Valve springs ??
Discussion
Well I got the griff back today after being taken in for the pre-loads setting hopeing to get rid of the tappet noise. All the pre-loads were low .015" to .020" so he had the pedestals skimmed .020" to bring them all within a good tolerance, He also checked all the rockers lifters rods etc which were all new and everything was fine. After it was rebuilt guess what the tapping is still there 
Now the person doing all this work builds race RV8 engine for stock cars and is in fact the world champion himself so knows about these engines inside out and to be honest he was pretty baffled. The only reason for the tapping he could think of was that maybe the valve spings are a little weak and due to the fact it has a mid range cam fitted the valves the litfters were were jumping slightly as they went over the lobe of the cam and slapping back to cause the tapping. So I have the car booked back in for new springs next week.
Anyone heard of this before?
also what is the max rpm for these engines? mine is great up to 5500rpm then at 6k it just dies like there is a rev limiter on the car.
Chris
Now the person doing all this work builds race RV8 engine for stock cars and is in fact the world champion himself so knows about these engines inside out and to be honest he was pretty baffled. The only reason for the tapping he could think of was that maybe the valve spings are a little weak and due to the fact it has a mid range cam fitted the valves the litfters were were jumping slightly as they went over the lobe of the cam and slapping back to cause the tapping. So I have the car booked back in for new springs next week.
Anyone heard of this before?
also what is the max rpm for these engines? mine is great up to 5500rpm then at 6k it just dies like there is a rev limiter on the car.
Chris
Edited by chris52 on Thursday 2nd July 21:58
Sorry disagree.
If all the clearances are low.. then it cannot be the valve springs.
Why.
Well at zero revs.. i.e. when he is checking them the valve is shut. Tight.
If there is still valve lash then you need to look else where.. cam, followers, bent rods, cam bearings, excessive wear on tappet pad / valve stem length.
If all the clearances are low.. then it cannot be the valve springs.
Why.
Well at zero revs.. i.e. when he is checking them the valve is shut. Tight.
If there is still valve lash then you need to look else where.. cam, followers, bent rods, cam bearings, excessive wear on tappet pad / valve stem length.
Are you absolutely convinced the noise is from the engine. A while ago I had what I and several “ experts” were convinced was a hydraulic lifter that was not priming correctly. The engine clattered from cold and then quietened down a fair bit but not completely when warm. Turned out to be the belt tensioner bearing. The spring loaded one on the alternator side (that is assuming you have a Serp engine)
Heard all sorts of different rev limit numbers programmed into the standard ECU so you could be hitting that. Where you rev it to is not only a case of where is safe but where the power is. Unless you have a fairly radical cam fitted the power will be all over well before 6000 so really there is no point in revving it there at all. You may simply be falling off the cam rather than reaching any sort of limit. With the appropriate cam and an adequate induction system to get the air in peak power can be a lot higher so revving above 6 may be beneficial, although I am told not a particularly good idea with the standard bottom end. All a bit safer if cross bolted and balanced. In some race car applications this engine revs to 7500 and a bit.
Heard all sorts of different rev limit numbers programmed into the standard ECU so you could be hitting that. Where you rev it to is not only a case of where is safe but where the power is. Unless you have a fairly radical cam fitted the power will be all over well before 6000 so really there is no point in revving it there at all. You may simply be falling off the cam rather than reaching any sort of limit. With the appropriate cam and an adequate induction system to get the air in peak power can be a lot higher so revving above 6 may be beneficial, although I am told not a particularly good idea with the standard bottom end. All a bit safer if cross bolted and balanced. In some race car applications this engine revs to 7500 and a bit.
steve-V8s said:
Are you absolutely convinced the noise is from the engine. A while ago I had what I and several “ experts” were convinced was a hydraulic lifter that was not priming correctly. The engine clattered from cold and then quietened down a fair bit but not completely when warm. Turned out to be the belt tensioner bearing. The spring loaded one on the alternator side (that is assuming you have a Serp engine)
Heard all sorts of different rev limit numbers programmed into the standard ECU so you could be hitting that. Where you rev it to is not only a case of where is safe but where the power is. Unless you have a fairly radical cam fitted the power will be all over well before 6000 so really there is no point in revving it there at all. You may simply be falling off the cam rather than reaching any sort of limit. With the appropriate cam and an adequate induction system to get the air in peak power can be a lot higher so revving above 6 may be beneficial, although I am told not a particularly good idea with the standard bottom end. All a bit safer if cross bolted and balanced. In some race car applications this engine revs to 7500 and a bit.
Rev limits are set in the ECU fuel map and seem to vary between about 5400 (Range Rover)and 6200 rpm, and it simply cuts the injectors off when you hit it, so its like hitting a brick wall. No progressive shut off of injectors on this one. Cam wise even a mild piper 270 will happily run to 6000 + rpm on stock valve springs and lifters (as in Range Rover).Heard all sorts of different rev limit numbers programmed into the standard ECU so you could be hitting that. Where you rev it to is not only a case of where is safe but where the power is. Unless you have a fairly radical cam fitted the power will be all over well before 6000 so really there is no point in revving it there at all. You may simply be falling off the cam rather than reaching any sort of limit. With the appropriate cam and an adequate induction system to get the air in peak power can be a lot higher so revving above 6 may be beneficial, although I am told not a particularly good idea with the standard bottom end. All a bit safer if cross bolted and balanced. In some race car applications this engine revs to 7500 and a bit.
Edited by blitzracing on Friday 3rd July 13:21
Hi guys thanks for the responses. The tappet noise is at idle and you can still hear it as you accelerate but the noise of the engine then takes over so its hard to tel if it is still noisey at higher revs. The noise is definatley from the tappet area, it has been run with the rocker covers off and you can hear the tappets there is about 3 or 4 that are playing up, you can actually quieten them down a little by pressing down on the rocker as its moving up and down. The cam thats in the car is a high torque mid range from Dave Ellis and according to his spec sheet the pre-load should be run at .060" 
mine have been set to .040" give or take .010" for uneven valve tops . So the plan of atack next week is firstly to machine the pedestals a touch more to get all the pre-loads to around .060". Try running again if the tapping is still there then the only thing within the whole valve train that has not been replaced is the valves and springs. All the lifters, pushrods, rocker's, shafts,pulley's and chain, cam have been replaced with new.
Chris
mine have been set to .040" give or take .010" for uneven valve tops . So the plan of atack next week is firstly to machine the pedestals a touch more to get all the pre-loads to around .060". Try running again if the tapping is still there then the only thing within the whole valve train that has not been replaced is the valves and springs. All the lifters, pushrods, rocker's, shafts,pulley's and chain, cam have been replaced with new.Chris
chris52 said:
it has been run with the rocker covers off and you can hear the tappets there is about 3 or 4 that are playing up, you can actually quieten them down a little by pressing down on the rocker as its moving up and down.
...
Try running again if the tapping is still there then the only thing within the whole valve train that has not been replaced is the valves and springs. All the lifters, pushrods, rocker's, shafts,pulley's and chain, cam have been replaced with new.
Chris
You mention that it's all new, but if it gets quieter when you push on the rocker arm doesn't that suggest movement between the rocker arm and shaft?...
Try running again if the tapping is still there then the only thing within the whole valve train that has not been replaced is the valves and springs. All the lifters, pushrods, rocker's, shafts,pulley's and chain, cam have been replaced with new.
Chris
[/quote]
You mention that it's all new, but if it gets quieter when you push on the rocker arm doesn't that suggest movement between the rocker arm and shaft?
[/quote]
Not necessarily by pushing on the rocker on the pushrod side you will be helping to tighten up the valve train, I have some after market rockers that when fitted give a pre-load of over .090" with these fitted the tapping disapears but with a major side effect "very low oil pressure" plus running the risk of the valve's not being able to close as the lifters pump up at high revs causing burnt valves.
Chris
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