Rocker arm to shaft clearance spec ???

[blykins]

Passing oil to the pushrod tip, roller tip, spring oiler, etc.

[pbf777]

Passing oil to the pushrod tip, roller tip, spring oiler, etc.

     If I understand, your intention is that we "need" a generous (?) clearance value in order to facilitate the flow volume required for these addition points of lubrication?   

     If so, then for consideration don't both these additional points of oil emission function "better" with the advent of oil pressure behind them?  This to "squirt" the oil fluid, in order to jump the distance, as these junctures don't possess a "direct" mechanical oil delivery mechanism to bridge this (depending on the rocker arm product)?  And as the clearance sum about the I.D. & O.D. relationship circumferences increases isn't the result going to be a loss of pressure in this area?  And this particularly with the popularity in the use of oil "restrictors" being present, which will, if effective, be limiting the oil delivery volume (more so than that of the self limiting function within the rocker/shaft relationship by design) and hence causing a loss of pressure as soon as the area of leakage (clearance sum) supersedes the area of the restriction?  And at this point 'even more' clearance probably isn't really going to help!      

     In other words, the greater the clearance, leads to greater leakage rates, that which then one finds excessive and unacceptable, so then they choose to install restrictors to limit the oil volume passage and leakage loss at the rocker arm to shaft juncture, this resulting in that oil volume as being made available is insufficient to create any significant pressure (aka. no "squirt", not to mention other oil starvation instances!), and resulting in it just drooling out onto the cylinder head emanating from the lower hemisphere just beyond the point of the clearance narrowing where the shaft and rockers are attempting to contact one another at the bottom in their eccentric positioning, and the greater the clearance the sooner and lower in these circumferences that this is going to take place.  And of course also, the greater the difference in these radii (due to clearance sum) this will result in less surface area interacting and reduction in the oil film load carrying capacity.   

     Or perhaps something like that might sorta be what I'm thinkin'.   

     Scott.

[blykins]

You're gonna have to dumb it down for this old hillbilly.  What point are you trying to impress upon us?

[blykins]

Scott...

Are you asking hypothetical questions, or are you saying you run a lot less clearance on rocker arms?  Spell it out for us.

[pbf777]

      Actually my "questions" might be regarded as "leading".   

      Scott.

[blykins]

I never was fond of being vague for attention sake.

It is not hard whatsoever just to say, "I've had luck with running them in this style of application at .xxx clearance".    Not hard at all.

[pbf777]

     I thought this was a "discussion" forum; sorry my bad!   

    But it seems to me, that just making declarations of "I've done this or I've done that", though may prove interesting, but never really provides possible explanations or answers, or even hypotheses, as of the "why" that process might actually have merit, this vs. the old adage of: "that's just how we always dun it!"  But yeah, the latter surely is easier! 

     It's sorta like:  Why are you doing it, if you don't know why?   

     And, it's not about "attention", other than perhaps an attempt to draw others into the discussion, whom might, even if only initially, be more reserved, but might also "actually" have something truly valuable to add to the "discussion".   

     Again, sorry,

     Scott.

      P.S.  Hey, I'd bet, that if reading a novel, your probably one of those whom will read the last chapter first!       Maybe?   

     

[MeanGene]

Not fond of, or impressed by word salads myself. Talking down your nose at folks is not the way to make friends, and definitely does not impress people- especially pretty knowledgeable, well respected people

[My427stang]

Scott, so what’s your target number on a performance FE, alum rockers, and may as well add wrist pin based on a stroker. No “teaching” just your recommendation for a number, we heard the why already

Make believe you are standing at the bench  doing the work

[blykins]

Scott, so what’s your target number on a performance FE, alum rockers, and may as well add wrist pin based on a stroker. No “teaching” just your recommendation for a number, we heard the why already

Make believe you are standing at the bench  doing the work

That would have been the logical thing to state instead of playing a game of 50 questions.

Most of us do things because they have worked well over time.  If someone has done something differently and it has worked, then that would have been some nice data to share. 

[MeanGene]

I have a slightly different philosophy, having spent many years around very large things with huge oil pans and hydraulic tanks, which get very hot and transfer the heat into the air- you'd never want to touch the hyd tank on a big excavator at the end of the day, as it makes a helluva big part of the cooling system. In those rockers, I like just enough clearance to ensure a good flow of oil for cooling of the rockers and springs, and concentrate on ways to efficiently return the heated oil to the pan and/ or cooler to carry the heat away. I like to have as much flow for cooling as I can without flooding the covers, rather than restrict the flow way down- there are ways. And managed to say that with words not exceeding 11 letters, as most of you already know I am just a Dumbshit 7th Class (AKA Hillbilly) like everyone else, and if I started trying to impress people with a lot of bullroar word salad, folks would think that Fender Lizard had hijacked my account- quite a few of you have been around long enough to get that one lol 

[RustyCrankshaft]

I have a slightly different philosophy, having spent many years around very large things with huge oil pans and hydraulic tanks, which get very hot and transfer the heat into the air- you'd never want to touch the hyd tank on a big excavator at the end of the day, as it makes a helluva big part of the cooling system. In those rockers, I like just enough clearance to ensure a good flow of oil for cooling of the rockers and springs, and concentrate on ways to efficiently return the heated oil to the pan and/ or cooler to carry the heat away. I like to have as much flow for cooling as I can without flooding the covers, rather than restrict the flow way down- there are ways. And managed to say that with words not exceeding 11 letters, as most of you already know I am just a Dumbshit 7th Class (AKA Hillbilly) like everyone else, and if I started trying to impress people with a lot of bullroar word salad, folks would think that Fender Lizard had hijacked my account- quite a few of you have been around long enough to get that one lol 

I worked on some logging processors that moved hyd oil through the tanks so fast we plumbed a line from the intake to the hyd tank with a check valve to put boost in the tank to help keep the suction side of the pumps from cavitating. Those tanks also had bolt on heat sinks on them and by mid-day you could cook bacon on them. I never tried, but I did heat up my lunch on them more than once while on long duration service calls!

I'm also a fan of oil flow within reason. Maybe in a drag race engine you would/could limit the amount of oil in there quite a bit. But for a street application as much oil flow is as practical without causing another issue like pumping the covers full or causing windage or drainback issues I think helps. The cooler stuff runs the longer it'll last. But that's just my .02 and it's probably not worth half that with inflation so....

[67xr7cat]

Passing oil to the pushrod tip, roller tip, spring oiler, etc.

     If I understand, your intention is that we "need" a generous (?) clearance value in order to facilitate the flow volume required for these addition points of lubrication?   

     If so, then for consideration don't both these additional points of oil emission function "better" with the advent of oil pressure behind them?  This to "squirt" the oil fluid, in order to jump the distance, as these junctures don't possess a "direct" mechanical oil delivery mechanism to bridge this (depending on the rocker arm product)?  And as the clearance sum about the I.D. & O.D. relationship circumferences increases isn't the result going to be a loss of pressure in this area?  And this particularly with the popularity in the use of oil "restrictors" being present, which will, if effective, be limiting the oil delivery volume (more so than that of the self limiting function within the rocker/shaft relationship by design) and hence causing a loss of pressure as soon as the area of leakage (clearance sum) supersedes the area of the restriction?  And at this point 'even more' clearance probably isn't really going to help!      

     In other words, the greater the clearance, leads to greater leakage rates, that which then one finds excessive and unacceptable, so then they choose to install restrictors to limit the oil volume passage and leakage loss at the rocker arm to shaft juncture, this resulting in that oil volume as being made available is insufficient to create any significant pressure (aka. no "squirt", not to mention other oil starvation instances!), and resulting in it just drooling out onto the cylinder head emanating from the lower hemisphere just beyond the point of the clearance narrowing where the shaft and rockers are attempting to contact one another at the bottom in their eccentric positioning, and the greater the clearance the sooner and lower in these circumferences that this is going to take place.  And of course also, the greater the difference in these radii (due to clearance sum) this will result in less surface area interacting and reduction in the oil film load carrying capacity.   

     Or perhaps something like that might sorta be what I'm thinkin'.   

     Scott.

I'd answer it this way, if you don't have enough clearance you will have galling or the rocker seizing to the shaft.  Too much clearance and you have excess oil loss. As for restricting oil feed to the rocker shafts that is an interesting one, Dove used to tell you not to do that. I also have a set of their shafts that have oil holes drilled both on the bottom and top.  Besides lubrication oil removes heat.  If you have a deep sump oil pan and enough oil volume having more oil to the head is not necessarily a bad thing.  Some race engines use spray bars to cool valve springs so that they will live. On the FE getting the oil to drain back from the heads can be an issue.

Short answer the FE been around for 68 years, it is an old antiquated design. Using .002" rocker to shaft clearance, making sure the shaft feed hole is slotted, and an .080" oil restrictor will meet the requirements of not galling or seizing the rockers and not flooding the heads with oil.

[pbf777]

   
As for restricting oil feed to the rocker shafts that is an interesting one, Dove used to tell you not to do that.

      And I agree, as in my book, most often restrictors are handy for major oil loss control in the instances of component failures, this to keep the vehicle on the track for a longer period even though the engine is in a state of self destruction.  But otherwise it's an admission that you haven't considered oiling requirements and delivery methodology adequately. 

On the FE getting the oil to drain back from the heads can be an issue.

      And I think the Ford engineers 'were' quite aware of the possible problem; as why do you suppose they went to the engineering effort and production expense for those oil catch & drain-back to the lifter valley tins, that mount under the rocker stands, this as an aid, with the intention of alleviating a certain sum of oil from having to traverse the cylinder head drain-back passages?  And for those here, how many re-utilize these (yeah, sometimes requiring reworking, or making anew, to fit aftermarket heads)?  Or did we toss 'em, and now are trying to figure out how to limit the oil to the top-end so as not to flood the under valve cover region?   


      Again, just food for thought in the "discussion".   

      Scott.

[blykins]

I've always maintained the thought that the rocker drip tins were for those cases where you pull a valve cover and there's a perfectly shaped mold of sludge that would keep any oil from getting back in the head drains. 

I've never used them.  Same with oil slingers.  Same with valley pans.

Have you ever used a Victor FE intake?  They don't have any provisions for rocker drip tins, but yet there are hundreds (thousands?) of FE's running around with Victor intakes, that haven't spontaneously combusted. 

There are many FE engine builders who are very successful at the way they do things and a lot of us do things quite differently.  To say that someone uses restrictors because they "haven't considered requirements and delivery methodology adequately" (along with some stupid emojis) is a pretty pompous thing to say.   I mean, I guess I'm sorry that I don't consult with almighty Scott before I put a bolt in.   

In addition, a lot of us use rocker systems that are totally different than a factory Ford rocker:  needle bearing fulcrums, pushrod oiling, etc.