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-   -   Oil restriction to rockers new question? (http://squarebirds.org/vbulletin/showthread.php?t=20479)

Brushwolf 05-09-2016 02:01 PM

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?

simplyconnected 05-09-2016 04:48 PM

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

Yadkin 05-09-2016 05:27 PM

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.

pbf777 05-10-2016 01:48 PM

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.

Brushwolf 05-11-2016 09:04 AM

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.

simplyconnected 05-11-2016 12:39 PM

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'.

pbf777 05-11-2016 06:46 PM

Aftermarket rocker shafts are just as difficult to get through the stands so I know they are NOT undersized.[/quote]
I appreciate your observation, and I totally agree as I have had the same experience. But, in my scenario, with further investigation and using an inside dial-bore gauge, we found that the shaft stand's bore collapses after being torqued down (particularly when over-torqued) & put into service for a period of time ("takes a set"), and does not recover completely (some, yes) when untorqued. This remaining ovality causes an apparent drag, when attempting to remove and/or install them; and therefore may not prove as an accurate measuring instrument to determine the true shaft O.D. dimension.
The most common material Ford used for these stands (FE) was an aluminum alloy which proved acceptable in most applications but was not impervious to failure and certainly doesn't hold size (round). It was (is) not uncommon to find these cracked in the "loop" from being compressed oval beyond the elasticity of the casting, or split at the top thru the bolt hole (usually) or down into the base due to the spreading effect as the stand squashes (& shaft) under the torque load (again effect amplified if over torqued).
Due to the popularity & long production life of the FE in it's many iterations, the rocker shaft assy. (shaft, stands & rockers) were still available thru Ford Parts departments @ the dealers well into the 1980's. By this time Ford no longer produced them, rather I believe they were sourced thru Fred Jones?; who rebuilt these components. We found that the shafts were reground undersize varying somes to "clean-up" the surfaces and put back into service.
In a discussion with a gentleman at Harland & Sharpe (who make rockers for FEs) concerning availability of new ("improved") shafts, he stated that in their search, they were unable to find anyone in the U.S. who could grind a shaft straight & true & to size (affordably), and that there's a great range in sizes (even in a single shaft!) experienced when measuring existing units. And, I concur with these observations.
Remember, we're dealing in .001" or less, plus-or-minus, clearance values here, if you want it even close to right (and that's kinda sloppy, but were not building a space shuttle here).
Also, the cast ductile iron rockers applied directly on the harden steel shafts was not such a good idea ("OK" for stock applications, I suppose). I believe Ford engineering realized such, but maybe the peanut counters won this one, so the quick & cheap solution was to make it a sloppy fit w/ excess clearance and resultant oil wash. Ford used similar components for other applications but w/ bronze bushings, so they weren't unknowing. Scott.

Brushwolf 05-15-2016 04:36 AM

Measuring Custom Pushrods length?
Found these rocker shafts while I was looking up something else.. They look to be pretty decent parts. Not cheap, but what is nowdays?


I measured my after market roller rocker set and shafts are ..084 same as those from Precision. Looks like my oil return shields from the 68 motor will fit with my rockers set too but cast aluminum valve covers need a tad of clearancing at flange to clear end saddles of rockers.

May have the TBird covers chromed and put those on after motor is back in car, but wouldn't be too upset if I have to keep the aftermarket covers on it either (Purty..)

Mounting studs for rocker stands don't seem to fit right thread wise so took my stock bolts off old rocker set to use and that seems to be better. Not as pretty but better fit.. Stands also same height as stockers..

Had this block decked about .020 but being I am using the thick .040 composition head gasket instead of the thin steel factory gasket it had at about .018 thickness, those two changes should mostly offset one another.

Test fit the ancient F427,intake with no gaskets and it shows light all the way through one one side, but not the other. Figure I just have it a little off center with no gaskets in there.

All the angles look right on intake ends, but wondering if the stock FelPro intake side gaskets will be thick enough? And end cork gaskets almost seem like they would be too thick, so silicone it is..

Also have to locate a new oil tube for intake as it had a rubber plug with a bolt through it. Must have been used on a newer motor with cap on valve covers. Know who sells a good stainless or chrome fill tube and cap. My valve covers have no caps and I like them that way.

Oil shields seem to clear everything on rockers though. Probably because the shields don't have the long fingers on them like the 62 shields do. And my rocker arms are stainless bushed rocker arms instead of aluminum which perhaps cannot be made as compact as the stainless versions.

Looks like my rocker arm inside bushed diameter is same as stock rockers also at .004. More than ideal perhaps, but will give them a try.

I got a couple push rod length checkers with rocker set that seem so close together in length I wonder why they bothered to use two instead of one?

Got any suggestions as to best or alternative procedures of how to determine correct push rod length? Pre-pump lifters before trying to determine length of pushrods? Read someplace that you should use a 12 inch caliper to measure the rod which does not seem real practical since I have never seen that large a caliper much less own one..

simplyconnected 05-15-2016 07:46 AM


Originally Posted by Brushwolf (Post 101051)
Found these rocker shafts while I was looking up something else.. They look to be pretty decent parts. Not cheap, but what is nowdays?...

Rockauto.com sells Sealed Power rocker shafts (RS621) for under $30/each, NOT $180. They exceed OEM spec's.

Steel hardness is mostly due to heat treat, which is why your high priced shafts have tapped end plugs instead of standard 1/2" push-in cup plugs. Are tapped holes better? I think the cotter pin does a great job because I never saw one fail yet.

I take it that you are using non-adjustable rocker arms. If that's true, buy a 'test pushrod'. It is adjustable so you can determine your exact pushrod length. Summit and Jegs both sell them at a reasonable price. I still can't get over $180 for shafts that cost $60.

You must assemble the heads and rocker shafts to determine correct length pushrods. I do not pump up the lifters before measuring for lifter preload.

The factory deals with parts that are all identical in size so it's easy to determine pushrod length, then buy them by the millions. You have made changes to the valve train 'stack' so you must measure. So many of us have changed cams, rocker arm ratios, pistons, heads, (roller) lifters, etc. So, measuring piston-to-valve clearance and pushrod length must be done.

Your engine is a precision machine that requires correct pushrod lengths. You only get .040" to play with for lifter preload. I hold my builds at .030".

I use FelPro intake gaskets regularly and have not had a problem. I also leave the end gaskets out of FE and SBF engines. Use Permatex Black sparingly. I can't emphasize enough, do not use too much gasket sealer because it will end up in your pan and eventually make it to your lifters and bearings.

I use valve covers to route my crankcase ventilation. It's important that the engine has an IN and an OUT for proper breathing. - Dave

Brushwolf 05-15-2016 04:04 PM

Anyone use a rear breather like this?
Not sure what this is. Never seen a rear breather for FE.


Since the F427 intake has no rear breather or pcv provision (does have a boss cast back there that appears to be placed there for that eventual possibility though...).

I figure the front stock type breather on intake fill tube for inlet and rig a PC valve at rear of intake routed to carb base for the outlet. Have to drill the intake though..

Yes, the cotter key seems to work fine for shaft plug insurance and I have never seen a loose rocker shaft plug either, whether in the Y block motors and early Mopar hemi with two shafts each side with press in plugs and no cotter key. They always seem to be in there pretty tight.

So screw in shaft plugs are probably overkill, but my new shafts have them. My rocker arms are the adjustable type with cup and ball. There are 2 pushrod adjustable length checking tools along with the rocker set. Just not sure how you read them once length is established.

I had originally planned on using the stock non-adjustable rockers, but figured they were probably worn so after checking cost to refurbish decided to just buy a new set instead. Tired of cleaning sludge off old parts and finding I still need to replace them anyway..

Now after inspecting and cleaning up stock rocker set to compare with new, they really don't look too bad. Stands even slide over with little effort and neither shafts or arms exhibit noticeable wear on fulcrum or valve end either. But being I have the new adjustable set now, I will just keep going with those.

I have one side of engine mocked up with rocker arm bolted on head loosely and intake just sitting on there to see how it lined up and bolts and end gaps and angles worked out.

Did not put lifters in yet because I was not sure if figuring out pushrod length was to be done with dry lifters or not. Lots of conflicting opinions out there.

My 268H Comp cam only has .494 gross valve lift and Pistons have valve reliefs for stock size stainless valves used in the 62 heads. Although block was decked .020, the thicker by .022 composition head gasket used should offset that and the .002 resurfacing of heads.

New rocker stands are the same height as stockers and oil shield fits so shaft height off head should be in the same relative position too. Theoretically anyway..

So with everything except higher ratio adjustable rocker arm and moderate cam lift over stock considered, it looks like on paper it is still pretty close to stock dimensions.

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