Alright so I bought a set of Kms dual valve springs and retainers for my all motor LS setup. Built short block all bolt ons etc. I ran crower 404s on them . Started it up idled ran good 2 stepped it a few times at 4 k everything held up great . I took it for a test drive 3rd to 4th gear on the freeway at about 4k and the motor dies . I pull over and my gates racing timing belt is laying over my motor mount … It snapped . I tow the car home take the valve cover off , the intake cam caps 2-4 are snapped in half like twigs. Now what I’m tryin to figure out is what happen? Did I tension the timing belt to tight and it snapped pistons hit valves and the force of that broke the cam caps? Is the valve springs not stiff enough for these cams leading to sticking the valves pistons hitting them then snapping the belt? Basically has any one ran these springs with 404s before? Since then I sent the head back to the machine shop for 6 new valves and machining for the new cam caps . I left the Kms springs in and put stock cams on them. Been driving it for 5 months with no problems . I have called Kms multiple times and they won’t respond. I stare at these 404s everyday and want to put them back in but fear fucking my motor up . Any help , or veteran advice would be helpful .
wtf cam cap snap? … never seen that ever cause i would imagine it requires torsional twist/bidning of the cam to do that or brute upward force.
Did I tension the timing belt to tight and it snapped pistons hit valves and the force of that broke the cam caps?
- nobody can answer that. If your not experianced, a novic could easily over tension a belt thinking that tighter is better.
Is the valve springs not stiff enough for these cams leading to sticking the valves pistons hitting them then snapping the belt? Basically has any one ran these springs with 404s before?
- My guess is that they are fine for 404. Before YOU made the decision to buy KMS springs, did you check with KMS on the the what their valve seat pressure are for the springs?
My guess is that you did NOT do your homework when buying them, since your don’t have anyone to referrence of ever running 404 with KMS springs. Lesson learned.
Since then I sent the head back to the machine shop for 6 new valves and machining for the new cam caps.
I left the Kms springs in and put stock cams on them. Been driving it for 5 months with no problems . I have called Kms multiple times and they won’t respond. I stare at these 404s everyday and want to put them back in but fear fucking my motor up . Any help , or veteran advice would be helpful .
- if i was KSM I wouldn’t respond too because there is no way to “help” you figure out what went wrong.
My guess is that you did not install cams properly.
- cams not degreed in properly causing clearance issues.
- valves hit pistons
- timing was off, tb tension not correct
My advice… pay someone who knows what they are doing to install the cams & check for clearance.
Spending money is saving money. For valve springs i’ve always reccomend rocketmotorsport snapfit springs which use stock seats and retainers & stiff enough for 404 or bigger cams.
Be glad that you didn’t lose the complete engine. If the valve hit the head hard enough it could have broke & cause complete havok for the engine.
Well I was just wondering if anyone at all has had this happen to them or is familiar with these cams on these cams . Anyways I should of figured I would get talked at like iv never worked on an engine before . This wasn’t my first cam install or motor build up. It was my first non vtec build. Anyways I said fuck it and put the cams back in anyways last weekend. It’s running fine . Rough idle and what not as it’s only on a street tune. So I guess I either tightened the cam caps past the 7.5 ft/lbs . Or I tightened the belt to tight. Either way it was a learning experience , and I’m glad I did things my self and learned along the way , rather than paying someone to do it for me. Besides the great thing about Hondas is if you fuck them up they are cheap to fix
yeah it happens to everyone.
few years ago I broke a rocker on a LS head… luckly it didn’t drop a valve or something but still puzzels me on what i did wrong.