Camshafts

[marshman]

Just come to fit the camshafts and though I thought I knew which one came from which head I'm not sure now:?

I stripped the original heads to get the valve spings etc outand I am certain I labeled the bits up left and right correctly. The replacement heads came with camshafts fitted but I also stripped those down to fit new valves. I am certain that the camshaft marked "L" came from the RH head as the rear bearing has some distinctive marks. Now logic tells me that the camshaft marked R goes in the RH head and the one marked L goes in the left hand head, but the way I laid the bits out from both sets it appears to me that they were both the otherway round. The service manual is of no help can one of you put me right please? I've had a quick go at working it out but my memory gives up just after 7 has fired and 5 starts to suck! In fact right now I'm thinking of fitting a 4 cylinder engine - preferably a diesel and just having a recording of the V8 playing on the stereo(To be perfectly clear to everyone that was just a jokefor my own entertainment - its bloody cold out in the garage right now:X)

cheers

Roger

[loudnproud]

imported post

Hi Roger just looked at a spare cylinder head in my shed and the camshaft is marked R and it is the R/H head, so I would fit L/H to left hand head and R/H to right hand head. Peter

[marshman]

imported post

Cheers Peter, Just wanted confirmation from somewhere - feel a bit silly really as its a bit a basic mistake.

[Kevin Garrod]

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Easy mistake to make.

[marshman]

imported post

Cheers Kevin, like the picture

I did find a bit in the manual that I missed earlier, the left hand camshaft has a ring cut into the flange that sits behind the sprocket. (as well as the large letter "L" stamped on the shaft

Now all I have to do is sort through and find the right thickness shims:X

[Kevin Garrod]

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If you are short of any let me know, got a bag full somewhere.

[Robin Searle]

I own a 73 Federal Mk2 Stag and recently had an issue with my RHS camshaft it had major scores on all 5 bearings and also the cam itself, which will now necessitate a line bore plus a replacement cam, this on an engine that was supposed to have been overhauled less than six months ago and was a replacement for my original engine which had been totally rebuilt including a crankshaft rebuild some 4 years ago. My original engine ran sweetly but oil pressure went down to 3 lb PSI in May of 2017,when the pan was dropped my very experienced mechanic discovered enough bearing material on the bottom of the pan,that my GKs could build sand castles in it.The guy who had rebuilt the crank had not hardened it or chromed it correctly, which resulted in taking all the bearings out. As I was leading 20 TRs all 360 degrees around Lake Superior [2620 miles] I wished to use my own Stag so I purchased a "recently" rebuilt engine and 2 days after its installation off we went,but the RHS was missing,especially on idle,but we continued on until all complete.

When this replacement engine was looked at, we found that there were major scores on the RH cam andon the bearing surfaces, now we find that on the LH cam, with only 26o5 miles on it, that that cam also has wear, but no where near that of the RH.My question is have cams been a source of problems on Stags, or by using Rimmers rebuilt cams is that the source of the problem???DSCF8207.jpg

[flying farmer]

I have rebuilt half a dozen Stag engines over the years and have only found problems like this when grit (normally casting sand) has been left in the engine from when it left the factory.
I haven't started cleaning out the engine I am currently working on, but the previous one was full of sand.

I don't know the engines history apart from the fact it was a factory replacement unit according to the engine number. The engine had definitely been fitted with a new jackshaft and new heads. It had been bored 40 thou oversize and had done little mileage since its last rebuild looking at the bore wear.

However, the oil pump was heavily scored, the crank was knackered and one timing chain was badly worn due to the oil hole in the tensioner being blocked.
Many hours of squirting petrol and brushing the internal areas of the engine produced about half a thimble full of sand from the main oil ways in the block, and about half an egg cup full of sand from the jackshaft gallery. This was in addition to over a litre by volume of casting sand from the water jacket.

All this was out of an engine that had been fully rebuilt at least once, maybe twice and had never been cleaned properly.

I would expect an unhardened crank to have a life expectancy of 30-40,000 miles in a clean engine.

Since your heads need a line bore it will true up the camshaft bore. The camshaft bore is often bent as a result of warped heads being skimmed flat on the block face after overheating related warping. Although the engine may well run with tight cams, it will heavily load the cam chains. Usually I have found the cams have worn themselves a clearance after a while without any scoring, but they will rattle in their bores when tried without any valves and springs.

I always end up hand fettling the cam bearings until I can get a free turning cam with no excess play.

The heads I am currently working on had very little wear in the bearings but both cams were tight in their bores. Checking with engineers blue revealed both heads were bent inwards at their ends. The only thing I can think of here is that the engine has overheated and the inlet manifold has restrained the centre of the heads but the sideways pull of the head studs has pulled the ends inwards slightly. I bought these heads from an auto jumble so I don't know their history.

The usual wear pattern I find is the front bearing is worn down towards the block due to the pull of the timing chain, and on all the other bearings the wear is upwards into the cap due to the pressure of the valve springs.

The worse foreign object damage is normally on the rear cam bearing. I imagine this is because sand particles will wash down the head oilway to the rear of the head due to oil flow and the rearwards slope of the engine. When they can't go any further the only way out is up through the bearing.

Neil

[Guest]

Interesting stuff from Neil, you really have to think of everything that could go wrong on those engines, then assume it has!

Bear in mind cam journals are NOT hardened.
When they chill cast cams, only the cam lobes are chilled (to make them hard).
This makes the cam journals uniquely vulnerable to damage from abrasion, as they are so soft they won't even register on a vickers or rockwell tester.

SAND in oil galleries grief!
The only thing I ever saw worse than that was valve grinding paste in an engine (deliberate vandalism from a disgruntled employee)...

[mjheathcote]

When I rebuilt my engine (early 90's) the block was also full (well a lot) of casting sand in the waterways, this a service exchange short engine too according to my engine number.
I did have general engine wear, applicable to the mileage, and yes scoring of the rear camshaft bearing surfaces too.
This was all corrected, and boy did I scrub all the oil feed holes before rebuilding even though the block had been re bored and chemically cleaned by the machine shop.
A few years ago I stripped out the camshafts while readjusting slightly the tappet shims, and it was a relief to see the repaired rear camshaft bearing surfaces unmarked.

[Stagdad]

You didn't fit newly finished cam covers did you? i know of someone who's engines top end was destroyed by shot blast sand stuck in the flame trap after fitting a newly chromed pair of covers.

[mole42]

Ouch!

[Rubce]

This was in addition to over a litre by volume of casting sand from the water jacket.

Neil

A litre of sand, WOW!!!!! The engine will presumably run a lot cooler after you rebuild it

Bruce

[Ctwidle]

Just removed the heads from my 74 Stag for the first time in my custodial period due to HGF. (Studs were found to be plated but that had not stopped all the corrosion but they still came out with little effort) The RH head (which was leaking outwards between 3 and 5) has quite a lot of crud in the water galleries, LH looks pretty good. Rear cam bearing on R has some scoring in the bottom half, along the line of the oil hole. This fits well with Neil’s description.
Ex mechanic neighbour has suggested that, as the rest of the bearings look ok and it is the top half that is subject to the most wear, it might be worth polishing the rear journal, taking a skim off the cap and doing an old fashioned bearing fit to gain a bit more life before align boring and replacing the cam. Oil pressure was good before the strip down.
Any comments would be appreciated.
seasons greetings,
chris.

[Ctwidle]

Just removed the heads from my 74 Stag for the first time in my custodial period due to HGF. (Studs were found to be plated but that had not stopped all the corrosion but they still came out with little effort) The RH head (which was leaking outwards between 3 and 5) has quite a lot of crud in the water galleries, LH looks pretty good. Rear cam bearing on R has some scoring in the bottom half, along the line of the oil hole. This fits well with Neil’s description.
Ex mechanic neighbour has suggested that, as the rest of the bearings look ok and it is the top half that is subject to the most wear, it might be worth polishing the rear journal, taking a skim off the cap and doing an old fashioned bearing fit to gain a bit more life before align boring and replacing the cam. Oil pressure was good before the strip down.
Any comments would be appreciated.
seasons greetings,
chris.