Head Gasket selection
Thread Starter
Racer
Joined: Nov 2020
Posts: 265
Likes: 76
Head Gasket selection
Hello All
I'm upgrading the top end on my L48 and have a head gasket question. The new heads are aluminum with 64cc chamber to improve compression ratio over stock heads. I ordered fel-pro 1094 head gaskets that have 3.2cc compressed volume. My concern is that although these .015" gaskets will pump up compression a bit more I may have issues with leaks due to gasket thickness.
Has anone used this thin gasket in the past?
Is the thinner gasket CR improvement worth the possible issue is the block isn't perfect?
I'm upgrading the top end on my L48 and have a head gasket question. The new heads are aluminum with 64cc chamber to improve compression ratio over stock heads. I ordered fel-pro 1094 head gaskets that have 3.2cc compressed volume. My concern is that although these .015" gaskets will pump up compression a bit more I may have issues with leaks due to gasket thickness.
Has anone used this thin gasket in the past?
Is the thinner gasket CR improvement worth the possible issue is the block isn't perfect?
Is my vette stock?? HAHA
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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I've used them and never had an issue until I blew well past 7000 rpm on the highway. I thought I had the rev limiter engages adn unfortunately I did not. I lost a solid roller lifter and the gasket. Other than that the engine was strong and ran great,.....but my mistake killed it, not the gaskets fault
Race Director
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From: Sunshine Coast, Queensland, Australia
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Cruise-In VIII Veteran
I'm running the Fel-Pro. 015 head gaskets on my engine, I was a bit sceptical at first as well. Spray them with permatex copper spray gasket on both sides before installing. Make certain everything is perfectly clean. don't forget to chase all the bolt holes with a thread cleaner.
No issues on my engine. Helps with more than compression. Also gets your quench right.
No issues on my engine. Helps with more than compression. Also gets your quench right.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
I keep a few of those .015" steel shim gaskets in stock here at the house. Copper sealer spray for them too. They might not be officially recommended for aluminum heads but I know people do it. Personally, I use them with iron heads but if I needed to get a good quench on an aluminum head engine, I would give them a try.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
The .015 gasket will not raise compression enough to be worried about it......it will come in at about 9.5 to 1 with the .015.
And yes...spray them down well on both sides and let tack up for 10 minutes or so before install......
Jebby
And yes...spray them down well on both sides and let tack up for 10 minutes or so before install......
Jebby
Le Mans Master
Joined: May 2007
Posts: 5,025
Likes: 1,120
From: North tonawanda NY
I'm running the Fel-Pro. 015 head gaskets on my engine, I was a bit sceptical at first as well. Spray them with permatex copper spray gasket on both sides before installing. Make certain everything is perfectly clean. don't forget to chase all the bolt holes with a thread cleaner.
No issues on my engine. Helps with more than compression. Also gets your quench right.
No issues on my engine. Helps with more than compression. Also gets your quench right.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I've had them in for 10 years + now. coated with copper coat first then installed. I'm using them with aluminum heads. Tight quench is good.
Very clean is important, but always is for such items.
Very clean is important, but always is for such items.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I am planning on doing the same thing this summer, (Aluminum head swap on an L-48) and I plan to use those same gaskets, (FelPro 1094) so I have done a little research on them. From what I have read, this gasket likes a very smooth, flat surface to seal against, so mating surface prep on the block deck will be very important. The instructions for this gasket say your mating surfaces should be less than 55 Ra. 150 grit sandpaper will give you a surface at about 40Ra, and that sounds just about right. Figure out some way to keep the sanding grit out of the engine. If we can find a big, long rat bastard file that will give an equivalent finish, that would be even better, since we would also be ensuring flatness. The mating surface of your brand-new heads should be just fine. Good luck!
Scotty
Scotty
Last edited by scottyp99; Apr 20, 2022 at 02:31 PM.
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Le Mans Master
Joined: Mar 2004
Posts: 7,493
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From: Little Rock AR
MLS gaskets (multi layer steel) are supposed to be intolerant of rough surfaces. 
Common steel shim head gaskets were used by the factory with a rough broached surface that varied all over the place as far as surface finish is concerned. You can't measure it anyway. These gaskets are used on un-decked blocks to get the quench right most of the time. I doubt surface finish matters much here.
Common steel shim head gaskets were used by the factory with a rough broached surface that varied all over the place as far as surface finish is concerned. You can't measure it anyway. These gaskets are used on un-decked blocks to get the quench right most of the time. I doubt surface finish matters much here.
Thread Starter
Racer
Joined: Nov 2020
Posts: 265
Likes: 76
I just got all the parts just waiting on heads and I've taken everything apart. These 1094 gaskets look very scary to me since they are just SS with no supporting material to help with the seal. The heads are new so they should be pretty smooth and I cleaned the deck as much as possible but I still don't have much confidence in prep skill to use these.
Another question:
In the disasembly I found that the harmonic balancer is no where near the pointer on the old timing cover when I'm at TDC. I really struggled to get timing right on this car and I'm guessing that's the issue. Would another Harmonic balancer fit on the car but have the timing slot/mark almost 180 degress from the pointer? The timing slot on the balancer is almost pointing straight down at TDC.
Another question:
In the disasembly I found that the harmonic balancer is no where near the pointer on the old timing cover when I'm at TDC. I really struggled to get timing right on this car and I'm guessing that's the issue. Would another Harmonic balancer fit on the car but have the timing slot/mark almost 180 degress from the pointer? The timing slot on the balancer is almost pointing straight down at TDC.
Le Mans Master
Joined: May 2007
Posts: 5,025
Likes: 1,120
From: North tonawanda NY
You asked, and so far everyone with experience has had nothing but positive feedback for the 1094.( I forgot to mention Ive been using mine 10 years also)... You can go to amazon or summit and read more positive reviews there. I wondered myself so I did some research a while bac and found felpro themselves do state these are ok with aluminum heads. I believe its mentioned on summit.
As for the balancer, maybe the outer ring slipped... the line should be about 10 degrees off from the keyway on the balancer.
As for the balancer, maybe the outer ring slipped... the line should be about 10 degrees off from the keyway on the balancer.
Last edited by augiedoggy; Apr 21, 2022 at 07:36 AM.
Safety Car
Joined: Nov 2001
Posts: 4,424
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From: northern CA
Also went with the Fel Pro 1094 when Trick Flow 175 heads went on my engine. Previously black, the newer 1094 head gaskets came silver coated. Both sides of the gaskets were also sprayed with Permatex copper coat.
The cylinders were sealed off and block surface was cleaned as best as possible, then prepped using a 4x6 inch piece of machined steel with sandpaper.
John
The cylinders were sealed off and block surface was cleaned as best as possible, then prepped using a 4x6 inch piece of machined steel with sandpaper.
John
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
The problem would come in if either the head or the block has a warble in it. The .015 is not going to seal that. That is where composite type gaskets that crush come in. If both the block and the heads are flat it won't be a problem.
My block has a slight .003" slope to it from front to back. No warbles or undulating surfaces though so it's good to go with a .015" shim. I did not get the deck machined either. It's still the factory finish product other than I cleaned it and ran a little sandpaper on a stick over it. If you do that (i wouldn't given your circumstance) be sure you don't get grit into the piston area and make every effort to keep it out of the coolant passages as well.
That grit can do some pretty good grinding over time running around the cooling system, probably not favorable for the pump shaft or seal.
On mine it was a rebuild so I had the block hot tanked and cleaned after I did the surface prep. Given you're not going to do that I would be more inclined to just wire wheel the deck and prep it with carb cleaner or something similar to get it nice and clean.
My block has a slight .003" slope to it from front to back. No warbles or undulating surfaces though so it's good to go with a .015" shim. I did not get the deck machined either. It's still the factory finish product other than I cleaned it and ran a little sandpaper on a stick over it. If you do that (i wouldn't given your circumstance) be sure you don't get grit into the piston area and make every effort to keep it out of the coolant passages as well.
That grit can do some pretty good grinding over time running around the cooling system, probably not favorable for the pump shaft or seal.
On mine it was a rebuild so I had the block hot tanked and cleaned after I did the surface prep. Given you're not going to do that I would be more inclined to just wire wheel the deck and prep it with carb cleaner or something similar to get it nice and clean.
Instructor
Joined: Feb 2018
Posts: 107
Likes: 20
From: Janesville WI
The problem would come in if either the head or the block has a warble in it. The .015 is not going to seal that. That is where composite type gaskets that crush come in. If both the block and the heads are flat it won't be a problem.
My block has a slight .003" slope to it from front to back. No warbles or undulating surfaces though so it's good to go with a .015" shim. I did not get the deck machined either. It's still the factory finish product other than I cleaned it and ran a little sandpaper on a stick over it. If you do that (i wouldn't given your circumstance) be sure you don't get grit into the piston area and make every effort to keep it out of the coolant passages as well.
That grit can do some pretty good grinding over time running around the cooling system, probably not favorable for the pump shaft or seal.
On mine it was a rebuild so I had the block hot tanked and cleaned after I did the surface prep. Given you're not going to do that I would be more inclined to just wire wheel the deck and prep it with carb cleaner or something similar to get it nice and clean.
My block has a slight .003" slope to it from front to back. No warbles or undulating surfaces though so it's good to go with a .015" shim. I did not get the deck machined either. It's still the factory finish product other than I cleaned it and ran a little sandpaper on a stick over it. If you do that (i wouldn't given your circumstance) be sure you don't get grit into the piston area and make every effort to keep it out of the coolant passages as well.
That grit can do some pretty good grinding over time running around the cooling system, probably not favorable for the pump shaft or seal.
On mine it was a rebuild so I had the block hot tanked and cleaned after I did the surface prep. Given you're not going to do that I would be more inclined to just wire wheel the deck and prep it with carb cleaner or something similar to get it nice and clean.
Wouldn't a wire wheel create "grit" as well? Honest question.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
loose wires maybe, not grit. Whatever is on the deck surface is what you’ll get coming off. If the last head gasket was the stock shim gasket then not much is going to be on that surface. If it was a aftermarket composite gasket I would scrape residual gasket off carefully then wire wheel to get it cleaner followed by carb cleaner.
The grit would come from sand paper as it gives up it’s “sand” to clean the surface.
The grit would come from sand paper as it gives up it’s “sand” to clean the surface.
Instructor
Joined: Feb 2018
Posts: 107
Likes: 20
From: Janesville WI
loose wires maybe, not grit. Whatever is on the deck surface is what you’ll get coming off. If the last head gasket was the stock shim gasket then not much is going to be on that surface. If it was a aftermarket composite gasket I would scrape residual gasket off carefully then wire wheel to get it cleaner followed by carb cleaner.
The grit would come from sand paper as it gives up it’s “sand” to clean the surface.
The grit would come from sand paper as it gives up it’s “sand” to clean the surface.
Ahh. Makes sense. Thanks!
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
My block deck isn't perfect, planing to use these and copper spray the block side https://www.competitionproducts.com/...info/PVT45746/ Bit thicker and composite gaskets are more forgiving I've herd, GM has a sim gasket for the C4's but cost more.