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pistons that kiss valves

4K views 16 replies 11 participants last post by  bullheimer 
#1 · (Edited)
new fed. mogul and sealed power pistons are kissing valves

my machinist will be hearing back from the engineer there and tell us what's going on. this is with a low lift .450 cam and 194 valves:pain: i'll post again when i hear from him. the engineer says the reliefs are supposed to be machined to 220 thous deep. as cast they are only 180 thous

okay we heard back, (gee that was fast you're thinking)
the engineer says that they are making their hyper's with a different material to make it lighter. he said the pistons are 10 thous taller. he took back what he said about them being machined and says the reliefs are as cast. the machinist he talked to didnt ask about the discrepancy about the depth of the relief.. he says the piston is now ten grams lighter than before as well. he says they are machined to accept a 2.02 valve. he says you no likee you can just send the damned thing back and buy a high performance piston. he says this piston is NOT designed for high performance. in other words he is full of sheeite moslem.

the valve relief on these pistons just barely fit the 1.94. i've seen it with my own two eyes. i saw the piston of the other engine with the .450 lift cam where it kissed the pistons and i have no reason not to believe my machinist when he says all 8 intake valves were bent that he took out of it. it was only a minor mark where the piston hit the valve but there was a contact mark.

that's all i can tell you. fed mogul is saying there is nothing wrong. i'm saying there is. that said, i just ordered another set. guess i will have to double check it when i have the heads on the block with some clay or something
 
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#4 ·
I would be interested in knowing the part number or numbers they are supposedly having this happen with. I really doubt that they are having problems with the pistons hitting the valves, especially with such low lift cam. I would guess the problem is with the valve timing, somthing where you would see the intake valve hitting. I think it's your machinist who is full of sheeite moslem, and is trying to pass off his incompetence onto the piston manufacturer.
 
#5 ·
pistons

I agree with tom,
I think you need to find another machinist.The numbers you are giving us do not line up with the problem you are having.....

I assume we are talking about a small block chevy. With a standard 23 deg head and no suprises that we are not hearing about????

Did the valve hit the piston square. like could you see where the whole face of the valve hit the cut-out or was it just a corner hit???

Keith
 
#9 ·
i will be putting the eingine together myself. but anyway. i always thought a sbc and all american v-8's to boot, where NOT negative interferance engines, so you could break the timing chain and still not hit anything with a stock engine. all i saw on the piston he showed me was a small nick. the p/n was H345NP, a hyper, and the factory says the casting is the same for the non-hyper. but there is NO way the relief was sized for a 2.02 valve, the 1.94 fit perfectly. there is a definite difference from the way they used to be according to the machinist. the reliefs definitely are not machined like he says they used to.
 
#10 ·
The factory reliefs were VERY generous, much more than necessary. The reliefs and deck height of the H345NP are just fine. You will have NO problems with your set up, providing the cam is installed properly. The comments I said earlier about the valves kissing (smooch) still stand as far as where the blame lies.................
 
#11 ·
I agree with Tom on this one. The most likely problem is cam indexing, but even if you don't have the 3-keyway set, there's another way.
I built a 400 SBC for my El Camino years back. (Still have the motor) I installed the crank with the "old" cam drive sprocket. What the heck, it was in good shape. Bought a new timing set and installed the chain and cam sprocket. Fortunately, I degreed the cam and found that, while the timing marks were lined up, the cam was nowhere close to being where it should be! Comparing the old and new pieces showed that the timing marks were NOT punched in the same location. The new crank sprocket was off by one tooth, which would make the new cam sprocket two teeth off with the timing marks lined up.
If I had not degreed the cam, I would undoubtedly have had the same problem you're having.
I wouldn't assemble an engine today without at least a degree wheel and a dial indicator.
 
#12 ·
it is now june 15, when i posted this i looked at my pistons and they had bigger valve reliefs so i didnt worry about it. i didn't clay them either. i was pretty confident and the aforementioned machinist isnt known for his competency. so i went to start it and it never fired, didnt crank it much, heard "snapping noise" pulled it apart and there are in fact marks on all my pistons. i used a regular fel pro gasket. i tried to warn you all and didn't heed my own advice, so serves me right.

has anybody else out there experienced this with this sealed power part no? i have not milled my heads more than .010 nor zero decked my block. this is pretty strange.
 
#13 ·
Just came to mind, when you set your lifter preload did you call zero lash the point when you couldn't turn the pushrod by fingers or the point that you couldn't get any vertical movement of the pushrod? Many people get the valves too tight by tightening the rocker nut until they can't spin the pushrod. perhaps it was timed right but the valves were way too tight.
 
#15 ·
i dont know. but my cech freind says he thinks they have. the original engine had 168K on it so the heads machine shop will check all that. MY pistons did not get hit with intake valves, like the other guys, mine got hit with all 8 exhausts. i swear to God i got the timing gears lined up on the straight up position. dot to dot. this was a 3 key set from cloyes and i wanted the damn thing straight up. it is a xe 262 comp with 462/469 lift. i adjusted on the stand before firing with dry lifters with zero lash, not the finger turning method. i had the intake off and was watching closely. i dont understand because with coil bind the valves should NOT have gone down as far as they will when i put the new springs on from comp. i used the factory way of adjusting rockers, half and half, not the comp cams way of one piston at a time. i am sure but not positive that my valves are stock length. this is a 72 350 2 bolt main block. i have about a 1/32 or so of clearance from piston tdc to block level. i dont know how much my heads have been milled before but they just took off .010 more. i am also using stock length pushrods. my bud got the engine spinning without making noise with the starter, good compression after adjusting the valves piston by piston as per Comp's instructions after we let the lifters soak in oil all night. he thinks it would have run if we hadn't pulled the heads off or if i would have soaked the lifters when i put it together. comp cams instructions say to definitely NOT soak or prime the lifters on assembly. so....???WTF?

:confused:
 
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