Valves hitting piston?

#1
Hi, I'm building a highly modified 212 and seems to be almost done. But I've run into a potential issue. I think the valves are hitting my piston. I'm thinking this because when I turn the thing over, it makes 4 clicking/clunking noises(?). Below I've attached a video (google drive) where I pull it over and you can hear the clicking noises twice. If it is hitting the piston, I'm really confused on why because I see people using the GPS stage 4 with an even bigger cam than I do, have the same 1.3 ratio rockers (that I also installed recently and that's when it started making the noise), and a flat top piston. Currently, I have a hot-265 cam from GPS, 1.3 black venom rockers, no flat-top piston (yet), 28.5 and 26mm valves, and no head shaving. Any help would be very much appreciated.


Video (Won't let me upload one on here): https://drive.google.com/file/d/1KuQhGJxiYZQcrMLHNFDcArboQHdBk4MA/view?usp=sharing
If it doesn't show up just let me know and I'll fix it asap
 
#2
Your best bet is to remove the head and lay a thin layer of clay on the piston bolt the head on snug and carefully turn the motor over a few times, Remove the head and check the clay for clearance If its hitting the piston there won't be any cay left where it hits, It will be smushed out, Have you tried loosening the valves to see if the noise stops? Good luck!
 
#3
You can check valve to piston clearance without taking apart the engine. Do you have a dial indicator? You check by finding TDC on overlap then back off 10 degrees then with valves adjusted correctly you can pry up the rocker on the pushrod side and see how much further the valve moves on the dial indicator repeat again but at 10 degrees after TDC. You should have at least .060 clearance to be safe. If you are using the gage rockers how did you set the valve side geometry ? How did you determine correct pushrod length?
 
#5
I've read of some people having problems with the valve cover getting hit by the new rockers... I'd start there since that's when you're problem started.
I've read about that too. I'm running a clear valve cover with mine and no issues with clearance. It's a 212 that has a Wiseco forged flat top piston, .308 cam, 1.3 Black Venom rockers and a 32/28 BVH running dual 60lb springs.

I had to use custom length push rods (the build your own ones) with them on my setup. The recommended length wasn't even close to being correct.
 
#6
Hi all. Thank you guys so much for all the wonderful advice. I haven't had the time yet in order to try these things out by I was looking around on YouTube and came across a video recently made by RBG. It's about valve ands and how to measure them and noticed something in that video. At 13:38 you can hear the exact same noise that I've been hearing (The double clicking) is that normal and am I just paranoid, or am I missing something. To answer the valve cover question, I have a billet one from GPS and it's fine. Sounds still occurs when it's off.

Note: I will still be checking piston to valve clearance just to be sure. Also when is the safe clearance?
 
#7
The noise may be your compression release when the tappet falls off the release onto the lobe. The minium V to P is in my post above., .060. The Exhaust is most critical as piston is chasing the closing ex valve and if it floats it can hit. Intake is just opening so it can't float at that critical time.
 
#8
The noise may be your compression release when the tappet falls off the release onto the lobe. The minium V to P is in my post above., .060. The Exhaust is most critical as piston is chasing the closing ex valve and if it floats it can hit. Intake is just opening so it can't float at that critical time.
Hi, sorry for the late reply. Recently I measured the valve clearance using the clay test. I used around an 1/8 thick piece of playdoh and only my intake valve barely touched it. So I have around .125 clearance. So maybe it is my cam?
 
#12
Exhaust lash could be different if ex lash is set loose then you will have too much compression to pull start it. No idea what your noise is. Did you try lizzardkings suggestion of removing the valve cover?
 
#13
Exhaust lash could be different if ex lash is set loose then you will have too much compression to pull start it. No idea what your noise is. Did you try lizzardkings suggestion of removing the valve cover?
yep I tried removing the valve cover as well. I'm pretty sure the sound is coming from my cam. Reason being is that it makes the noise when both the intake and exhaust springs are fully compressed and when the springs return back to normal. Could it be too much weight for the cam to handle? It is a 265 but the ratio rockers make it around 345 and that lift does fit into that spring weight category

Also, so having that ease of pull is normal?
 
#14
Exhaust lash could be different if ex lash is set loose then you will have too much compression to pull start it. No idea what your noise is. Did you try lizzardkings suggestion of removing the valve cover?
Ok i've done some more research and I'm 90% sure its too much thrust play, a user on another form had the same exact issue, same noise, same parts in the cycle too. Below I have attached the forum if u are interested.

https://4cycle.com/karting/threads/vc460-interesting-noise-camshaft-knock.111735/
 
#19
I agree, if you turn it over by hand can you tell if the noise happens just as rocker hits max lift and just starts to close? That is the point when the lobe goes from pushing up the lifter to the lifter pushing the lobe, and if too much cam endplay the helical gear could push cam from one side to the other.
 
#20
I agree, if you turn it over by hand can you tell if the noise happens just as rocker hits max lift and just starts to close? That is the point when the lobe goes from pushing up the lifter to the lifter pushing the lobe, and if too much cam endplay the helical gear could push cam from one side to the other.
So what would be the solution to this? It does only happen when the spring is compressed and starts to let off.
 
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