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| V6/60 head bolts... same for 3.4 as they are for 2.8? (Page 2/3) |
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1985 Fiero GT
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MAY 24, 04:15 PM
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| quote | Originally posted by cartercarbaficionado:
on some 2.8s it's both actually. these get super weird and weirdly enough some 3.4s and 2.8l use the same headbolts despite having different head thicknesses and my 84 iron duke and my v6 actually directly use the same headbolts..which is the exception not the norm for Fieros |
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I'm 99% sure that the 3.4l and the 2.8 use exactly the same heads, at least the pushrod 3.4l that 82-T/A is installing with ported 2.8l heads, and sending me the regular 3.4l heads to install on my 2.8l. definitely the dual twin cam 3.4 had different heads, maybe that's what you are talking about.
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La fiera
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MAY 24, 05:32 PM
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The 3.4L/2.8L head bolts are exactly the same and they are not reusable. If the instruction says to torque them in stages of specific lbs/ft values and then add specific degrees then is a torque to yield bolt and they can't be re used.
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1985 Fiero GT
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MAY 24, 08:12 PM
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| quote | Originally posted by La fiera:
The 3.4L/2.8L head bolts are exactly the same and they are not reusable. If the instruction says to torque them in stages of specific lbs/ft values and then add specific degrees then is a torque to yield bolt and they can't be re used. |
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The factory service manual, talking about the factory installed bolts, only mentions one torque spec, and says to clean and reinstall the old ones, indicating that they are reusable. I think replacement bolts are TTY but I'm not sure about that.
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fierofool
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MAY 25, 09:51 AM
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| quote | Originally posted by cartercarbaficionado:
on some 2.8s it's both actually. these get super weird and weirdly enough some 3.4s and 2.8l use the same headbolts despite having different head thicknesses and my 84 iron duke and my v6 actually directly use the same headbolts..which is the exception not the norm for Fieros |
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If the part number is exactly the same on the Fiero 2.8 and the Camaro/Firebird 3.4 heads, why would head thickness be different?
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82-T/A [At Work]
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MAY 25, 11:48 AM
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I don't know if the Iron Duke bolts were TTY, but we torqued them in three increments... 35-65-90 (or whatever the final torque specification was).
I've watched enough shows to know that even though a bolt may say "torque to this spec," it can be better to torque it down in proper sequence in three stages. Since the bolts do stretch somewhat, it'll ensure the final torque is more accurate when everything settles.
I don't know anything about an "extra turn" though... that makes me worried, and makes me wonder if that's why (back in the day), I ripped the threads out of my V6/60 engine block when I was re-installing the cyl head. I had to remove it because my exhaust manifold cracked, and the exhaust stud broke off on it.
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La fiera
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MAY 26, 11:08 PM
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| quote | Originally posted by 1985 Fiero GT:
The factory service manual, talking about the factory installed bolts, only mentions one torque spec, and says to clean and reinstall the old ones, indicating that they are reusable. I think replacement bolts are TTY but I'm not sure about that. |
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That is a vintage manual.
https://www.fiero.nl/forum/Forum2/HTML/143273.html
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1985 Fiero GT
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MAY 27, 12:36 AM
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What do you mean? Of course it is vintage, it was made specifically by gm for the Fiero, which is itself vintage. The only thing relevant in that thread is that the replacement bolts were very slightly smaller then the original Pontiac bolts, which led to the new ones stripping out, just one more reason to reuse old bolts in this case, especially since gm says to. When I put my heads on, I will carefully compare the new felpro bolts and the old gm ones, if the fel pro bolts are any thinner, I will certainly clean and reuse the gm ones, as that is what gm says to do, and I don't want to risk stripping out my block like the OP in that thread did because the replacement bolts were to thin. I will use sealant and will torque to 66 lb. Ft. as found in the factory service manual.[This message has been edited by 1985 Fiero GT (edited 05-27-2024).]
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La fiera
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MAY 30, 11:02 PM
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| quote | Originally posted by 1985 Fiero GT:
What do you mean? Of course it is vintage, it was made specifically by gm for the Fiero, which is itself vintage. The only thing relevant in that thread is that the replacement bolts were very slightly smaller then the original Pontiac bolts, which led to the new ones stripping out, just one more reason to reuse old bolts in this case, especially since gm says to. When I put my heads on, I will carefully compare the new felpro bolts and the old gm ones, if the fel pro bolts are any thinner, I will certainly clean and reuse the gm ones, as that is what gm says to do, and I don't want to risk stripping out my block like the OP in that thread did because the replacement bolts were to thin. I will use sealant and will torque to 66 lb. Ft. as found in the factory service manual.
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Of course you'll have to use sealant on a 2.8 because the bolt threads are exposed to the coolant! That doesn't happen on the 3.4L or any other 60 degree V6![This message has been edited by La fiera (edited 05-30-2024).]
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XxdjxX89
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MAY 31, 10:23 AM
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Il be straight forward , yes the head bolts are reusable
Just inspect them
If they are super rusted from sitting in the coolant passages then yes I would run a different set , they are the same for all that have iron heads so yes 3.1 and 3.4 are same head bolt
Valve lash 3/4 turn after zero has been the go to
Even had delta cams confirm 3/4
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La fiera
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MAY 31, 10:42 PM
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| quote | Originally posted by XxdjxX89:
Valve lash 3/4 turn after zero has been the go to
Even had delta cams confirm 3/4 |
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I don't have that problem, I use solid flat tappets. When I used to use hydraulics I used 1/8 turn. Reason being in case the lifters do pump up there were less chances for the valves held open to kiss the pistons. The other problem with hydraulics is that as the oil gets hot it gets thinner and also gets aerated. That means more air bubbles that can collapse making the cam loose duration and lift immensely.
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