check ptv clearance tell me what yall think!
04-25-2010, 05:16 PM
#1
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check ptv clearance tell me what yall think! got a lq9 6.0L stock fresh rebuild
afr225 59cc
stock gasket 051
243/248 611/613 on 110 cam
i did the clay thing away the intake hit the piston {just barely} but the exhaust did not even come close to hitting the clay and the clay was .185 thick so does this mean i dont have to cut the exhaust?
need 080 intake and 100 exhaust rite?
afr225 59cc
stock gasket 051
243/248 611/613 on 110 cam
i did the clay thing away the intake hit the piston {just barely} but the exhaust did not even come close to hitting the clay and the clay was .185 thick so does this mean i dont have to cut the exhaust?
need 080 intake and 100 exhaust rite?
04-25-2010, 06:12 PM
#2
got a lq9 6.0L stock fresh rebuild
afr225 59cc
stock gasket 051
243/248 611/613 on 110 cam
i did the clay thing away the intake hit the piston {just barely} but the exhaust did not even come close to hitting the clay and the clay was .185 thick so does this mean i dont have to cut the exhaust?
need 080 intake and 100 exhaust rite?
afr225 59cc
stock gasket 051
243/248 611/613 on 110 cam
i did the clay thing away the intake hit the piston {just barely} but the exhaust did not even come close to hitting the clay and the clay was .185 thick so does this mean i dont have to cut the exhaust?
need 080 intake and 100 exhaust rite?
04-25-2010, 06:20 PM
#3
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the cam was installed str8 up dot to dot off the shelf trex cam u think it was cut wrong?
well it barely touched the clay{exhaust}
well it barely touched the clay{exhaust}
Last edited by johnster; 04-25-2010 at 06:23 PM. Reason: add
04-25-2010, 06:25 PM
#4
dots both up or regular SBC/BBC method?
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04-26-2010, 03:37 PM
#8
.040 57.5cc
04-26-2010, 07:53 PM
#10
It just depends on the cam. I have a custom cam - 231/237 .614/.619 113+4 with LSL lobes that had a LOT of exhaust clearance with about 0.070" intake clearance IIRC and that's with milled heads. I ended up flycutting 0.025" on the intake side just to give me plenty of room.
04-26-2010, 07:53 PM
#11
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weld it.
or if its anything like the lifters im used to usign (in my 5.7L hemi, latemodel) then you can pull em apart and insert some washers. close em up and they wont compress.
then you can pull em back apart and put the original guts back in and youre good to go. didnt even have to destroy one.
is it normal practice to flycut the intake with .075 of clearance?
technically the valve would never ever get closer to the piston since it would retard away from the intake and closer to exhaust
ive always heard that .060 or more is plenty of clear (on the intake side)
(also based on my hemi experience... just trying to learn about LSx stuff as i will be coming to the dark side very, very soon
)
or if its anything like the lifters im used to usign (in my 5.7L hemi, latemodel) then you can pull em apart and insert some washers. close em up and they wont compress.
then you can pull em back apart and put the original guts back in and youre good to go. didnt even have to destroy one.
is it normal practice to flycut the intake with .075 of clearance?
technically the valve would never ever get closer to the piston since it would retard away from the intake and closer to exhaust
ive always heard that .060 or more is plenty of clear (on the intake side)
(also based on my hemi experience... just trying to learn about LSx stuff as i will be coming to the dark side very, very soon
)
04-26-2010, 08:04 PM
#12
^I think the common LSx criteria is 0.080" on the intake and 0.100" on the exhaust. I could've left mine but I wanted to be damn sure I was safe. I agree that it should never hit but you're leaving room for a small amount of thermal expansion as well as any other slack I guess.
04-27-2010, 04:47 AM
#15
Hard to tell because you don't know how much the plunger moved. I wouldn't trust any measurements taken so far. If you don't have a solid lifter (or can't make one from an old lifter) then use the dial indicator method for checking PTV with a check spring. You will still need to measure very carefully to ensure that the plunger in the lifter isn't moving but it can be done.
04-27-2010, 12:52 PM
#16
it doesnt matter on LS engines which way the dots point. either both at 12 o'clock or the crank at 12 and the cam at 6. eitherway, its fine.
typically, you need .100 on the exhaust and .080 on the intake. i like to run them a little looser just to be on the safe(er) side of life. im not suprised the intake valve hit. the intake valve is considerably larger and that cam has quite a bit of duration and lift. double check cam timing one more time if your not sure, then if it is ok, or still hits if you have to change it, then its time to cut the pistons.
typically, you need .100 on the exhaust and .080 on the intake. i like to run them a little looser just to be on the safe(er) side of life. im not suprised the intake valve hit. the intake valve is considerably larger and that cam has quite a bit of duration and lift. double check cam timing one more time if your not sure, then if it is ok, or still hits if you have to change it, then its time to cut the pistons.
04-27-2010, 05:09 PM
#17
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ok made me a solid lifter 2day out of a old one, and a hole different story the exhaust has .020, wow big difference! So u guys think i should get a smallr cam or cut the hell out of the pistons? i dont wont to use the solid lifter on the intake cause it barly knick the piston with the ls7 lifter. get me some input guys