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within the law
Samba Member
Joined: February 14, 2005
Posts: 25
Location: san francisco, ca
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 Posted: Mon Feb 21, 2005 1:00 pm Post subject: hydraulic lifter & cam lobe inspection on top-end rebiul |
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this type 4 motor has only 10-15k on a total rebiuld by a shop in Chico CA (receipts from PO).....the heads cracked prematuraly so iv'e bought a set of reconditioned heads... had the cylinders honed...new rings. but i've also been trying to inspect the lifters and cam lobes....new cam/lifters and crank were in the recent rebuild.... so i was hoping on only a top end fix..... i've got video & pics here : http://homepage.mac.com/bob.jen/type_4_rebuild/iMovieTheater67.html
my Q @ large are:
1. are the lifters supposed to sit flat against ea. other or should they be slightly convex (like solid lifters)?
2. can poor ones be replaced from another type 4? ive got an '83 for parts, they are all flat too..but not pitted...
3. how bad is bad wear on the cam lobes.... #1 (front) is the worst...and one of it's lifters has a bit of a protruding pipple in the center?
4. on re-installing the top end i'm trying to eliminate the head seal between the cylinder & head per a tech bullitin by vw in '90 that suggests eliminating it and replacing it w/ a 1.6 mm shim.... but all my local shop had was a .035 & .015 in.barrel shims....that equate to .050in. or 1.270mm
they said just stack 'em.....?....is this close enough & will this promote additional leaks?
any thoughts would be great.......the engine has beenin my living room a week now?!...ahhh haaaaaaaa  |
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jberger
Samba Member
Joined: November 17, 2003
Posts: 2476
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| Posted: Mon Feb 21, 2005 2:47 pm Post subject: |
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| Worn lifters will be convex; you should be ok if they are pretty flat. I have heard differing opinions on cam lobe wear. If the case was open it would be an easy decision, since it isn't |
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within the law
Samba Member
Joined: February 14, 2005
Posts: 25
Location: san francisco, ca
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| Posted: Tue Feb 22, 2005 4:41 pm Post subject: piston ring gap? |
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another mystery to me.... i was checking my piston ring end gap....(by sliding a ring in from the bottom of the cylinder like 5mm & checking the gap....so both my compression rings are w/in specs but the oil scrapers are way off ...a gap like .036 (should be .010-.016 according to bentley).... it's the three piece oill ring type made by grant for stock 2 liter?>.... is this right?...
cheers |
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Amskeptic
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Joined: October 18, 2002
Posts: 8586
Location: All Across The Country
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| Posted: Thu Feb 24, 2005 7:48 am Post subject: |
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| jberger wrote: |
| Worn lifters will be convex; you should be ok if they are pretty flat. I have heard differing opinions on cam lobe wear. If the case was open it would be an easy decision, since it isn't |
Convex, as in protrudes very slightly at the center of the lifter, is what a new solid lifter should be. A worn lifter goes flat to concave even. The hydraulic lifter is not ground with as much convex "ity". A Type 4 cam with any noticeable groove that your finger can notice is evidence that the cam is done.
Three piece rings can have that horrible end gap. Stagger the little rings.
Stacking shims at the bottom of the cylinder barrel is doable but definitely leakable, there is subtle shuffling that will find its way through the recommended Permatex Aviation-but-not-silicone-glop-ever sealant over time. Let your final guide be the deck height measurement. You may not need to stack anyway. Stock cam profiles will have no problem with a .040" deck, and if you have the typical dished pistons, your compression is unlikely to be affected in any negative way.
Colin
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Rocknrod
Samba Member
Joined: November 02, 2004
Posts: 2157
Location: North Carolina
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| Posted: Thu Feb 24, 2005 8:02 am Post subject: |
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Colin... Forever onward I will think of new lifters having tits.
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jberger
Samba Member
Joined: November 17, 2003
Posts: 2476
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| Posted: Thu Feb 24, 2005 9:01 am Post subject: |
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| Amskeptic wrote: |
| jberger wrote: |
| Worn lifters will be convex; you should be ok if they are pretty flat. I have heard differing opinions on cam lobe wear. If the case was open it would be an easy decision, since it isn't |
Convex, as in protrudes very slightly at the center of the lifter, is what a new solid lifter should be. A worn lifter goes flat to concave even. The hydraulic lifter is not ground with as much convex "ity". A Type 4 cam with any noticeable groove that your finger can notice is evidence that the cam is done.
Three piece rings can have that horrible end gap. Stagger the little rings.
Stacking shims at the bottom of the cylinder barrel is doable but definitely leakable, there is subtle shuffling that will find its way through the recommended Permatex Aviation-but-not-silicone-glop-ever sealant over time. Let your final guide be the deck height measurement. You may not need to stack anyway. Stock cam profiles will have no problem with a .040" deck, and if you have the typical dished pistons, your compression is unlikely to be affected in any negative way.
Colin |
I meant concave, dyslexia I guess.  |
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Rocknrod
Samba Member
Joined: November 02, 2004
Posts: 2157
Location: North Carolina
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| Posted: Thu Feb 24, 2005 10:17 am Post subject: |
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| jberger wrote: |
I meant concave, dyslexia I guess. |
Ah ha! Another person who can get away with left turns on red... "Officer, I thought I was making a right turn." |
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