Help diagnose what went wrong
09-17-2009, 10:29 AM
#26
lulz. I've blown several Felpro's. They are cheap for a reason. Check HBZ... I'm sure most of the heavy L-Series builders don't use Felpro (especially for turbo applications).
09-17-2009, 11:17 AM
#27
w0rld's l0ngest m0t0rswap
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My wonderings aren't about head gaskets, i'll probably go the beck/arnley route though but my question is: why are there water passages from the head that don't go anywhere into the block? Do they just sit and cook the water for me? I find it odd...
10-19-2009, 10:27 AM
#32
w0rld's l0ngest m0t0rswap
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P90 head re-surfacing question, warpage tolerance, etc
Well I have a dilemma going on, I want to have my baby up and running by next friday and its totally possible because I currently have all the parts I need to re-assemble the whole engine, however last thursday presented itself with quite a problem.
When checking the flatness of the Cylinder head there was a .0075" gap!! The straight edge is NEW from central tools so I have no doubt in it, but here's the thing. There are high points at each end of the cylinder (specifically high on the front cover end, where the 2 10mm screws go) which accounts for the .0075" gap in the middle. Throughout the cylinder head regions, however the largest gap is around .003-.004 which is just within factory specs (.0039) My question is this, Do i NEED to resurface the head?? If I do, do I need to get cam tower shims, even for just cutting away .005" from each end? Could I torque it down, allow for some gasket crush, then retorque it after initial startup? What is the highest warpage that these can tolerate while being able to run some 7-12 boost?
When checking the flatness of the Cylinder head there was a .0075" gap!! The straight edge is NEW from central tools so I have no doubt in it, but here's the thing. There are high points at each end of the cylinder (specifically high on the front cover end, where the 2 10mm screws go) which accounts for the .0075" gap in the middle. Throughout the cylinder head regions, however the largest gap is around .003-.004 which is just within factory specs (.0039) My question is this, Do i NEED to resurface the head?? If I do, do I need to get cam tower shims, even for just cutting away .005" from each end? Could I torque it down, allow for some gasket crush, then retorque it after initial startup? What is the highest warpage that these can tolerate while being able to run some 7-12 boost?
10-19-2009, 11:28 AM
#35
Why in the hell do you keep making new threads for the same problem? Just freaking post replies in your other thread so we don't have to do the whole guessing game on what happened and what has been checked.
SO... you are doing this 2nd rebuild because your head gasket blew... most likely due to a warped head. SO... unless you want to do this a 3rd time... GET THE HEAD CHECKED AT A MACHINE SHOP.
PS... I am combining this with your other thread.
SO... you are doing this 2nd rebuild because your head gasket blew... most likely due to a warped head. SO... unless you want to do this a 3rd time... GET THE HEAD CHECKED AT A MACHINE SHOP.
PS... I am combining this with your other thread.
Last edited by NismoPick; 10-19-2009 at 11:30 AM.
10-19-2009, 11:41 AM
#36
w0rld's l0ngest m0t0rswap
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alright!! i was just making a new thread because its sorta related but maybe someone else wants to know what the head tolerances are. but nismo...do u think that I would need to shim and if .005" would retard cam too much?
10-19-2009, 11:51 AM
#37
You only need shims if you've shaved the head a ton. I can't remember right off the top of my head, but I think the specs are on HBZ or Atlanticz... something like anything over .050".
Has that head ever been shaved?
Has that head ever been shaved?
10-19-2009, 09:35 PM
#38
w0rld's l0ngest m0t0rswap
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yeah I'm not sure ever since I got it from Pierree'z I've had nothing but problems...I went back to the shop and they literally yelled and cussed at me saying i had a bad attitude or something then proceeded to tell me the head was fine....complete bullshit if you ask me
10-20-2009, 12:32 PM
#41
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yeah my DSM head got shaved 2 times, the first was a massive amount, no shims. and its a day job for them and 40 bucks, don't be a bitch and get it dooone. and get a good MLS headgasket and ARP head studs and you'll never have to pull that fudger again for HG problems. also you can reuse MLS head gaskets and ARP studs if you torque to spec and the HG comes off undamaged. if you over torque though the studs are shot, however over-torqueing ARP head studs is sometimes done alot because its a stronger hold. gooooo figure...
10-23-2009, 12:26 AM
#42
w0rld's l0ngest m0t0rswap
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Update!
Last edited by thetremendousti; 10-23-2009 at 12:34 AM.
10-26-2009, 05:33 PM
#44
w0rld's l0ngest m0t0rswap
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so I am just about to put the head on the block but here's the thing...During the weekend I took off the cam towers to get it surfaced. He took off .010" but uh i'm thinking as i put the cam towers back on.....so then i search and lo an behold i read that i should get my cam towers realigned!! so any thoughts?
Last edited by thetremendousti; 10-26-2009 at 05:50 PM.
10-26-2009, 05:37 PM
#45
There's people that swear by either way...
#1: you need to have the cam towers line honed if removed.
#2: you don't need to have the cam towers line honed, because the towers can't move laterally.
I think BRAAP swears by the second one... do a quick search for "cam towers" here & on HBZ.
You could have let the machine shop re-install them & the cam for you....
#1: you need to have the cam towers line honed if removed.
#2: you don't need to have the cam towers line honed, because the towers can't move laterally.
I think BRAAP swears by the second one... do a quick search for "cam towers" here & on HBZ.
You could have let the machine shop re-install them & the cam for you....
10-26-2009, 05:40 PM
#46
w0rld's l0ngest m0t0rswap
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i just read about the two finger rule and i think after i get the head on i'll try to knock-align them with a rubber mallet
Last edited by thetremendousti; 10-26-2009 at 05:47 PM.
10-26-2009, 05:45 PM
#47
I believe you don't have to get them line honed, as you can keep the cam towers semi loose, install the cam, then torque down the towers. That would insure that they are all lined up completely. Maybe even have someone rotate the cam as you torque... maybe that's overkill. What's the FSM say?
10-26-2009, 05:57 PM
#49
Intrawebz Wizard
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FSM has nothing on it at all but I found a little bit of info else were
Originally Posted by http://datsunzgarage.com/p79/
*
REPLACING TOWER WITH SHIMS
* While replacing the cam towers is not difficult, it requires some concentration and a quiet place to work. Note that the towers are stamped with a number before you remove them.
* Make sure the shims are free of grit and oil. Put the shims on each tower base, and tap the towers down over the studs (it helps to have them loosely around the cam).
* Make sure the cam journals are lubed with motor oil or install lube. What you're doing is slowly tightening, and tapping the towers so they all end up in line. They can't move side to side, only up and down. The straight cam forces them to line up, so with manipulation they will eventually match. Binding is usually caused by one tower.
* Spend a few minutes moving from tower to tower, when the cam finally spins easily, STOP. Resist the temptation to keep on tightening to "make it better". The bolts only torque to 10-12lb, you will strip one out if you're not careful.
* This tip from the Nissan rebuild bible is the secret: "If the cam binds when torquing the bolts on a particular tower, simply loosen the 2 bolts and rap the top of the tower with a hammer and retighten."
* Before you begin use blue Loctite on the bolts, you don't want to remove them once you get it right!
It took me about 20 minutes of tapping and retightening to get the shimmed towers to line up, but it worked just fine. Be careful not to overtighten the bolts and ream out the boltholes. The cam should spin fairly freely with just two fingers.
REPLACING TOWER WITH SHIMS
* While replacing the cam towers is not difficult, it requires some concentration and a quiet place to work. Note that the towers are stamped with a number before you remove them.
* Make sure the shims are free of grit and oil. Put the shims on each tower base, and tap the towers down over the studs (it helps to have them loosely around the cam).
* Make sure the cam journals are lubed with motor oil or install lube. What you're doing is slowly tightening, and tapping the towers so they all end up in line. They can't move side to side, only up and down. The straight cam forces them to line up, so with manipulation they will eventually match. Binding is usually caused by one tower.
* Spend a few minutes moving from tower to tower, when the cam finally spins easily, STOP. Resist the temptation to keep on tightening to "make it better". The bolts only torque to 10-12lb, you will strip one out if you're not careful.
* This tip from the Nissan rebuild bible is the secret: "If the cam binds when torquing the bolts on a particular tower, simply loosen the 2 bolts and rap the top of the tower with a hammer and retighten."
* Before you begin use blue Loctite on the bolts, you don't want to remove them once you get it right!
It took me about 20 minutes of tapping and retightening to get the shimmed towers to line up, but it worked just fine. Be careful not to overtighten the bolts and ream out the boltholes. The cam should spin fairly freely with just two fingers.
10-26-2009, 05:58 PM
#50
Intrawebz Wizard
Join Date: Feb 2009
Location: Vernal, UT
Posts: 3,176
