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MG TD TF 1500 - Oilflow from rocker area to cam area

I would appreciate the boards opinion about influencing the oilflow that goes from the rocker area to the cam-camfollowers area. The surplus oil upstairs will flow down the "wide" holes around the pushrods and gets handed over to the camfollowers. And than being taken down through the holes in those camfollowers and kind of reaching the critical area between cam and camfollower.
Looking down from upstairs, there are quite some possibilities for the oil to flow down through holes that only let it drip into the oilsump.
What about closing off those holes and by doing so forcing the oil to go where it is needed: camfollowers, camgears and timing chain area. I marked them in the image.
Anybody experienced with this?
Greetings, Huib

Huib Bruijstens

Huib,

I believe if you closed the upper holes in the head you'd soon be pumping oil out of your valve cover, ditto out the side cover if you close the ones in the block if you leave the big holes open in the head.

There's a large volume of oil being pumped into the head and it's not all going to escape down the pushrods.

If you want more oil to your cam you can modify your cam followers but other than that I wouldn't modify the drainage.

Gene
Gene Gillam

I certainly don't think it would hurt. I suspect, however, that the oil escaping the rod big end bearings and slinging probably contributes the most oil to the cam.

Where's Superman when you need him? It would be nice to have his X-ray vision to see inside.
J E Carroll

I wouldn't. I think the side cover will overfill and the excess will go on the ground out the vent. I've noticed that the XPAG cam wears very little, the followers taking the abuse. I would consider crowning and heat treating the followers. Inspecting the followers every 25,000 miles or so would do it, at the cost of a side cover gasket, and checking the lift with a dial indicator and magnetic base.

Warmly,
Dave
Dave Braun

Huib,

Your subject is one dear to my heart. Whenever my oil pressure would get lower, I would always suspect main or rod bearings. After changing them, the oil pressure was still low.

As Gene has noted, there's a lot of oil going into the head, and that a pressure drop could also come there and in 1963, I finally figured that out, too.

I changed the rocker bushings and the rocker shaft (1963), and to my amazement and complete satisfaction, pressure was back. And ironically, 50 years later, I am experiencing the same problem. I rebuilt the engine in 2006, but not the valve gear.

My garage is today a balmy -28ºC so when the warmer weather arrives, I will be rebuilding my valve gear, now for the 4th time in the life of the car.

When one gets old, some of this stuff, finally gets through!

Gord Clark
Rockburn, Qué.
Gordon Clark

huib, i will echo what the others here have posted...don't close of any holes. i will offer that there is on ebay right now a set of modified cam followers that are engineered to supply more oil to cam/lifter area. regards, tom

http://www.ebay.com/itm/230838764162?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
tom peterson

I hadn't thought of a drainage problem since the oil feed to the rockers is one small pipe. I did, however have trouble with a Chevy small block not being able to drain, so it might be an issue. The SBC wouldn't drain fast enough so that I was suffering oil starvation to the #1 journal, the farthest away from the oil pump. That engine, with a high volume pump and high (7500) RPM, would empty the sump into the rocker covers and lifter galley. The fix was to actually enlarge and polish the returns and fit a larger sump. The oil supply to the rockers is through every lifter and up hollow push rods rather than the trickle down system of the XPAG.

J E Carroll

The critcal point is oil flow to the cam and to improve this flow cut a groove down the side of the followers. Be careful not to leave a sharp edge which could cut the housing.
A small grinder or even a file will produce the desired result.
R J Marshall

Here is what RJ was talking about...

Gene Gillam

Thank you for these interesting comments.
I did some measurements to collect soem facts.
The oilline feeding upstairs, has an internal diameter of about 3 mm, so square 7 mm2. And of course the oil comes out pressurised. (too long time ago i new the formulas to calculate the volume)
The 8 pushrods in their wide holes offer a free flow square of 310 mm2.
The big extra hole (the one to may be closed) in the head has an opening of about 230 mm2.

What about your thoughts on these numbers?


The longer I look at and think about the camfollowers, the more enthousiastic I become about just another prove of those days innovativenes. One wants a pretty good guidance of the follower in its place in the block so not too much space in between to allow oil to drain. And than, someone came up with those sideholes: the one on top to collect oil when the follower is upstairs and the one below to pee out when the follower is downstairs. Those guys must have been really excited when this suggestion came on the table.

So, once these camfollowers have been in operation, their little reservoir down under is filled with oil and the next drop in will cause a drop out, that's fine. But on first use, the first drips of oil coming in have to fill the reservoir first before any drip can overflow from the bottom holes. From that, I can understand the thinking for deepening thos holes all the way to the bottom of the reservoir as showed in the picture on the e-bay that Tom mentioned.
At least I will fill the reservoirs when i replace the camfollowers to gain a better starting position.

But what is the thinking behind those groves?

In Tom's e-bay they made a grove all the way from the upper hole till the bottom and in Gene's picture this groove goes from the lower hole to the bottom. But why?
Greetings, huib
Huib Bruijstens

Huib,

I believe you've got the photos mixed up...in mine the groove runs all the way down the side of the lifter, the eBay ones just run it from the bottom hole to the bottom of the lifter.

Either way, the idea is to get the oil as quickly as possible to the bottom of the lifter and to the top of the cam lobe. You are aware that the lifter rotates on the cam lobe as the cam rotates, right? These grooves ensure that oiling is taking place at all times...without the grooves, oiling only occurs when the lower holes in the followers reach the bottom of their respective guides.

As for filling the reservoirs with oil before assembling, it's much more important that you use a good cam lube on the lobes and the bottom of the lifters during assembly.
Gene Gillam

Gene, you are right (of course): I mixed up those camfollower images.
It made me take some measurements and I represent them in this image.
The red lines represent the blockguidance when the camfollower is in its lower position (most of the time). The holes on the right are the original ones, The holes on the left show my changes.
I concluded that the oilinlet in this lower position is not too much: the gap is small, so, I changed that by making the hole larger upwards.
The oiloutlet in this position looks fine: enough gap at the lower hole to flow out.
The blue lines mark the high position of the camfollower in its blockguidance. At the oilinlet, the camfer of the hole in the camfollower does not support an easy oilentry. So, I made that a flat one.
The oilexit in this position is just closed by the guidance, so I lowered that hole and also changed its camfer to flat to allow an easy exit.
Looks now that in all positions, there is an easy flow possible from upperdeck to cam area.
I am still considering closing the holes that just let the oil flow back into the sump instead of passing the cams, gears or timing chain.
Greetings, Huib



Huib Bruijstens

Here is what I did with the big hole in the head that just lets the oil flow down to the sump instead of leading it via the pushrods and camfollowers. I took your comments about risking a too high level so thats why I made it an overflow. First attempt was with a thick wall rubber hose but that allowed in the end a too small innner opening. So, then I took a piece of copper tube, made it rectangular, glowed it redhot to soften and carefully "hamered" it into the heads hole. By spreading it on both sides, it is fixed in place. The top is about 3 mm below the covergasket. Greetings, Huib

Huib Bruijstens

Now that looks like a good solution, more flow down your pushrods while preserving the ability to drain the head area.
Gene Gillam

Gentlemen:
I'm at the point of assembling the XPAG that I will use in my TF project so this subject is very timely.
I notice that the "grooves/slots" cut into the cam followers/lifters is shown 2 ways.1)the grooves cut from the top hole all the way tothe lower end of the lifter and 2) the groove cut from just the bottom hole to the very bottom of the lifter. Is there a preference ?
Best regards
Rod Murray
Rodney G Murray

I have observed differences in tappet wear on many 1275, which have the oil from the head channeled such that 4 tappets get extra oil and 4 do not. If you take the engine apart at the right point, the differences in wear are obvious, so this is a good thing to attend to. I grind grooves in the head to split the oil so it runs equally down all 8 pushrods.

Grinding grooves in tappets is not good. They do crack and cracks start at grooves and edges. If the tappet is any good, you cannot file grooves near the bottom anyway, as the material is too hard. Grinding such material often leads to invisible micro cracks which leads to total disaster sometime later. The corner where the groove meets the working face is very highly stressed, and we hope it is very hard. This is like hitting a crystal glass with a hammer.

Huib's fix is perfect - but it is in the wrong place. You do not want any more oil than necessary in the head, and any wear that leads to flooding should be fixed.

After that, make the standpipes in the drain holes in the block, such that the oil is maintained just above the tops of the tappet bores. Chamfer the top edges of the bores to act as funnels to get the oil down the tappet bore. The chamfer does not need to be large - 1/16" is plenty. If you want to be really certain of oiling, cut a ring groove and a vertical groove in the bottom of the bore to lead oil to the approach side of the cam/tappet interface.

FRM
FR Millmore

FRM,

I respectfully agree to disagree with you on grinding the grooves in the tappets. MG vintage racers in England have been doing it for years and the XPAG racers are doing it over here now. If it led to damaged tappets it would be around the internet by now...your's is the first voice I've ever heard saying it was a bad idea.

R/Gene

Gene Gillam

Gene
Just another thing that adds some risk, with little point that I can see. Would like to see hardness tests on the lifters being ground.
Main thing is that while it sort of floods the cam, the oil would be better used at the critical point.

FRM
FR Millmore

FRM,
could you show us a picture of the grooves that you grinded in your head?
And what did you do with that big hole in the head?
greetings, Huib
Huib Bruijstens

FRM,

Since the tappet actually is offset on the cam lobe, every time it (the tappet) rotates it floods the cam face with oil from the groove. Where is a "more critical" point than that?

Gene
Gene Gillam

Huib-
It was not a T series head, but a 1275 A series; presented as a clear example of tappet wear vs oiling.

Gene -
The critical area is the approach side of the cam/tappet interface. That is the only place that matters. Otherwise, you are just dumping oil randomly, a useless enterprise, as there is lots of oil flying around where you do not need it. Ideally, you would have a pressure jet aimed into the contact area, but that is a bit tricky.

FRM
FR Millmore

FRM,

That "approach side of the cam/tappet interface" is encountered with every rotation of the cam and the 4 grooves. Yes, oil is splashed (dumped) randomly but *some, more than normal* is deposited right where it's needed because of the grooves. I'm afraid you're not going to convince me that no grooves are better than some grooves and that increasing the oil drainage to the push rods is better than the grooves.

Like I said above, I agree to disagree.

R/Gene
Gene Gillam

Gene-
Yes "*some, more than normal* is deposited " NEAR "right where it's needed " And a bullet grazing his ear is near but does not kill da deer. And, even if one groove is depositing oil at the correct place, 3 other grooves are draining it where it is useless. The action of the cam wipes ALL of the oil out of the critical area, exacerbated by low engine speeds, high spring pressures, and thin oil. That's why you do break in with high engine speed and heavy assembly lubricants, and sometimes light valve springs.
Put the groove where it needs to be, and in the bargain eliminate the possibility of tappet failure from grooves, grinding cracks etc - even if you've never seen one fail.
I am not talking about pushrods here, it is the tappets and cam I'm looking at.

Addendum for Huib-
You leave the hole in the head alone, build the standpipes in the block/tappet chest. Oil in the head is evil, and should be supplied at minimum required and removed as quickly as possible.

FRM
FR Millmore

FRM,

Again, the tappets *spin*, they do not ride statically on the cam lobe. One groove should always be feeding oil to the surface of the cam where the tappet is touching.

I believe this was initially developed (or popularized) by George Edney of XPAG Engineering in England. I first saw it on the XPAG rebuild video he produced for the owners club in England.

Gene
Gene Gillam

Gene-
Tappets are designed to <rotate> a part of a turn - a few degrees is sufficient- at each operation, in order to equalize wear. If they "spin", there is something wrong. Most commonly this is an error of too much taper on the cam lobe, too flat a face on the tappet, too much offset, or inclination of the tappet bore relative to the cam axis, or any combination of these.
"Spinning" tappets wear out the tappet and cam, since it represents too much edge loading of the cam lobe, and the block, since it was not designed as a "spinning" element.

With 4 grooves, there will be times when no groove is dumping oil where and when we need it. 6 would be better, but you still have the rest of the grooves dumping oil uselessly.
I fail to see why putting one groove where it does the most good is difficult to understand.

Mr Edney may have had some part of this design, at least for MG, but it is a well known technique. I own several dozen technical papers, from every major engine manufacturer in the world, relating to the then emerging problem of cam and tappet wear in the late 1940-1950s era. These collectively cover every trick they - ALL of the world's experts on cam/tappet design - could think of, from basic design (locked tappets, forced rotation tappets, finger tappets etc) to material/heat treat to oils, voodoo, and finally the use of ZDDP. The discovery of ZDDP for this application was the result of a single barrel of oil that had many times the usual dose in it due to a blending error. (ZDDP had been used as a corrosion reducer previously and routinely.)

FRM
FR Millmore

Great to get such different views on the table. Thanks Gene and FRM, please keep doing so and also other BBS friends, speak up and treat us with your thoughts. For me, this is a great learning opportunity and i love it.
And I do hope that Rod who entered this thread with his question about the grooves, can find his answers in here too.

FRM, yes, condition of the rockerbearings should be so that oilflow is about whats designed for.
Of course, one does not want a "sump" upthere but why are you so furious about getting oil out of the head area "as quickly as possible" as you said.
greetings, huib
Huib Bruijstens

I don't think the tappet wear/destruction thing was an issue until 10 or so years ago. Moss came out with the elongated hole tappets, believeing that the long available large base circle Moss/Crane cam prevented the lower hole from dropping down enough to open and allow oil to flow on the cam. There were poor quality metal problems also, and some were found to not rotate for various reasons (worn cams, lifter bore issues, etc). Then the Zinc/oil issue came to light. Valve cover leakage could be a big issue with a lake of oil sloshing around, and perhaps could end up in the breather or going down the intake guides? Just my thoughts. George
George Butz

supplemental lubrication how much experience you have with XPAG tappets but in the 5 XPAG engines I've seen/worked on they rotate a minimum of 1/3 to a 1/2 a turn when they come up on the cam lobe. Based on those observations I'd have to say that appears to be the norm. Granted these are engines with at least 3/4 race cams but there's no reason to believe that there's a problem with the cam surface, taper, offset, etc., to cause them to spin more than a "few" degrees.

From the internet...more importantly the bottom of the second paragraph in the first link:

http://www.enginebuildermag.com/Article/102957/camshaft__valvetrain_technology_overview.aspx

"One
Gene Gillam

Gene, good to see that so many studies were taken on on this topic. I do not have access to the second article. Could you e-mail this to me please. greetings, huib
Huib Bruijstens

Fascinating subject and fascinating insights, especially because I'm in the midst of my XPAG overhaul.

From what I know/heard I conclude that the XPAG cam and followers have always been a weak point, especially when low quality oil was used, or the oil wasn't changed often enough.

Suspect quality of new parts won't help. That's why I decided to have my old cam and followers reground and hardened by a Belgian specialist. The kind of universal camshaft specialist with a four week waiting list and that instantly recognizes the part as a TC camshaft when you put it on the counter unannounced (even when it comes from a Y-type, but that is nittpicking).
This specialist advised my to let him treat the followers instead of buying new because the uncertain quality of the hardening of the new parts. He said they would be much better than they ever were when new, so I do hope he is right.

I've always wondered why the grooves would be beneficial. I figured that the big holes (when used with the standard radius cam) would pump through enough oil to lubricate the cam.
Reading the second quote from Gene, I now think grooves would help to spread oil in the bores of the followers and this would help the free turning of them?

I like the idea of the standpipes, but then in the block. I'll post pictures if/when I succeed in making them.



Willem vd Veer

Thinking about the camfollowers, I decided not to groove for two reasons: first I do not want to break through into the hardened part of the follower near the bottom (about the lower 4 - 5 mm).
Second: if oil flows out the lower hole, it will kind of spread over the surface whilst flowing down to the edge and hopefully around the edge towards the erea to be: between camfollower and cam.
Grinding a relatively narrow groove, will to my expectation, have a tendency for dropforming through such a channel rather than spreading around the surface. A drop of oil that easyly will get kick-off by the tremendous accelleration the follower gets during its lift and so, disappearing into the sump instead of offering services to cam and follower.
For improving the oilflow through and by the camfollowers, I extended the upper holes upwards (about 2 mm), flattenend the entrance of the upper hole and extended the lower holes downwards (about 4 mm and still just before the hardened part of it). I all campositions now there is a lot of gateway for the oil to pass through.
As suggested by FRM, the topedges in the bores are camfered (they were already) to collect oil aroung the camfollower.
I kept my copper standpipe in the head because I am convinced that the is more than enough space for the oil to flow down along the pushrods (320mm2) and above, it will act as overflow just in case. I made rubbers pipes in the "useless" holes in the block (picture).
greetings, Huib
Huib Bruijstens

Here is the picture

Huib Bruijstens

Huib, can you please mail that picture to me?

vdveery5888 at gmail dot com.

Are you very sure the rubber is oil resistant? I'd hate to see them dissolve in the engine....
Willem vd Veer

Huib, Just my opinion, but nothing about those rubber tubes being stuck in holes in an area of hot oil and vibration looks good to me. The risk of something working loose and the resulting damage far out weighs the gain....but what do I know. Perhaps i am misinterpreting the picture. Regards, tom
tom peterson

Thanks for sharing your concerns. The rubber I used is "automotive quality", the small one is petrol tube and the thicker one is a heater tube. I guess they will not get eaten by the oil.
Since the place is quite good accessable, I will check that perodically.
The tubes are really thickwall : 23x15mm diameter and 10.5x5mm diameter. Length about 30mm. In the middle I cut a circumferencial groove (Dremel) of about 1-2 mm deep. The hole in the block has a kind of edge due tue the casting proces. The tubes groove is catched by this edge.
I played with several diameter tubes and the one selected really needed quite some force to get pushed and wobbled and hamered in. Because the hole in the block more downwards does not get wider, I recon that no way the tube can go down by itself, also not if hot and oily. Getting out: I needed plyers and force to get one out. But if one would come out, in that surrounding not much harm can be done by a piece of rubber. It is to big to enter the camfollowers holes and it cannot get in between camfollower and pushrod. So, it wil be hanging or dancing around till next inspection of the sidecover.

If my block would be nacked (no camshaft, no crankshaft, than I would have made these tubes from copper as in the head but with those shafts installed, i could not get access from below.
But than, I would have considered FRM suggestion to change the holes with grooves so that the oil would flow to the cam entering side.
Greetings, huib
Huib Bruijstens

This thread was discussed between 25/01/2013 and 11/02/2013

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