Best Intake gaskets

Skip Fix · Jun 3, 2022

Yep cleaned up the intake ports and plenum port entrances. The Blueprint heads have rectangular ports vs the trapezoid of the intake mainfold or even Fast Burn heads. That looks like the rubber gaskets in the pictures vs the 1255s I have.

L31MaxExpress · Jun 3, 2022

Skip Fix said:
Yep cleaned up the intake ports and plenum port entrances. The Blueprint heads have rectangular ports vs the trapezoid of the intake mainfold or even Fast Burn heads. That looks like the rubber gaskets in the pictures vs the 1255s I have.

The rubber ones were just some I had kicking around that came off the 305 in my Tahoe or 350 in my Van. Merely to show the difference in port work. Ports are matched well to a 1255.

Danimal08 · Monday at 9:52 PM

I know this is a couple year old post, but I wanted to point out a potential issue when using the 1255s for anyone who stumbles on this thread like I did...

After a lot of research on what to use on my project, I bought a set of 1255s because it seemed like the logical choice when evaluating the failure modes of intake gaskets on the vortecs. I had also bought a Mahle complete gasket set for the rest of the engine that had the composite intake gaskets.

As I was gluing the gaskets to the heads using studs to line everything up, I noticed that the "center ports" on the manifold (no idea what the purpose is on them other than oil drain back and potential oil cooling in the valley) were lining up slightly above the gasket. I applied gaskesinch to the intake to confirm my suspicions ( used glue as layout fluid). It appeared that the single opening side was right at the top of the gasket, and the side with 2 were just proud by .5 to 1mm.

Not sure if these gaskets have had any revisions lately, but they would most likely allowed a vacuum leak in my application once torqued. I've seen many accounts across various forums complaining of a whistle and leak on vortecs discovered by vacuum tests...I suspect this could be a culprit of a few. May not be an issue on all due to manifold production variation, etc., but its something to look out for. Seems like felpro could just raise that top bar 1/8" and would likely be okay. I had a spare manifold so I snagged a few pics to show. Hope this might help someone.

L31MaxExpress · Monday at 10:36 PM

Danimal08 said:
I know this is a couple year old post, but I wanted to point out a potential issue when using the 1255s for anyone who stumbles on this thread like I did...

After a lot of research on what to use on my project, I bought a set of 1255s because it seemed like the logical choice when evaluating the failure modes of intake gaskets on the vortecs. I had also bought a Mahle complete gasket set for the rest of the engine that had the composite intake gaskets.

As I was gluing the gaskets to the heads using studs to line everything up, I noticed that the "center ports" on the manifold (no idea what the purpose is on them other than oil drain back and potential oil cooling in the valley) were lining up slightly above the gasket. I applied gaskesinch to the intake to confirm my suspicions ( used glue as layout fluid). It appeared that the single opening side was right at the top of the gasket, and the side with 2 were just proud by .5 to 1mm.

Not sure if these gaskets have had any revisions lately, but they would most likely allowed a vacuum leak in my application once torqued. I've seen many accounts across various forums complaining of a whistle and leak on vortecs discovered by vacuum tests...I suspect this could be a culprit of a few. May not be an issue on all due to manifold production variation, etc., but its something to look out for. Seems like felpro could just raise that top bar 1/8" and would likely be okay. I had a spare manifold so I snagged a few pics to show. Hope this might help someone.

I ran and still run the Edelbrock 7235s but nice catch on the 1255s.

rebelyell · Tuesday at 6:31 AM

I prefer the rubber-steel Vortec L30/L31 combo.
In addition to Fel-Pro, Mahle also has a good rubber-steel intake gasket.

On a Vortec 4.3L V6, I've been pleased with rubber-Aluminum gasket. The rubber was a light mint green color silicone on an Aluminum carrier. Sorry, don't recall brand. Perhaps it was intended for a Marine app. Wish I could find same design for Vortec V8.

Vortecs' 45* angle-bolts present a rather different clamping dynamic.

Danimal08 · Tuesday at 7:45 AM

I'd agree- not an optimal bolted joint design. Guessing they prioritized clampload of the coolant passages when they went to vortec heads which likely had a little more heat in them. Seems like they used the composite gasket to allow for some flex in the aluminum.

Ended up using the Mahle composites that were in the kit torqued to their spec (they had torque limiters on them also). I'll recheck after a heat cycle. Had a green seal and seemed well-made (USA also). Surfaces on heads and intake were good. If it pukes these, shes getting 5.3 with a hairdryer. Not messing with another one.

L31MaxExpress · Tuesday at 1:40 PM

rebelyell said:
I prefer the rubber-steel Vortec L30/L31 combo.
In addition to Fel-Pro, Mahle also has a good rubber-steel intake gasket.

On a Vortec 4.3L V6, I've been pleased with rubber-Aluminum gasket. The rubber was a light mint green color silicone on an Aluminum carrier. Sorry, don't recall brand. Perhaps it was intended for a Marine app. Wish I could find same design for Vortec V8.

Vortecs' 45* angle-bolts present a rather different clamping dynamic.

They have not lasted at all for me. 3-4 years and they are junk. I still have the Vortec TPI 383 that was in the 1983 G20. It still runs perfectly with ~15 year old 7235s on it.

Danimal08 · 2024-04-24T10:47:58-0400

L31MaxExpress said:
They have not lasted at all for me. 3-4 years and they are junk. I still have the Vortec TPI 383 that was in the 1983 G20. It still runs perfectly with ~15 year old 7235s on it.

I doubt they last also, but gonna give the benefit of the doubt for now...the fiber gasket seems like the way to go on them with sufficient torque. That'll be perfect timing to build a nice little "eco-boost" 5.3 for it. I'll update here and in my project thread when they fail...

I've had two of these trucks with 250k plus miles on original intake gaskets- my Dad still drives one. All the other gaskets leaked on them, but those held. Looks like the Exxon Valdez crashed where it parks.

Best Intake gaskets

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