So I recently took my cylinder head off and took it to a machine shop who has done my mustang heads in the past. The owner called me today saying it needs a valve job and valve guides saying it was out of spec. I asked him what his referencese was because I thought it was suspicious that they were all bad and making sure he was using the SVT specs but he has no reference to VIN 5 in his shop manual. So my question being what are the specs that I need to tell him so he can fix my head.
SVT Cylinder head specs
Kingfresh
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So I recently took my cylinder head off and took it to a machine shop who has done my mustang heads in the past. The owner called me today saying it needs a valve job and valve guides saying it was out of spec. I asked him what his referencese was because I thought it was suspicious that they were all bad and making sure he was using the SVT specs but he has no reference to VIN 5 in his shop manual. So my question being what are the specs that I need to tell him so he can fix my head.
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If he doesnt have the specs then how can he say there bad ?
Tom
Tom
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Curious to see how you solve the valve clearance issue. The "buckets" are no longer available from Ford, and the supply of used buckets in random lengths (with regard to the stems) is hit or miss. My recent solution involved putting lash caps on the valve stems and machining the bucket stems to give the desired valve lash. Cat Cams makes a cam with a smaller base circle that is designed to use lash caps.
Pappy
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Not saying your guides are not bad but again if he doesnt have the specs how does he know ? I have built dozens of the SVT heads and have yet to find one with bad guides
My next questions is can he buy new guides for the SVT head ? Zetec wont work
Cam timing was off , What damage did it do to the head ?
Tom
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88 Posts
according to my spec sheet (for vin 5)
guide clearance is .0007-.0025 for in/ex, i would want about .001 in and .0015 ex
installed stem height is 1.800 in/ex
lash for in is .0043-.007, ex .0106-.0133
if it does have to much guide clearance then guide-liners may be a good fix as long as your not boosted or plan on boost
if lash is out after a valve job the shop can probably still set lash by tipping the valves, its a total PAIN to do it that way but it can be done
guide clearance is .0007-.0025 for in/ex, i would want about .001 in and .0015 ex
installed stem height is 1.800 in/ex
lash for in is .0043-.007, ex .0106-.0133
if it does have to much guide clearance then guide-liners may be a good fix as long as your not boosted or plan on boost
if lash is out after a valve job the shop can probably still set lash by tipping the valves, its a total PAIN to do it that way but it can be done
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I wouldnt do liners in bronze guides only cast
Tom
Tom
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88 Posts
we do them every day on BMWs (S52's and the like) and have never had a problem with them, why do you see a problem with guide liners on bronze guides???
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Most machine shops I have seen use the cheaper liners , you have liners made from many different materials and the guides made from many different materials , they all deal with head differently and with the materials they come in contact with differently
I have installed 10`s of thousands of these personally owning a Machine shop , I wont do it and I dont recommend it being done
Buying guides for a Alum had and removing the old and installing the new proper guides is the best way , yes liners are cheaper but they also give more trouble then solid stock type guides
If I owned a high end BMW and found the BMW dealer cheeped out with with guide sleeves/liners , I would be pissed ! To make it worse dealers that do this charge like they installed guides lol
Tom
I have installed 10`s of thousands of these personally owning a Machine shop , I wont do it and I dont recommend it being done
Buying guides for a Alum had and removing the old and installing the new proper guides is the best way , yes liners are cheaper but they also give more trouble then solid stock type guides
If I owned a high end BMW and found the BMW dealer cheeped out with with guide sleeves/liners , I would be pissed ! To make it worse dealers that do this charge like they installed guides lol
Tom
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88 Posts
the shop we do the liners for regularly is a performance shop not a dealership, a lot of the cars are track only cars, and we charge them for liners not guides. granted i haven't done thousands of liner myself but i know my boss in his 40+ years owning the shop has, and to the best of my knowledge there has been no issue running liners in heads with removable guides.
i cant argue that replacing the guide inst a better repair, but like wise forged pistons are much stronger pistons than hyperutectic but not every engine needs it, so if a cheaper alternative will do the job for that specific application then i think it is defiantly worth consideration, and are replacement guides available for the SVT head?
the thermal property between the head, guide and valve are indeed critical, but given that the SVT uses ferrous guides to begin with i doubt that the liners would reduce the ability of the valve to transfer heat.
what problems have you seen when using liners in heads like the SVT, stuck valves? premature wear of valve? dropped liners?
if the shop is using sub par parts then it sounds like that's the shops fault not the repair itself, and sounds like the same shop would likely do a sub par job replacing the guides as well, either way sounds like finding a new machine shop is in order
i cant argue that replacing the guide inst a better repair, but like wise forged pistons are much stronger pistons than hyperutectic but not every engine needs it, so if a cheaper alternative will do the job for that specific application then i think it is defiantly worth consideration, and are replacement guides available for the SVT head?
the thermal property between the head, guide and valve are indeed critical, but given that the SVT uses ferrous guides to begin with i doubt that the liners would reduce the ability of the valve to transfer heat.
what problems have you seen when using liners in heads like the SVT, stuck valves? premature wear of valve? dropped liners?
if the shop is using sub par parts then it sounds like that's the shops fault not the repair itself, and sounds like the same shop would likely do a sub par job replacing the guides as well, either way sounds like finding a new machine shop is in order
well long story short, what he ended up doing was he ground the valve faces or the grounded the valve seat to get the desired clearance. so far so good ive put 500 miles on it. he also found his "svt" book with all the desired tolerances.
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great to hear you made out on top!!
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