valve timing

[Ennva]

Thank you for the post below (see ticked off below), she is now running again a little rough but going, however I belive I have some loud tappets (think pot4), admitably after running for 10 mins start to sound better, can anyone please provide a simple valve clearence guide for the beginner with engine cold.

Thanks in advance

- Turn it over by hand (5/8 socket on crank pull bolt and turn the engine clockwise), ensure it will turn a complete cycle - Done
- Check Timing chain tension - Done
- Check the valve timing - Help required
- Make sure the oil pump is primed (slacken the oil pressure sender and turn the engine by hand, any oil coming out?) - loads of pressure
- Compression test the engine (watch to see if it builds oil pressure) - After some great advice all running around 160psi
- Consider replacing ignition system, plug, rotor, cap and leads - Done
- Consider rebuilding the carbs - DONE
- Check the static timing - TO DO
- New fuel - DONE
- Check for fuel leaks - SEE Other post

[RogerFrench]

According to workshop manual, cold clearances are:

Inlet - .005" to .007"

Exhaust - ..006" to .008" up to engine no 9951
.009" to .011" from engine 9952 onwards.

[Ennva]

Many thanks, is there a quick guide to ascertaining what engine I have for the exhaust clearences

[rgh0]

Set it to the later engine larger clearances. It is not clear why the later engines specified a larger exhaust clearance but it was probably due to a change in valve material or camshaft clearance take-up ramp design. What ever the reason the larger clearance works on all engines these days.

cheers
Rohan

[Ennva]

Hi all, thanks for the advice, Im not sure what engine I have (LP9951 OR LP 9952) any advice on where to find this?
Anyhow measured clearences as follows, I do however note that whilst the feeling guage whent under at some of the measurements it was bit of a push, is this right?

Exhaust
Pot 4 0.009 (push) 0.008 easy
Pot 3 0.010 (push) 0.009 easy
Pot 2 0.011
Pot 1 0.010 (push) 0.009 easy
Inlet
Pot 4 0.040
Pot 3 0.040 (push) 0.035 easy
Pot 2 0.050
Pot 1 0.050

I still however have the rattling noise, timing chain is fine, engine was bebuilt with head skimmed pots relined about 800 miles ago. Any thoughts.

[rgh0]

I assume you inlet measurements are in the same units as your exhaust and in thousandths of an inch ?

40 or 50 thou are far to big on the inlets and would cause a rattle or is it a typo and you mean 4 or 5 thou in which case they are at the bottom end of clearance specification?

If the clearances are in specification and timing chain tension in correct then the other cause of rattle is worn followers and or follower bore in the head.

cheers
Rohan

[Ennva]

yes typo these are Thou! measurements so at bottom end of scale, what is the follower check method.
many thanks

[rgh0]

To check the followers you need to remove the cams and pull the followers from the bores. You need a micrometer to accurately measure the diameter along their length as they wear into a barrel shape. The sleeves they run in wear into an hourglass shape but this cant be measured unless you remove the head and remove the valves and springs so you can get a bore gauge into measure the sleeves diameter along their length.

A rough check can also be done just by removing the followers and cleaning off the oil film and also cleaning the oil film of the inside of the sleeves. Then reinsert the followers and see if you can rock the followers in the sleeves. Any signficant rocking movement probably means they are worn into the barrel and hourglass shapes and are outside the specified tolerance and this causes the clicking you hear.

cheers
Rohan