New Camshafts needed

[JerryL770]

Took my E-type to the Splined Hub today for a general service, oil change etc. I asked for the valve clearances to be checked because I thought it sounded a bit noisy. The cams are worn out, through the hardening.

Where to get replacements? SNGB only has an exhaust cam, no inlets.

Any advice on reasonable cost source for decent cams appreciated.

Heard of Newman Cams? They have a pair at £400 +VAT SC Parts: £834 incl VAT OUCH!!

Thanks, Jerry

[chrisfell]

I'd be asking why the cams wore out before fitting replacements. They don't normally wear unless there has been a breakdown in oil delivery.

Many years ago my engine had just such a failure, It was caused by swarf, from an unrelated failure of big end split pins, blocking the cam oil feed pipe. Additionally, the break down in oil delivery trashed several of the cam followers.

This was the damage:


If yours looks like this, something is preventing sufficient oil getting to the cams.

[JerryL770]

Thank you Chris. I have just been advised by a friend that as long as the oil feed has been OK there's little likelihood that the lobes have worn through. Measurement of the lobe heights need to be checked?

I will go tomorrow for a look see myself.

[Heuer]

Piper Cams have a choice depending on how much extra power you want (specs are for XJ6, not sure if they apply to the E-Type): https://www.pipercams.co.uk/Camshafts-C ... -CYLINDER/

Here are the cam specs from the Forum Knowledge Base: Camshaft specs (standard, fast road, race etc): https://www.dropbox.com/s/og5m55kzkh9zoll/cams.jpg?dl=1

Rob Beere can supply: http://www.rob-beere-racing.co.uk/cams.html

"The XK cams were quoted as 15,57;57,15 (252 degrees duration) with 0.375” lift, being of simple geometric design, originally with clearances of 0.004” inlet, 0.006” exhaust, then evolving to a more modern cam profile based on parabolic acceleration curves in the late 1960s with constant velocity ramps allowing the clearances to be opened up to 0.012 – 0.014”."

[JerryL770]

Thank you David.

Apparently the cams fitted have only 2 bolt fixing of the chainwheels (which have 4 bolt holes) which would make them S1 cams? And therefore should be set with .004/.006" clearances. If they had been set with 12/14 thou clearances, this would account for being noisy.

Is it general opinion that XK cams simply don't wear out from normal use unless starved of oil? as Chris states?

[mgcjag]

The 12-14 cams also had 2 holes but also have a groove around the flange...even later 4 holes but no groove...have a look here..http://www.georgiajag.com/Documents/Camshafts.html re do cams wear out in general without oil feed problems....icant ever remember it mentioned before on the forum.....Steve

[christopher storey]

I think it unlikely that you would get cam wear without either some lubrication failure ( which in my limited experience of it usually results first in seizure, or some foreign body intervention, unless at some stage new camshafts had been installed but using the old buckets , which is never a good idea . As far as replacement is concerned, unless you want to pay top whack for new ones I would try David Kelly dismantlers at Rhostyllen, Wrexham, who usually has a stock of XJ6s which provide all sorts of used spares !

[abowie]

While obviously I haven't seen your cams, in over 20 ground up restos over 10 years with the boys we have not ever had to bin a set of cams to my knowledge. They just get cleaned up and put straight back in.

If there is doubt about your cams why not just get them reground and surface treated?

Or if they are really completely buggered buy a used set as Christopher suggests.

[JerryL770]

Thank you all. We will have a good look this morning.

Thanks for the link Steve. I saw that a few days ago and was wondering where it was. Bookmarked!

[JerryL770]

This is the problem, apparently:

20200821_103050s2.jpg (207.52 KiB) Viewed 9644 times

The stripes are reported as evidence of wearing through the hardened layer. This is the only lobe on which such marking can be seen without rotating the engine. The cam is a S2 cam, groove on the flange.

This cam will be extracted next week and carefully measured to try to establish the amount of wear. I'm assured that a suitable solution will be found . . . this to be agreed, whatever it turns out to be

[chrisfell]

The damage on my car, which appears to be worse than yours, was only found some 13,000 miles after the event which caused it. The damaged cam was the exhaust cam, and I found swarf blocking that side of the oil feed pipe. It was actually in the banjo bolt in the cylinder head.



Damage included the camshaft, three followers and the camshaft bearings. All were replaced.

Once I'd found the cause of the wear, I was happy to replace the trashed parts.

[JerryL770]

Well, we came to the conclusion that there is little to worry about. I spoke also with our local engine machine shop which has years of experience refurbushing XK engines including cylinder heads and they cannot recall a need to replace a cam which has not been abused by lack of oil. Excess wear will most likely show most easily by wear marking on the cam followers - none visible.

So all my valve clearances were checked and it was closed up. The carb tune has made tickover much better.

[rswaffie]

Hi Jerry
I’ve been reading the posts a couple of time’s and I’m still confused.

You asked for valve clearances to be checked and was told the cam(s) had worn through the hardened metal on the lobes.
You went and had a look and your pics apparently show the evidence of the wearing.
You’ve had another look and agreed nothing is wrong and issues are resolved via correct clearances.

So no wear to the hardening? What was the striping in the pics?

[JerryL770]

So no wear to the hardening? What was the striping in the pics?

There might be some wear to the hardening, question is: how much? Nobody seems to be able to give a definitive answer, it cannot be found by dimension measurement. Andy at Splined Hub worked on Subaru's in the States and would replace cams when such "evidence" appeared and has carried this through to the XK engine. We know how performance Subaru's are likely treated

Our opinion is to suck-it-and-see. I don't do huge mileage and so it's probably not cost effective to spend a lot on what might just be speculation.

[abowie]

There might be some wear to the hardening, question is: how much?

I don't know. It depends on the hardening method and I have no idea how the original XK cams were hardened.

Modern cams are often "Tufftrided" (ferritic nitrocarburizing); this only produces a maximum 2 thou thick hardened layer.

Heat or induction case hardening can produce between 10 to 60 thou; an enormous amount more, but can result in the piece being distorted which you don't want with a camshaft.

I don't think that Tufftriding a cam is a difficult process as it seems to be offered by cam grinders. If you were concerned you could get your cams done, and as above you could get the cam grinder to give the cams "a lick" to ensure the profiles were spot on.

As I said, the guys I work for never do anything to the cams on our restos and AFAIK we have never had a problem with any of the cars.

[tinworm]

The only time I have had to scrap some XK camshafts was due to an engine being run for a long time with filthy oil - an imported US engine - all the journals were undersized , the cams were fine amazingly.

Barrie

[PeterCrespin]

This thread went wrong in the first post.

XK cams are not case hardened AFAIK. They and the buckets are made of chilled iron and are through-hard. The wiping/turning movement of lobe over tappet prevents wear from being a problem unless starved of oil (and even that has to be prolonged). I ran my first race bike with aluminium tappets I fitted that weren’t even anodised, just raw Dural, operating on a similar burnishing principle. The engine never had clearances open up during my time with the bike.

Clean the cams inside and plug both ends. Avoid braided hoses made for brake applications - especially if you’ve already had trouble and a few components might be marginal?

[JerryL770]

Thank you Peter. That is most re-assuring