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MG TD TF 1500 - Cam followers

Hi Everyone,

On a recent examination of my TD engine whilst it was out of the car I was shocked at the condition of the cam follower contact faces.

When I built the engine in 2008 I modified the followers by extending the lower oil slot and grooving below it to the cam face. The cam was a Crane 340-0002.

I spoke to Moss who claimed that they do not have a problem with them!!!! and then to Peter Edney who suggested that the followers should be regarded as a service item and changed every 5000 miles. Judging by the condition of mine I think he might be right.

Anyone else received this advice?

Regards,

David



David Tinker

The Blowers manual says about 10000 miles for them. If I had the money I would go with the rollers,
T Maine

I have a near perfect set (but not perfect enough to put back in) I pulled out after 20,000+ miles, I would be looking at the cam lobes right about now.

Put one of Len's cams in, now I don't worry about it.

Blair
Blair Weiss

Interesting to see the way the oilholes are elongated: not all the way through. Never seen these before. Huib
Huib Bruijstens

did you number them? I have seen followers like this before and I thought strange as the wear pattern is not uniform. as the follower should rotate, then wear should be all around? yes. 2 look ok?

followers? cams indeed, all rather complicated in their design of movement, what is the method in a td of getting them to turn, is the cam flat or beveled, what thrust control is there?
mog

Huib,
I had modified the followers myself based on the modification that Peter Edney has on the followers he supplies. With the Crane cam the lobes are on a larger base circle so that the followers sit higher which means that if the holes were not extended the cam/follower faces may be starved of oil.

mog,
No I did not number them but the wear does appear random. The cam lobes are tapered side to side by almost 2 thou which promotes a turning motion to the follower.

Many thanks,

David
David Tinker

I've modified mine in the same way. Sound crude, but just used a worn grinding disc in an angle grinder to take a shallow slot down to the base. Too soon to tell if it made any difference.
Dave H
Dave Hill

Here's a (bad) photo of two followers that were resurfaced and hardened. I removed them to check for wear patterns during running in.

The left one is rotating as it should, the one on the right isn't. You can see clearly that a non rotating follower has a very distinct almost rectangular wear pattern.

Willem van der Veer

If needed I have 8 serviceable used cam followers, 2 need resurfacing.
And a new camshaft.
Len Fanelli

You could have your lifters and cam checked & hardened etc, did you put new rods&rockers in ?
mog

David, do you remember details of your running in procedure back in 2008? Huib
Huib Bruijstens

Hi All,

Thanks for your input, one thing I forgot to mention was that during my conversation with Peter Edney he said that the surface of the followers should not be harder than the cam lobes. Makes sense which is why I decided to buy new followers and modify them by elongating the holes then examine them every 5000 miles.

Huib,

No special running in procedure other than lubricating the cam and followers with the grease that Crane supplies. For the engine I used Running In oil for the first 500 or so miles and then Morris Classic Goldenfilm 15/50.

With the reconditioned engine I was advised to get in and drive it quite hard right from the start and up a few steep hills!!

Good luck,

David


David Tinker

This is what I saw after 10000 miles of pretty hard driving with the Crane cam and tappets.

MG LaVerne

Another one

MG LaVerne

The initial start up is critical David which I guess is what Huib is inquiring about. It seems it's ESSENTIAL to run the new followers in at (from memory) 2000 RPM for about 20 minutes, with the first 5 minutes really, really important. The revs/duration are detailed in the archive somewhere. Cheers
Peter TD 5801
P Hehir

All were clearly spinning as they should. Moss sold me another set at a largely discounted price. Another 10000 mile check revealed about the same condition as these. I sent them off to Delta cams for reconditioning and have not inspected them since. I was advised by an experienced XPAG engine builder to plan on replacing them as often as I would Spark plugs due to design faults of the engine. I'd say he is correct. I'd say that Len's roller cam would be the way to eliminate this.

I don't see the part number for your cam on either Moss USA or Moss UK, but I'm wondering if the followers were crowned as required for the offset lobes which it appears that you have based on the photo. If you used flat followers with the off set tapperd lobes, I think that would explain why they were not rotating as they should. Just some thoughts.

MG LaVerne

No one has jumped in about the Zinc/Phosphorus in the oil. Does the oil you have been using have a lot of that stuff in it? With an admittedly small sample size (3), years ago XPAGs did not used to have this problem. My own motor had about 12K miles on the tappets and they were in very good shape at rebuild. Moss noted the problem at first with the large base circle cams, which did hold the lifters up so high minimal oil could drain onto the cam/lifter face, hence the elongated holes. Seems to be an across the board problem now. I don't think anyone really knows if it is the oil or bad metal or what. George
George Butz

did you measure the follower bore?
mog

Hi David and others,

I was told by Tony Ohlmeyer (MG expert from the 1930s to 1980s) that the followers were "chilled" iron and got harder as they are faced back further. So they should never be hardened but they can be ground when necessary. (I guess there is a limit to how much metal can be removed.)

It is far better to lighten the valve gear than to fit stronger springs. Followers can be lightened a lot by chamfering or radiusing (inwards) the top edge and opening up the holes. Rockers can be ground smooth. The spring caps can be slightly reduced in radius, chamfered and ground smooth. The inner spring shrouds can be cut back (hardened, so use grinder). Beware of using alloy pushrods unless you give extra valve clearance to compensate for their greater heat expansion rate.

I believe the cam follower surface is meant to have a very slight positive radius (protruding a few extra thou at the centre). That is how I do mine. Has anyone else heard this?

Bob Schapel

R L Schapel

This thread was discussed between 29/01/2015 and 06/02/2015

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