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Old 05-09-2016, 02:01 PM
Brushwolf Brushwolf is offline
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Default Oil restriction to rockers new question?

I am assembling my 68 390 for my 62 TBird - finally - and had read extensively about FE oiling systems including oil restrictions to rockers. It being a 68 motor, it already has the larger passages 68-up oil filter adapter.

Used the 62 heads with new stainless valves, positive seals and hardened exhaust seats, as the large intake ports in those heads match the Edelbrock F427 aluminum intake that I have had lying around for the last 15 years.

Block is decked, heads resurfaced, 268H cam and matching springs, forged pistons. 9.3:1 CC'd CR with composition gasket. New electronic distributor, ARP pump drive shaft, stock oil pump. FPA ceramic coated headers and rebuilt C6 with shift kit.

I did the block passage enlargement and tapering at oil filter adapter to increase oil flow and have just very slightly tapered the main saddle feed holes to better feed misaligned main bearing feeds on 1,2 and 4, as well as putting restricters in heads that now leave about 7/64th (0.109) inch diameter oil passage remaining open now.

However, when placing the Fel Pro head gaskets in position, I just noticed the oil passage hole in the head gasket is also only about 7/64th in diameter.

So, it seems to me that the head gasket is already restricting the oil flow to top end, since the feed hole coming up is about 5/16th (0.3125), but the head gasket opening over the hole is only 0.109.

The oil has to pass through that small hole in the head gasket before it goes up into head, so doesn't that effectively create the same amount of oil restriction as the restriction I placed in the head passages? Has FE head gasket always had that same size hole at that passage?

I have an additional composition McCord gasket set here that is about 15-20 years old and those gaskets also have the 7/64th oil feed hole in them. So I am wondering why that small hole in the gasket doesn't make my addition of an additional restriction of the rocker feed holes in the heads moot?

Am I missing something? And driver side head gasket is upside-down compared to passenger side? (Printed side up on passenger side, down on driver side). Offends my sense of order but if water passages in back are open and passages in front closed, seems like I have the head gaskets on right...

I understand that type of rockers arms used has implications as to oil flow required to keep them oiled but not an excess amount of oil pooling in valve covers.

Decided to try a new aftermarket set of 1.75 adjustable stainless rockers with bushed arms and roller tips as the cost of refurbishing an old adjustable set cost just as much as just using new ones with the stiffer saddle-type end stands included in the new set.

Not sure if either my 68 or 62 oil return shields will fit with them, but one problem at a time..

But why isn't the small head gasket hole over oil feed a built-in restrictor and how does adding the second restriction make sense unless you want flow restricted even further?
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Old 05-09-2016, 04:48 PM
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simplyconnected simplyconnected is offline
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Your concerns are all valid.
Rocker arms don't need much oil. In some setups, they are in open air. In other setups they only get a mist of oil from blowby. I guess you need to know, this is Ford's second attempt at building an overhead valve engine and the problems associated with the first attempt (the Y-Block).

Yes, oil tends to 'hang' in the rocker area so many FE folks add an extra quart or half quart when going on a long trip. Does it need it? Not really but that little bit extra adds a sense of confidence.

In the Y-Block days, oil was fed from the center cam bearing to BOTH heads. There was a groove around the center of the cam which was never deep enough. Consequently, the bearing would wear, closing up the groove which starved oil flow to both heads. There was another 'problem' because the oil hole was not a straight shot. It zig-zagged at the head gasket.

The rocker shafts were open to atmosphere which ended up bypassing oil when each rocker arm clogged the little holes with dirt/oil/sludge. This also lowered oil pressure. The problems were extensive.

FE rocker shafts are fed from two cam bearings. The oil groove is not in the cam but under #2 and #4 cam bearings. Click on the following picture for my oil modifications:

This ensures the oil has plenty of flow to the heads. Your head gasket is not supposed to restrict 70-psi of 300F oil, at least not all the way. I restrict my rocker arm flow with a very liberal .093" drill. Some go down to .060". This keeps overall oil pressure up as well.

It's hard to say every gasket company maintained the same oil hole diameter because they change so much over the years.

Do not be confused regarding your head gaskets. I always check for a square corner in front and on top. Yes, coolant flow is shut off in the front and wide open in the rear of the engine because water takes the path of least resistance. If the gaskets were open in front, all the flow would try to get through the shortest route especially at idle speeds when coolant pressure is low.

I also block off the exhaust port at the intake manifold with a patch of shim stock. So all the exhaust heat goes out the exhaust. Be sure your heat riser valve is not stuck shut. I gutted mine with a torch and left steel in the holes.

Be careful with the shields, especially if your rocker arms are not adjustable. I simply left mine out but used shorter pushrods. You have a different ratio rocker arm which can drastically change the geometry of your rocker arms if the shield is removed. It's about .030" thick which makes a huge difference on the height of the stands. - Dave
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
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Old 05-09-2016, 05:27 PM
Yadkin Yadkin is offline
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Check your install instructions of your rocker set. My PQ set states to use restrictors 0.060" to 0.090" ID, with a caveat that these numbers are merely a guide. They don't need a lot of oil.

Regards to drain back shields, mine didn't fit with the rocker set.
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Old 05-10-2016, 01:48 PM
pbf777 pbf777 is offline
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Oil restriction to the rocker arms for the purpose of limiting excessive oil supply and lost from needed supply (and resulting pressure) for the bottom end is not a new practice, particularly with the FE engine. Unfortunately, it is not always executed properly.
First, if your valve train components and other clearances thru out the engine, were original Ford pieces, in the condition (dimensionally) that they left Ford, and you operate your vehicle in a normal fashion, you wouldn't need restriction to the rockers or want to.
The problem begins when we change oil clearance relationships, particularly, but not limited to, increasing bearing (rod & main) clearances, rod side clearances, camshaft, (most after-market cams are ground under-size) etc., this all increases oil leakage rate to a point where the pump can no longer "keep-up". Sometimes this is due high mileage, warn "out-of-spec" surfaces, and sometimes it's intentional for performance applications, right or wrong.
And the whole purpose for the latter was so we could install the bigger camshaft profile and turn higher RPMs which also increases the oil shed rate; not to mention the oil pumps volumetric efficiency starts falling off somewhere along the way as the speed increases. And then, someone discovers that they can limit the oil supply to the valve train and recover "some" pressure for the bottom end. This does work, "sort of" (and yeah, I know, "all the old guys did it that way") but, this qualifies as a patch not a fix.
This shaft system in the FE was intended to be pressurized, and if not, component life is lost due to lack of oil distribution, lubrication & cooling, leading to excessive heat, galling of rocker arms/shafts, arms/valve stem tips, rocker/push rod & even shaft breakage. As you restrict the available oil supply, you reduce the effective pressure, you begin to defeat the system. And, if you are going to increase cam lift/rocker pitch motion, ramp rates/inertia, spring rates/load, etc., add increased RPMs, why would you need less oil & it's qualities?
Your question on head gasket orifice size; this dimension has changed over the years & by manufacturer, why I don't know, but there's a lot of "monkey see, monkey do" in this industry and reasons may abound. Another example, for thought, is Ford #C8AE-6051B steel shim (racing) gasket for the 427's, the orifice measures approx. .150", go figure.
The limit to the oil loss/bleed rate should be controlled with the clearances between the rocker arm & shaft (as was when the parts were new), and this also creates other benefits such as reducing the specific loading & oil displacement.
For this, I prefer a bronze bushed bearing surface rockers; With round holes (not oval due to poor quality (China) or worn-out!) and proper clearances (approx. .001' - .0015") and with this, no restriction is required and all things function properly. Unfortunately, most after-market shafts are ground under-size, and most rocker's trunnion I.D.'s are oversize (intentionally for marketing reasons) leading to excessive clearance & hence, excessive oil loss. Response from parts manufacturer, "hey, all you gotta-do is put restrictors in, everyone knows that"!
If the your original rockers & shafts are worn out, replace them; they are a wear item. Once the shaft is worn, galled, etc. polishing it only reduces its diameter (increasing the clearance), besides, the only proper repair would be to hard chrome, straighten & finish grind them to proper size. And if the rocker bores are worn to where the oil groove is not visible, honing (round & straight?) & grinding a new groove does not "fix" them (increases the clearances, even more oil loss!). The proper repair is to bush (bronze?) down the I.D. and bore/hone to size. Also, the shaft could be built-up in the chroming to allow for oversize rocker I.D.s or rockers could be bushed down to allow under size (but proper ground true) shafts. But, these repairs are not cheap, but are presented to explain what is necessary to correct these damaged components. Generally, for this application, cheaper to buy new (hopefully good) replacements.
Roller rocker arms, (be careful of cheap China/ebay stuff) sound neat (can be noisy to!) but definitely allow more oil to pass. Most manufactures have the same size holes drilled in the shafts whether for rollers or bushings and this is wrong. One of the benefits of the rollers is it ability function in lower oil saturated environments, which we are not capitalizing on, and due to the clearances between the rollers the oil just pours.
Also, addressing the oil drain-backs to increase efficiency is good practice. Blend the trough to passage in head & check drain-back orifice alignment between head/gasket/block at deck.
If your engine has low oil pressure (5 p.s.i. ?) and you feel that restricting the valve train is the "fix", well, maybe one should look a little closer at the machining/building/assembling technique involved (if you what a "proper fix").
I think I had better quit now before some blows their top.
And, your head gasket observation is correct, lack of symmetry, once you drop the head on, out-of-sight, out-of mind. Scott.
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Old 05-11-2016, 09:04 AM
Brushwolf Brushwolf is offline
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Default Rocker arm oil bleed

All good info.. I had read this comprehensive article as well as the one by simply connected and used those and others as guides in going about this.

It seems pretty clear from this article that the largest designed-in leaks for FE are the cumulative leaks in the rocker pivot area, even assuming both the rocker system and all other components are within spec. And with any excess wear or clearances in rocker system, the amount of oil that can go through them far exceeds what is required.

In the chart it shows 40% of total leak area is the rockers and down to 3% with a .070 restrictor. I went a little more at the .109 which is about the same passage diameter as a Holley 90 jet. Happy medium?

My new aftermarket set has the bushed rocker arm so shouldn't bleed off as much as those with needle bearing fulcrum and I will check to see what the clearances are before I install them.

I have built a few earlier Y-blocks with the solid lifters and those were notorious for inadequate rocker arm oiling. After looking at the FE in depth, it almost seems like Ford over-compensated for that issue with the 292-312 motors when designing the FE.
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Old 05-11-2016, 12:39 PM
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simplyconnected simplyconnected is offline
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Where to start?.. Normally we put soft material with hard, like Babbitt bearings with a steel or cast iron crankshaft. Not in the case of rocker arms, they are forged and the rocker shafts are file-hard. All lifters follow the same plan.

I use stock rocker arms in both my Y-Blocks and FEs. I also modify the Y-Block setup by grinding the bottom rocker shaft slots (like FEs already have) and by pressurizing the shafts (again, like FE does). Ford engine engineers must have felt that a small drop of oil was enough on each Y-Block rocker arm. They did not think 'down the road' as dirt packed the tiny oil holes in the rocker arms because oil was then bypassed down the end tube. Well hey, they had no experience and this was their first try. When the engine is new the original setup works well.

When dirty oil is present in the arms, oil pressure effectively pushes it out keeping the holes clear.

Aftermarket rocker shafts are just as difficult to get through the stands so I know they are NOT undersized. That little groove inside the bottom of the arms simply directs oil to the holes for proper pushrod and valve stem oiling. Since valve springs keep pressure on the bottom of the arms, they naturally wear first. Groove or no groove, the arms still rotate on a sheet of oil. I prefer to re-define the groove when needed.

There was no restriction on the Y-Block shafts AND the end tube opened pressure to atmosphere. Pressurizing the shafts immediately raises oil pressure. Restricting the flow keeps more oil on that center cam bearing so it doesn't wear and close off the cam's oil groove. Again, FEs benefit from these 'factory improvements'.
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
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