9 replies to this topic

[karlnz]

surely its cold? to allow for expansion...?

 

i mooched around the forums, and actually found one that said do them hot so thats why im asking.

 

also, would you expect an a series to be a little rattly till it warms up a bit?

 

and where else could i expect to find rattles?

 

thank you

[Mighty made]

I always do it cold, after leaving it overnight.

(0.3mm).

 

The A series is always tappetty when it's cold but as it warms up the 

clearances close up and becomes much quieter.

 

Adjusting the tappets every 6 months or so is a good practice, as

it ensures that the valves are opening at the right times and for the right amount.

 

I have heard about people adjusting them hot, whilst the engine is running.... looks a bit messy and dangerous for me. 

 

Other rattles on the engine can come from worn timing chains

[nickhallencourt]

Are all the clearances the same on each valve or are thy different?

[maccers]

My dad used to do his 850 while running, he gave me his feeler guage that still has the dents on some of the feelers where its been battered a bit!! I would say do it cold though engine off.

[Mighty made]

Clearances depend who you talk to.

 

A series (unleaded) was always 12 thou)

 

Some people say that when the change to unleaded happened, the fuel burned hotter and so the exhaust  

needed additional 3 thou clearance..... of couse unleader fuel now is different with 5% or 10% ethanol added to mix.

 

However with non standard engines, turbos, different cams, different rocker ratio's etc. then additional clearance might be needed. 

 

The Haynes book of (*****) gives 12 thou (0.3mm) for earlier engines and then (0.27- 0.33mm) for later engines.

 

For what it's worth, I'd start with a wider setting and once warm (after a good run)  listen..

If it's still tapetty (light tapping from the top of the engine) then tighten down a few thou. 

 

If the rattle comes from the end of the engine near the radiator, rather than the top, then it's likely to be the timing chain.

 

I use a bit of wood as a listening stick, as it helps me to determine the place where the rattle is coming from, rather than sticking my

head near the fan  

[Guess-Works.com]

12 thou is pretty standard, 14-16 thou for high lift cams, and if you use high ratio rockers you should adjust the clearance according to the increase in ratio, give that standard is approx 1.25:1

[KernowCooper]

It could well be that the rocker pad contact area is worn, so when you insert a 12thou feeler the feeler gauge is on the high points outside the circular pad wear, so the actual clearance is in fact larger then you think, I have seen the contact pads refaced but the hardness is affected and the wear comes back quite quickly. Time for new rockers is the solution when they get that worn. SPQR used to make a tappet adjusting tool to be able to adjust then if worn, never had one though.

Edited by KernowCooper, 12 November 2013 - 11:51 AM.

[finch661]

http://www.theminifo...arance-tappets/

 

good guide!

[karlnz]

morning gentelmen!

 

thanks for the replies. just as i thought...

 

yes good point about the listening stick, i use a large screwdriver... put the end on suspected part (i.e. bearing housing) and vibration will travel up along it

 

and yeah true about the rocker gear wear scenario... i work on larger marine deisels and this is a major on the older stuff, completley overlooked by most people

 

i have the older pressed ones, might invest....

 

anyway its a fine summers day out there! thanks!

[jaydee]

http://www.theminifo...nstead-of-cold/

 

http://www.theminifo...pet-clearances/