[leeklm]

These gaskets have been on my KRE head motor for about 2 years. Noticed an intake leak at the track last wknd and found this... gaskets were installed dry. Any idea what may have caused this to happen on all four dividers?

On the other 3 dividers, the gasket material was completely missing... meanwhile I still won the bracket class that day. Maybe the trick for me is to have more broken parts

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[tjs72lemans]

Sounds like maybe the heads and intake may not be seating correctly. Has the intake been cut to match the heads if block was decked?

[leeklm]

Originally Posted by tjs72lemans

Sounds like maybe the heads and intake may not be seating correctly. Has the intake been cut to match the heads if block was decked?

Yes. Doing a little checking around sounds like it can be an issue with ported heads and intakes , especially if not gluing them down.

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[NeighborsComplaint]

Are those the plain composition gaskets with no heat riser opening from Mr. Gasket? If plain gaskets are not glued down, the dividers are weak and can displace from the vacuum as the intake charge flows past. The heat riser block-offs can also burst and burn through from the exhaust pulses.

Better gaskets with the silicone sealing beads like FelPro and Edelbrock combined with the supplied rigid, flame-proof heat riser block off plate won't do that.

Fortunately for you, the water passages remained sealed (which says they were clamped tightly so no intake to head issues) or you would have a motor full of antifreeze.

[leeklm]

One other thing... the centers of the other ports are knocked out, but the upper and lower edges are fine (except for the one in this pick). One would assume the upper or lower edge would be the first to go if the intake/head angle was off?

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[leeklm]

Originally Posted by NeighborsComplaint

Are those the plain composition gaskets with no heat riser opening from Mr. Gasket? If plain gaskets are not glued down, the dividers are weak and can displace from the vacuum as the intake charge flows past. The heat riser block-offs can also burst and burn through from the exhaust pulses.



Better gaskets with the silicone sealing beads like FelPro and Edelbrock combined with the supplied rigid, flame-proof heat riser block off plate won't do that.



Fortunately for you, the water passages remained sealed (which says they were clamped tightly so no intake to head issues) or you would have a motor full of antifreeze.

These are plain Tin Indian gaskets made for the large ports found on the 305/310 cfm heads. No exhaust crossover on the heads. I forget the exact size, but a little larger than the felpro RA4 gaskets.

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[NeighborsComplaint]

If all the basket damage is along the bottom, then yes the surfaces may not be matching (intake flanges and head mating surfaces not at 90 degrees). As the coolant passages are higher on the heads, so you may have lucked out without leaks there.

I have run those style gaskets doubled up (glued together) with stainless block offs under the gaskets where I had an intake/heads mismatch. I sprayed the intake side with gasket cinch before installing. They were fine with no leaks for years until I swapped to a different intake and a single gasket.

[leeklm]

I do have a couple of new sets of 1233 gaskets. Looks like I can cut those as shown in the pic and glue them down to the head....

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[Formulajones]

Those plain black gaskets are horrible for that. Felpro makes a version of those too and I avoid them like the plague.

[surfsama]

Originally Posted by leeklm

These are plain Tin Indian gaskets...k

That happened to my engine too with those gaskets. Replaced them with Felpros and Mr Gaskets and never had that issue again.

[lust4speed]

Backfire will do that. Could be caused by anything including an intake valve hanging open during the combustion process. Only gasket failures I've seen is where something went south and there was unusually high pressure in the affected ports.

The 1972 H.O. heads were cast with a recess that allowed intake gasses to flow from one cylinder to another. No idea why Pontiac did that but it didn't hurt performance.

[Cliff R]

"Those plain black gaskets are horrible for that. Felpro makes a version of those too and I avoid them like the plague."

+2, 3, 4 5 and 6.......those are JUNK!!!!

Even the black Felpro's they sell for the RAIV and SD heads aren't any better. I use the blue Felpro's with the metal reinforced material in them. Glue them to the heads with a little RTV, use some car paste wax on the top side, and you will be able to remove the intakes scores of times and leave the gaskets in place.......Cliff

[leeklm]

"The 1972 H.O. heads were cast with a recess that allowed intake gasses to flow from one cylinder to another. No idea why Pontiac did that but it didn't hurt performance."

Interesting. As mentioned, all four of my intake dividers were damaged or missing, so the engine would have been running like this for some time. The engine pulls strong to 6200rpm, and no issues anywhere- except of course where the one port finally leaked directly to outside air this past wknd.

Does having a completely sealed intake port at the head really do anything? I mean, all 8 are fully connected just a few inches up the line via the intake plenum....

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[Formulajones]

Originally Posted by Cliff R

"Those plain black gaskets are horrible for that. Felpro makes a version of those too and I avoid them like the plague."

+2, 3, 4 5 and 6.......those are JUNK!!!!

Even the black Felpro's they sell for the RAIV and SD heads aren't any better. I use the blue Felpro's with the metal reinforced material in them. Glue them to the heads with a little RTV, use some car paste wax on the top side, and you will be able to remove the intakes scores of times and leave the gaskets in place.......Cliff

Spot on, glad to see I'm not the only one that has seen those things fall apart countless times. I also prefer the blue Felpro's

[Formulajones]

Originally Posted by leeklm

"The 1972 H.O. heads were cast with a recess that allowed intake gasses to flow from one cylinder to another. No idea why Pontiac did that but it didn't hurt performance."

Interesting. As mentioned, all four of my intake dividers were damaged or missing, so the engine would have been running like this for some time. The engine pulls strong to 6200rpm, and no issues anywhere- except of course where the one port finally leaked directly to outside air this past wknd.

Does having a completely sealed intake port at the head really do anything? I mean, all 8 are fully connected just a few inches up the line via the intake plenum....

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I really can't fathom that being a good thing Leeklm. As that piston starts down the bore it's going to pull from multiple cylinders. I tend to think that would cause really funky AFR readings from cylinder to cylinder and probably impossible to read a plug from that bank, giving you no idea where your tune is or needs to be.