Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 
Like Tree9Likes

Thread: Deck flatness specification?
          
   
   

Reply To Thread
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 24
  1. #1
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    14

    Deck flatness specification?

     



    This is a continuation of my thread regarding "White Smoke". Engine is an L98 that I ran hot for a short distance due to being close to home.
    Well the heads are off to the shop for a pressure test. Cylinder bores look good with the exception of #5 which has a pit near the top of stroke about 1/8" x 3/8". It can be felt by touch which if memory serves means it's at least .002" deep. This cylinder registered 140 PSI before pulling the heads. #3 read 145 & #7 138. Running a straight edge along the left deck checked pretty good. Couldn't get a .0015" gauge under anywhere however the right bank deck is a different story. Most of the deformation of the right deck in the top front of #2 cylinder. So the question arises: just how flat does the deck need to be? Additionally is one gasket manufacturer better at accommodating out of flatness. In another world I'd be fixing the block but money is really tight and since we're in AZ I want to get back on the road.

  2. #2
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    city
    Car Year, Make, Model: bug
    Posts
    824

    Quote Originally Posted by mr-natural View Post
    This is a continuation of my thread regarding "White Smoke". Engine is an L98 that I ran hot for a short distance due to being close to home.
    Well the heads are off to the shop for a pressure test. Cylinder bores look good with the exception of #5 which has a pit near the top of stroke about 1/8" x 3/8". It can be felt by touch which if memory serves means it's at least .002" deep. This cylinder registered 140 PSI before pulling the heads. #3 read 145 & #7 138. Running a straight edge along the left deck checked pretty good. Couldn't get a .0015" gauge under anywhere however the right bank deck is a different story. Most of the deformation of the right deck in the top front of #2 cylinder. So the question arises: just how flat does the deck need to be? Additionally is one gasket manufacturer better at accommodating out of flatness. In another world I'd be fixing the block but money is really tight and since we're in AZ I want to get back on the road.
    A little info for ya. From what you said, Match the area to the rest for finish. 0.001 feeler goes, but a 0.015 does not, your ok.
    I use a burr buster after I know the areas are within specs. But, at the same time, you must use what is needed for what you plan to do with the motor, and combos you plan on using.
    On mine, I finished the surface, and run steel shims. 11.5 compression, Never had any problems.

    Wrong Surface Finish
    To seal properly, a head gasket requires a surface finish that is within a recommended range. The specifications vary depending on the type of head gasket. If the surface is too rough, or in some cases too smooth, the gasket may not seal properly and leak or fail. One common mistake to avoid here is not looking up the recommended specifications for a particular engine and/or a particular type of head gasket.
    As a rule, the recommended surface finish for a traditional composition style soft-face head gasket in an engine with cast iron heads and block is 60 to 120 microinches Ra (roughness average). But the recommended surface finish for the same type of head gasket in an engine with an aluminum head on a cast iron block is smoother, typically 20 to 50 microinches Ra. On late model engines with multi-layer steel (MLS) head gaskets, the OEM surface finish recommendations tend to be even smoother, say 20 to 30 microinches Ra or even 7 to 15 Ra. But the aftermarket also sells MLS gaskets with special coatings for many of these same applications that can handle surface finishes in the 50 to 60 microinch Ra range. So you have to know your gaskets and the surface finish recommendations for them by the gasket manufacturer, or the OEM if you are using a factory-style replacement head gasket.

    PS: Myself, I've always had good luck with Fel Pro Gaskets.
    Last edited by DennyW; 01-12-2018 at 01:09 PM.



  3. #3
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    14

    Thanks DennyW for your quick response. As I mentioned in my post I exceed that .0015" upper limit for out of flatness spec only at the upper front area of #2 cylinder. Do I need a new block, since the existing block has already been milled some years back?
    Last edited by mr-natural; 01-12-2018 at 02:46 PM.

  4. #4
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    city
    Car Year, Make, Model: bug
    Posts
    824

    Quote Originally Posted by mr-natural View Post
    Thanks DennyW for your quick response. As I mentioned in my post I exceed that .0015" upper limit for out of flatness spec only at the upper front area of #2 cylinder. Do I need a new block, since the existing block has already been milled some years back?
    Is it possible for you to take a picture as clear as you can and post it.

    Or email me a picture. The bigger the better.
    Last edited by DennyW; 01-12-2018 at 01:43 PM.



  5. #5
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    14

    I'm in CA right now and the car is in AZ and the only picture I have with me is of the whole right bank. I'm uncertain as to how to upload a photo to this post. If you would text me you email address or phone number via my phone I'll send it directly to you Denny. If I can figure out how to do that.
    Last edited by mr-natural; 01-12-2018 at 03:13 PM.

  6. #6
    glennsexton's Avatar
    glennsexton is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Mar 2005
    Location
    Tigard
    Car Year, Make, Model: 63 Nova SS
    Posts
    2,081

    On page 75 of his book, Gaskets and Gasketed Joints, author John Bickford has a table showing the “maximum out-of-flat amounts” for internal combustion engines. For V8 engines he recommends .004” in the length and .002” in the width of the gasketed surface. (This is a well-known 20 year old college level text book typically used by mechanical engineering students – Sells in the $250-$300 range on line!) He also has this note;

    “This is the sum of the values of the cylinder head plus block combined. Since cylinder blocks usually do not display major out-of-flat conditions, out-of-flat conditions are usually associated with the cylinder head; but the sum of the two must be kept in mind and must not exceed the recommended specification.”

    That said, I have seen factory GM blocks that measure 9.020” - 9.027” with as much as a .003” variance corner-to-corner. I still use a carpenter’s framing square and feelers (like the long one below) but have used a deck bridge with a dial caliper from time-to-time if I think there’s an issue. I’ve put a lot of engines together with Fel-Pro 1010 (.039) and 1003 (.041) gaskets that were .002” - .003” off corner-to-corner and never had problems. To Denny’s point, the 60 to 120 micro inches Ra is important and too smooth for Chevy small block can be a problem. It might be ok for aluminum Japanese engines, but cast iron should be a bit rough.

    I have a lot of measuring tools – but I have consistently used these guys a lot. Inside and outside calipers, straight edges, feelers from .001” to .025”, a manual caliper (I have a digital one as well – but like this one), a lighted 10X loupe (great as the eyes age!) and my prize position the 1” micrometer that was my fathers and is more than 70 years old – still smooth as butter and dead accurate.

    Keep us posted!
    Glenn
    Attached Images
    DennyW likes this.
    "Where the people fear the government you have tyranny. Where the government fears the people you have liberty." John Basil Barnhil

  7. #7
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    14

    Wow, thanks Glenn for all the detailed information. I'll spend more time measuring when I get back home and post again. Hopefully I'll have a reading from the shop as to the condition of my head by that time too.

  8. #8
    techinspector1's Avatar
    techinspector1 is offline CHR Member Visit my Photo Gallery
    Join Date
    May 2003
    Location
    Zephyrhills, Florida, USA
    Car Year, Make, Model: '32 Henway
    Posts
    12,104

    Quote Originally Posted by mr-natural View Post
    Thanks DennyW for your quick response. As I mentioned in my post I exceed that .0015" upper limit for out of flatness spec only at the upper front area of #2 cylinder. Do I need a new block, since the existing block has already been milled some years back?
    You will need to measure the block deck height (distance from the centerline of the main bearing bore to the flat surface of the block where the heads bolt on). Design deck height of a small block Chevy is 9.025", but I have found them to be off by 0.020" from one end on one side of the block to the other end on the other side of the block. I would never, ever build a motor without decking the block to square it up. Normally, the "stack" of parts that go into the block measure out to 9.000", leaving 0.025" piston deck height above the piston.

    So, it depends how much the block has been decked and what the block originally measured when released by the factory. Measure your block.
    .
    glennsexton likes this.
    PLANET EARTH, INSANE ASYLUM FOR THE UNIVERSE.

  9. #9
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    city
    Car Year, Make, Model: bug
    Posts
    824

    This is the area of most interest in my mind at this point. ( I exceed that .0015" upper limit for out of flatness spec only at the upper front area of #2 cylinder. ). This could be minor, or a major problem. If not a major problem, it is possible to lap in the surface.
    Good info though guys.
    glennsexton likes this.



  10. #10
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    city
    Car Year, Make, Model: bug
    Posts
    824

    By the picture I saw, it looks like a head gasket failure. Try Felpro head gaskets for your engine. Much better that the one in the picture. I would say deterioration was the cause. See closely around the cylinders where the sealing rings are. You can see seepage past that, and the one piston on the left is clean.
    (RIGHT CLICK, and pick view. You can then enlarge it even bigger to see the image better.
    Attachment 68972



  11. #11
    jerry clayton's Avatar
    jerry clayton is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2006
    Location
    Bartlett
    Posts
    6,541

    that the right or left side??????

  12. #12
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    city
    Car Year, Make, Model: bug
    Posts
    824

    Quote Originally Posted by jerry clayton View Post
    that the right or left side??????
    I think he told me right side. I hope it was while sitting inside the vehicle...

    ps: In the upper right corner, is that the distributor hole?
    Last edited by DennyW; 01-12-2018 at 09:26 PM.



  13. #13
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    14

    I apologize for the confusion. I sent that picture from my very old phone and didn't look closely enough to see that I was sending a picture of the left bank head gasket and not the right bank. I don't have a right bank picture with me but when I get home I'll post one.

  14. #14
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    city
    Car Year, Make, Model: bug
    Posts
    824

    Quote Originally Posted by mr-natural View Post
    I apologize for the confusion. I sent that picture from my very old phone and didn't look closely enough to see that I was sending a picture of the left bank head gasket and not the right bank. I don't have a right bank picture with me but when I get home I'll post one.
    No problem. Mistakes happen.

    Ok, I am posting another picture. The red circles, is pointing to the areas where the head gasket was failing, allowing coolant to seep into the cylinders. Do you run anti-freeze in your coolant? Some people do not, when they live in a warm area. But, the benefits really make a difference, with the anti-rust additives. I mention that because of the rust color I see in the photo. In the red circle, it shows also the areas close to the water jackets of the block. The real shinny areas in the circles know as the ridge area (dark brown at the tops), it where the coolant leaked in.

    PS:
    (( This photo is of #5 cylinder showing the pit he mentioned in his post. He won't be back in AZ until mid week to take another photo. ).
    Just providing info to help others also.

    Attachment 68978
    Last edited by DennyW; 01-13-2018 at 11:29 AM.
    glennsexton likes this.



  15. #15
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    14

    techinspector1 from my understanding of the methodology of metrology I would need to pull a piston which of course involves lots of work i don't want to do at this time. Plus I don't have the instruments to make the measurement. All I have is several micrometers, a 1" depth micrometer and some calipers. Is there a simple way to make this measurement?

Reply To Thread
Page 1 of 2 1 2 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink