broken valve
#1
broken valve
Hey guys has anyone on here ever taken the f54 block and put flat top pistons in it and tried to run the n47 on it cuz i'm have a pretty big issue on how this is going to work.... I bolted the head on the motor set at tdc than when i tied the cam to the motor the first and last intake and exhaust vavles hit the pistons left a valve shaped imprint and broke the #1 cylinder exhaust valve. i guess my first question is can u run the n47 with flat top pistons? second will the little indentions in the pistons hurt the motor?
http://i83.photobucket.com/albums/j3...7/100_1360.jpg
Thats where i found the exhaust valve when i pulled the head off the motor.
http://i83.photobucket.com/albums/j3...7/100_1359.jpg
this is the dent left in teh #1 cylinder.
http://i83.photobucket.com/albums/j3...7/100_1356.jpg
and the remains of a broken valve stuck in the head....
http://i83.photobucket.com/albums/j3...7/100_1360.jpg
Thats where i found the exhaust valve when i pulled the head off the motor.
http://i83.photobucket.com/albums/j3...7/100_1359.jpg
this is the dent left in teh #1 cylinder.
http://i83.photobucket.com/albums/j3...7/100_1356.jpg
and the remains of a broken valve stuck in the head....
#2
wow you musta really cranked on it, or started the engine to break it off. yeah you can run the n47 head, but youll have higher compression, and youll need to prolly change the piston with the mark in it, cause it could crack.
#7
on my 81 with flat tops and an n47 with a stock HG, all that was done to it was to make a fly cut of .50 to clear the valves, since you have the head off, you should convert you oiling system to the spray bar, much better for a higher C/R IMO..
#8
hah te best part of this whole thing is i wasn't cranking on it very hard just enough to get the ca to turn over. and i was using an adjustable wrench.. a little one i had no leverage. so do i have to have the pistons cut to clear teh valves or jsut run the timing off?
#11
you prolly had the chain on wrong, that is the ONLY way that could ever make contact, my clearances are tight, and i got .5" lift on my valves, so i dunno how it was assembled, but double check, its easy to miss stuff.
#14
heck always set everything at tdc before even putting the head on to the block. and yeah if your flatops come right up to deck height youll be o.k, but if your pistons come above deck height, then your gonna be screwed. you need at least .025" clearance from the head to the piston top. its in the datsun engine builder book.
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