said his son owns a race shop and being a mopar guy had done some work on the oil issue, he attached a pressure gauge to the # 4 main feed and found that it was 20 lbs lower than the main galley pressure and some times s much as 35 lbs. lower, they run their rocker feed off the rear of the block and thru the end of the rocker shaft but recommend against using the Harlan Sharps as the pass a lot of oil, all they use are bushed rockers.

 

[lewtot184]

there may be some variations at the passage from the main to the cam journal, or least i've heard this. i think if i was greatly concerned about oil supply to the #4 main i'd open up the passage from the galley to the main. some folks do this. another thing to keep in mind is how fluid pressure works. we know we can't compress a liquid so for a given pressure it takes very little fluid loss to notice reduced pressure. being concerned about the #4 main is very relevant and i've always wondered if a 4-7 swap would be more relevant than trying to move the oiling around.

 

[Ian Robinson]

there may be some variations at the passage from the main to the cam journal, or least i've heard this. i think if i was greatly concerned about oil supply to the #4 main i'd open up the passage from the galley to the main. some folks do this. another thing to keep in mind is how fluid pressure works. we know we can't compress a liquid so for a given pressure it takes very little fluid loss to notice reduced pressure. being concerned about the #4 main is very relevant and i've always wondered if a 4-7 swap would be more relevant than trying to move the oiling around.

I'd heardof some talk around changing the firing order and that would help especially under detonation, but too late for that the cam has already been ground, thanks for the input