laznat 0 #1 Posted December 17, 2010 hello is there any mods to do to a k181 i.e. cam ,porting or milling ? Share this post Link to post Share on other sites
oldandred 15 #2 Posted December 17, 2010 yes but you want gain any thing Share this post Link to post Share on other sites
laznat 0 #3 Posted December 17, 2010 oldandred its piece of mind lol what about sound? Share this post Link to post Share on other sites
TT-(Moderator) 1,128 #4 Posted December 17, 2010 About the only thing you can do is clean up the ports and the valves, but without anything "extra" to accompany that work, it's basically a waste of time. -As far as decking the block goes - a few thousandths to clean it up is alright, but getting carried away means valve clearance issues.. -The head can be milled enough to level it up if it's slightly warped. (probably not more than .005" to .008") Any more than that and - once again - there could be valve clearance issues. If the head was already lapped or planed once, it shouldn't be attempted again. Note: These heads are thin (casting-wise) to start with. -There are no "off the shelf" cams available. You'd have to pay for a special weld & grind job which isn't really worth it. Too much valvetrain pressure will cause the cam to break in half ~ since they're already weaker from being clearanced for the connecting rod. -There's absolutely no room left to increase the crankshaft stroke. The connecting rod almost hits the camshaft as it is. -As far as I know, no bearing inserts are available for the "big end" of the rod, so offset boring to achieve a "pop up" of the piston can't be easily done. Doesn't leave much, does it? How do I know this? This started out as a 1975 K-181 from a B-80: Share this post Link to post Share on other sites
clintonnut 126 #5 Posted December 17, 2010 Well you can do a little. The camshaft duration can be increased by just clamping the cam down and running over the top of the lobe to increase the width of the point of the lobe. You might be losing some lift but that can be changed by adjusting the lifters. Lightening the valves in a lathe will help. You can lighten them by reducing the stem size and cutting center of the top of the valve down (a little). As far as the head you can get an idea for clearance by sticking a chunk of silly putty on top of each valve and rotating the engine with a toqued head. Measure the clearance and allow at least .010" of clearance from there. The end mill can take care of the rest. You might have to sharpen the edges of the combustion chamber of the head to gain clearance. Also you can cut the intake valve and seat to 30 degrees seat angle and then double cut it so it has a 45 degree lower lip to increase flow. Leave the exhaust valve at 45 degree angle but round the seat off with a 30 degree cutting head. This allows engine to breath better. Porting is best done by taking a gasket the same size as the carb bore and porting the engine to that size. Take any casting lines off and make the ports smooth. That's about all you can do for a K181. If you have access to an end mill, lathe and pneumatic die grinder and some tootsie roll sandpaper ends and some grinding tips. You can do all this fairly easily. I happen to own valve seat cutting heads so that made easy work of double cutting the seats. Check out Brian Millers gardentractorpullingtips.com. They mainly are about the 10-16hp engines but many of the concepts of modification can be applied to your K181. Charlie Share this post Link to post Share on other sites
Jim_M 178 #6 Posted December 18, 2010 While you're on Brian Miller's site, read up on running your engine on E-85. You can gain some cheap horsepower running E-85. Share this post Link to post Share on other sites
laznat 0 #7 Posted December 18, 2010 Great input!! you guys have done this once or twice. I just bought a end mill still waiting to level it and run power to it. I port gm ls heads,intakes and tb for a living so porting i can handle. I am in pretty good with the guy at the cylinder head shop here so im good there. we don't have e85 here yet its a hour drive from here but i wasn't planning on re-jeting ether i would think i would to run e85. thanks for all the input. p.s sry my spelling sucks Share this post Link to post Share on other sites
