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post #3 of (permalink) Old 07-10-2011, 09:59 AM Thread Starter
Gone Fishing
Join Date: Apr 2010
Location: Gods country
Posts: 4,511
Blog Entries: 2
Found a younger gentleman that had a 360 to sell that was supposedly solid. Was unable to hear it run but took the guys word for it. That was a bad decision but really only cost some time and a little money. While performing a leakdown test it was found that the number 4 cylinder was not sealing properly. the culprit was a burnt exhaust valve that is a common problem with the 304 but not so much with the 360.

I'm actually glad that we found this first because whoever had rebuilt the engine prior to me receiving it had cut all the intake seats at a 45 degree angle and the valves at 30 degrees for some reason. I'd have burnt every intake valve in it after a few thousand miles probably.

The block had been bored .040 over by the previous owner and would need another .020 to clean up the cylinders. Of course new pistons would be needed so my good buddy who is a machinist ordered up a rebuilt kit including camshaft, lifters, pistons, rings, and gasket set for around $450. Machine work on the block was farmed out to a neighboring town while my friend did the head work.

He replaced the one burnt valve and recut the rest with a performance three angle valve job and a wide face for better longevity. Valve springs were shot with hardly any spring pressure even fully compressed so a set of edelbrock springs were ordered to match the camshaft. Jeff likes to have alot of spring pressure for customers he knows will drive a rig hard and that's what my intentions are.

The high spring pressure keeps you from throwing the lifter off the camshaft at high rpm in what is called valve float. I'm sure some of you have revved up an engine so far that it actually starts to slow down and that's what this is.

The block was bored, honed, decked, and the rotating assembly was balanced for around $400. Back at the shop it was ready to start assembly. First things first we tapped every bolt hole in the block, cleaned up some casting flash in the lifter valley that will allow the oil to fall back into the crankcase more easily and did some work to the oiling system.

Pic of the casting material clean up here. The four holes in the middle were the main problem areas. Now they're all nice and round. Other than that the casting was very solid and much better than alot of engines I've messed with.

The first pic is not very good but this is where the pickup tube in the pan screws into. There was some casting material removed here to ease the flow of oil through the oil galley and into the pump.

From here the oil goes through to the front of the engine where we also removed material to improve pressure and volume through these two openings. This should help the not terrible but slightly inadequate AMC oiling system.

Once this was done we thoroughly cleaned the block with soap and hot water using a scrub brush and rifle cleaning rods on oil passages, bolt holes, cylinders, and lifter bores. After drying the motor with an air hose we took shop rags moistened with transmission fluid and wiped down the cylinders until no dirt was evident. We then sprayed the inside of the block with a wd-40 type solution to prevent rust in the meantime.

We were preparing to begin assembly when Jeff noticed that the main bearings were the incorrect size. The main journals on the crankshaft had been turned down .010 to clean it up but the bearings were a standard set. Using these would have resulted in poor bearing clearance, low oil pressure, and a short life in general.

The only things we could do without the crankshaft in place was check the rod bearing clearances, install freeze plugs, and put the rings on the pistons. The freeze plugs sent were brass and personally I like their contrast against a painted engine so we decided to wait until it's painted. We could have set the ring gap and rod clearances but by then I was pretty well run down from the heat and dissapointment of the incorrect main bearings.

We went ahead and put the bearings in the rods, applied assembly lube to the bolts, and called it a day. Hopefully today Jeff won't have much going on and we can do a few more small things while we wait for the bearings. Here's a pic of one of the main bearings prior to any machine work. It had some miles on it but could have been much worse.

Here's a pic of the pistons and rods before the bearings were installed. Nothing special really, just cast pistons that will have a standard tension ring package.

I'm currently trying to decide on the color of the engine. I usually paint AMC engines red but since this Jeep will have orange accents like before I thought about Chevy orange instead. If anyone has a preference either way I'd like to know.

That's all for now but hope to have some new stuff up soon. Hope you guys like it
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