You neglected to mention measuring flat on the diagonal. I have seen heads and blocks that measure flat in length, flat across the head, but have a twist that shows up diagonally.
I used to work in R&D for a automotive manufacturer and we were having some head gasket issues and we started playing with different RA's on both the head and block stealing surfaces and we actually had the best results from what is normally considered an RA surface that's too rough... the engines coming out of the plant were machined to low to mid 30's in RA but we had the best results with a 55-60 RA while still using the same factory MLS gaskets.... I doubt that you will see this post as old as this video is but if buy chance you do I would love to hear your input on this... because it shouldn't be this way in all of my personal experience but it is.... thoughts? BTW that OEM did adjust the machine program a small amount but not anywhere close to the numbers we found to get the best results..and they are still having HG problems to this day ... I don't work for them still but I do have a passion for the brand still
Fel Pro is recommending 70 Ra cast iron and 55 Ra Aluminium for their permatorque MLS gasket install. 80Ra should still work. They claim better coatings allow this but I bet it's just viton. Maybe they do add extra viton in places help with weak spots in heads and blocks that need it. But your comment is making me wonder if the other head gasket makers just haven't tested their headgaskets with rougher surfaces. It makes sense you want the head gasket to not slide back and forth as the block and head expand and contract differently as things go from cold to hot to cold. And the viton should be able to adhere well to a rougher but not too rough surface. HP academy has some interesting videos on headgaskets.
great video and explination of surface roughness, the only issue i saw with the video is the demenstrator measured the surface of the block's RA, then showed the surface of the head.
at 9:46, a black mouse is visible at the roof of the red car. If is not your pet, the shop can use a resident cat, which would make a great pet. Thanks for the info on the very thin stainless gasket, I'm debating wether to copper spray and reuse a set I have brushed down to metal or just install new composite gaskets.
A lot of good information here. I am building a high compression ford 302 with trick flow heads and want the best possible gasket. I also want the same RA number on the deck surface and the head surface. I am old school and perma-torque was always the choice.
Yes. I came across this with my 460. I hand sanded the machining marks out of my heads and block. (Using a hard plastic hand block) started with 400 grit. Then 600, then 800, then 1000grit. Its almost a clean mirror finish.
Please post what profilometer you used for reference? Consider listing typical RA ranges by head gasket and links to gasket mfg technical data supporting.
Lol, surface finish. Use good head gaskets and you don't have worry about stupid bullshit. The vehicle needs to work with imperfect tolerances. Like an AK47.
@@SummitRacing block surface is not smooth surface, only skim silinder head, can i use carbon head gasket + copper spray for proper seal? coz aluminium head gasket still leak, that,s why i need to replace again with another head gasket
I know what you're saying but my machine shop uses a fly cutter for MLS gaskets for OE aplications. They don't have a deck grinder and we've never had a head gasket job come back. So OE engine over heats alloy on alloy OE gasket is MLS. We use a scotchbright die grinder pad on the block and get the head fly cut. These cars are day to day run arounds and a full engine build would right the car off so we offer the cheap fix. These cars can see over 100,000km out of the job. So I'm very skeptical about the RA finish values for MLS gaskets. Yes if I was spending 20k on an engine I'll get the head and deck ground to the correct RA for safety factor. But I don't believe it's necessary to finish the blocks to the level stated here. Even the OE just fly cut the block and head then throw a MLS gasket on some TTY bolts and call it a day and most engines will do 300,000+km. I call BS.
Yeah I think these Summit Racing guys spend a bit too much time in the world of 800hp boosted motors. When you've got an 8-71 trying to lift the heads off the block and blow them up through the hood, you probably do want to have your ducks in a row on the gasket front. It only makes sense that things would be a smidge more forgiving on a daily driver with 9:1 compression.
It's really difficult finding a machine shop that actually uses a profilometer to check the surface finish. Most, if not all, just do an eye ball check. I absolutely hate that.
I’m going through this right now. When I asked the first shop I called about their finish ra measurements, the guy told me, “that’s some internet myth, I’m not sure where it started, but you don’t need to worry about it.” Someone else online speculated that that is probably the actual reason some manufacturers are recommending to replace modern engine blocks and heads when found to be out of spec instead of having them decked!
It really depends on the application because both will seal great, but on high compression, boosted and nitrous applications, an MLS gasket will be the best for sealing between the two.
this is interesting. I get it. what the discussion is not telling you is that an MLS only needs to be super Smooth in the sealing areas. It is possible and not difficult to on an Iron block use only a razor blade and maybe some emery cloth in certain areas to ensure the surface is viable. now the cylinder head would be the same but aluminum is prevalent now and it needs to be resurfaced. I have done this on a BMW s54 block(iron) without any issues at all. Yes in areas the factory surface is obvious after some work, MLS is the standard for this block so it is not time consuming 4-6hours. I spent time, instead of money on the process. But I didn't have to haul the block around to shops and have some body work it, I don't trust almost any services in my area, any. But in general taking all the hardware to a machine shop and saying do this some might reply "the customer is wrong, we always do it this way". One other thing on MLS is that apparently the non crush sealant is Viton, all of that material needs to be blemish free, and carefully inspected. I have had 3 Elring head gaskets with this lately, post CV-19 world.
As one doing a budget-conscious project, I don't have the means to acquire a profileometer. I know I'm 'cavemanning', but I watched this in the hope of *_seeing_* what a 15-to-20 RA finish looks like in comparison to the rather mirror-like finish I've achieved by old-school sanding. Who the fuck makes this kind of video without even showing the surfaces of the 'finished' head and the 15 RA crank journal? That would have been an effortless edit-in. : /
Check out old school funk.channel He doesn't use a belt sander but he uses a flat table with sandpaper glued on it. Swears it works excellent on aluminum heads. I wouldn't try doing it with cast iron. I'm actually going to try doing it someday when the need arises. Old school funk really explains how it works well on the aluminum heads. And I trust him he seems like a decent guy. Hey it's worth a try when you're broke.
The ones you spray on head gaskets before installing, like Permatex Copper Spray ? I been told is sacrilege to do it on the MLS kind. I did it anyways, wish me luck.🤞😬
@@GearheadOutlaw is holding up perfectly fine. I have pulled it's hair back HARD a couple(more like 10-15) of times now going thru the gears and some highway time at high-ish rpms(3500-4000) and it hasn't blow up yet. No oil in coolant, no coolant in cylinders. It has worked for me. My block and head surfaces weren't in the best of conditions. I'm convinced without the copper spray it would have leaked. MLS is the shit but only if you start with perfect surfaces.👌 If I were to do it again I would still spray it BUT I would make sure the head gasket that came with the set is the "composite" type, same as the OEM part in my case as those are more forgiving to surface imperfections and there's 0 issues on spraying it.
If you spray each side of each layer of a mls its fine. No need for all this ra measuring outside a high performance or abused engines. Not that it really is anyway imo.
What doesn't add up is a MLS gaskets on rough cut heads and blocks straight from the manufacturers. I'm doing a engine now, 4.6 Ford off a 97 f150 and I could clearly make out the rough machine surfaces of the block and heads. I'll get it down to at least 40RA or where I can't feel anything by much and copper spray both sides of the MLS gasket. I assure you it will be better than it was.
@@jakefriesenjake sandpaper with a flat sanding block starting with coarse then to fine, constantly checking it with a straight edge for flatness. Working from end to the other not working in one area more than the other areas. I got it done, been nearly two years with zero issues despite my previous comment saying one year ago... it's wrong,... and I did apply one layer of copper spray on each side of the gasket. I also did the block the same way... just be sure to remove those doll pins first. Sand down the block and heads no more than necessary. The paper really need no more than 360 grit for finished grade. However, I wouldn't recommend doing this if the parts already have warpage, this method is only good when the parts are already flat... warpage will need machined.
@@garyr7027 cool. Just got word my heads are finished up at the machine shop. I had to fill some corrosion with extreme temp jb weld (only around the coolant ports, not the fire ring area). He put a certified Mls surface finish on the aluminum heads. My iron block looks pretty smooth, by I should probably hit it with a hard block and 400 grit. I have the paper already. I want the machinist to swing by to check it out, he's only down the road 2 minutes.
@@jakefriesenjake nice, I hope it all goes good for ya. This is one of those jobs you really only wanna do once and not having to redo it. On my engine both the block and the heads had rough factory surfaces, only reason why I even messed with the block, and both surfaces needs to be pretty smooth for MLS gaskets. If in doubt, that copper spray works, but not designed to fill in too much... don't over doo that stuff if you do use it, one thin layer only. Exhaust manifolds are another story, you can go to town with copper spray on those with zero issues... it's what I did.
Hate the Multi Layer Steel Gaskets from Mahle / Victor Reinz....they are so flat, even the original Hemi/Chrysler surface isn't smooth enough and they will begin to leak.
I think he just plain ole & bored that poor little ole mouse right to death in this video... 9:46 little ole black mouse on the roof of the Nova car high tails it out of the video.. ..
![50HP To 5000HP | Choosing Your Head Gasket | SCE Gaskets [TECH TALK]](http://i.ytimg.com/vi/tcMF7DuugEI/mqdefault.jpg)
As a machinist who uses said tools on a daily basis, thanks for posting a real useful video for the novice.
You neglected to mention measuring flat on the diagonal. I have seen heads and blocks that measure flat in length, flat across the head, but have a twist that shows up diagonally.
I used to work in R&D for a automotive manufacturer and we were having some head gasket issues and we started playing with different RA's on both the head and block stealing surfaces and we actually had the best results from what is normally considered an RA surface that's too rough... the engines coming out of the plant were machined to low to mid 30's in RA but we had the best results with a 55-60 RA while still using the same factory MLS gaskets.... I doubt that you will see this post as old as this video is but if buy chance you do I would love to hear your input on this... because it shouldn't be this way in all of my personal experience but it is.... thoughts?
BTW that OEM did adjust the machine program a small amount but not anywhere close to the numbers we found to get the best results..and they are still having HG problems to this day ... I don't work for them still but I do have a passion for the brand still
Fel Pro is recommending 70 Ra cast iron and 55 Ra Aluminium for their permatorque MLS gasket install. 80Ra should still work. They claim better coatings allow this but I bet it's just viton. Maybe they do add extra viton in places help with weak spots in heads and blocks that need it.
But your comment is making me wonder if the other head gasket makers just haven't tested their headgaskets with rougher surfaces. It makes sense you want the head gasket to not slide back and forth as the block and head expand and contract differently as things go from cold to hot to cold. And the viton should be able to adhere well to a rougher but not too rough surface.
HP academy has some interesting videos on headgaskets.
great video and explination of surface roughness, the only issue i saw with the video is the demenstrator measured the surface of the block's RA, then showed the surface of the head.
Explained very well, I did not realise it was such a technical subject. Many Thanks.
Thanks for watching Rod!
Very helpful. I beginning to get this head gasket thing figured out.
Thank you for watching, Chris!
at 9:46, a black mouse is visible at the roof of the red car. If is not your pet, the shop can use a resident cat, which would make a great pet. Thanks for the info on the very thin stainless gasket, I'm debating wether to copper spray and reuse a set I have brushed down to metal or just install new composite gaskets.
How do ya think they make rat engines huh...
thats a head
@@makimano1990 guess that means you need a bigger cat... Tigers maybe 😂🐯🦁🐆🐅
I saw it! Lol
You know thats a persons head right?
A lot of good information here. I am building a high compression ford 302 with trick flow heads and want the best possible gasket. I also want the same RA number on the deck surface and the head surface. I am old school and perma-torque was always the choice.
Which is the best for high compression like racing style? I wanna use nitro and turbo.
Doesn't Fel-Pro have a blue rubberized surface finish on their MLS gaskets that accommodates rougher aftermarket finishes??
What a beautiful lesson.
As alloy heads expand more than the engine block does that mean the head slides back and forth long ways on the gasket?
Yes
Really Good, This is very important. And I learned something new
Hi.
On modern common rail turbo diesels would you advise to spray Hylomar onto gasket prior to installation?..
Really good information, thanks.
That RA gauge is almost $2k
Is there a way to use sandpaper as a roughness standard?
For example...220 grit = 50 RA
We do not have any type of charts, but if you do a Goggle search for “RA vs grit chart”, you find a bunch of them.
Yes. I came across this with my 460.
I hand sanded the machining marks out of my heads and block. (Using a hard plastic hand block) started with 400 grit. Then 600, then 800, then 1000grit.
Its almost a clean mirror finish.
So informative...👍👌
What does a composite head gasket actually consist of? Graphite?
Please post what profilometer you used for reference? Consider listing typical RA ranges by head gasket and links to gasket mfg technical data supporting.
what head gasket do you recomend for a sbc cast iron 100ra stock street use?
What about copper spray???
Which gasket is better for overheat engine? Block heat stainless steel
Lol, surface finish. Use good head gaskets and you don't have worry about stupid bullshit. The vehicle needs to work with imperfect tolerances. Like an AK47.
This is all Ra micro inches imperial I guess. So the composite in metric Ra is good for 0.8 um to 2.5 um (factor 40x microinch to micrometer)
Perfect video left nothing out and everything handy in
carbon head gasket for better seal ? with additional copper spray better? for proper seal
I would not use any copper spray on that gasket. The only material on a head gasket that I recommend copper on is aluminum, steel shim or MLS.
@@SummitRacing block surface is not smooth surface, only skim silinder head, can i use carbon head gasket + copper spray for proper seal? coz aluminium head gasket still leak, that,s why i need to replace again with another head gasket
I know what you're saying but my machine shop uses a fly cutter for MLS gaskets for OE aplications. They don't have a deck grinder and we've never had a head gasket job come back.
So OE engine over heats alloy on alloy OE gasket is MLS. We use a scotchbright die grinder pad on the block and get the head fly cut. These cars are day to day run arounds and a full engine build would right the car off so we offer the cheap fix.
These cars can see over 100,000km out of the job.
So I'm very skeptical about the RA finish values for MLS gaskets. Yes if I was spending 20k on an engine I'll get the head and deck ground to the correct RA for safety factor. But I don't believe it's necessary to finish the blocks to the level stated here.
Even the OE just fly cut the block and head then throw a MLS gasket on some TTY bolts and call it a day and most engines will do 300,000+km.
I call BS.
Yeah I think these Summit Racing guys spend a bit too much time in the world of 800hp boosted motors. When you've got an 8-71 trying to lift the heads off the block and blow them up through the hood, you probably do want to have your ducks in a row on the gasket front. It only makes sense that things would be a smidge more forgiving on a daily driver with 9:1 compression.
It's really difficult finding a machine shop that actually uses a profilometer to check the surface finish. Most, if not all, just do an eye ball check. I absolutely hate that.
You should see the machine shops around here. They don't even know what surface roughness average is...
"It's true but you might wanna slap some copper spray on it cause my mill left witness marks on it"
I’m going through this right now. When I asked the first shop I called about their finish ra measurements, the guy told me, “that’s some internet myth, I’m not sure where it started, but you don’t need to worry about it.” Someone else online speculated that that is probably the actual reason some manufacturers are recommending to replace modern engine blocks and heads when found to be out of spec instead of having them decked!
And the second you question them their ego is so badly bruised they don't even want you in their shop
Which is better Carbon or St eel Cyliner gasket? Need help coz i need buy to replace my blown gasket
It really depends on the application because both will seal great, but on high compression, boosted and nitrous applications, an MLS gasket will be the best for sealing between the two.
this is interesting. I get it. what the discussion is not telling you is that an MLS only needs to be super Smooth in the sealing areas. It is possible and not difficult to on an Iron block use only a razor blade and maybe some emery cloth in certain areas to ensure the surface is viable. now the cylinder head would be the same but aluminum is prevalent now and it needs to be resurfaced. I have done this on a BMW s54 block(iron) without any issues at all. Yes in areas the factory surface is obvious after some work, MLS is the standard for this block so it is not time consuming 4-6hours. I spent time, instead of money on the process. But I didn't have to haul the block around to shops and have some body work it, I don't trust almost any services in my area, any. But in general taking all the hardware to a machine shop and saying do this some might reply "the customer is wrong, we always do it this way". One other thing on MLS is that apparently the non crush sealant is Viton, all of that material needs to be blemish free, and carefully inspected. I have had 3 Elring head gaskets with this lately, post CV-19 world.
As one doing a budget-conscious project, I don't have the means to acquire a profileometer. I know I'm 'cavemanning', but I watched this in the hope of *_seeing_* what a 15-to-20 RA finish looks like in comparison to the rather mirror-like finish I've achieved by old-school sanding. Who the fuck makes this kind of video without even showing the surfaces of the 'finished' head and the 15 RA crank journal? That would have been an effortless edit-in. : /
MLS gasket?
Multi-layer Steel
Thank you
Has anyone ever tried using a belt sander and straight edge?
Are you serious?
Do you think they call me Track Master for no reason, of course I'm serious...
No but I think that belt sander might have run across your head a couple of times...
Check out old school funk.channel
He doesn't use a belt sander but he uses a flat table with sandpaper glued on it. Swears it works excellent on aluminum heads. I wouldn't try doing it with cast iron. I'm actually going to try doing it someday when the need arises. Old school funk really explains how it works well on the aluminum heads. And I trust him he seems like a decent guy. Hey it's worth a try when you're broke.
@@TORCHBROTHERS checked him out. Would be a great channel if he didn't do the church sermons
No mention of sealers?
The ones you spray on head gaskets before installing, like Permatex Copper Spray ? I been told is sacrilege to do it on the MLS kind. I did it anyways, wish me luck.🤞😬
@@GIGABACHI how did it go?
@@GearheadOutlaw is holding up perfectly fine. I have pulled it's hair back HARD a couple(more like 10-15) of times now going thru the gears and some highway time at high-ish rpms(3500-4000) and it hasn't blow up yet. No oil in coolant, no coolant in cylinders. It has worked for me.
My block and head surfaces weren't in the best of conditions. I'm convinced without the copper spray it would have leaked. MLS is the shit but only if you start with perfect surfaces.👌
If I were to do it again I would still spray it BUT I would make sure the head gasket that came with the set is the "composite" type, same as the OEM part in my case as those are more forgiving to surface imperfections and there's 0 issues on spraying it.
If you spray each side of each layer of a mls its fine. No need for all this ra measuring outside a high performance or abused engines. Not that it really is anyway imo.
What doesn't add up is a MLS gaskets on rough cut heads and blocks straight from the manufacturers. I'm doing a engine now, 4.6 Ford off a 97 f150 and I could clearly make out the rough machine surfaces of the block and heads. I'll get it down to at least 40RA or where I can't feel anything by much and copper spray both sides of the MLS gasket. I assure you it will be better than it was.
You are correct.
How will you "get it down", to ra 40?
@@jakefriesenjake sandpaper with a flat sanding block starting with coarse then to fine, constantly checking it with a straight edge for flatness. Working from end to the other not working in one area more than the other areas. I got it done, been nearly two years with zero issues despite my previous comment saying one year ago... it's wrong,... and I did apply one layer of copper spray on each side of the gasket. I also did the block the same way... just be sure to remove those doll pins first. Sand down the block and heads no more than necessary. The paper really need no more than 360 grit for finished grade. However, I wouldn't recommend doing this if the parts already have warpage, this method is only good when the parts are already flat... warpage will need machined.
@@garyr7027 cool. Just got word my heads are finished up at the machine shop. I had to fill some corrosion with extreme temp jb weld (only around the coolant ports, not the fire ring area). He put a certified Mls surface finish on the aluminum heads.
My iron block looks pretty smooth, by I should probably hit it with a hard block and 400 grit. I have the paper already. I want the machinist to swing by to check it out, he's only down the road 2 minutes.
@@jakefriesenjake nice, I hope it all goes good for ya. This is one of those jobs you really only wanna do once and not having to redo it. On my engine both the block and the heads had rough factory surfaces, only reason why I even messed with the block, and both surfaces needs to be pretty smooth for MLS gaskets. If in doubt, that copper spray works, but not designed to fill in too much... don't over doo that stuff if you do use it, one thin layer only. Exhaust manifolds are another story, you can go to town with copper spray on those with zero issues... it's what I did.
nice info thanks buddy
2:43
“If you take a look here”…..and the camera focuses on the head, he is measuring the block 🙄🙄
Hate the Multi Layer Steel Gaskets from Mahle / Victor Reinz....they are so flat, even the original Hemi/Chrysler surface isn't smooth enough and they will begin to leak.
He is measuring the block but the camera is showing the head.
So?
@@GearheadOutlaw Would you want me to show you the water pump while I am talking about the brakes?
@@puzzled4163 he was talking about (surfaces) in general and their finish roughness.
So........
Why are you talking about the block surface and show a 36 head surface
what profilometer your using please send link where I can buy. what brand is good want to use it to make sure piston bore is finished to perfection.
You never showed a 60
This could have been a much shorter video. It felt like you didn't want to say the numbers.
Not enough can be said for properly measuring and machining the crank, cam, then deck of the block.
🇦🇺🤜🏼🤛🏼🍀😎🤓
Thank you for watching, Steve!
I think he just plain ole & bored that poor little ole mouse right to death in this video... 9:46 little ole black mouse on the roof of the Nova car high tails it out of the video.. ..
ARE COPPER GASKETS ANNEALED?
IF NO THEN ALL THAT TALKING MAKES NO SENSE AS NON ANNEALED COPPER GASKET WILL LEAK
Thank you