Head Gasket opinion for GT-40 clone aluminum heads + 351W

[foothilltom 33]

Hey guys, if you've been following, I managed to create a pretty bad situation with a poor choice of intake manifold gasket on my 351W rebuild.  Now, my attention turns to the head gaskets I used on my cast iron block and GT-40 clone aluminum heads.  I used the regular single shim style gasket that came with my Fel-Pro kit.  I've got the intake off and just about to go through the valve train (again) after re-lubing everything, and am pausing for some sanity.

Are there strong opinions on there about a properly installed single-shim style vs. something else?

I've got no reasons to suspect a leak of any kind, but I would prefer not to have to regret that decision later.

Oh, and is there conventional wisdom on re-torquing the heads after a breakin cycle?  If so, does that mean loosening them, and then re-torquing?  It seems weird to just stick a torque wrench on there and expect it to move...seems like the static friction of the bolt would make a false positive.  Thoughts?

Thanks as always.

Tom

[barnett468 418]

 

2 hours ago, foothilltom said:

I used the regular single shim style gasket that came with my Fel-Pro kit. 

Oh, and is there conventional wisdom on re-torquing the heads after a breakin cycle?  If so, does that mean loosening them, and then re-torquing?  It seems weird to just stick a torque wrench on there and expect it to move...seems like the static friction of the bolt would make a false positive.  Thoughts?

ummm...exactly what type of gasket is it?

In general, never loosen any bolt to retorque it, and it is not necessary to torque them again after break in.

[foothilltom 33]

At the moment, the gasket is installed, so I can't say with 100% certainty, but it came with my 351W gasket kit from Summit.  As near as I can tell from the Summit page, the number is 8548PT-2.

My question is more generic: is it considered bad practice to use the single shim style head gasket with aluminum heads.  It's hard searching for a distinct answer.  Folks talk about layered gaskets and other stuff due to the differences between alum and cast iron.  Just trying to get out in front of a potential bad choice while I'm taking everything apart again.

[barnett468 418]

that is not a steel shim gasket. it is a steel core laminated gasket, and although it is not the best choice, it should be fine.

[foothilltom 33]

Thanks!

[1969_Mach1 333]

My 1969 351W has the original 1969 cast iron heads, but I use the Fel Pro 9333PT1 head gaskets.  It is a Perma Torque head gasket and NOT one of their performance line of head gaskets.  They are available at most parts stores or mail order from Jegs or Summit.

I spoke to fel pro tech support before using them.  What they told me was: (1)  their performance line of head gaskets do indeed require retorquing after initial break in.  And to retorque you must do the head bolts one at a time in the tightening pattern, loosen the bolt about 1/4 turn then pull back down to full torque.  Without loosening you usually will not overcome static friction so the bolt will not be properly retorqued.  As a Mechanical Engineer that is true, static friction is easily twice sliding friction.  (2) The 9333PT1 is a Perma Torque head gasket that can still tolerate higher compression ratio motors up to about 12:1 static compression ratio.  My static compression ratio is 10.7:1 so they recommended the 9333PT1 since I did not want to have to retorque head bolts.

I would contact Fel Pro tech support and see if the 9333PT1 is suitable for aluminum heads as well.  If it is, it's a fairly good gasket that's easy to get and less costly than some performance gaskets.

https://www.felpro.com/contact-us.html

[foothilltom 33]

Hey guys, am mocking up the intake with the Fel-Pro 1250S-3 steel core gasket that was recommended.  I'm starting to thing that something is off with the geometry of my block, heads, manifold, whatever.  When I mock up the manifold with the side rail gaskets in place, but no front/rear gaskets, the manifold sits "very low" and the top of the rail doesn't even cover the top of my ports on my heads.  This can't be good.  :)

When I measure the gap between the manifold and the front/rear of the block, I get 1/16th in the front and 3/32" in the rear, so not a very big gap at all.

I then mocked it up by putting the cork front/rear gaskets in place and the manifold obviously set up a bit higher, but it now just barely covers the blue outline on the gasket around the intake ports.  This is the bit that creates the seal.  I have a picture of this with the suspected port areas outlined in blue.

I'm starting to believe that, yes, I may have had the wrong gasket set initially, but am also now wondering if the basic geometry of my setup is bogus and that something may have been modified, the heads not sized correctly, etc.  This is all coming from a newbie, so please forgive the poorly constructed thoughts.

I don't have another manifold lying about, but I am willing to do whatever to measure, verify, etc. 

As important, I don't plan on using the cork gaskets in the final install, which has be concerned that my height problem will be even worse since the RTV will "crush" much more readily than the cork.

Thoughts and ideas are very welcome.

Tom

[foothilltom 33]

I'm starting to answer my own questions...maybe that's a sign of growth?  I doubt it.

Careful measurement reveals that the tops of the ports of my GT-40 Chi-Clone heads are .2" higher than the cast iron heads.  This manifold obviously fit great with stock heads.

So, it seems that my original vacuum leak was probably not a result of poorly installed or poorly chosen gaskets, but a result of myopically installing an intake w/out any regard to its fit with this setup.

Did somebody recommend the Weiand Stealth?  I am thinking about calling the manufacturer to see if it accommodates this much taller head port.

Still, your insights are appreciated.  

[1969_Mach1 333]

The Weiand Stealth is a good manifold for street 351W motors.  That's what I use.  Plus it provides a little better hood clearance for an air cleaner than the Edelbrock Performer RPM.  But, you better see if it will work with your cylinder heads.

[unilec 57]

I'm not an engine guy, but I thought you could get thicker inlet gasket up to 0.120".

[foothilltom 33]

I think it might be kismet!  A friend of mine came over today to take a look at my stalled project.  He's a chevy guy (as many are).  When I told my story of woe about the Performer 351, he casually mentioned he had a Ford intake in his garage that he was going to sell for a friend who has given up on wrenching.  We went over and damn if it wasn't a Stealth 8023.  Never been installed.  Dirty and in need of cleaning.  We test fit it (after cleaning it up) and it was perfect!

He asked for $50 but I gave him $100 as I was *this close* to paying $256 (plus CA tax) for it today from Holley.  I'll sell the Edelbrock that came with my block and hope to break as even as possible.

Super happy with the manifold.  Fits my air cleaner setup and the hood closes!

Look for better stories from me in the days ahead as I think I've solved my big vacuum crisis.

Good weekend, all.

Tom

[barnett468 418]

On 8/16/2019 at 3:22 PM, foothilltom said:

I'm starting to answer my own questions...maybe that's a sign of growth?  I doubt it.

Careful measurement reveals that the tops of the ports of my GT-40 Chi-Clone heads are .2" higher than the cast iron heads.  This manifold obviously fit great with stock heads.

So, it seems that my original vacuum leak was probably not a result of poorly installed or poorly chosen gaskets, but a result of myopically installing an intake w/out any regard to its fit with this setup.

Did somebody recommend the Weiand Stealth?  I am thinking about calling the manufacturer to see if it accommodates this much taller head port.

Still, your insights are appreciated.  

the ports are above the head, not just higher than the port on the head?.

[foothilltom 33]

I'd answer it like this: the top rail of the old intake sat literally below the top of the ports on the heads with no gasket at the end seals.  The Stealth sits about 1/4" higher than the Edelbrock in the valley and covers the ports correctly.  It took me a long time to realize this, but when I mocked up the Edelbrock with my new gasket, I realized it.  I think these Chinese manufactured heads are the culprit.  When I carefully measured the top of the port from the bottom of the head (where it meets the block), the aluminum heads were .2" higher than the cast iron.  That plus the low-slung manifold created a no-fit situation.

I was concerned that a beat of RTV at the end seals was not going to "raise" the manifold high enough.  The Stealth doesn't have this issue.  So I'm ready to say that my Edelbrock just couldn't possibly work with these heads.

 

[1969_Mach1 333]

11 hours ago, foothilltom said:

I think it might be kismet!  A friend of mine came over today to take a look at my stalled project.  He's a chevy guy (as many are).  When I told my story of woe about the Performer 351, he casually mentioned he had a Ford intake in his garage that he was going to sell for a friend who has given up on wrenching.  We went over and damn if it wasn't a Stealth 8023.  Never been installed.  Dirty and in need of cleaning.  We test fit it (after cleaning it up) and it was perfect!

He asked for $50 but I gave him $100 as I was *this close* to paying $256 (plus CA tax) for it today from Holley.  I'll sell the Edelbrock that came with my block and hope to break as even as possible.

Super happy with the manifold.  Fits my air cleaner setup and the hood closes!

Look for better stories from me in the days ahead as I think I've solved my big vacuum crisis.

Good weekend, all.

Tom

Great to hear some good news!  You'll be happy with the Stealth intake.  It works great on 351W motors.  Plus it looks better than the Edelbrock Performer or Performer RPM.

If you look on the bottom of that Stealth intake, I've noticed what looks like a small Buddy Bar logo.  That intake has been around for a while.  I wonder if Buddy Bar was involved in the design.  Maybe somebody else here might have more information on that?

[barnett468 418]

On 8/17/2019 at 7:54 AM, foothilltom said:

I'd answer it like this: the top rail of the old intake sat literally below the top of the ports on the heads with no gasket at the end seals.  The Stealth sits about 1/4" higher than the Edelbrock in the valley and covers the ports correctly.  It took me a long time to realize this, but when I mocked up the Edelbrock with my new gasket, I realized it.  I think these Chinese manufactured heads are the culprit.  When I carefully measured the top of the port from the bottom of the head (where it meets the block), the aluminum heads were .2" higher than the cast iron.  That plus the low-slung manifold created a no-fit situation.

I was concerned that a beat of RTV at the end seals was not going to "raise" the manifold high enough.  The Stealth doesn't have this issue.  So I'm ready to say that my Edelbrock just couldn't possibly work with these heads.

 

wow, how odd, however, the stealth should fit exactly like the edelbrock intake, and if the stealth fits higher, then the edelbrock intake had to have been milled which is uncommon.

the end seals have zero affect on intake manifold port height.

 

 

[DocWok 30]

barnett468

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Posted August 12

"if the gaskets are not the problem, the heads are most likely the problem because it is extremely rare that someone mills down an intake manifold.

You can do a few tests to try and determine exactly what part may be wrong. This will require a protractor which is cheap and a few spacers etc."

 

I'm glad that you found the problem with the Edelbrock manifold having been milled, it always pays to check this with a used manifold no matter how 'Extremely Rare' it is that some machining may have been done in the past.

I have come across this issue a couple of times before where cylinder heads have been machined and then the intake milled to suit.

[barnett468 418]

On 8/16/2019 at 3:22 PM, foothilltom said:

Careful measurement reveals that the tops of the ports of my GT-40 Chi-Clone heads are .2" higher than the cast iron heads.  This manifold obviously fit great with stock heads.

I'm glad you determined that the heads were at least part of the problem with the fitment of the intake, especially since the edelbrock fit the stock heads properly. It is quite possible that the weiand is not machined exactly to spec, causing it to sit higher than a correctly machined intake would thereby fitting your obviously incorrectly made heads, but you would need an unmodified original intake to determine this.

[1969_Mach1 333]

foothilltom seems to now have a combination that fits together.  I wouldn't think there is anything wrong with the Weiand intake manifold.

[barnett468 418]

6 hours ago, 1969_Mach1 said:

foothilltom seems to now have a combination that fits together.  I wouldn't think there is anything wrong with the Weiand intake manifold.

1. the 2 manifolds are not machined the same.

2. he says the edelbrock fit the stock heads fine.

3. he said the "rails" meaning possibly the top of the ports as well were .200" taller on the chinese heads than on the stock heads.

4. he said the weiand covers the ports.

[DocWok 30]

More likely the the original heads had been machined sometime in the past and the Edelbrock was milled to match the original heads.

I doubt Weiand  machined an oversize manifold and foothilltorn just happened to find it and it solved a non-existant problem with new aftermarket heads.

[barnett468 418]

30 minutes ago, DocWok said:

More likely the the original heads had been machined sometime in the past and the Edelbrock was milled to match the original heads.

I doubt Weiand  machined an oversize manifold and foothilltorn just happened to find it and it solved a non-existant problem with new aftermarket heads.

You can not mill heads .200" and I have seen aftermarket manifolds that were not machined exactly the same as a stock one.

[1969_Mach1 333]

I wonder if it has something to do with the fact that Weiand states this manifold also fits GT40 and TFS cylinder heads.  I haven't seen that listed for the Edelbrock Performer intake.

[barnett468 418]

6 hours ago, 1969_Mach1 said:

I wonder if it has something to do with the fact that Weiand states this manifold also fits GT40 and TFS cylinder heads.  I haven't seen that listed for the Edelbrock Performer intake.

That's a good and interesting observation and may be part of the puzzle. Of course it is possible that the edelbrock was milled a little, but there is a huge difference between how the two manifolds fit and there shouldn't be if both intakes were designed to fit the same heads even if the eddy was milled, because as I mentioned, heads can't be milled .200". That's almost 1/4" which is massive.

[DocWok 30]

On 8/17/2019 at 2:22 AM, foothilltom said:

I'm starting to answer my own questions...maybe that's a sign of growth?  I doubt it.

Careful measurement reveals that the tops of the ports of my GT-40 Chi-Clone heads are .2" higher than the cast iron heads.  This manifold obviously fit great with stock heads.

So, it seems that my original vacuum leak was probably not a result of poorly installed or poorly chosen gaskets, but a result of myopically installing an intake w/out any regard to its fit with this setup.

Did somebody recommend the Weiand Stealth?  I am thinking about calling the manufacturer to see if it accommodates this much taller head port.

Still, your insights are appreciated.  

Nobody (except Barnett) ever mentioned that the original heads had been milled .200".

The OP only said that the tops of the ports are .2" higher than the cast iron heads.

The new heads probably have larger inlet ports compared to a standard head.

[barnett468 418]

14 hours ago, DocWok said:

Nobody (except Barnett) ever mentioned that the original heads had been milled .200".

I never stated, or even remotely suggested his stock heads were milled .200", and to the contrary, I clearly stated TWICE that heads can NOT be milled .200", and it was in fact YOU that stated his original heads were likely milled, as can clearly be seen in your quote below.

"More likely the the original heads had been machined sometime in the past and the Edelbrock was milled to match the original heads."