decked block question
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decked block question

  1. #1
    Aquacraft Eddie's Avatar
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    Default decked block question

    well since I have the heads off, a friend of mine pointed out that the numbers that are usually on the passenger side upper deck part are not there and it looks like my block was decked , who knows how much but that would explain me having to mill the intake,,,now I'm wondering if I should just take all the internals out and put in another block that I have, I kniw id have to get a new intake but I'm just worried about my compression now. I have 781 heads with 22cc dome pistons and the heads have also been milled , I was thinking my compression should be around 9.5.1 but now that it looks like the block was decked I have no idea what the compression is and the shop seems as though they cant figure it out, as far as how much it was decked,,,,,lets just say it was decked like crazy whats the worst my compression would be? how far can you deck a block? I have no idea??any thoughts...
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    Last edited by Eddie; 08-18-2016 at 07:51 AM.

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  3. #2
    Aquacraft Eddie's Avatar
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    I don't have a pic of the passenger side where the numbers usually are but the piston does look higher up in the cylinder but I have nothing to compare this to or measure ,,, just by looking you guys think this will be ok? I know 781 heads are between 118cc- 12ish cc and I could get a thicker head gasket but I don't want to be dealing with it detonating or running high octane fuel ,,,,any thoughts? I know its hard tell tell without measuring stuff but just by the looks of it ,,,,the builder said it should have 9.1 comp but never said anything about the block being decked.... also the pistons have molly rings and I'm wondering if I should change them to regular rings because it seems that the motor always runs cold and I have heard its really hard for the rings to seat? and if I do change them to regular rings do I have to re hone the cylinders? they still have the hone marks just wondering and if some of my questions sound stupid its because they probably are but I'm just looking for advice thanks
    Last edited by Eddie; 08-18-2016 at 08:09 AM.

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    Just Me snoc653's Avatar
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    It's not hard to lay a straight edge across the deck and measure how far down in the hole the piston is. You can get a good guesstimate with a feeler gauge and a nice metal straight edge. If the pistons are down in the hole at all, you might not be that bad off. Summit Racing has a compression calculator on their site. I found it when looking for pistons. With your 23cc domed pistons, zero deck (pistons flush with the surface), 112 cc heads, and a standard marine head gasket of .039, your worst case you will be at 10.51:1. Looking at your pictures, your pistons look down in the hole some. At a minimal .015 down, your compression drops to 10.18:1.

    In my opinion: If your machine shop can't figure out how far down in the hole your pistons are, you need a new machine shop. But given the parts you have, if you use any block, you are going to be looking at a compression ratio over 10:1. You certainly don't want the pistons too far down in the hole and if you keep those 112 cc heads there is only so much you can do. If the heads were 118cc and the piston was down in the hole .015 then you would be around 9.67:1 according to the calculator.

    Barry has been giving you good advice so far, so just find one knowledgeable sources and go with what they tell you. You can shop for the answer you want and someone will eventually tell you what you want to hear, but it might not be right. I've been down this same road trying to mix and match my various pieces to make one working engine (one that gives me the most for the least amount of cash). Your 112 CC heads would have been perfect for the motor I have with 13.8 cc dome pistons. But we have the parts we have and there are only so many ways to assemble them.

    Good luck with your build

    Edit: pistons are only .030 over.
    Last edited by snoc653; 08-18-2016 at 08:45 AM.
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    Aquacraft Eddie's Avatar
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    Thanks for the help !, yup I have been saying I have no good shops it seems like here , I just don't want the compression to high , I'm just curious I have another block that has not been decked and it has a fresh bore so I'm thinking of taking all the internals out of my engine now and putting them in the other block but I'm wondering if that requires a line bore or not ? I have heard a lot of different stuff and this was just an idea , I think I can just use the block I Have now but I am now worried tha other crap may not be right so I'm tearing it down and not sure if it's worth staying with this one or going to the other one , and yes I'm just trying to make something work from multiple parts , I did order new valves for the heads , Manley stainless , and the heads have new locks , retainers , guides so at least one thing will be right , I hope

  7. #5
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    Quote Originally Posted by Eddie View Post
    Thanks for the help !, yup I have been saying I have no good shops it seems like here , I just don't want the compression to high , I'm just curious I have another block that has not been decked and it has a fresh bore so I'm thinking of taking all the internals out of my engine now and putting them in the other block but I'm wondering if that requires a line bore or not ? I have heard a lot of different stuff and this was just an idea , I think I can just use the block I Have now but I am now worried tha other crap may not be right so I'm tearing it down and not sure if it's worth staying with this one or going to the other one , and yes I'm just trying to make something work from multiple parts , I did order new valves for the heads , Manley stainless , and the heads have new locks , retainers , guides so at least one thing will be right , I hope
    Check all of the head bolt holes before making the decision. The one I saw in the pic looks rotten.
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    Stop whatever it is you're doing with the dremel and wire brush. Whatever you're doing that requires you to have to bag and tape up the engine like that...stop.
    If you're willing to take the engine apart to swap the rotating assembly, then you should be willing to take it apart to clean whatever you're trying to clean to that extent.
    You can get a fairly good idea what the deck height is by using a straight edge, but because the piston can rock in the bore, you have to check both the top and bottom side of the piston and get an average. It;s best done with a dial indicator and magnetic base, but a feeler gauge will get you close. Decking a block usually isn;t going to cause intake fitment issues, but decking the block combined with milling the heads will.
    I thought you said 22cc pistons and I don't know where the 112 cc came from, but that would mean more than .030" taken off your heads. That's a lot. Lets say your heads are 115cc, 22cc pistons, .039 gasket, zero deck; you have 10.2:1 cr. IMO That's a little high for anything but premium fuel in a marine build. You'd like to see closer to 9.5:1.
    Keep the Moly rings. They are not hard to seat. Quite the opposite. If your engine runs cold you need to get it to run warmer, but that's not an issue as far as rings are concerned.

    My advice; find out how big the chambers are in the heads. Find someone competent enough to check out both blocks. Use the best block, and accurately find out what the deck height is. Depending on the deck height of the BEST block, use whatever head gasket you need to get your compression height to around .045", then calculate your compression. That's the right way to do it. If it's worth doing, it's worth taking the time to do right, or you'll be doing it over.
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    Aquacraft Eddie's Avatar
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    Thank you guys I really appreciate , yes I stopped the Dremmel tool and I am taking the bottom end apart to check things , the heads are 781 and I read they are anywhere from 118cc to 122 or higher not sure if I miss typed it to 112, but I have no idea how much the heads or the block has been cut and when I get home I will get the straight edge and measure thank you Scott !, the motor was sold to me as having 9.1 compression but it would seem higher to me and the builder acts like he had no idea the block was decked and who knows he may not but that's kinda hard to believe from a shop that rebuilds motors , they mainly build dirt track motors and I had a 3 year warranty which is expired because it took me longer than expected to get it in the boat , never again will I do this , this is my 1st experience buying a supposed crate motor and now I'm having to basically rebuild it or possibly not even use the block , and the only reason is because the couple of shops I have here I don't really trust and the one that I do kinda trust have a huge wait , like 7 months or something , I plan on taking it all apart and can't wait to see what else just sucks , you guys advised me to take it down last time and I should have listened but I thought I had found my problem with the intake leak and here I am again so thank you guys for all the help and sorry I didn't listen last time .

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    Also I bought new arp head bolts also , I did notice that , thanks piston in the wind ..

  11. #9
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    Quote Originally Posted by Eddie View Post
    Thank you guys I really appreciate , yes I stopped the Dremmel tool and I am taking the bottom end apart to check things , the heads are 781 and I read they are anywhere from 118cc to 122 or higher not sure if I miss typed it to 112, but I have no idea how much the heads or the block has been cut and when I get home I will get the straight edge and measure thank you Scott !, the motor was sold to me as having 9.1 compression but it would seem higher to me and the builder acts like he had no idea the block was decked and who knows he may not but that's kinda hard to believe from a shop that rebuilds motors , they mainly build dirt track motors and I had a 3 year warranty which is expired because it took me longer than expected to get it in the boat , never again will I do this , this is my 1st experience buying a supposed crate motor and now I'm having to basically rebuild it or possibly not even use the block , and the only reason is because the couple of shops I have here I don't really trust and the one that I do kinda trust have a huge wait , like 7 months or something , I plan on taking it all apart and can't wait to see what else just sucks , you guys advised me to take it down last time and I should have listened but I thought I had found my problem with the intake leak and here I am again so thank you guys for all the help and sorry I didn't listen last time .
    You're on the right track. The 112 was something snoc posted...not sure where it came from.
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    Quote Originally Posted by scott foxwell View Post
    You're on the right track. The 112 was something snoc posted...not sure where it came from.
    In his post he had "between 118cc- 12ish cc" Since he said the heads had been milled, I figured he knew what the new volume was. So I used the worse case number. Also gave him the 118 cc numbers. The first step is always knowing what you have before you can change it.
    Last edited by snoc653; 08-19-2016 at 09:37 AM.
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    Aquacraft Eddie's Avatar
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    I have asked the machine shop to cc my heads and one of the guys is like what's that ?? So that's where I'm at , very frustrating sorry if I got confused on the 112 , but that's good that you figured it as my worse case cenario , I get it now . I m wondering if I have to line bore the block if I take the rotating assembly from one block and put it in another ? I have heard different opinions on this so any thoughts ? I thought as long as I use the same assembly which is balanced and drop it in the other block it would be ok other than checking piston to wlall clearance and stuff , but I'm just not sure about the line bore ? Or can I just plasti gauge the mains and rods and if it's ok go for it ?

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    Eddie, let me throw my two cents in. If you are looking to swap blocks due to the decks being cut, don't. You can get a good measurement with a straight edge to see how much the piston is in the hole or if it is out of the hole. Even if it is out of the hole you can get thicker head gaskets to make up for it. Thicker Cometic gaskets would be cheaper than having to pay to have another block all machined up. Felpro also does some thicker head gaskets. Don't stress too much until you have all the facts. You can also buy your own CC kit to measure the chamber CC's of your heads. That way you don't have to wait for a shop, and you can KNOW it is accurate. I recommend it as if will pay for itself in knowing that the job is done right. Good luck and keep us posted.

    Paul

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    Aquacraft Eddie's Avatar
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    Thanks fcpilot , I just looked into the cc kit , I'm going to buy one and it's just not the block being decked but I had to have the intake milled a lot to fit in the valley so I'm thinking my compression is around 10 or 10.5 or higher but like you said I won't know until I measure stuff , I'm out of town right now for work so it's going to be a while , and man I have been stressing thinking about how much more money and time this is going to take , I guess if I was going to buy a crate motor I should have got one from a well known company like blue print or atk instead of what I did , on another forum my friend belongs to these guys said this shop builds really good motors for a good price so I called and it all seemed good , it Had good reviews and people seemed to like the work , so either I just got a bad apple or it's a bunch of crap and they do shit work and people just don't even realize what's going on , the one good shop here says they have a 7 to 9 month waiting period !!! That's insane and probably because they are the only shop that does decent work and I have still heard a lot of bad stuff about them , ohh well I need to stop stressing out and thank you guys for the help ,

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    Quote Originally Posted by Eddie View Post
    Thanks fcpilot , I just looked into the cc kit , I'm going to buy one and it's just not the block being decked but I had to have the intake milled a lot to fit in the valley so I'm thinking my compression is around 10 or 10.5 or higher but like you said I won't know until I measure stuff , I'm out of town right now for work so it's going to be a while , and man I have been stressing thinking about how much more money and time this is going to take , I guess if I was going to buy a crate motor I should have got one from a well known company like blue print or atk instead of what I did , on another forum my friend belongs to these guys said this shop builds really good motors for a good price so I called and it all seemed good , it Had good reviews and people seemed to like the work , so either I just got a bad apple or it's a bunch of crap and they do shit work and people just don't even realize what's going on , the one good shop here says they have a 7 to 9 month waiting period !!! That's insane and probably because they are the only shop that does decent work and I have still heard a lot of bad stuff about them , ohh well I need to stop stressing out and thank you guys for the help ,
    Don't worry bud. they also make thicker intake gaskets if you end up needing them. Also, if the compression in too high, you can either grind some of the dome off the pistons, or some material out of the chambers of the heads. Neither one would hurt you, and if you grind in the right place will end up helping you. There is nothing done that can't be fixed with a little bit of clear planning and patients. This thing will be just fine. We can help walk you through it step my step. Ask lots of questions and you can make it happen. Hang in there.

    Paul

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