Can tappets cause misfires?

[Wobba]

I know some engine designs they can, but not sure about F7R's.

I have a subaruesque warble from my exhaust and very loud tappet noise. It seems to have a misfire when the tappets are playing up...

[Flash Arghhh]

Suppose if one was sticking down but then that would cause the piston to hit the valve, wouldn't it?

[Wobba]

Suppose if one was sticking down but then that would cause the piston to hit the valve, wouldn't it?

Fookin hope not!

[MAXIBOY]

no....

if they tap then the slack is not being taken up by the oil filled tappet thus you are not getting maximum valve opening lift meaning less chance of it hitting the piston and maybe a decrease in performance thats noticeable but i doubt a misfire unless there really bad

but i could be wrong..

try a compression test ..low reading would indicate poor cylinder filling..

[Wobba]

DROPS IN PERFORMANCE!? NOOOOOOO!

Poor cylinder filling? What's that, fill with fuel or air?

If there is incorrect lift on the valves then that would change exhaust note/beat would it now? Hence the Sccoby noise.

The tappets are EXTREMELY loud at mo.

[MAXIBOY]

poor cylinder filling means air in this cases as the fuel is injected in directly..

if the tappets are not working you will lose lift and duration as they wont have the correct clearance.

doubt they would cause a scooby noise though..i would look elsewhere first..

[Wobba]

Well I have considered injectors being a possible suspect. I may unplug one at a time later on and see if it has any effect.

If I were to replace tappets, it would just be a case of cover off, cam followers off, cams out, bash the lifters out with a hammer and replace right? Easy?

[MAXIBOY]

cam cover off.
timing belt cover off.
pulleys off or remove with cams.
cams retainers off.
cams out.
lifter followers out with a magnet.
reassemble with a load of graphogen patse or cam lube.
run in for 20 minutes @ 3000rpm.
oil change.

[Wobba]

Excellent thanks mate!

[Wobba]

cam cover off.
timing belt cover off.
pulleys off or remove with cams.
cams retainers off.
cams out.
lifter followers out with a magnet.
reassemble with a load of graphogen patse or cam lube.
run in for 20 minutes @ 3000rpm.
oil change.

Do I simply put the paste/lub over the cam lobes before refitting?