Re: 1150 Merc. Melted #1 piston WHY?
Inlines usually lose pistons because of carbon buildup (cheap oil); too much timing advance (no more than 21 deg BTDC); running lean (plugged jets etc); and overpropping (too big of a prop lugs the motor).<br /><br />Definitely inspect the carbs. Pull the float bowl covers off, pull the main jet plugs, and remove the idle screws. Unless they are really bad, you should be able to spray carb cleaner thru all the orifices, then blow out with compressed air. It's not usually necessary to dismantle every little piece on the carbs, unless they're full of old, varnished fuel deposits.<br /><br />Do yourself a favor and replace the floats; the newer ones are updated and better. Get a a set of float needle/seats and replace those too. Adjust the float levels per specs.<br /><br />If your motor has a single fuel pump mounted on the lower motor pan, you probably have 'back-drag' carbs. This type of carb is designed to lean out in the midrange for better economy. Inlines don't really like this feature!!!<br /><br />There are 'vent jets' screwed into the outside of the float bowl covers. Remove this brass jet from each cover. Note, if you have the type of carb that has a filter on top of each float bowl, this doesn't apply.<br /><br />Be sure to install a new impeller and renew any worn parts in the pump assy. <br /> <br />Re: your broken bolt problems, the best way is to heat the bolts so they don't break. If you do break one, drilling stainless out of alum is pretty tough as you've seen! I've had good luck with drilling the bolts all the way out and installing Heli-coils.<br /><br />Remove the exhaust side cover and inspect the exhaust baffle carefully for corrosion. If it perforates and leaks, it'll flood the cyl's with water. <br /><br />Inspect the inner cover around the exhaust ports. If it's cracked or corroded you'll need to replace it. Use extreme caution pulling this apart as the bolts can get nasty. If the block looks bad, have it machined to good metal. You must mill both inner and outer surfaces of the exh manifold area the same amount if this is done. <br /><br />The nice thing about this is, you've got a nice new surface for the gaskets to bite into.<br /><br />Once she's back together, prop it so it'll spin up to around 5800 rpm at Wide Open Throttle (WOT) with no load. After a proper 20-hour break-in, of course!<br /><br />Use a full synthetic oil such as Penzoil and use mid-grade or premium Non-Alcohol unleaded gas.<br /><br />If you do the above, your Tower of Power should have a long and happy life!<br /><br />BTW you can't put the pistons in one-at-a-time if you use the older-style rods with thru-bolts, such as what your motor has in it. You can't get at the rod nuts to tighten them down with a torque wrench (180 inch-lbs with a drop of Red Loctite). <br /><br />If you upgrade to the newer style rods with 'cracked caps' and normal bolts you can install the pistons one-at-a-time, as these bolts are accessible after the crank's installed. A special precaution on this type of rod bolt, it's a true 'stretch' bolt and Must Not be re-used or it'll break.<br /><br />The older-style thru-bolts can be reused.<br /><br />You can suspend the crank and slowly guide it down, easing one piston in at a time. Takes a while but it can be done. Just have a few extra new piston rings, you may break a few before you get the feel for it! Factory ring compressors are a bit spendy, and even those take a good amount of practice to use properly. Try eBay for used sets.<br /><br />On the distributor, just clean the cap out real good and inspect, if you don't see anything nasty, I wouldn't worry about it. Make sure the carbon contact in the center of the cap is free to move, sometimes the spring gets gunked up. <br /><br />Spark plug wires are solid-core and shouldn't need replacing unless they are in very bad shape. Get new wires at
www.oldmercs.com and also check out this site for lots of repair info:
www.maxxrules.com<br /><br />Hang around this site as there's lots of good inline knowledge here to help you get your Merc back together. It'd also help greatly if you pick up a good manual such as Seloc. Try eBay or Amazon, amongst others.<br /><br />There's a good Inlines Newsgroup located at news.kraits.org called bigweek.mercury-inlines that's loaded with Tower of Power info and help. <br /><br />Some of the players (such as Clams Canino and myself) also post here at iBoats. Check it out.<br /><br />HTH and Happy Rebuilding...........ed
