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By oldcarmark - 2 Months Ago
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I got my Rebuild running this Week. I had the Camshaft Oil Groove deepened to .035 as suggested in the Y-Block Book because most of the New Cams don't have sufficient depth from Factory. I also had a Set of Schumann's Cam Bearings installed with the External Oil Groove on Centre Bearing. I may have to restrict the Flow to Head as too much Oil can't drain fast enough. I did this last Time by tapping the Shaft stand and putting in a Pipe Plug with Hole drilled in it. Problem solved. How big a Pipe Plug do I need and how big Hole to drill in Plug? Can't remember from last Time. TED? Thanks!
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By Ted - 2 Months Ago
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The second from the right rocker arm stand bottom hole in each rocker arm assembly can be tapped with a 5/16-18 tap. It goes without saying that the stands should be thorughly cleaned after doing this before using. A 5/64” (0.078”) or smaller hole can then be drilled in a 5/16-18 set screw and that screw installed in the tapped hole in the rocker arm stand. I prefer to shallow tap the hole in the rocker arm stand and use a short set screw so that the set screw itself can be tightened within the tapped hole so it can be tight without contacting the rocker arm shaft.
Here are some links to past threads on the oil restrictor topic.
http://forums.y-blocksforever.com/FindPost167301.aspx
http://forums.y-blocksforever.com/FindPost167301.aspx
http://forums.y-blocksforever.com/FindPost152225.aspx
http://forums.y-blocksforever.com/FindPost57506.aspx
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By oldcarmark - 2 Months Ago
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Thanks Ted!
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By 55blacktie - 2 Months Ago
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oldcarmark (8/30/2026)
I got my Rebuild running this Week. I had the Camshaft Oil Groove deepened to .035 as suggested in the Y-Block Book because most of the New Cams don't have sufficient depth from Factory. I also had a Set of Schumann's Cam Bearings installed with the External Oil Groove on Centre Bearing. I may have to restrict the Flow to Head as too much Oil can't drain fast enough. I did this last Time by tapping the Shaft stand and putting in a Pipe Plug with Hole drilled in it. Problem solved. How big a Pipe Plug do I need and how big Hole to drill in Plug? Can't remember from last Time. TED? Thanks!
Interesting. I bought a Howard's cam that will be used in my rebuild. Howard's said that the groove is .020. I later compared it to the groove in an original Ford cam. The groove in the Ford cam doesn't appear to be any deeper, and it's narrower. I, too, bought the Shumann cam bearings. Dan Jessup (hotrodreverend.com) has run aftermarket cams with the Schumann Cam Bearings and has found no need for a deeper cam groove. He has, however, followed Tim McMaster's advice and pressurized the rocker arms on at least one engine.
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By oldcarmark - 2 Months Ago
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What Size are the One's used in the Block Oil Passages? 1/2 inch? I have one of those I took out to put in Taps for Coolant in Block. so I want next size Smaller I assume? Definetley have to do it. Oil overwhelming the Rocker Cover Gaskets. Oil on Floor. Otherwise the Engine is running better than I had imagined. Not surprised I have to install restrictors. Easier to restrict than get Oil Pressure where it is insuffiient.
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By oldcarmark - Last Month
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I had my Machinist install restrictors as per Teds Specs. Pretty small Hole for Oil Flow but it does allow more than sufficient Flow to rockers. New Gaskets installed so hopefully that is the end of Leaks from up Top.
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By oldcarmark - Last Month
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Attention Ted! I had my Machinist install the Size Restrictor You suggested. Still having leak on right side only from I assume is the Rocker Cover Gasket still. Every else on Engine is Dry. What size would You suggest trying now while still getting sufficient Oil to Rocker Shafts? Trial and error. Thanks Ted.
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By Ted - Last Month
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Can you give some more detail on the valve covers that you are using? Are the cylinder heads machined on the valve cover rail or is the valve cover rail or sealing surface ‘as cast’?
The 0.078” hole size is usually my go to number for restricting the top end oil for the Ford Y. As a general rule, I will not go smaller than 1/16” (0.062”) for top end oil restrictors on any engine. It’s important that the valve springs get some oil overspray just for cooling purposes.
When prelubing Ford Y engines prior to running them on the dyno, I have noticed that the left bank will typically flow more oil than the right bank as it’s the left bank that will overflow the valve cover rail first. For whatever reason, when the cam bearings wear, it’s also the right bank that quits oiling first.
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By Litshoot - Last Month
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I'm a little confused. Do you believe your valve cover is filling with oil and pressure building to push out past the gasket or the gasket isn't sealing properly letting it leak. the gaskets shouldnt be any iss do you have pressurized rockers or still have the drain tubes on them? I would assume 2- 3/8"+ drain back hole should be plenty with a .078 feed. Have you smoothed out the oil drain back paths and made sure the there aren't any obstructions in them.
Seth
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By FORD DEARBORN - Last Month
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Greetings everyone - I recently had a similar valve cover problem and solved the issue with a specific type of gasket. I purchased neoprene gaskets well over 10 years ago from John Mummery with no issues for well over 10 years. This year there was some weeping from the right rear corner of the right cover. The neoprene gasket at that area became a bit spongy as neoprene often does from long term exposure to motor oil. I purchased a pair newly offered silicone gaskets with disastrous results. Long story shortened, after placing a steel rule across the cover gasket surfaces, that corner was bent slightly up providing little clamping force at that area. I then purchased another pair of neoprene gaskets and problem solved. I partially pinched closed the overflow tubes years ago to add more oil flow to the rockers and valve cover area than normal. Idling the engine with valve cover removed there is indeed a good deal of oil flow to the point of slightly flowing over the gasket surface of the cylinder head rear corner. The neoprene gaskets are 1/4" thick, very pliable with an excellent memory. The valve cover is not filling up with oil but in my case, the valve cover sealing rail is bent upward probably by prying screwdrivers from the past. If I can get another 12 years service from the new neoprene gasket I will accept that. I have to believe there is a sealing rail issue with your valve cover leak also. A gasket properly clinched should hold back oil especially when not pressurized. Hope this helps....
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By DANIEL TINDER - Last Month
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Ted (9/23/2026)
Can you give some more detail on the valve covers that you are using? Are the cylinder heads machined on the valve cover rail or is the valve cover rail or sealing surface ‘as cast’?
The 0.078” hole size usually my go to number for restricting the top end oil for the Ford Y. As a general rule, I will not go smaller than 1/16” (0.062”) for top end oil restrictors on any engine. It’s important that the valve springs get some oil overspray just for cooling purposes.
When prelubing Ford Y engines prior to running them on the dyno, I have noticed that the left bank will typically flow more oil than the right bank as it’s the left bank that will overflow the valve cover rail first. For whatever reason, when the cam bearings wear, it’s also the right bank the quits oiling first.
Wouldn’t that mean the the left restrictor passage should then be smaller than the right? Or is the flow difference irrelevant as long as the lubrication is adequate and the rockers aren’t flooded?
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By Ted - Last Month
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As long as the overall oil pressure is not being affected, then any excess amount of flow to the top end would be considered irreverent. Always better to have an excess rather than not enough.
While I have considered using 0.062” restrictors in the left bank rockers to reduce the oil flow further just for that bank, I have not experienced any valve cover oil leaks as a result of the difference in oil flow between the two banks. What I did not mention earlier was that the right bank would also eventually overflow if I had continued to prelube the engine. It must be kept in mind that the engine prelubing is being performed with cold or ambient temperature oil and that cooler oil does not flow as easily as warmed up oil thus overflowing the valve cover rails more easily when the valve covers are not on the engine. Because the oil pressure for the engines with the 0.078” restrictors has been good, I continue to use the same restrictor sizing for both banks.
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By oldcarmark - Last Month
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I just had another look at the Engine. The Left bank is fine as far as seepage. there is none. The right side has Oil all along the lower edge below the Rocker Cover. Maybe worth just restricting that side with .062 restrictor? I don't know what else to try. Tee-Bird Covers and the Rail etc is as stock. No mods at al. I have tightened down the Covers several Times. Still seeping. I assume it is leaking when being driven and after sitting when parked there is Oil on the Floor on right side only. Pan is dry, rear main Seal Dry. Oil Pump Dry.. Has to be the Rocker Cover with excess Oil not draining quickly enough. Maybe just restrict the One side and see what that does? Just a reminder this Engine is a new rebuild. Completely clean inside so there should be no reason for Oil not to drain from heads other than may be more Oil than Drain at rear can handle. I had my machinist cut the Oil Groove in Cam to .035 and installed the Cam Bearing with outside Groove.
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By KULTULZ - Last Month
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What would be nice (IMO) (also $$$) is to have a pair of clear acrylic rocker covers fashioned to see exactly what is happening.
It seems (to me) much of this style modification is guess work.
If the head has umbrella type valve seals, flooding may cause cylinder fouling(?) ...
And the longer return oil stays on the cylinder head instead of hitting the pan(?) ...
I still think the drain tubes (and possibly the older valve seal shields) should be retained in some fashion with the restrictions.
There should be a system calibration for a street engine, mild street and race?
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By KULTULZ - Last Month
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By DANIEL TINDER - Last Month
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KULTULZ (9/24/2026)
What would be nice (IMO) (also $$$) is to have a pair of clear acrylic rocker covers…..
I have a clean set of steel Y-Block valve covers I had planed to cut the tops off and cover with taped-on clear plastic, but likely won’t bother as probably overkill, since I’ve never had a problem with leaking covers before (T-Bird alum. with neoprene gaskets attached with RTV & sealed to the head with grease).
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By KULTULZ - Last Month
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I have a clean set of steel Y-Block valve covers I had planed to cut the tops off and cover with taped-on clear plastic, but likely won’t bother as probably overkill, since I’ve never had a problem with leaking covers before ...
Now that is a good suggestion.
It is not the question of leaking rocker cover(s) but the quantity of oil up top and how quickly it takes to drain back to the pan, especially with umbrella type valve seals.
And it is also going to differ if the engine is street, hot street or race.
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