Cylinder Head

[sonscar]

On the 4 cyl engine how does the oil drain from the head to the sump?I have looked at pictures of heads and looked at various rebuild manuals but am still not able to easily see how it is done.I am attempting to reduce the appetite for oil my car suffers with.The engine slopes markedly to the rear,investigation shows considerable up/down movement on the gearbox mounting(as much as 50mm?) so it looks like that old chestnut needs fixing.Removing the cam cover reveals a veritable lake of oil where the tappet blocks are and I feel that this oil is being sucked into the breather and thus the carbs on theoverrun.I have taken delivery of an oil catch tank today and will be fitting it this weekend.Hoping for some success,Steve..


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[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by sonscar</i>

... considerable up/down movement on the gearbox mounting(as much as 50mm?) <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Looks like your gearbox mount needs replacing.

As for the oil return, the lakes you mention are there to lubricate the cam buckets.
This is the normal amount of oil sitting there in a healthy engine ...



If the engine is half decent there won't be much oil loss there.

<center>
<font color="blue"><i>1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng
</font id="blue"><b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">Click this link for a full version of my blog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Hasbeen]

Hi Steve, my 7s engine looks just like Beans, & in a 170,000 kilometre engine never had to have oil added to it between oil changes. That is with the breather plumbed straight into the manifolds UK style, rather than a charcoal canister US style as our Oz cars came.

The cam buckets get noisy before there is too much wear, but If you want to confirm it's not them, add a bottle of STP oil treatment to the thing. That will definitely stop anything going down there, if the clearance is not so great you can see down it.

Hasbeen

[sonscar]

Yes my engine looks just like that but the worn gearbox mount means that the tide of oil is much higher at one end than pictured.HEY HO it never stops does it?.Thanks Steve..P.S looks like the motor is in the twighlite of it's life.

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[sonscar]

After 25k miles or so since I renewed all the valves when the previous ones had all had intimate contact with the pistons i measured the clearances.The inlets were 4/5 thou and the exhaust 16thou on one and 20thou on the other 3,compared with Haynes manual 8/18.From your collective experience is this very urgent to remedy or can it wait?.When I did it last the shims were only available from Rimmer's in limited sizes and I had to resort to grinding some down, not a quick task and with attendant problems I am sure.Steve.

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[Workshop Help]

Try this.

Step & fetch an old feeler gauge. Determine the amount needed to bring the oversize gaps back to the inlet valve 8 and exhaust valve 18. Trim the appropriate size piece off the needed thickness of the particular feeler gauge blade. Install the piece twixt the inside of the bucket follower and the existing shim.

This will bring you back to the specified gaps. Test run the engine to make sure all is chugging along correctly.

The wonderful advantage to our TR7 engines is the camshaft can be removed in under 15 minutes and installed back in 20 minutes.

Mildred Hargis

[Hasbeen]

Steve first, too small clearance on particularly inlet valves has a very detrimental effect on performance, much greater than you would expect, & when down to 4 or less, is getting far too close to riding. If they start that, it is not long before they are burning. In my engine I would correct at anything less than 6 thou.

4 thou is a long way for new valves to close up in a short space of time. How were the seats done? Were they lapped with paste, or were the valves & seats faced at a slightly different angle & allowed to hammer in. We used to do the final lap of our valves with Brasso metal polish, as the polished faces did not hammer down, changing the clearance.


Grinding the valve stems is very much a no no. It is particularly so with our engines. If you can't get the correct shims, get some shims, thicker than required, & have then ground down by a surface grinder, rather than grind the valve stem. I have been told Saab shims are suitable.

There is a ridge cast into the top of the spring cap, which forms the retainer for the shims. The control of the height of these was never taken seriously. I have found them ranging from 250 thou to 400 thou high. The higher of these is very close to the underside of the cam follower bucket. It is only the shims that stop this ridge bearing on the bucket

As the valves & seats wear the valve sinks into the head/seat. You require thinner shims to adjust your clearance, & as this gets thinner you find the spring cap ridge is bearing on the underside of the cam follower. If your required shim is less than 70 thou this is likely to be happening.

Once this happens you can no longer adjust your valve clearance, the spring cap is being driven by the cam, rather than the valve, working the collets up & down at every valve opening. It is only a matter of time to valve failure at the collet grooves.

When this occurs you can see the round impression of the ridge in the underside of the bucket. This will appear as a round cleaner area in the carbon staining in the bucket. If it is more than this correct immediately, if not sooner, failure is imminent.

The ridge itself can be safely ground down to a moderate extent to renew clearance, but this should really only be done out of the car, as the amount of grinding dust will damage your engine if any gets in.

The other critical thing is to keep the valves, spring caps & cam buckets matched. The variations are large, & what worked fine on no 3 can easily be riding on no 2 or 4.

It is good practice to keep these things in sets anyway, but is critical in our engines as they wear.

Hasbeen

Mildred, should this go in the workshop section?

[Workshop Help]

Not yet. What's needed is for me, one of these days, to pull off the rocker box with camera in hand. However, with my engine percolating just fine, it won't be happening any time soon.

This is one of those topics best left to dedicated machine shops as it borders just over the line for competent amateurs. As Clint Eastwood's character, 'Dirty Harry' said at the end of 'Magnum Force', "A man's got to know his limitations."

A paucity of parts is one thing. Applying skilled machine shop techniques is another when we can't see what's actually the problem half way around the world.

Mildred Hargis

[sonscar]

So today I attempted to adjust the valve clearances.Should the front camsprocket support in its normal state fit over the protruding stud or should it stand away from it?Also when fitting a nut onto this stud and holding the larger nut behind it the large nut came loose making it a harder task than it might have been.This nut seems to be a press fit onto this spigot,should it be?These setbacks notwithstanding I measured the clearances and suitably adjusted the shims to hopefully correct the clearances.Too late/cold now to progress but tomorrow is another day.Sorry to appear needy,thanks in advance ,Steve..

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[Hasbeen]

I can't remember what it was now Steve, but someone had mucked with my sprocket pulley post & stud. I had to sort it to do my first clearance job too.

What were your clearances, & how close to ideal did you get?

Well done anyway. I can remember when over head cams were so exotic, doing a valve clearance job on an XK Jag engine was considered in the black magic area, & those who did it charged about 5 times the usual hourly rate. Well done if this was your first.

Hasbeen

[Cobber]

C'mon, every knows that you can only adjust OHC valve clearances, at midnight on a full moon, whilst consulting the entrails of a chicken, after dancing about the fire naked with a bat on one shoulder a raven on the other and a black cat swinging off your naughty bits by its claws! [:D]

"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

80'Triumph TR7, 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.

[Workshop Help]

45 years ago, I would have considered that exhibition as a serious matrimonial offer.

Mildred Hargis

[dursleyman]

Those cam sprocket bolts/nuts are a bit weird. When I came to take it apart I was amazed that there is no thread in the nut! It just seems to press onto the tapered bit of the bolt which sticks through? It doesn't seem to go up tight to the sprocket either?
Couple of pictures showing the ones on my Sprint engine but the standard 8v seems to be the same. Please note the "butcher" marks are not mine but a DPO job.





Russ

1981 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

[jeffremj]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Should the front camsprocket support in its normal state fit over the protruding stud or should it stand away from it?<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">Stand away.

[sonscar]

So here is the results,I carefully measured the clearances with my trusty feeler guages and noted them down.Then I removed the cam and the buckets and shims being careful to keep them together and in the correct positions.I then cleaned the oil from them and measured them with my trusty micrometer.I used a carborundum stone to grind the shims to the new calculated size.Anyone who has done this will know it is a slow job and removing too much material is not an easy task.I then refitted the shims and buckets being careful to keep them together and in the correct positions.I refitted the cam,turned the motor over several times by hand and remeasured the gaps,all of them now being two thousands or so too large.I can only surmise that this is the difference made by them being dry versus them originally oiled.Somewhat disappointed I boxed it up and started it.It runs and sounds exactly as it did before but now secure in the knowledge the valves should seat ok and not burn out.Not exactly a rewarding task but possibly a necessary one.Thanks for your replies.P.S I was surprised to find the nut was not fitted to the cam securing post and with the bracket standing off I was concerned it may fall off so I fitted a nylock nut to it.Thanks again,Steve..

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