I first give some background information, and at the end of this long post, I recap my questions.<br /><br />I have a 85hp force, on a 1978 15' Glastron Bass boat. It does not have a tag that I can find, other then one that is unreadable.<br /><br />It is 72 inches wide, and 15' feet long, with a 21" transom. According to the formula of:<br /><br />(2 x Width x Length)-90<br /><br />I get (2 x 6 x 15)= 180 -90 = 90HP<br /><br />It appears the largest engine my boat can have is a 90hp. I have an 85hp Force model 856X8A.<br /><br />I bought the boat without a lower unit, or a prop, so I don't know where to start propping it out at. I went through the formula above to show that my boat is not very big.<br /><br />I don't believe it weighs over 1200 or 1500 pounds, so from what I have read I should start at a 19 pitch. Is this correct? According the the following link, I might even use a 21 pitch, because my boat is so small.<br /><br /> http://www.miwheel.com/MIWheel/html/products/outboard/PSearch.asp <br /><br />But according to the link above, for under 16 they show a 21 pitch, but only a stainless and not an aluminum. They show a cupped and a uncupped prop, but I have read that I should stay away from a uncupped prop, because it will pull to the left. Is this true in all circumstances?<br /><br />When calculating the weight of your boat for Prop sizing, do you include the weight of the engine?<br /><br />Does a 15' fiberglass bass boat that is 72 inches wide weigh over 1200 pounds? I wouldn't think so, but just thought I would ask what something like this normally weighs.<br /><br />I am thinking about going with a 19 pitch aluminum to start out with. Is this a fair guess??<br /><br />I guess one other thing I should consider, is when fishing, me and my son weigh about 400 pounds together, and we also carry about 200 to 300 pounds of gear and tackle. Should that change my guess of a 19 pitch prop? I take it you should add that weight to the weight of the boat?<br /><br />So does this mean that a 17 pitch prop would be better, with the extra weight?<br /><br />I am also looking for what kind of tachometer I could get for this motor.<br /><br />If I was to pick one up off of Ebay, what should I be looking for in a tach, to make sure it will work with my 1988 85 hp Force engine, model 856X8A? I understand you use the purple wire under the dash? You also have to have a ground wire to the tach I presume?<br /><br />I also have another problem I noticed the other day while doing a compression test. <br /><br />Two of my cylinders are 130, and the other appears to be 135. I figured that was good. I warmed the engine up for a few minutes and checked again and it was the same. <br /><br />But, I noticed that the previous owner had snapped off a headbolt. He must have been running it like this, as he had the hole where the head bolt was filled with some blue silicone. <br /><br />My question is, I suppose to do the right thing, I should yank the head off, drill a hole in the bolt, and use a easy out, to get it out. Correct?<br /><br />I really wish I didn't have to take the head off, to get this bolt out. Is that the only way. It appears the head is about 1 1\2 inches thick, so I would have a hard time getting an easy out in there even if I could get a decent hole drilled in the center of the bolt, unless I could purchase a longer easy out then the ones I currently own. It is broken off flush with the block. So it is recessed in there the thickness of the head, which is about 1 1/2 inches. <br />I was going to try to get it out without taking the head off, but I noticed it looked like without a bolt in there, it was open to the water jacket, so I figured if I drilled, I would get some shavings in my water jacket. Maybe it's not open like I think, but I will look again.<br /><br />Where is the best place to get a head gasket for this? Does a head gasket set usually come with a water plate gasket as well?<br /><br />To recap, here are the questions someone might be able to help me with. <br /><br /><br />1. What size prop? A 17 pitch perhaps to start? I want to use aluminum. From what I have read, I should look for 4800 to 5200 RPM's at WOT? Should I stay away from the uncupped prop, like I heard? Does it pull hard to the left with the uncupped prop? What are the pro's and con's?<br /><br />2. What should I look for in a Tachometer to make sure it will work with my engine?<br /><br />3. Could anyone comment on my broken off head bolt problem? Easiest, and least expensive possible solution? Maybe I can find a longer easy out then the one's I currently own? LOL <br />At least I wouldn't have to take the head off then.<br /><br />4. Best place to find a Head Gasket? I read somewhere that after you warm it up, and let it cool again, you should re-torgue the head bolts to specs. Is this true?<br /><br />5. What kind of decarbonizer should I use?<br /><br />6. If I am taking the head off, should I do a little manual decarbonizing then? <br /><br />7. If I understand correctly I should use nothing on the head gasket? <br /><br />8. Should I use some type of sealer on the water jacket plate gasket?<br /><br />9. I have rebuilt Motorcyle engines and have only taking two cars to the shop in 25 years, so I do have mechanical ability, just not alot of experience with outboards. I do know the bolt sequence and head bolt torque specs, but is there any other hints or tips for me, if I must tackle this head gasket job? Any other things I should, or could do while I am in there, that is not included in the manual? <br /><br />10. I need to get a manual for this. Should I get the "Seloc" or the "Clymer" manual? Which one shows the tune up procedure the best? Which is the best all around manual, for the mechanically inclined?<br /><br />Thanks to Roscoe for the help on the other thread. I have a Lower unit on the way now. I probably wouldn't sent out for the lower unit, if I had known the head bolt problem before hand. <br /><br />I slowly got sucked into this thing. LOL <br />Before I knew it, I have spent to much time and money on this engine. Oh well, it wouldn't be the first time. I hope it will be the last, but I know better. 
