barkerwilliams Posted January 26, 2015 Report Share Posted January 26, 2015 There are many differing camshaft profiles available for a new shaft, but does any new make or style of camshaft offer improved rocker shaft oil flow? Quote Link to post Share on other sites
Nigel Triumph Posted January 26, 2015 Report Share Posted January 26, 2015 No, choice of cam won't influence how much oil reaches the rocker shaft. Provided the engine bottom end is in good condition, sufficient oil will reach the rocker shaft. There is an external oil feed pipe available as an accessory from the usual big suppliers but views on its efficacy vary. Many would say that piping extra oil to the rockers simultaneously steals oil flow from the crank and cam, and risks high oil consumption as all the extra oil up at the rockers finds its way down the valve guides. Just make sure the engine is in good condition, use good quality oil and filters, change them regularly and all will be well. Nigel Quote Link to post Share on other sites
barkerwilliams Posted January 26, 2015 Author Report Share Posted January 26, 2015 I have an external oil pipe, but as the original rocker oil feed is governed by the spiral in the camshaft rear journal I wondered if any manufacturer had improved the throughput of this journal. Quote Link to post Share on other sites
Ragtag Posted January 27, 2015 Report Share Posted January 27, 2015 I have an external oil pipe, Your car, your choice but I wouldn't. Quote Link to post Share on other sites
TRTOM2498PI Posted January 27, 2015 Report Share Posted January 27, 2015 Hi There, There are many different cam profiles out there in the market place, chose wisely. There is not a need / requirement for an external rocker feed / supply. If there engine is built correctly, and all oil ways / galleries clear, you will not have an issue to supply oil to the top of the engine. Cheers. Quote Link to post Share on other sites
TriumphV8 Posted January 27, 2015 Report Share Posted January 27, 2015 The amount of oil metered to the rockers is done by the flat spot milled into the last cam bearing. There are two oil lines feeding the rear bearing. One comes from the pump, one goes to the head. They are close together but not connectet. When the flat spot drives over the openings they are connected via the flat spot for short time and oil splashes into the line to the head. Than the flat spot has passed and the flow stops untill next rotation the process starts again. It has nothing to do with the spiral lines that only spread the oil. That can be increased easily by grinding the flat spot bigger so I wonder why people like the additional oil feed to the rocker but anyway the rockers have no bearings like crank that need constant oil pressure. Also the whole cylinder head is designed for little oil spray and if oil supply is increased something must be done not to feed the valve guides with too much oil leading to white smoke from exhaust, oil consumption and deposits in the engine. Much better idea is to pay attention on bearings of the rockers. Tuftrided shaft and bronze bearings help, the radical way is full needle bearing roller rockers. I use the additional oil feed when running in for good oil supply to the cam but later strip that off because I think its not required: When used rocker items are bad quality it cannot cure the problem if all is in in proper order it is not necessary and lets only the oil pressure drop. The only good reason to use additional oil feed are worn rockers and from some strange reason not to change them to better ones: The worn rockers let the oil drop and as the oil is feed from one side the opposite rockers, also wounded by excessive wear, will get even less or no more oil. Quote Link to post Share on other sites
barkerwilliams Posted January 27, 2015 Author Report Share Posted January 27, 2015 Andreas, many thanks for your answer. Yes I now have roller rockers, hence the oil pipe. But there is so much controversy whether an external pipe is needed, or even damaging to the lower engine. As I am vaguely planning a bottom end rebuild I was wondering if a cam manufacturer had improved the feed up to the rocker shaft. From your answer that would seem to be very easy to achieve on a camshaft swap. Not as easy as fitting the external pipe though; so I presume the external pipe is for expediency when swapping rockers. Alan Quote Link to post Share on other sites
john.r.davies Posted January 27, 2015 Report Share Posted January 27, 2015 (edited) I'm sure that the external pipe was inspired by Kastner's Octopus. No that he ever ran n external pipe to the head but tithe main crank bearings to avoid the unequal flow he found. It was a tour de force of engeering when the external head supply was its bastard child. Andreas , Your ex plantation that it's the flat on the rear camshaft bearing not the scroll is a revelation to me! Thankyou! Now we need some tribology PhD to work out how much bigger it should be to oil a roller rocker! John Edited January 27, 2015 by john.r.davies Quote Link to post Share on other sites
barkerwilliams Posted January 27, 2015 Author Report Share Posted January 27, 2015 John, Yes we need the loan of a block, a scrap camshaft we can file down and a Black & Decker to spin the shaft and we could experiment on flow rates - and then goodbye external pipe. Alan Quote Link to post Share on other sites
RogerH Posted January 27, 2015 Report Share Posted January 27, 2015 Hi Alan, why not machine a groove around the rear bearing journal on the cam so that the oil feed and delivery are constantly connected. Vary the size of the groove to vary the amount. Roger Quote Link to post Share on other sites
graeme Posted January 27, 2015 Report Share Posted January 27, 2015 John, Yes we need the loan of a block, a scrap camshaft we can file down and a Black & Decker to spin the shaft and we could experiment on flow rates - and then goodbye external pipe. Alan Hi Alan, why not machine a groove around the rear bearing journal on the cam so that the oil feed and delivery are constantly connected. Vary the size of the groove to vary the amount. Roger I would suggest caution here as there is a theory that the rear camshaft scroll/flat has a major effect on the oil pressure. Too big a space and the oil pressure will drop! Cheers Graeme Quote Link to post Share on other sites
Guest ntc Posted January 27, 2015 Report Share Posted January 27, 2015 I would suggest caution here as there is a theory that the rear camshaft scroll/flat has a major effect on the oil pressure. Too big a space and the oil pressure will drop! Cheers Graeme Graeme Correct that and the fact at the time that replacements were made of cheese is why so many failed. Quote Link to post Share on other sites
Tom Fremont Posted January 27, 2015 Report Share Posted January 27, 2015 For the record, my TR250 driver's engine ( on Webers with ~ 150 BHP ) has done over 100K miles with an external oil feed line. Oil consumption is 1 quart every 3000 miles and oil pressure is 65 psi @ 2000 rpm when as hot as it gets ( with oil cooler and thermostat ). There are no valve guide seals. Yes, the oil grooves are critical in controlling hot oil pressure. Too large and you won't have decent pressure no matter how snug the fit in the bearings. I proved this years ago when switching a cam with 150 miles on it suspecting its grooves were too large and the pressure went from 35 psi @ 2000 rpm hot to 65 with the new cam and its relatively diminutive grooves. OTOH, too small or non-existent grooves can cause seizures . As for the function of the original rocker oiling, I would say that the pressurized oil finds an escape route to the rocker gallery precisely when the flat is aligned with it once per rev of the camshaft - a guess would be 10% of the time or less. Quote Link to post Share on other sites
Peter Cobbold Posted January 27, 2015 Report Share Posted January 27, 2015 Andreas' flat spot would ensure that for the brief period that it aligns inlet and outlet the oil reaches the rocker shaft at full gallery pressure. It will briefly squirt out. I can envisage squirting being better than a continous 'oozing' flow, of the same average rate, at a much lower pressure. Peter Quote Link to post Share on other sites
bluebob Posted January 27, 2015 Report Share Posted January 27, 2015 I have had my car for 26 years now and fitted an external feed years ago which caused to much oil getting where it wasn't needed as already mentioned, then I found out the reason for the external feed was produced for a replacement feed as if the oil had not been changed/maintained at the service intervals then the internal oil gallery could/would sludge/block up oil causing damage to rockers etc this was a cheap fix rather than have the engine to bits etc, hope this helps bluebob Quote Link to post Share on other sites
whatmore179 Posted January 27, 2015 Report Share Posted January 27, 2015 If you have roller rockets you need the extra feed. Limit the flow by soldering the banjo and drill in a 1 mm or less hole. Steve Quote Link to post Share on other sites
barkerwilliams Posted January 27, 2015 Author Report Share Posted January 27, 2015 Reading all the contributors above and many other similar topics there seems to be a general consensus that the additional rocker feed pipe delivers too much oil, and that the original design, whilst effective on an engine in good condition probably supplies only just enough to the rockers, not quite enough if upgraded to roller rockers. Is there any information out there on what any rocker assembly needs in any other make or type of engine, is it 10ml per thousand revs, or 1 litre per thousand revs? Contributors above suggest that a modification to the camshaft would be relatively easy and could be engineered to produce any particular oil flow required, if only there was an oil flow target to aim for. Most oil flow in an engine is cooling, just a percentage for lubrication, is the rocker problem one of cooling, or lubrication? Quote Link to post Share on other sites
Tom Fremont Posted January 27, 2015 Report Share Posted January 27, 2015 A hard chrome plated rocker shaft with bronze bushed arms will ensure indefinite life of the rocker assembly, at least with the rocker feed but likely without as well. This was not the original spec but there are ( were? ) specialists in the 'States who provided rebuilt assemblies that way; I have them in both my engines. Quote Link to post Share on other sites
Richard71 Posted January 27, 2015 Report Share Posted January 27, 2015 Tom, are you referring to "The Rocker Arm Specialist" of somehwere (I can't remember) in the U.S. They rebuilt an assembly for me to the spec you mention above. As yet the assembly is unused and untested. What benefits have you noticed and are you suggesting they may no longer be trading? Quote Link to post Share on other sites
Tom Fremont Posted January 27, 2015 Report Share Posted January 27, 2015 Hi Richard, Yes - that's what I have in mine and the benefits are no apparent wear after at least 50K miles ( I'd have to check the log book to see the actual figure ). I haven't had to adjust clearances in years on my driver, though I check every 10K miles or so. You shouldn't ever need rocker renewal after fitting one of theirs. They touted a finer product than factory, seemingly with reason. I haven't tried to find them in recent years but I think they have at least moved if they exist at all. Quote Link to post Share on other sites
TriumphV8 Posted January 28, 2015 Report Share Posted January 28, 2015 Reading all the contributors above and many other similar topics there seems to be a general consensus that the additional rocker feed pipe delivers too much oil, and that the original design, whilst effective on an engine in good condition probably supplies only just enough to the rockers, not quite enough if upgraded to roller rockers. Most oil flow in an engine is cooling, just a percentage for lubrication, is the rocker problem one of cooling, or lubrication? Do not think they need more oiling. As additional oil pipe for TR6 is well known the roller rocker manufacturers would have recommended them if better. Many rollers have similar but improved bearing (Bronze on steel shaft) some are full rollers with needle bearings which need less oil anyway. Steel on steel ex works was okay for 100k+ miles and really not the best solution. The improved version is much better and fit and forget. The only thing I do is take a look at the flat spot at the cam to ensure that it has similar size and position like expected what can be compared to an on old ex works cam. If somebody wants to double check I would recommend to watch the idling engine without cover and look if oil comes out at every rocker especially at the item far away from oil feed located at the water thermostat side. Quote Link to post Share on other sites
SpitFireSIX Posted January 28, 2015 Report Share Posted January 28, 2015 ******* I proved this years ago when switching a cam with 150 miles on it suspecting its grooves were too large and the pressure went from 35 psi @ 2000 rpm hot to 65 with the new cam and its relatively diminutive grooves. **********. ***** Hi Tom, Do you think that 65PSI @ 2000 when at operating temperature is on the high side? If you have nice and tight modern clearances, should you not look at reducing the viscosity of your oil to increase your oil flow? Just curious. Cheers, Iain. Quote Link to post Share on other sites
Tom Fremont Posted January 29, 2015 Report Share Posted January 29, 2015 Hi Iain, 65 psi @ 2000 rpm is the high end of the proper range for these engines indeed. Mine would be 5-10 psi lower in summer without an oil cooler so I don't think it's out of line. I do employ a heater overnight in winter below freezing if the car is to be driven the following day since I'm using 20W-50 oil! Still, when idling at 550 rpm in summer the pressure drops to 14 psi which makes me a bit uncomfortable so lighter weight oil is not on for me. So far the oil seems to be getting to where it is needed; the engine shows no sign of wearing out in the foreseeable future with 108K on it... Cheers, Tom Quote Link to post Share on other sites
john.r.davies Posted January 29, 2015 Report Share Posted January 29, 2015 Tom, You don't say if you have a flow-limiting restrictor in your external supply. And - forgive me, I forget who raised this - the restrictor isn't a simple answer. You suggested filling the banjo with solder and drilling a 1mm hole. That would produce a tube much narrower than its length, in contrast to an orifice, a hole in a plate, that is much wider than its length. The flow through the first, the tube, is determined by Pouseuilles Equation, the fourth power of the radius, the length and the viscosity of the fluid. Flow through an orifice is more complicated, as the flow goes turbulent, and depends on the density. So an orifice is to be preferred, as the viscosity of the oil varies with temperature, but it's important to define what sort of orifice, as the shape of the hole, for instance drilled or pierced, is critical.. The pragmatic solution is to note the oil pressure, hot engine and at a certain RPM. Fit the external supply - the pressure will be lower. Now fit progressively smaller orifices (?) until the pressure is restored. That is where the 1mm - an orifice, not a tube - comes from. John Quote Link to post Share on other sites
barkerwilliams Posted January 29, 2015 Author Report Share Posted January 29, 2015 John, Could not agree more with your post. I started this thread because I do not understand what supply is needed for the rocker shaft. there is mention of roll pins in the external feed pipe, or other restrictors such as proposed above. But there seems to be no target supply to aim for. The internal camshaft supply pulses oil to the rocker shaft for perhaps 60 degrees of camshaft rotation, crudely this is about 1/6th of the oil supply from the external additional pipe and furthermore it will always pulse oil at the same point in camshaft revolution when one or two valves are working their hardest - the rest of the valves will have to take their chance on the reservoir effect of the rocker shaft and feed pipes. The original design is more or less (depending on who you believe) good enough for the rockers. So why is the additional pipe capable of delivering 6 or more times that quantity of oil? There may be additional flow from the external pipe due to pipe diameter considerations. So I was asking if a camshaft manufacturer had adjusted the camshaft to increase the rocker oil feed so that an external pipe would not be needed. But it seems not. TR owners seems split between leave it original, and fit the external pipe, I would like to be a little bit better informed before I commit permanently . I am now fabricating a fitting to measure the oil pressure (second temporary gauge) at the head bolt where the second pipe attaches together with a needle valve in the external additional oil pipe. I can then measure the "original pressure" with the pipe shut off and then all points to full bore on the external pipe. In the workshop with the rocker cover off perhaps I can determine what appears to be a good supply to the rockers and measure that pressure. I will then probably leave the needle valve in the external oil pipe. It might lead nowhere but I am trying to proceed on the basis of some sort of factual results. Quote Link to post Share on other sites
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