Head gasket info needed

Engine, Transmission & Driveline

  1. CanCritter

    CanCritter Senior Member

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    have 516 stock heads and engine has flat tops and block hasn't been bored....trying to sort out what l should be using for a head gasket...a little outa my league here to be honest...
    will be using felpro 1215 intake gasket as recommended by few members..thanx
    IMG_0901.JPG
     
  2. twostick

    twostick Senior Member

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    That's one of those it depends questions. Lol

    The original was most likely a steel shim gasket which depending on how far in the hole the pistons are at least gives you a fighting chance of having some quench. Problem is it also puts the compression ratio at the high end for your combination.

    The .039" or thicker composition head gaskets will lower the CR some but kill any quench you might have had and could make it detonate worse than it would have with the thin steel shim gasket and the higher compression.

    In any case it's going to be premium fuel only and probably have to play with the timing curve to make it play nice especially in hot weather.

    This is all assuming a stock or very mild camshaft. If you have a more lumpy cam it will bleed off a lot of cylinder pressure in the lower rpm range and it won't be quite so apt to rattle when you get on it.

    Kevin
     
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  3. CanCritter

    CanCritter Senior Member

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    All stock short of cam which will be a 268...whats best way to measure where positions sit when at tdc?...put a straight edge across block and measure down?
    Previous gasket was steel and heads were 906s which are bein replaced with 516s...wish l was a little more knowledgeable when it came to this stuff ...dont wanna screw something up and end up with issues down the road :(
     
  4. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    I've used the Fel-Pro permatorque head gaskets and have been happy with the results. I've pulled a lot of engines apart with steel shim gaskets and it wasn't unusual to see some evidence of leakage between cylinders. Never saw it with composition gaskets. I think they seal better. There is a slight drop in compression over a steel shim type gasket, but I don't know as that's such a bad thing given the lower octane gas they have now. I also think that the loss is made up by reliability.
     
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  5. CanCritter

    CanCritter Senior Member

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    thanx John....guessin l need to try and bring myself up to speed on this stuff...
    gona try to get some No,s and go from there l guess..
    will start with tryin to measure how low below (deck) ? am assuming this is from top of block to top of piston....
    will also see if l still have a steel gasket l took off kickin about...not sure that would make any difference considering 906s were on block to start
    am going on the assumption everything in this motor is stock...
    is there a way to measure 516 heads lm putting on in place of the 906s to see if they've been milled or are still stock?
     
  6. CanCritter

    CanCritter Senior Member

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    Okay.. .over the years have learned assumptions and guess s ussualy leave ya with grief...
    FACTS to date....
    PISTION TO DECK....5/64 in. .. 0.078125
    BORE...... 4" 5/16 in.....4.3125 in...
    Johns Felpro gasket....039 compressed
    516 heads....?
    20190710_110829.jpg 20190710_110728.jpg 20190710_110255.jpg 20190710_110231.jpg
     
    Last edited: Jul 10, 2019
  7. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    FWIW, that caliper could be off .015" based on it counting out in fractions.
     
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  8. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    There is a dial type indicator that bolts to the cylinder block with a probe that touches the piston top. The unit is zeroed by first setting the probe flush with the block. The unit is then moved to the cylinder with #1 at TDC. The gives a preliminary reading of how far down the hole the piston is sitting. Crank should be rotated slightly back and forth to confirm TDC. Any good machine shop can do this test for you and it is usually not expensive. A 360 degree harmonic balancer is sometimes installed to check the other 7 cylinders. These cars all had steel shim gaskets from the factory, the modern composite gaskets will drop the compression ratio about a half a point from where ever it was to start with. It would not hurt to have these pistons polished as the rough spots are a potential source for preignition.

    Dave
     
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  9. twostick

    twostick Senior Member

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    If you are starting out at .078 in the hole, even with the shim gasket you will wind up with .100 piston to head clearance so basically no quench.

    Plug those numbers you have with chamber volume into a compression ratio calculator and see where it lands. Advertised chamber volume is usually less than actual volume by about 8-10cc.

    If I had to guess with a .039 gasket you will land around 8.5:1 +/-. The 440 smog engines with pistons .140 in the hole are lucky to measure out at 7.8:1.

    Kevin
     
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  10. CanCritter

    CanCritter Senior Member

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    What would l need to get my quench back?...stick with thinner steel gasket at .020?
    Appoligies....this is Greek translated into chinesse to me....have alotta readin to do tonight me thinks.....
     
  11. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    Which year engine is this? On a '71 or older I would stay with the shim gasket, and are these the factory heads for this engine? '67

    Dave
     
    Last edited: Jul 10, 2019
  12. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    My 440 pistons are .095 down in the hole. My 906 heads have been milled alot 80 cc measured. With a .020 gasket I'm at 9.55 if I remember (really need to write this crap down). Your 516 heads should be around 78 cc best guess. You will have a solid ~10:1 engine I would use the feel pros as you have nothing to gain with the extra
    .019 thickness (see twostick post). A cheap and crafty way to volume your head without expensive burette is get a graduated cylinder as long as it reads milliliters (1 millilitre =1cc). I use a 3# coffee can lid to seal up head with a little grease, hole in the center and cut the outer lip off so it lays flat. Fill water through the hole until you see it touch the under side of the lid read the ml and there is your Ccs. I would not use this for NHRA stock class racing rules but to get in the ballpark it works.
     
  13. CanCritter

    CanCritter Senior Member

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    this was a 440 out of a 70 newyorker
    IMG_0694.JPG ...no serial no so am assuming its a stock warrantee block.
    the 440 had 906s on them and am replacing them with 67-516s l got from another member...
     
  14. twostick

    twostick Senior Member

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    Are you sure those aren't 915's? That was the closed chamber head for 67. They were a 1 year only win win head. Closed 516 type chamber with the somewhat better 906 ports.

    Kevin
     
  15. CanCritter

    CanCritter Senior Member

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    so basicly go with the .020 steel gasket?....wouldn't the 516s already have a set chamber cc if stock?...is this how you tell if heads been milled?...srry folks..havein a hard time wrappin my head around this stuff..
     
  16. CanCritter

    CanCritter Senior Member

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    have been told their specifically the 67 /516s and have seen the markings...am also sure 906s came off the 440 that came out of the newyorker...guessing l should round up some pics for clarification...
    spent the day finishing up a little port matching on the 516s...thought l had some pics but will throw some up tomorrow after l hit carwash to give these things a final cleanin and reassemble
     
  17. CanCritter

    CanCritter Senior Member

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    off 70 newyorker IMG_0849.JPG IMG_0856.JPG
     
  18. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    The answer should be yes to both questions assuming the '70 block is unmolested, which as a standard bore it should be.

    Dave
     
    Last edited: Jul 11, 2019
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  19. twostick

    twostick Senior Member

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    The advertised spec on the 516 and 915 closed chamber head is 73.5 cc but most measure in at 84cc +/-.

    The open chamber 906/452 etc advertised spec is 80cc and usually measure at least 90cc.

    If your numbers were correct, you piston to head clearance is around .100" with the shim gasket

    Conventional wisdom says the quench effect starts to drop off after .040 piston to head and would be pretty much gone at .100" so I'd calculate CR with a .039 gasket and see where you are. If it's less than you want you can go with the shim gasket and if it's still too high Felpro makes a marine head gasket that is .051 IIRC.

    With a mild cam I think it will be a challenge to keep it happy with pump gas if you start to approach 10:1 with iron heads especially with no quench.

    Kevin
     
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  20. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    Twostick makes a good point in that today's crap gas with the best premium blends are not the equal to yesterdays fuels. Unless you are planning to run some Sunoco 360 with you premium pump gas, you probably do not want to go much over 9.5 on the compression ratio. I find that running the Real Gas premium I can get away with a 10-1 ratio and it runs fine, but at about $5 a gallon if any significant miles are to be put on the car, that makes for some fairly expensive driving on a 10-12mpg car. The '67 516 head was to designed to run at 10-1 with 100 octane fuel using the old measuring system. You can compensate for today's crap gas some by fiddling with the timing, advance curve and carb metering and that can take some time. The choice for you would be if you are looking to avoid all of the fiddling, then calculate a 9.5 comp ratio and figure out which gasket will get you there. With the shim gasket you will probably be running a solid 10-1 and your timing, advance and metering are all going to have to be spot on to get it to run right.

    Dave
     
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