Club 80-90 Forums

Hi all, I have a1983 t25 1900 water cooled,it won't run right since I adjusted the tappets, I did the run them down untill no play then 11/2 turns, now this seems wrong to me because it pressing on the valves trying to open them, I've seen other people saying do them with a 6 thou gap , which does make more sense to me, also do you adjust them hot or cold, push rods are squidgy and at best near impossible to get a true start point of just touching the valve, any thoughts pleases, thanks

It’s tricky to do the first time , I would say youve set them incorrectly , the 1.5 turns is correct, judging the start point is the most important part

Hello my T25 is air cooled so I’m not familiar with your model but the valves should be adjusted when cold. At the risk of sounding very dim, you are slackening off the valve by 1.5 turns?

Hi , it's 11/2 turns tightening isn't it, that's what I don't understand, it's pressing on the valve

It's called pre-load. Slightly warm. Adjust valves from zero lash, meaning just touching, to 1.5 to 2 revolutions.
Are you setting the valves at the correct point? On the combustion stroke.
Easiest way is to remove all plugs. Turn engine clockwise until combustion stroke hits number one cylinder. Check dissy rotor is aligned with small cutout on dissy. And go from there.

The hydraulic tappet has a spring inside which compresses slightly instead of opening the valve. That way, you never have any clearance so there's never* valvetrain noise

Do you know if the engine is a rebuild? some engine builders use cheap lifters and they always bleed down and make a racket.
are you adjusting the lifters in firing order at TDC for each cylinder?

Hi yes I'm doing them in reverse 1234, screwdriver in each plug to get tdc, I've done them hot /cold and every thing in between,I've gone one turn, 11/2 turns ,2 turns, think I'll try screw them in untill no lash then back them off 1/2 a turn, carnt be any worse, as I say some YouTube videos say a gap of 6 thou,

6 thou gap is for solid lifters, mostly used on earlier air cooled engines, the WBX should have hydraulic lifters fitted which need preloading as described.
Have you done a compression test ? Might be worth doing one once you have them set as spec. If that is good then I would check the timing as well, and then the carb tuning

wayne wrote: ↑26 Jul 2025, 20:53 Hi yes I'm doing them in reverse 1234, screwdriver in each plug to get tdc, I've done them hot /cold and every thing in between,I've gone one turn, 11/2 turns ,2 turns, think I'll try screw them in untill no lash then back them off 1/2 a turn, carnt be any worse, as I say some YouTube videos say a gap of 6 thou,

I am not a petrol guy but firing order isn't usually 1-2-3-4 is it? 1-4-3-2 springs to mind.
Are you sure that you are on the compression stroke for tdc and not exhaust stroke? I always used to use a finger or something else to ensure that I could feel the compression to make sure before using something solid for tdc.

It can be done in reverse 1234. Find number one cylinder TDC on firing stroke. Both valves lash plus 1.5 revolutions.
Turn engine anti clockwise 180 degrees and do number two. And same for three and four.

wayne wrote: ↑26 Jul 2025, 20:53 Hi yes I'm doing them in reverse 1234, screwdriver in each plug to get tdc, I've done them hot /cold and every thing in between,I've gone one turn, 11/2 turns ,2 turns, think I'll try screw them in untill no lash then back them off 1/2 a turn, carnt be any worse, as I say some YouTube videos say a gap of 6 thou,

Rotating anti clockwise?

Hi all, thank you for your replies, that's cleared that up if the 6 thou gap is for the early air cooled with solid lifters, so mine is 11/2 turns when warm, it's obviously the starting point I'm not getting right, I find the lifters to be squidgy and you can move the tappets 10 mm if you want to, I'll have another go

It's not a critically accurate measurement and doesn't need to be done warm. 1 turn, 1.5 turns, 2 turns, all will work fine. 
You shouldn't be able to move anything 10mm by hand, though!

wayne wrote: ↑27 Jul 2025, 19:48 Hi all, thank you for your replies, that's cleared that up if the 6 thou gap is for the early air cooled with solid lifters, so mine is 11/2 turns when warm, it's obviously the starting point I'm not getting right, I find the lifters to be squidgy and you can move the tappets 10 mm if you want to, I'll have another go

That squidgyness is likely due to drained down tappets. You need a very delicate touch to recognise when the adjuster is at zero lash.