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92 Honda Civic VTI
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838 Posts
Discussion Starter #1
well when my car was on the dyno yesterday it droped a valve and shattered the sleve.

what im wanting to know is y it would drop a valve?.
currently the car had a P&P, new springs and retainers, crower stage 2 cam.
also all the clearence specs were checked before the motor was started up.

can anyone help me out please
 

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D-Series Post Be-itch... gimme gimme gimme
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3,203 Posts
how long since teh P&P and cam/ valve job?? and who did it? reason I ask is could it be that teh retainers weren't installed properly?? that would be my guess.
 

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ridin on rotas
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1,980 Posts
I think the only thing that would drop a valve is a failed keeper or retainer.

if the spring "failed" then the valve wouldn't drop but it would get smashed by the piston. which could bend it all the way up and cause it to be dropped into the cylinder.
 

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same^^^
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678 Posts
did you clay the motor with the vtec lobe follower engauged? This could be part of the problem...

-josh-
 

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I
95 Civic coupe
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3,984 Posts
horny_devil said:
D15B vtec head D15B2 block milled head and the guy reconed about high 11's compression.

as for RPM not sure as i wasnt there
. and like i said the clearences will all good and the motor was blued and clayed before being put back together.
if you were in america, you could sue.. and prolly win... i dont know how it is over in new zealand... here you can sue for anything!
 

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92 Honda Civic VTI
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838 Posts
Discussion Starter #12
right have found out what happened. all the springs retaniners are all sweet and looking from the top at it u cant tell that anything is wrong. but from the bottom the head of the valve has disapeared on one of the intake valves and has slightly moved its valve guide as the valve is still sticking through the guide.

the valve broke under deacceleration and it was only reved to the stock revlimit of 7200rpm.

on a side note he was looking at the dyno graphs and he said that from about about 2500rpm it was making more than 10wkw more (untuned) and a shit load more torque.

he also has between 2 different blocks and a heap of pistons (he even has some 1300 pistons:) ) that hes gonna try different combinations in to get one thats gonna give the a compression ratio of about 11.6:1 so its easy to tune for pump gas. so thats whats gonna be happening over the holidays.
 

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Brokedick Millionaire
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40,237 Posts
sucked a valve in when you closed the throttle.......

the SUCTION when the TB closes is like adding boost on the back of the valve, need stiffer valvesprings....and more clearance :)

Boost or high vacuum makes the valve spring seem weaker.......
 

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92 Honda Civic VTI
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838 Posts
Discussion Starter #14
transzex said:
sucked a valve in when you closed the throttle.......

the SUCTION when the TB closes is like adding boost on the back of the valve, need stiffer valvesprings....and more clearance :)

Boost or high vacuum makes the valve spring seem weaker.......

im running crower springs and retainers :sad: and the was plenty of clearence or so ive been told.

oh well looks like ill have to build a 1600 now :p
 
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