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View Full Version : Valve springs - how often should they be replaced?


Toddler78
06-05-2016, 10:37 AM
So title pretty much sums it up, a bit of back ground knowledge to help with answers.
I have PAC 918's in my monaro, they have been in now for approx 110k and of the last 25k I have had the cam in (comp cam 222/224 XFI high lift .566 lift)

I dont drive the car much any more (approx 5k per year) but I the car doesn't seem to have the same acceleration it once had and I was wondering if they valve springs have exceeded their life expectancy.

cars done 185,000 by the way.

cheers guys
white lie
06-05-2016, 11:23 AM
How long have they been in there? If you've only done 5k per year since the can went in then they'd be close to 5 years old so I'd change them. If you did more kms initially and it's only recently become a weekender then they may be ok.
They will still soften/sag even though the car isn't being driven. If it's sitting for long periods, the same springs are constantly compressed so it doesn't hurt to turn it over every now and then.

If it doesn't feel as strong perhaps get it run up on a dyno. See if it's actually down on power and if so may be able to point you in the right direction, especially if you're starting to get a bit of valve float or similar.
Micks
06-05-2016, 01:04 PM
Todd if your not driving the car much for peace of mind just change them out, cheap insurance.
macca_779
06-05-2016, 06:34 PM
Thats hardly high lift. In fact thats baby lift. They're probably fine
white lie
06-05-2016, 06:42 PM
Thats hardly high lift. In fact thats baby lift. They're probably fine
I did think the same but if they've been in there for 5 years I'd personally still do it. If it's only been a couple then I wouldn't bother just yet
macca_779
06-05-2016, 06:44 PM
I did think the same but if they've been in there for 5 years I'd personally still do it. If it's only been a couple then I wouldn't bother just yet

certainly wont hurt.
duke5700
06-05-2016, 07:12 PM
Pull a few and test them.

It is only a baby cam, so I would expect they would last a while. Yours is more simply just the length of time they have been in there. It also comes down to driving habit.. how much time it sits at the higher end of the rev range.