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How can I find a good performance Camshaft?


geharvey

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Years ago, I purchased a Piper 285 cam for my Vitesse engine rebuild. I purchased a kit with cam, followers and valve springs. The cam came with a bottle of ‘cam lube’ what could go wrong? I followed the fitting instructions to the letter, started the engine and ran it for 20 minutes above 2000 RPM before letting it tick over.

After 500 miles, at the rolling road, the performance was not as good as expected. Eventually I took the head off and found that most of the cam followers were concave and had chunks of metal missing. The cam also was badly pitted.

For my next rebuild; new engine, new pistons re-grind, re-bore, new cam, followers and springs. This time I had purchased a Kent cam kit, thinking that the Piper product was of inferior quality. Same start-up procedure, plenty of cam lube, start and run for over 20 minutes at 2500-3000 RPM. I ran the car for 1500 miles and it seemed OK. Once again, a trip to the rolling road reviled a lower than expected performance. I have just taken the head off and once again, cam and followers are chewed to blazes. What do I have to do to get a good cam? Has anyone else had the same problem? Where can I get a replacement cam from now?

I am very disheartened about the whole thing. :'(

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It sounds so much like the modern oil and flat tappets problem:
http://www.foreignpartspositively.com/Article1.htm

Are these old tappets run for years on leaded fuel, new "old stock" tappets, newly manufactured replacement tappets, or what?

I have heard that the latest flat tappets aren't hardened like the originals.

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Try Newman Cams.  Only heard good things about them.  Buy the tappets from them as well.  Ask them for their recommended run-in procedure.

The points Bill makes above are valid - use an oil intended for older engines - should have correct ZDDP levels.

On other thing - what valve springs are you using.  Some of the ones sold as performance ones are way too hard and this won't help matters.  If using roller rockers with increased ratio this will also increase camshaft loading.

You also need to be sure that the springs are not getting coil-bound before full lift is reached.

Cheers

Nick

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Nick_Jones wrote:


The points Bill makes above are valid - use an oil intended for older engines - should have correct ZDDP levels.


Anybody got a list of suitable oils? seems I can't find much about ZDDP levels in the oils. Maybe I am not looking in the right place  :B

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I use 20/50 multigrade mixed with STP about 50 -50 and cover the cams and followers as I assemble then always turn the engine over without plugs etc to get the oil circulating etc. never had any problems .

Agree with the comment on Newman cams, used them when I was racing no probs and David Newman is very knowledgable.

Cheers,

Nigel

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Hello,

Thanks very much for the information. I had no idea about modern engine oils and flat tappet engines. I always use Duckhams 20/50. I guess this is one of the bad ones, but most oils are very thin these days and they bring the oil pressure down.

I always use the tappets and springs from the manufacture of the camshaft, to prevent any problems.

I did fit roller rockers for a while, but the engine barely managed standard power output on the rolling road, it worked much better with standard rockers, eventhough the roller rockers were only 1.5:1 (1.42:1 standard). I did also check that the valve springs did not close completely when fully open. Kent Cams confirmed that a rocker ratio of 1.5:1 was accepable for my cam.

I don't know what to do now; the correct solution is obviously a new cam, follower and springs. This however, is the most expensive solution.

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cliftyhanger wrote:


Anybody got a list of suitable oils? seems I can't find much about ZDDP levels in the oils. Maybe I am not looking in the right place  :B



Castol Classic, Pentrite, Miller,  MIllers seem to have a lot of info on ZDDP


http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9014106&contentId=7027097

http://www.penriteoil.com.au/products/classic-car-oil/classic_engine_oils_heavy

http://www.millersoils.net/1_Millers_frame_CLASSIC.htm

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In both cases, I had a high pressure oil feed to the head, there seems to be plenty of oil getting to the top of the engine. All the cam followers are full of oil.

I went to my local motor engineer to pick up my new head (not that I have an engine to put it on at the moment). I asked him about the cam failure and the situation with modern oils and flat tappets. He said that they had seen the problem several times and they recommend the use of an oil additive for the first 500 miles (He could have told me that when he did my last engine!). It looks like a different oil and an additive will be required next time.

The most concerning point is that the bits of cam and followers are now floating round my engine. They have all been through the oil pump I expect. I dread to think what that is like now. Still get good oil pressure though.

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geharvey wrote:
In both cases, I had a high pressure oil feed to the head, there seems to be plenty of oil getting to the top of the engine. All the cam followers are full of oil.

I went to my local motor engineer to pick up my new head (not that I have an engine to put it on at the moment). I asked him about the cam failure and the situation with modern oils and flat tappets. He said that they had seen the problem several times and they recommend the use of an oil additive for the first 500 miles (He could have told me that when he did my last engine!). It looks like a different oil and an additive will be required next time.

The most concerning point is that the bits of cam and followers are now floating round my engine. They have all been through the oil pump I expect. I dread to think what that is like now. Still get good oil pressure though.





I'm sure I've read that those oli feeds actually make the supply of oil to the front bearings of the engine even worse than standard

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I think the cam faces are lubricated by splash (oil flung off big ends mostly) from below - hence the running at 2000 rpm for 20 minutes after first start to ensure plenty of splash.

I've found (and I've heard others mention this too) that the two lobes/followers at the ends of the engine ie 1 & 6 exhaust lobes (or 1 & 4 in  a 4 pot) tend to fail first.  On my current engine (standard, high mileage), No1 exhaust follower is very pitted and No 6 just starting to pit.  No 1 exhaust lift measured 1mm less than the others in summer 2008.  The car's done another 12k odd since then so probably rather less now  :(.

I suppose this is because these lobes are "sheltered" on one side and only get splash from 1 direction.  Makes the correct lubricant all the more important.

Nick

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Hi, if you put the stuff on as above, it will stay put till you want to start it up

I my self, have been useing a spray on bearing film,

spray it on cam / tappetts, and agive it a few thick coats,  and let it set,.

you can turn engine over and over , and it wont come off,

but will dissolve with hot oil, so is good for  starting up, turning over ect,

been ok with mine, over the years,


if you going to get a new cam, Did you mention  roller rockers, !!

well if you going to get a cam with these,

THEN TELL the cam grinder, you got them, and the ratio,

a standard cam prophile, is different for ones with higher lift rockers,

the cam will work, but will no be as good, as one to match the rockers,

a good grinder should know this, but if they say, it does nae matter, then GO some where else,

I got  PIPER do an   experimentle one , and its really good,  for the first go !!!

only 268 degs,



there a  rr print out , at bottom of page, on photo bucket

regards Marcus

regards Marcus

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I used the cam assembly lube, supplied by the manufacturers in both cases, I think that the cam survives while the lubricant is there and then, once washed off by the engine oil, as it should be, the problems start.

As I understand it, the idea of running the engine at above 2000 RPM for 20 minutes is to prevent the situation where two rough pieces of metal are rubbing together to produce heat and if they are moving slowly, the metal can momentarily weld itself together and the weld breaks, leaving a minute lump of metal on one surface, which comes round on the next revolution to contact with the other surface and generate more heat. At above 2000 RPM, the metal does not have a chance to weld itself together and the metal surfaces ware together to form a smooth surface which will then run at a slower speed without producing as much heat.  

If the oil lubrication is not as good as it should be, this localised heating will cause the damage that I have seen. It also seems to be random; some lubes are fine and others have characteristic pitting. No. 1 is lightly pitted, No. 2 is fine, then No's 3 & 4 are quite bad. The cam is actually in quite good condition, compared to the followers. The followers are very badly pitted and some have started to concave.

I take the point about the high pressure oil feed to the head, dropping the oil feed to the rest of the engine, but I have seen some very worn rocker gear due to oil starvation. It's very difficult to know what to do for the best.

Graham.  

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My mate has just fitted a Newman Cam + followers and it is giving best ever performance.

http://triumphwestoz.blogspot.com/2009/06/cam-failure-and-remedy.html

So theoretically it can't have eaten itself on initial start up LOL. Ground on a new blank with a large base circle. Works for him. We used Penrite assembly lube (Molyslip??) plus overfill the sump by a litre (gets the splash lube thing really happening). To be sure to be sure tuftride the cam too..

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geharvey wrote:


I take the point about the high pressure oil feed to the head, dropping the oil feed to the rest of the engine, but I have seen some very worn rocker gear due to oil starvation. It's very difficult to know what to do for the best.

Graham.  




Complete new set of rockers, pedestals and shaft… £80, and takes only an hour or so to replace the lot and reset the gaps.


New camshaft or bottom end rebuild?

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Hello,

Thanks to everyone for their comments. I have ordered a new camshaft and followers, plus a bottle of ZDDP oil additive. I may well buy a new set of rockers and not bother with the roller rockers, as they did nothing for the performance.

I will post the results of my rebuild, as soon as I get my engine running again,

Graham.

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Well, I;m back on the forum. I have my new cam, new followers, new head and I am ready for re-assembly. However, I tried to remove the cam this afternoon. The camshaft will not come out. This is because the 3rd journal (the one above the oil pump) is badly scored and won't pass through the second journal.

This is obvoiusly due to the fact that the metal pieces that have broken off the cam and followers, have been throught the oil pump and thanks to an ill fitting, MOCAL oil adapter plate the metal parts have bypassed the oil filter and have been pumped round the oil gallery and to the cam journals and big end and main bearings. This of course meens that the block is now scrap! If I'm very very lucky (I don't think so), I may be able to use the pistons again, but the rest of it will be going to the scap yard, with the cam still jammed in the block.

I was very upset with the dammaged camshaft, now I am beside myself with the prospect of starting all over again.

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geharvey wrote:
Well, I;m back on the forum. I have my new cam, new followers, new head and I am ready for re-assembly. However, I tried to remove the cam this afternoon. The camshaft will not come out. This is because the 3rd journal (the one above the oil pump) is badly scored and won't pass through the second journal.



Why not have the camshaft bearings line bored to fit proper cam bearings? This will save the block and is far better than running the cam direct in the block.  You can always cut up the old camshaft to remove it

mike

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geharvey wrote:
Hello Mike,

Thanks for your comment, I hadn't thought of that. Having the cam running in the block is not really a good design. The Spitfire block has white metal cam bearings (I think) I will have a chat with my machine shop on Monday.

Graham.  


There are not too many machine shops equipped to do this, but if yours can they will fit Spitfire cam bearings. good luck

mike

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