'71 A65L valve timing

[Caulky]

Hi All
Before the winter break and fitting the pushrods. rocker gear, etc, turning the engine using a spanner on the rotor nut, it jammed BTDC.
So, I thought piston hitting the inlet valves.
I set it up with just the right inlet valve, clock and degree-wheel.
Today, I thought, check the timing marks... they are OK, but for the left valve, hence I had to rotate the engine 360* for the R/H side.
I set the gap to .015" as per the book.
The valve should open at 51* BTDC, but mine begins to open 16* before that, but strangely the piston and valve doesn't collide!
So it must be the left?
I should add that everything is new and the head was sent away for an overhaul, new seats, valves, gas-flowed, etc.
Something is wrong, any suggestions would be appreciated.
 

[AWJDThumper]

I'm not entirely clear what you have done to set up the valve timing. If you lined up the timing marks on the three pinions during assembly then the valve timing should be correct?

[Bess]

Hi,
     As the only thing you have had overhauled is the head, check the push rods are installed correctly. Or more worryingly you could have an issue with the valve spring cups or valve springs.

Some cups and spring combinations are not compatible and the spring diameter doesn't fit into the cup lip but rests on the lip, hence the spring is under additional compression causing coil bind.
or
Some aftermarket springs have larger diameter wire in the coils or an extra coil causing coil bind.

When this happens the push rods take the stress and either bend/break, or if you're turning over slowly give a small but noticeable resistance. I suggest taking the rocker cover off, turn the engine slowly and check for a gap between the coils with a feeler gauge.

If you are having an issue buy new springs from SRM, they have commissioned springs to match the originals.

Best wishes...

[JulianS]

If I read it correct you have just one valve fitted?

Are you certain that you have linked the correct cam follower to that valve.

Make sure you set the valve clearance 180 degrees after fully open so that it is not set when the follower is already starting to rise on to  the quietening ramp.

[Caulky]

Thank you, I will check it out and get back to you.
Dave

[ChrisG]

Its easy to get the pushrods on the wrong cam follower on the OIF machines as due the the frame top spine being so close, its difficult to see down there. I did mine on Saturday and I got them wrong at first!
Chris

[Caulky]

Sorry about the time lapse, can only work when the weather is reasonable.
The data I have is from the book, at .015" gap, inlet opens 51* BTDC, closes 68* ABDC.
I presume the mid-lobe is not half-way between these two points...uneven ramps?
Now, SRM give at .020" gap, inlet opens 45* BTDC, closes 78* ABDC, duration 303*.
Some time ago Mr Pete of Australia RIP, stated set the gap to .040" to avoid the inaccuracies of the lead-in ramp.
Inlet opens 28* BTDC, closes 47* ABDC, Lobe centre 99.5 ATDC.

Results for mine, @ .020" gap, opens 63* BTDC.
At .040" gap, opens 45* BTDC, closes 34* ABDC, mid lobe 92* ATDC.
Far too early.
So, is the mid-lobe 99.5*?
If I set the mid-lobe at the correct point on the crankshaft, remove the jocky-wheel, then rotate the camshaft wheel to suit, then re-insert the jocky-wheel, is this a good move?

[AWJDThumper]

Have you measured all the valve timings (x4) at the specified 15 thou gap? That way, it's easier to make sense of what's going on. My experience of measuring numerous sets of valve timings in the past is that they have always been inline with the specified settings, at least, within the achievable measurement error.

[JulianS]

If it was me I would assemble all the valve gear, set the tappets at 15 thou in the normal way, and see what I got for all the valves. Using a setting other than the factory 15 thou is bound to give different readings from those published. I would also check and double check that the degree disc is correctly zero'd at TDC and that it is firmly attached to the crank. It is easy to introduce an error in the reading here.

It can be difficult to establish the exact point at which the valve starts to open and the exact position it is just fully closed. It is also easy to introduce an error in the reading here.

Other potential sources of errors can include wear in the valve gear, machining errors in the cam and backlash in the timing gears.

[Caulky]

Thanks chaps.
I think firstly I'll put both inlet valves in, to see if it still locks-up.
Which was the original problem.
As you say, things could be out, just using one valve fitted.
Alternatively, I could try clocking from just from the pushrods. (inaccurate I know).
I used the R/H inlet valve because the clock faces the wrong way on the left side, frame in the way, and its a long type.
Its bad enough trying to get the clock rigid as it is.

[AWJDThumper]

Do you know which valve hit the piston, originally? For the inlet valve that's in the engine, have you measured the angle at which it closes at 0.015" gap or does this one hit the piston?

[Caulky]

There is no problem with the R/H inlet valve, except the timing is too early.
This is why I am going to try both inlet valves fitted.
I suppose it could be valve to valve clash, with all valves fitted, rather than valve to piston.

[AWJDThumper]

If you measure both the opening and closing angles for the fitted inlet valve, this should be sufficient to confirm whether the camshaft timing is correct, provided you do it at 0.015" gap. Once confirmed, this should then mean the timing will be correct for the other 3 valves. If there is a problem with valve timing, then this will need to be investigated but doesn't need the other valves to be fitted in the meantime.