Gaskets
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 31
Likes: 0
From: Flower Mound Texas
Gaskets
It's been a long time since I've had an engine completely (or mostly)apart, so I wanted a refresh and current tech from all of you who have done this recently or frequently. Below, I will give my assumptions and you can correct me (pre-Vortec SBC):
Head Gasket - Fel-Pro PermaTorque composite gasket installed dry with head bolt threads coated with sealer. Further question: some of the head bolt info I've read talks about reducing the target ft-lb torque numbers so that you don't over-torque (over-stretch - tensile) the head bolts due to the thread sealer "lubricating" the threads...does this makes sense? Seems strange to me, in that, I thought you always torqued bolts to a particular value that were lubricated, not dry?
Intake - Again, high quality Fel-Pro, Edelbrock, etc. gaskets with sealant for the head/port interface, and engine grade silicone only for the end seal.
Exhaust - Composite (perf metal core) gaskets installed dry
Timing cover - paper gasket with sealer
Water Pump - paper gasket with sealer
Comments, suggestions, corrections, best practices all welcome. Thanks in advance.
Head Gasket - Fel-Pro PermaTorque composite gasket installed dry with head bolt threads coated with sealer. Further question: some of the head bolt info I've read talks about reducing the target ft-lb torque numbers so that you don't over-torque (over-stretch - tensile) the head bolts due to the thread sealer "lubricating" the threads...does this makes sense? Seems strange to me, in that, I thought you always torqued bolts to a particular value that were lubricated, not dry?
Intake - Again, high quality Fel-Pro, Edelbrock, etc. gaskets with sealant for the head/port interface, and engine grade silicone only for the end seal.
Exhaust - Composite (perf metal core) gaskets installed dry
Timing cover - paper gasket with sealer
Water Pump - paper gasket with sealer
Comments, suggestions, corrections, best practices all welcome. Thanks in advance.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
you have no choice but to put some type sealer on SBC head bolts (Unless you have a block that's blind tapped!) GM suggested torque of 70 ft/lbs. knowing they had to have sealer and the sealer would act as a lube. I use 70 on the long bolts an 65 on the short ones since they don't stretch as much and never had a problem.
On the intake end seals, don't forget to wipe the china walls and the botton end rails on the intake with alcohol. Any, ANY oil and the RTV won't stick.
Exhaust- dry Headers only- no gasket needed on cast iron manifolds.
I use grease on the timing cover and water pump gaskets just to hold them in place. Makes replacing any of that easy too. same with the t'stat housing Use antiseize n the bolts.
pack the cavity on the back of the timing cover seal with grease. That will prevent the hammer blows from knocking out the little spring around the OD of the seal lip
On the intake end seals, don't forget to wipe the china walls and the botton end rails on the intake with alcohol. Any, ANY oil and the RTV won't stick.
Exhaust- dry Headers only- no gasket needed on cast iron manifolds.
I use grease on the timing cover and water pump gaskets just to hold them in place. Makes replacing any of that easy too. same with the t'stat housing Use antiseize n the bolts.
pack the cavity on the back of the timing cover seal with grease. That will prevent the hammer blows from knocking out the little spring around the OD of the seal lip
Last edited by TimAT; Apr 29, 2009 at 12:27 AM. Reason: My Bad. I just always assume headers!
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 39
From: Fremont CA
Don't use gaskets on exhaust manifolds! Use Hylomar gasket sealer on WP, intake gaskets and use RTV (Silicon sealer) for end seals on intake manifold and corners of intake. I take a chisel or punch and rough up the end rails of the block and underside of the intake to give the RTV something to grab onto for positive retention. I have beenusing this method since the late 1970's with good results. Rector seal (from hardware store) ARP seal or Permatex #2 all work well to seal head bolts, and use them to seal intake bolts to prevent oil leaks onto your intake manifold. Torque bolts to factory specs.
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 31
Likes: 0
From: Flower Mound Texas
Many thanks for the great info. A folow-up question or two:
Not familiar with Hylomar...is it a contact-type cement/sealer like Gasgacinch or ??
Regarding intake gaskets, I have heard lots of things i.e. only use sealer on the head side, not the intake side? And in that case, use a smal bead of silicone around the water passages? Or use sealer on both surfaces, or...?
Thanks again.
Not familiar with Hylomar...is it a contact-type cement/sealer like Gasgacinch or ??
Regarding intake gaskets, I have heard lots of things i.e. only use sealer on the head side, not the intake side? And in that case, use a smal bead of silicone around the water passages? Or use sealer on both surfaces, or...?
Thanks again.
Burning Brakes
Joined: Jul 2008
Posts: 923
Likes: 37
From: Green Bay Wisconsin
Further question: some of the head bolt info I've read talks about reducing the target ft-lb torque numbers so that you don't over-torque (over-stretch - tensile) the head bolts due to the thread sealer "lubricating" the threads...does this makes sense? Seems strange to me, in that, I thought you always torqued bolts to a particular value that were lubricated, not dry?
Hello,
You are correct that lubricating the threads changes the torque reading, but also understand that GM may have already taken that into account so read and understand your Service Manual.
Here's the rule to follow.
If the dry torque called for is 100 ft/lbs.
If you lubricate the bolt with oil you would only torque to 75 ft/lbs.
Hope this helps and good luck with the rebuild.
Douglas in Green Bay
Hello,
You are correct that lubricating the threads changes the torque reading, but also understand that GM may have already taken that into account so read and understand your Service Manual.
Here's the rule to follow.
If the dry torque called for is 100 ft/lbs.
If you lubricate the bolt with oil you would only torque to 75 ft/lbs.
Hope this helps and good luck with the rebuild.
Douglas in Green Bay
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Hylomar is a sealer- really good sealer. It's made for machined surfaces that need to be sealed and no room for a gasket but works great to stick gaskets in place.
I use 3M weatherstrip adhesive around just the water ports on the heads. Just enough to hold them in place. Then RTV at the head/block junction and across the china wall, with a good blob at the junction.
I use 3M weatherstrip adhesive around just the water ports on the heads. Just enough to hold them in place. Then RTV at the head/block junction and across the china wall, with a good blob at the junction.
