781 heads- Gasket
+ Reply to Thread
Results 1 to 14 of 14

Thread:
781 heads- Gasket

  1. #1
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default 781 heads- Gasket

    Guys- I'm getting a list of parts up to put my .030" over 454 mill back together and I'm looking at head gaskets. I have set of 781 Iron heads, stock 454 Crank & Rods, and my pistons are forged L2349. I have the deck height stack-up written down somewhere but have not been able to locate it yet. The engine had a set of Fel-pro 1017-2 (.051 thick) head gaskets on it and I'm trying to figure out why I may have went with that gasket specifically. It's been 11 years since I picked these parts up from the machine shop and the guy that did the machine work is out of business now. I recall talking about quench, deck height, compression and which gasket I should get with him when I picked it up but for the life of me I cannot recall the details of the conversation so now I'm trying to get back with the program and pick out some head gaskets. I do remember putting clay on the piston top, and assembling the engine to check clearances and had no issues- I also don't think the block has been excessively decked but I am going to measure that as soon as I get a chance. Is the L2349 a 'funky' piston for some reason? I don't even see them being mentioned or listed anymore. Other than a possible clearance issue, why would the guy have recommended me use a thicker gasket? From what I understand now, it is undesirable for quench to use one that thick? The gasket would have very minimal effect on compression wouldn't it?

    The 1017-2 apparently was doing it's job- there were no issues with the head seal.
    What gasket style & thickness would you guys think I ought to be looking at?

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member vmaxed's Avatar
    Join Date
    Sep 2010
    Location
    EAST LA (Lower Arkansas)
    Posts
    719

    Default Felpro

    Fel Pro 1017-1 Stainless Steel .039 thick 10.5 cc
    Fel Pro 1027 Copper .039 thick 9.7cc
    Unless you have a bunch of compression and or huge lift cam shaft you shouldn't need to worry about piston to valve.
    "DON'T JUST TELL ME IT WON'T WORK TELL ME WHAT WILL"

  4. #3
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default Gaskets

    The .039 thickness was what I am considering. Just kinda wondering what we may have been up to at the time. We used a closed chamber piston design with an open chamber head trying to make a deal that would maximize compression and still run on pump gas plus an octane booster- or at least a more economical mixture of race fuel and pump gas. Didn't have as many affordable piston options then as now. I smoothed the chambers and the piston tops and did everything I knew at the time to help reduce detonation. I'm thinking the extra thickness in the head gasket may have been another attempt at lowering the compression every little bit I could until I could see how it ran. I have always just run it on a mixture of race gas and premium unleaded so detonation has really never been an issue. Seems that I recall calculating the static ratio around 10.7:1 range. Was kinda scared of the dynamic ratio, and didn't know a good way to calculate it back then. If I have to do it all over again, I'm going pump gas all the way. This boat is what it is- and it ain't a race boat.
    Last edited by hollbrow; 09-27-2011 at 09:09 AM.

  5. #4
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Here is my best guess as to what you were doing then. there was a huge selection of off the shelf pistons for an open chamber 454. You had flat top at around 8.2 to 1 and domes at around 11+ to 1. Too get to a reasonable compression it was common to use a domed closed chamber piston that came in around 10 to 10.5 to one depending on the head and depth in the hole. The crate LS6 from GM used the same setup. That was still alittle high for an iron headed 454 with a short camshaft. I am guessing you used a .051 gasket to lower to around a half point.
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  6. #5
    Some guy obnoxious001's Avatar
    Join Date
    Dec 2007
    Posts
    2,699

    Default

    Speed Pro ZL2349F - Speed-Pro Forged Pistons - Overview - SummitRacing.com

    According to that,, 30.6cc dome volume, so 10.7-1 may have been one of your calculations, depending on deck height,, and probably very close to 11-1 with the .039 gasket.

    Depending on the thickness of the dome, you may be able to have some of it removed if you plan to reuse the pistons.

  7. #6
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default Pistons

    Thanks for the replies- the pistons are in fine shape and I have a good balance on the rotating assembly so for now I am going to reuse them. They are a pretty heavy piece- I probably could machine a good bit of material from the domes but then my balance would be out the window. The engine ran pretty well set up like it was. I have never even tried to run straight pump gas in it- I don't have a knock sensor, or a wideband, or any tuning aids so I have been pretty conservative with the deal. I think by the time I got everything together, and crunched all the numbers I had decided it just wasn't gonna be a strictly pump gas engine and resigned myself to using a bit higher octane fuel. Since I have been running the octane anyway, I figure at this point I may as well use that .039 head gasket and at least have a little better quench.

    Should I try to use a gasket that has a bore size a little closer to actual bore size or is that a non issue here? (1017-1 is 4.540" bore size) and my cylinder bore is 4.280". Also, will the .012" difference in gasket thickness between the 1017-2 & 1017-1 make me have to re-evaluate my pushrod length? My geometry was pretty good with the .051" 1017-2.

    It's hilarious how quickly the costs rise on this parts list for a minor freshen-up.

  8. #7
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by hollbrow View Post
    Thanks for the replies- the pistons are in fine shape and I have a good balance on the rotating assembly so for now I am going to reuse them. They are a pretty heavy piece- I probably could machine a good bit of material from the domes but then my balance would be out the window. The engine ran pretty well set up like it was. I have never even tried to run straight pump gas in it- I don't have a knock sensor, or a wideband, or any tuning aids so I have been pretty conservative with the deal. I think by the time I got everything together, and crunched all the numbers I had decided it just wasn't gonna be a strictly pump gas engine and resigned myself to using a bit higher octane fuel. Since I have been running the octane anyway, I figure at this point I may as well use that .039 head gasket and at least have a little better quench.

    Should I try to use a gasket that has a bore size a little closer to actual bore size or is that a non issue here? (1017-1 is 4.540" bore size) and my cylinder bore is 4.280". Also, will the .012" difference in gasket thickness between the 1017-2 & 1017-1 make me have to re-evaluate my pushrod length? My geometry was pretty good with the .051" 1017-2.

    It's hilarious how quickly the costs rise on this parts list for a minor freshen-up.
    Don't worry about the gasket thickness effect on your puchrods. Yes go with a gasket that is closer ro 4.370-4.375 bore
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  9. #8
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default Gasket

    Okay- I'm lookin' at head gaskets til' my head hurts. I'm kinda partial to the Fel-Pro's- never had a problem with them on my engines. Trying to find a BBC Mark IV gasket that has .039" thickness AND a 4.380" bore size leads me to a 1037 which says it works for all big blocks and is marine compatible but that I need to drill holes in the deck for the cooling holes to work right. While drilling the deck is no big deal from a work standpoint, why the heck do they not seem to make this style gasket with the right bore dimensions, right holes, in the right places for my Mark IV block & heads? Will it cool better if I drill the deck and go to parallel cooling instead of series? I know the 1017 gasket lines up with all my coolant holes. My heads/block were made in 1982. I seem to be having more trouble optimizing this head gasket thing than I ought to have. Now I'm looking at Cometic and others. I don't mind spending the $$$ if I get something I feel good about.
    Last edited by hollbrow; 09-28-2011 at 03:02 PM.

  10. #9
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by hollbrow View Post
    Okay- I'm lookin' at head gaskets til' my head hurts. I'm kinda partial to the Fel-Pro's- never had a problem with them on my engines. Trying to find a BBC Mark IV gasket that has .039" thickness AND a 4.380" bore size leads me to a 1037 which says it works for all big blocks and is marine compatible but that I need to drill holes in the deck for the cooling holes to work right. While drilling the deck is no big deal from a work standpoint, why the heck do they not seem to make this style gasket with the right bore dimensions, right holes, in the right places for my Mark IV block & heads? Will it cool better if I drill the deck and go to parallel cooling instead of series? I know the 1017 gasket lines up with all my coolant holes. My heads/block were made in 1982. I seem to be having more trouble optimizing this head gasket thing than I ought to have. Now I'm looking at Cometic and others. I don't mind spending the $$$ if I get something I feel good about.
    The holes they are asking you to drill in your deck exist align with holes that exist is all gaskets except one particular early BBC Felpro. They make it unclear the way they wrote that. If you installed Cometics, the same holes are there, and unless your dealing with a pre 1969 427 block, the holes are in your deck already.

    Read this. Read it all. Absorb it. Become one with the bulletin and you will be a BBC head gasket guru. Hollbrow, THERE WILL BE A TEST!!!!

    link: FelPro tech bulletin
    Last edited by gn7; 09-28-2011 at 03:08 PM. Reason: forgot link
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  11. #10
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default Gasket

    Ok- found the Fel-Pro Q17040 and it seems to meet my requirements- Mark IV, 366/427/454, 4.370 bore, .039" thick, S/S, MLS composition, marine compatible. Anyone see a reason that would not be a good choice?

  12. #11
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Go back and read my last post, and then put the 1037 gasket on it.
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  13. #12
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default gasket

    Ok- read through that Fel-Pro bulletin.
    My block looks exactly like that 'figure 1' block and already has those three holes in it.
    So, even though the 1037 has only one hole at the rear of the block- the top smaller one- that is ok and there should be no problems according to the document.

    The 17040 is an MLS S/S Marine gasket- and it has both of those rear holes open.

    Is the 17040 MLS a superior gasket than the 1037? Hardly any cost difference- just a few bucks...
    Last edited by hollbrow; 09-28-2011 at 03:35 PM.

  14. #13
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by hollbrow View Post
    Ok- read through that Fel-Pro bulletin.
    My block looks exactly like that 'figure 1' block and already has those three holes in it.
    So, even though the 1037 has only one hole at the rear of the block- the top smaller one- that is ok and there should be no problems according to the document.

    The 17040 is an MLS S/S Marine gasket- and it has both of those rear holes open.

    Is the 17040 MLS a superior gasket than the 1037? Hardly any cost difference- just a few bucks...
    You dont need that hole! Go back and look at the bullettin again and you will see 3 cutaways if gaskets on the left side of page 3. The top is the MLS SS gasket, then a wire ringed gasket, and on the bottom a "marine gasket" They are listed best to stock. The bottom "marine gasket is slightly better than standard stock gasket in that has a SS core. But you'll notice it has no fire ring. Your not exactly making 13 to 1 compression, but the 1037 is a better gasket. JMO
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  15. #14
    Member hollbrow's Avatar
    Join Date
    May 2009
    Location
    South Ga.
    Posts
    186

    Default gasket

    Thanks for your help GN7- I appreciate it. I'm comfortable with the 1037 now- thats what I will go with.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93