1098 valve timing & lift

[MikeNash]

Here’s a “thought you might like to know” piece.
According to Vizard (on pages 284 & 5 of my 3rd edition at column 3) my 1098 engine should have the following valve timing when measured with 19thou tappet clearances;
Inlet open BTDC Inlet close ABDC Exhaust open BBDC Exhaust close ABDC
5 degrees 45 degrees 51 degrees 21 degrees

But I’ve actually got on No1 cylinder (nearest the radiator)
0 47 41 17
On No 2 cylinder
4 45 47 20
On No 3 cylinder
2 42 52 21
On No 4 cylinder
1 45 47 18
Maximum lift is according to Vizard 0.318 inches but mine vary from 0.296 to 0.307 inches.

Doing it all again with the actual running tappet clearance of 12thou I’ve got
On No 1 cylinder
12 54 50 22
On No 2 cylinder
6 49 50 32
On No 3 cylinder
8 52 62 35
On No 4 cylinder
10 65 53 24
Max lifts now vary from 0.304 to 0.312 inches

All measurements were repeated several times using a clock gauge to detect valve movement and measure lift. The timing is probably a little retarded due to camshaft drive chain wear and the variations are perhaps generated by worn tappets, but overall I suppose these results are representative of a fairly good but slightly worn engine. And I suppose that production tolerances were greater then.
Regards, MikeN.

[bmcecosse]

Which is why Mike - there is good power to be gained when 'blue-printing' an engine. Where competition regs require the engine to be 'standard' - there is often considerable benefit to be had from making sure everything is exactly to that standard spec - taking advantage of any useful tolerances at the same time! You can see the very considerable difference just by closing up the valve gaps slightly - I rather suspect there will likely be wear and ratio variation in the rocker gear and that may be giving part of the variation - more so than from the 'tappets'. Did you mike (!) up the camshaft directly on the lobes to see if there is any 'lift' variation there?

[MikeNash]

I agree Bmc; while blueprinting is the way for power (and I've done enough in my time - mainly Manx Nortons) here I'm just recording what I've got, i.e. what's typical of a good but elderly engine and what most minor owners might have. (And my interest is economy at high cruising speeds not max power and performance.) Like you suspect the rocker gear for the variation; at the moment I've the heavy ungainly sintered rockers fitted 'cos my original pressed ones have a couple of seized adjusters and I'm afraid I'm going to snap the screwdriver slots off if I'm not careful. In view of the indentations caused by the valve end into the rocker pad, I wonder if the sintered type isn't as hard as the pads pushed into the pressed rockers. Anyway the latter will be rectified and cleaned up and re-fitted in due cause.
Regarding the valve lift measurements they were made at the valves not direct on the cam, so they include as you suspect the influence of variation in the rocker leverage.
Regards, MikeN.

[bmcecosse]

Oh yes - do 'stone' the pads on the sintered rockers to make them smooth. However just had a discussion on the mini forum where it appears pressed steel rockers are 1.28 ratio and sintered are 1.22(although there may be some that are 1.25). So it would be interesting - since you are doing measurements anyway - to compare the two types. Soak the adjusters in diesel - apply a bit of heat if necessary!

[MikeNash]

Yes Bmc, I've give that go. When I've sorted the car (bit of welding and installation of Wolseley front brakes - harrah!)and run the re-built engine, I've try and set up the pressed rockers on an old head and see if it tells me anything. Re deisel, well, central heating oil is much same but cheaper and nearer at hand!
Regards, MikeN.

[MikeNash]

I've done some more measurements of valve timings and here they are for the record. Again I believe its a standard cam this time in a replacement engine and it seems to be giving figures closer to "official" timings: less wear, I suppose. All the figures are degrees and were done at the required 19 thou valve clearances.

For No1 cylinder the inlet opens at 3 BTDC and closes at 48 ABDC. Exhaust opens at 51 BBDC and closes at 20 ATDC.
For No2 cylinder the inlet opens at 5 BTDC and closes at 49 ABDC. Exhaust opens at 53 BBDC and closes at 22 ATDC.
For No3 cylinder the inlet opens at 5 BTDC and closes at 52 ABDC. Exhaust opens at 60 BBDC and closes at 22 ATDC.
For No4 cylinder the inlet opens at 4 BTDC and closes at 47 ABDC. Exhaust opens at 49 BBDC and closes at 21 ATDC.

Compared with the quoted figures in Vizard, etc of 5/45 and 51/21 they're not far off except for No3's exhaust. I suppose they're just representative of production variability and variation in wear. But its a caution about being dogmatic about cams and cam timings!

Regards, MikeN.

[bmcecosse]

Is this with a new chain and sprockets? As you say -all 'within limits' except for that #3 exhaust which is a surprise. How about the lifts ?

[MikeNash]

The chain sprockets are the same ones as when I bought the engine from you, Roy! See here[frame][/frame]
Seems all OK to me!
Re the valve lifts, I recently put my clock gauge "somewhere safe" while I reorganised the garage to install a Myford lathe. And, of course, I can't find. So lifts will have to wait!
Regards, MikeN.

[bmcecosse]

Ahh - I thought this was another engine... Note the 'trademark' chisel mark on the cam nut! So - if you don't have your gauge at the moment - how have you been measuring the opening and closing points of each cam ?
For others reading this - that excellent picture above shows the BEST chain drive set-up you can have (assuming no super high-lift cam or stupidly strong springs) and will give long and quiet service with no nasty rattles or timing variations....

[les]

Chisel marks on the 'doing up side' tut tut, That's 2 steering wheel size nuts, making it worth getting a socket and dumping the chisel!

[philthehill]

Ahh - I thought this was another engine... Note the 'trademark' chisel mark on the cam nut! So - if you don't have your gauge at the moment - how have you been measuring the opening and closing points of each cam ?
For others reading this - that excellent picture above shows the BEST chain drive set-up you can have (assuming no super high-lift cam or stupidly strong springs) and will give long and quiet service with no nasty rattles or timing variations....

As regards the best chain drive - If you do have the super high lift cam and or stupidly strong springs the duplex set up with the above tensioner is the way to go.
The tensioner is only there to take out the chain return slack mainly caused by wear.
Any variation in timing is caused by chain and sprocket tooth wear on the pulling/load side (opposite side to the tensioner).

And yes use the correct spanner/socket to tighten the camshaft nut preferably with the crankshaft locked.
Knocking the camshaft nut with a hammer and chisel to do up and/or undo the nut can cause damage to the front cam white metal bearing.

Mike
That undrilled hole (under the dynamo adjuster post) for the timing chain cover does need to be used. Whilst you may get away with not fitting a bolt there; having it installed does ensure that you have reduced the possibility of a possible oil leak.[frame][/frame]

[bmcecosse]

I do have the socket, but didn't always have it .... and it never leaked without that hole drilled.... The tensioner helps to stop chain 'flutter' - so it is a good idea. However when I tried it with duplex the rubber disintegrated and the noise then was h*llish till I got the car home. Maybe I had it set too tight.

[philthehill]

It is better if the hole is used. It is there for a purpose and is easy to install even with the front engine plate fitted.
The duplex chain and the simplex tensioner assy fitted to my Minor which has a very high performance cam fitted and much stronger valve springs has never given any trouble and has completed many hours of use.
As regards adjustment the adjuster pad should be firm against the chain but not too tight. If it is too tight the pad will wear rapidly. There is adjustment within the pad holder to enable the initial tension to be set correctly and to take up any slack at a later date if required. Note elongated hole in the pad support bracket to enable the tension to be set correctly.[frame][/frame]

[MikeNash]

Thanks gents!

Re the chisel marks, well Roy, what other iniquities have you perpetrated on innocent engines? (But perhaps we shouldn't go there! Thinx; if you can recognise your chisel handiwork then others might too; perhaps there's a whole new branch of forensic science opening up here.)

Re measuring the timing without a clock gauge, firstly I downloaded from this site the "Declan Burns" timing disc, laminated it, stuck it to a piece of cardboard and then cut it to a circle; it worked perfectly. To judge when the valves were opening or closing I found that the pushrods could be "finger-turned" easily just before the transition to lift off or after the closing point. This needed a bit of practice because its possible to turn the pushrods as the load comes on to the valves but then they're distinctly stiffer. But with a bit of practice you can literally get the feel of it.

Re the undrilled hole Phil, I was surprised by it for I'd thought there was a missing bolt. Why is this backplate to the timing chest not drilled and tapped at this point? I'm not sure, but it looks on mine as though the required hole at the back where it presses up against the crankcase would straddle the edge of the crankcase itself and that to do a proper job the plate should come off and then it needs to be fitted with a special short bolt. I think I'll leave it alone at the moment (it hasn't leaked so far) but its a bit of mystery. To be prepared, please can you tell me the thread of that bolt?

I note Phil you've still got the canister type of breather on your timing chest whose innards you warned us in a previous post could rust and break up. This I found had happened in mine, but unlike yours, mine could not be disassembled. So I've cut it off and have a circular hole in the timing cover to fill, either with a bung or a soldered on plate.

Finally, the valve timing figures I give above are, of course, measured at the required 19 thou clearances, and when the latter is changed to the running values of 12 thou we get broader valve timings. From my first measurement in 2011 (at the top of this thread) this can extent either end by about as much as 12 or as little as 4 degrees. I assume that the greater test clearance is to avoid the quietening ramps ahead of the proper valve lift point (and behind its closure) which perhaps may be more uncontrolled in their manufacture (?) But considering that all materials are flexible, even conrods and crankshafts and of course especially the pushrods themselves, quite what ACTUAL timings we get is a bit of a mystery. And what is the tappet clearance when the engine is hot? That'll change it too.

Regards, MikeN.

[philthehill]

Mike
The Minor front engine plate was not manufactured with the necessary holes to fit the 'A' Plus timing cover - so the hole was never there.
Only when the 'A' Plus timing cover is fitted is the extra bolt hole in the Minor front engine plate required.
When fitting the 'A' Plus timing chain tensioner a hole for the head of the tensioner locating pin has also to be drilled.
The nut and bolt is 5/16" UNF and there is enough room to fit the bolt.
Below is a Minor front engine plate with all the necessary holes drilled to suit an 'A' Plus simplex chain set up and timing cover.

I would recommend that the front timing cover with breather is ditched and a simplex cover without breather is fitted.
for example:
http://www.ebay.co.uk/itm/Classic-A-ser ... Swys5WVMWx
Now that I have got the breather canister on the unused fuel pump aperture I will in due course be ditching the timing chain cover with the integral canister breather and fitting one of the type featured in the link but without the ignition sensor bracket and indentation. Here is the reworked timing chain cover grit blasted, painted and all ready to fit.
Phil[frame][/frame][frame][/frame]

[MikeNash]

Corr!! That was a quick reply Phil. Do you never sleep? Thanks for the link but I think I'll stick with my cover and patch it, probably with an 1/4 inch central heating fitting so I can fit a breather.

Thanks for everybody's comment and advice, MikeN.

[philthehill]

Mike
Short answer NO.
Phil