Vortec heads & intake gaskets
Thread Starter
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Vortec heads & intake gaskets
A few years back I helped a buddy build a 350. He used Vortec heads (P/N 25534421) with an Edelbrock Performer (P/N 2116) intake manifold with Fel Pro 1255 gaskets. The specified torque was a measly 11 ft-lbs. A few years later the gaskets are moving and we feel they need to be replaced. Our impression is that the gaskets are too thick (.120") and the torque is inadequate. I'd love to hear from anyone who has experience with these heads. What is the best gasket to use? Is it necessary to use a .120" gasket or is .060" adequate? Is 11 ft-lbs. of torque adequate? And finally is thread locker a good idea with these low torque settings?
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
I never use a torque spec on intake bolts and 11ft/lbs. is pathetic. Hell, Honda calls for that on an 8mm fastener!
When tightening an intake.....of course you know to do the pancake pattern......but I like to go around 3 or four times.....you will feel when the bolt starts to get tight enough to where the gasket is thoroughly crushed....when the gasket reaches peak crush....the force gets real hard to move the bolt any further. I never use Loctite on intake bolts but I do use PTFE pipe sealant to prevent oil "creep" through and around the bolts. Of course a Vortec has only 8 bolts instead of 12 so getting it properly cinched down is even more critical then the 12 bolt heads. I think if I ever do another Vortec head engine....I would use studs on it....to me it would seem like a no-brainer to drop the intake on.....but I do not play with those heads much.
As far as .60 vs. .120 gaskets.....it all depends on port alignment and the front and rear "china wall" clearance......I have .120 gaskets on my Dart headed 406 because the Team G ports were too low compared to the heads. A .120 is going to crush a bit more than the .060 and even if you had a torque spec, you would have to check it again after a few heat cycles....especially at 11 ft/lbs.
Jebby
When tightening an intake.....of course you know to do the pancake pattern......but I like to go around 3 or four times.....you will feel when the bolt starts to get tight enough to where the gasket is thoroughly crushed....when the gasket reaches peak crush....the force gets real hard to move the bolt any further. I never use Loctite on intake bolts but I do use PTFE pipe sealant to prevent oil "creep" through and around the bolts. Of course a Vortec has only 8 bolts instead of 12 so getting it properly cinched down is even more critical then the 12 bolt heads. I think if I ever do another Vortec head engine....I would use studs on it....to me it would seem like a no-brainer to drop the intake on.....but I do not play with those heads much.
As far as .60 vs. .120 gaskets.....it all depends on port alignment and the front and rear "china wall" clearance......I have .120 gaskets on my Dart headed 406 because the Team G ports were too low compared to the heads. A .120 is going to crush a bit more than the .060 and even if you had a torque spec, you would have to check it again after a few heat cycles....especially at 11 ft/lbs.
Jebby
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 786
From: Lebanon Township New Jersey
I've bolted an intake to my Vortec heads several times. I do it like Jebby suggests (no torque wrench) and just tighten them down, several times, using sealer on the threads. I use Edelbrock gaskets and they are thick so they seem to compress quite a bit.
Racer
Joined: Mar 2001
Posts: 272
Likes: 3
From: Marion Ia
A few years back I helped a buddy build a 350. He used Vortec heads (P/N 25534421) with an Edelbrock Performer (P/N 2116) intake manifold with Fel Pro 1255 gaskets. The specified torque was a measly 11 ft-lbs. A few years later the gaskets are moving and we feel they need to be replaced. Our impression is that the gaskets are too thick (.120") and the torque is inadequate. I'd love to hear from anyone who has experience with these heads. What is the best gasket to use? Is it necessary to use a .120" gasket or is .060" adequate? Is 11 ft-lbs. of torque adequate? And finally is thread locker a good idea with these low torque settings?
i have had the vortec heads with an performer intake for about 10 years. My intake has never been removed and does not leak. It is torqued to 11 ft-lbs. sometimes the manufacturers know what they are doing. How the manifold is installed is totally different than the old heads. The bolts pull it strait down instead of at an angle.
Thread Starter
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Yes I have never used a torque wrench on intake bolts since I was a teenager, but my buddy is a little **** and when he saw that 11 ft-lb. torque spec he figured he should, since neither of us knows what 11 ft-lbs. feels like. That's basically finger tight. And yes that's the correct spec. I've also seen it listed as 140 in-lbs. I also know he retorqued them for weeks until he felt they were no longer moving. The gasket is still moving. The whole system just doesn't make sense to me. Thick gasket, small bolts, undertorqued, not enough bolts - not sure what the General was thinking.
I like the idea of the studs, but strangely ARP does not list a kit for that application. I think I will suggest a little more torque and I'm a fan of Permatex Spray-a-Gasket so I may try to talk him in to that. Many thanks for the input.
I like the idea of the studs, but strangely ARP does not list a kit for that application. I think I will suggest a little more torque and I'm a fan of Permatex Spray-a-Gasket so I may try to talk him in to that. Many thanks for the input.
Racer
Joined: Mar 2001
Posts: 272
Likes: 3
From: Marion Ia
A few years back I helped a buddy build a 350. He used Vortec heads (P/N 25534421) with an Edelbrock Performer (P/N 2116) intake manifold with Fel Pro 1255 gaskets. The specified torque was a measly 11 ft-lbs. A few years later the gaskets are moving and we feel they need to be replaced. Our impression is that the gaskets are too thick (.120") and the torque is inadequate. I'd love to hear from anyone who has experience with these heads. What is the best gasket to use? Is it necessary to use a .120" gasket or is .060" adequate? Is 11 ft-lbs. of torque adequate? And finally is thread locker a good idea with these low torque settings?
i have had the vortec heads with a performer intake for about 10 years. My intake has never been removed and does not leak. It is torqued to 11 ft-lbs, sometimes the manufacturers know what they are doing. How the manifold is installed is totally different than the old heads. The bolts pull it strait down instead of at an angle. I think it also recommends thread lock, but its been 10 years and I’m getting up in years
Burning Brakes
Joined: Jan 2003
Posts: 961
Likes: 275
From: Frederick MD
Crazy dumb question. Are we sure the bolts were actually at 11 ft lbs and not hanging up on a thread burr or similar? Granted 11 ft lbs isn’t very tight but that is actually the fastening torque on a lot of GMs intakes now. Granted you have a lot more wiggle room with an aluminum intake in this application but let’s consider the engine is say a Chevy Cruze. I’ve had to replace both the valve cover and intake on that car 2x because of the crappy PCV setup. Intake is something like 11 and the valve cover is something like 6. In this application both are plastic with the O-ring gaskets. You take them too tight and they leak, I can guarantee that.
In this case I would imagine using a higher torque with a more traditional crushable gasket so as to get the crush effect. Ultimately when the gasket settles and heat cycles I’d be willing to bet the clamping force is similar. If your using the O-ring style gaskets 11 is all it would need being it doesn’t crush.
In this case I would imagine using a higher torque with a more traditional crushable gasket so as to get the crush effect. Ultimately when the gasket settles and heat cycles I’d be willing to bet the clamping force is similar. If your using the O-ring style gaskets 11 is all it would need being it doesn’t crush.
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If your cylinder heads are aluminum, the torque for intake bolts would be reduced for that material difference. But not down to 11 ft-lb.!!! Normal 3/8-16 bolts into iron cylinder heads get 30 ft-lbs. I think around 25 ft-lbs. would be about right for 3/8-16 bolts going into aluminum. (Lower torque because the aluminum head will not accept as much load on those threads.)
Thread Starter
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
If your cylinder heads are aluminum, the torque for intake bolts would be reduced for that material difference. But not down to 11 ft-lb.!!! Normal 3/8-16 bolts into iron cylinder heads get 30 ft-lbs. I think around 25 ft-lbs. would be about right for 3/8-16 bolts going into aluminum. (Lower torque because the aluminum head will not accept as much load on those threads.)
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
11 ft-lbs will put a significant amount of clamping load on the gasket (maybe not as much as intended). But that torque is so low, it does not put the bolt shank in 'elastic deformation' condition. Therefore, those bolts are free to vibrate loose! I would be very surprised to find as much as 5 ft-lbs on them after several heat cycles on the engine.
The torque required by a joint must put adequate clamping loads on the gasket AND it must cause some stretching of the bolt, so that it will retain its load and not loosen. To that end, the FASTENER is what specifies how much torque must be placed on it. And the choice of fastener is based on what clamping requirements are placed on the joint.
The torque required by a joint must put adequate clamping loads on the gasket AND it must cause some stretching of the bolt, so that it will retain its load and not loosen. To that end, the FASTENER is what specifies how much torque must be placed on it. And the choice of fastener is based on what clamping requirements are placed on the joint.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
A few years back I helped a buddy build a 350. He used Vortec heads (P/N 25534421) with an Edelbrock Performer (P/N 2116) intake manifold with Fel Pro 1255 gaskets. The specified torque was a measly 11 ft-lbs. A few years later the gaskets are moving and we feel they need to be replaced. Our impression is that the gaskets are too thick (.120") and the torque is inadequate. I'd love to hear from anyone who has experience with these heads. What is the best gasket to use? Is it necessary to use a .120" gasket or is .060" adequate? Is 11 ft-lbs. of torque adequate? And finally is thread locker a good idea with these low torque settings?
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
11 ft-lbs is correct. I have vortec ramjet 350 intake and it's bolted down at 11 ft-lbs and it has NEVER leaked. Per specificatios you torque down to 9 ft-lbs on first pass and 11 ft-lbs on second pass.
Last edited by carriljc; Jan 19, 2021 at 11:35 AM.
Instructor
Joined: Apr 2007
Posts: 184
Likes: 17
From: GUTHRIE OKLAHOMA
Aren’t the vortec intake gaskets the plastic with silicone o-ring type? I seem to remember the bolts are special to the application and bottom out in the heads, achieving the correct “crush” on the seals.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Aftermarket intake should not use the plastic/o-ring gasket....use paper or composite.
FYI....these were notorious for intake leaks too....and shaving a little off the bolts fixes it....
Jebby
Last edited by Jebbysan; Jan 19, 2021 at 01:44 PM.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Yes I have never used a torque wrench on intake bolts since I was a teenager, but my buddy is a little **** and when he saw that 11 ft-lb. torque spec he figured he should, since neither of us knows what 11 ft-lbs. feels like. That's basically finger tight. And yes that's the correct spec. I've also seen it listed as 140 in-lbs. I also know he retorqued them for weeks until he felt they were no longer moving. The gasket is still moving. The whole system just doesn't make sense to me. Thick gasket, small bolts, undertorqued, not enough bolts - not sure what the General was thinking.
I like the idea of the studs, but strangely ARP does not list a kit for that application. I think I will suggest a little more torque and I'm a fan of Permatex Spray-a-Gasket so I may try to talk him in to that. Many thanks for the input.
I like the idea of the studs, but strangely ARP does not list a kit for that application. I think I will suggest a little more torque and I'm a fan of Permatex Spray-a-Gasket so I may try to talk him in to that. Many thanks for the input.
Something that gets widely overlooked is the torque wrench calibration. 11ft-lbs is really low in the setting dial for a click type torque wrench and that's when/where they are least accurate. Better to try with inch-pounds wrench so 11x12=132in-lbs. You want the 132in-lbs to be somewhat in the middle of the range of the torque wrench if possible. Myself I use my beam wrenches whenever possible. I calibrated them at work when new and they never lose calibration unless dropped. And please don't even consider Harbor Freight torque wrenches. I didn't realize how poor their accuracy was until I snapped several 1/4-20 bolt heads off. Those HF wrenches are what you give away to the competition to compromise their work.
Le Mans Master
Joined: Nov 2009
Posts: 6,882
Likes: 234
From: Bangkok, Thailand
I know this thread is old, but wanted to add this: when I built my small block with GMPP vortec heads, I used long ARP carb studs instead of bolts. They hold the gaskets in place perfectly, and guide the manifold straight into place. I'm pretty sure I used 2.5" long studs, but it's been 5 years, so I could be off there. I did call ARP tech support to let them know it worked, so they may have a part number for a set now.
