Aluminum Heads Problems - Chevelle Tech
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post #1 of 23 (permalink) Old Sep 30th, 07, 7:30 PM Thread Starter
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Aluminum Heads Problems

Since just about everyone is running aluminum heads these days, I am curious the types of problems, if any, people are having.

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post #2 of 23 (permalink) Old Sep 30th, 07, 9:28 PM
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Re: Aluminum Heads Problems

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Originally Posted by Sandy View Post
Since just about everyone is running aluminum heads these days, I am curious the types of problems, if any, people are having.
The only problems that I've heard anyone ever having with aluminum heads is that with some of them (such as AFR, and World/Merlin ) the rocker arm stud holes break into the intake ports (as with some of the AFR's) and the header bolt holes break into the coolant passages (as with some of the World/Merlin aluminum heads).

This might not be a major problem, and should be easily remedied by the inclusion of some good thread sealant such as ARP sealant placed on the threads (as long as the customer/installer remembers to do that). However, it isn't any evidence of quality control on the manufacturer's part. I'm not a business owner myself, but I would like to think that if I did own a cylinder head biz, that I wouldn't want to ship heads to my customers that have coolant passages and/or intake ports in which the drill bit poked through during the machining process!

The only other things that I can think of that is specific to the aluminum heads, is that spring cups must be used underneath the valve springs when they're installed to protect the head from being damaged. But you probably already knew about that one. And that may or not be enough to effect the installed height of the springs.

And the other thing that you're likely already aware of is that during engine assembly it's best to keep the torque of the intake manifold bolts to 30 ft/lbs to avoid stripping the threaded holes in the heads. You might be able to get away with 35 ft/lbs if you're lucky, but ever since I stripped a couple holes in the AFR heads I once had, when bringing the intake manifold bolts to 36 ft/lbs, I routinely keep it at 30 ft/lbs. If you can get the head manufacture to deliver the heads with both the intake and exhaust manifold bolt holes heli-coiled, then that would be best. At the time, AFR was only doing that on the exhaust manifold bolt holes.

EDIT: I also keep the torque on the rocker arm studs at 50 ft/lbs on aluminum heads (which is what most installers do as far as I know).

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Last edited by BillyGman; Sep 30th, 07 at 9:50 PM.
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post #3 of 23 (permalink) Old Sep 30th, 07, 11:10 PM
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Re: Aluminum Heads Problems

Billy, with all Rect. port BBC heads that I am aware of (iron or aluminum, GM or aftermarket) the rocker studs actually protrude into the intake ports. It's not a flaw, they are made that way. And yes, you have to use sealant on the rocker studs. It's standard procedure. I've not personally seen a header bolt hole go inot the water jacket, but I'm sure it's possible.

Sandy, one other thing that happens a lot is the rocker arm tips don't line up in the center of the valve tip. Pretty common with most aftermarket heads. It may actually be the guide plates that are the culprit. It can be fixed/helped by enlarging the holes in the guide plates and adjusting them to fit. Or cutting the guide plates and adjusting them individually then welding them back together. Older GM castings are very prone to breaking the rocker stud bosses, but most aftermarket heads have them beefed up so that is no longer a common problem.

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post #4 of 23 (permalink) Old Oct 1st, 07, 12:49 AM Thread Starter
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Re: Aluminum Heads Problems

thanks guys, keep em coming!

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post #5 of 23 (permalink) Old Oct 1st, 07, 1:02 AM
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Re: Aluminum Heads Problems

Quote:
Originally Posted by Sandy View Post
Since just about everyone is running aluminum heads these days, I am curious the types of problems, if any, people are having.
=
You are aware there are not many cars or trucks you can buy today that do not have aluminum heads right?

My opinion there are no issues running aluminum heads that you would not see in aftermarket iron heads too.

As far as the studs going into the intake runner go it has nothing to do with quality control or the machining process
It has to do with the size of the ports.

As Jay stated, every BB rectangle port head out there with any amount of volume is going to have the studs intrude into the intake port
AFR, Brodix, Dart, doesn't make any difference there is only so much room above the port in a conventional casting

BTW, Most SB heads with a port of over about 190 or so cc's also has a stud sticking into the intake port too.
This includes a number of GM heads.

I guess by the same logic GM messed up the machining on blocks because the head bolt holes go into water

And in all the years I have been messing with this stuff I have never stripped the threads in a new aluminum head or a used one assuming someone had not already hamburgered up the threads,,,
All you have to do is use a bit of common sense when installing things like don't go nuts tightening, use the correct length bolt,,

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post #6 of 23 (permalink) Old Oct 1st, 07, 1:34 AM
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Re: Aluminum Heads Problems

If they are going to be used hard heli-coil the intake,ex and spark plug holes it will save you grief at the races some day.
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post #7 of 23 (permalink) Old Oct 1st, 07, 1:49 AM
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Re: Aluminum Heads Problems

Quote:
Originally Posted by Wolfplace View Post
=
All you have to do is use a bit of common sense when installing things like don't go nuts tightening, use the correct length bolt,,

And be sure to use Anti Sieze compound on ANY steel bolt, fitting, or spark plug that you thread into aluminum and expect to be able to remove later. Including the header bolts and intake bolts, etc.

Randy

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post #8 of 23 (permalink) Old Oct 1st, 07, 2:48 AM
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Re: Aluminum Heads Problems

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Originally Posted by jbird View Post
Billy, with all Rect. port BBC heads that I am aware of (iron or aluminum, GM or aftermarket) the rocker studs actually protrude into the intake ports. It's not a flaw, they are made that way. And yes, you have to use sealant on the rocker studs. It's standard procedure. I've not personally seen a header bolt hole go inot the water jacket, but I'm sure it's possible.

.
Okay, thanks for the correction. I didn't realize they were all like that as far as the rocker arm studs go. But as far as the header bolt holes, yes, I have seen World BBC heads that the holes broke into the water jackets.

Quote:
Originally Posted by Wolfplace View Post
=
BTW, Most SB heads with a port of over about 190 or so cc's also has a stud sticking into the intake port too.
This includes a number of GM heads.

And in all the years I have been messing with this stuff I have never stripped the threads in a new aluminum head or a used one assuming someone had not already hamburgered up the threads,,,
All you have to do is use a bit of common sense when installing things like don't go nuts tightening, use the correct length bolt,,
I stand corrected on the BBC rocker studs going into the intake ports. That just seemed kinda weird to me. But as far as the SBC heads go, I had a set of AFR aluminum heads with 195cc ports, and none of the rocker studs went into the intake ports.

As far as the intake manifold bolts, I used ARP bolts, along with ARP thread sealent, and stripped 2 of the threaded holes on my AFR heads with just 36 ft/lbs of torque. So that's why I alwys keep it to 30 ft/lbs for those bolts. I ended up having to heli-coil the bolt holes because of that.

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post #9 of 23 (permalink) Old Oct 1st, 07, 10:24 AM
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Re: Aluminum Heads Problems

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Originally Posted by BillyGman View Post
Okay, thanks for the correction. I didn't realize they were all like that as far as the rocker arm studs go. But as far as the header bolt holes, yes, I have seen World BBC heads that the holes broke into the water jackets.

I stand corrected on the BBC rocker studs going into the intake ports. That just seemed kinda weird to me. But as far as the SBC heads go, I had a set of AFR aluminum heads with 195cc ports, and none of the rocker studs went into the intake ports.

As far as the intake manifold bolts, I used ARP bolts, along with ARP thread sealent, and stripped 2 of the threaded holes on my AFR heads with just 36 ft/lbs of torque. So that's why I alwys keep it to 30 ft/lbs for those bolts. I ended up having to heli-coil the bolt holes because of that.
Billy, I haven't used a torque wrench on intake bolts in many years(like almost 20). Just get tight by "feel". I doubt they are 35 ft lbs and I don't have problems with them sealing. The center two bolts on each side of an intake like a BBC Victor are not easy to get a tq wrench on. I just use a box end wrench and get them tight enough that way. I also use GM gasket sealer on them as some go into the water jackets. But that's just me.

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post #10 of 23 (permalink) Old Oct 1st, 07, 11:07 AM
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Re: Aluminum Heads Problems

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Billy, I haven't used a torque wrench on intake bolts in many years(like almost 20). Just get tight by "feel". I doubt they are 35 ft lbs and I don't have problems with them sealing. The center two bolts on each side of an intake like a BBC Victor are not easy to get a tq wrench on. I just use a box end wrench and get them tight enough that way. I also use GM gasket sealer on them as some go into the water jackets. But that's just me.
I hear ya Jay. I do have a tendency to overtighten everything, which is precisely why I use a torque wrench. I often use a boxed extension (kind of like a crows foot, but boxed) on the center bolts to get at that them. As long as you keep it at a 90 degree angle to the torque wrench, your torque values won't change, and will be exactly what your torque wrench is reading. But I don't want to get too far off topic here. Maybe we should get back to Sandy's question.

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post #11 of 23 (permalink) Old Oct 1st, 07, 11:31 AM
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Re: Aluminum Heads Problems

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Originally Posted by BillyGman View Post
As long as you keep it at a 90 degree angle to the torque wrench, your torque values won't change, and will be exactly what your torque wrench is reading.
Actually, you're lengthening the arm and the torque value will change a bit.

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post #12 of 23 (permalink) Old Oct 1st, 07, 12:06 PM
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Re: Aluminum Heads Problems

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Originally Posted by Rick Dorion View Post
Actually, you're lengthening the arm and the torque value will change a bit.
You're only lengthening the arm if you keep the extension straight with the torque wrench. If you put it at a right angle ( 90 degrees) then you're not lenghtening it at all. That's the way I do it.

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post #13 of 23 (permalink) Old Oct 1st, 07, 12:30 PM
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Re: Aluminum Heads Problems

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Originally Posted by BillyGman View Post
You're only lengthening the arm if you keep the extension straight with the torque wrench. If you put it at a right angle ( 90 degrees) then you're not lenghtening it at all. That's the way I do it.

Thats the way I do it too. Straight out multiplies the torque where 90* keeps it the same length. In my job I use torque adaptors or "dogbones" alot and I have to admit that sometimes I do use them straight out where space is tight. In this case I would use the minimum recomended torque, Harleys always have a min. and a max. torque spec. The lower torque measurments don`t multiply it too much, only 1-3 ft.lbs.
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post #14 of 23 (permalink) Old Oct 1st, 07, 3:04 PM
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Re: Aluminum Heads Problems

I gotta tell you I must be doing something wrong

I just don't seem to have all these problems & have been running aluminum heads for over 30 years,,,,,
In that time I think I may have stripped maybe one or two plugs & a couple of bolts
But I certainly have fixed a number of stripped holes so I guess the gorilla tightening system is used on occasion

Like Jay, I have not used a torque wrench on an intake or exhaust bolt in probably 20 of those years now & just do not have problems.

And you are all aware that even the best torque wrenches may have an error of about 3% right?
This is assuming they are calibrated once in a while,,,,
Add another 5 or so percent for "operator" error,,,
and another 5 or so for the different lubes folks use,,,,

Sandy,
Again, my opinion there are just not all these issues with aluminum heads if you use a modicum of common sense with them
There are of course a few "rules"
You don't use straight water
You change your coolant on occasion
You use anti-seize on the fasteners
You use the correct length fasteners
You do not use the "gorilla tightening system"

And,,,
When all else fails follow the instructions,,


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post #15 of 23 (permalink) Old Oct 1st, 07, 3:18 PM
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Re: Aluminum Heads Problems

I haven`t torqued a intake manifold or headers ever either and never had a problem. I was just adding my $.02 on the torque adaptor issue.
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