martini
03-15-2005, 11:17 AM
This might be long and it's been slow around here lately, so here goes.
A couple of years ago I bought a remanufactured marine long block from a good source to repower my 84(pics have been posted of it here before). The engine itself was fine and has worked very good for 100 hours, however a mistake I stupidly made prevented 3 of the cylinders from sealing properly. Essentially it overheated on break in, good for the cam, not so good for the piston rings.
Long story short, I installed the raw water pump on backwards, so instead of pulling water in, it was pushing water back out. Once I installed the pump, the right way, the temperature came down and it seemed to settle in. It made good power, but I was consistently oil fouling 3 plugs over the course of a season. I knew what the problem was and I knew I would have to fix it eventually, so I decided to go ahead and bite the bullet this off season and tear it apart, rehone the cylinders and re-ring the pistons. I figured I would replace all the bearings as well too, since I would be in there anyway.
Once I got the engine apart and could see what had happened, it basically confirmed what I had originally feared. Glazed cylinder walls, caused from overheating. I checked out the bearing surfaces and they a looked brand new! That was great news! The block is essentially at the end of it's serviceable life as told by the overbore at 4.060, which is fine on a 351. I knew the deglazing wouldn't take too much material, if any, and I was going to use a good set of Sealed Power file fit rings to fit them to each cylinder perfectly. By the way, the cylinders had almost no taper to them what so ever, even more good news! So the honing began. The cross hatch pattern was not as difficult to master as I thought it was going to be with the honing stones. Actually very easy and fast. It was nice when I was done to see the cylinders look brand new.
I figured since I had it apart, I would also put a set of GT-40 heads and some nice FRPP roller rockers from my 94 Cobra on it I had lying around. Took the heads to a machine shop to clean and inspect, valve job, mounting holes drilled to accept 1/2" head bolts and brass freeze plugs installed. The heads checked out, so all was good.
Once I had everything I needed, I cleaned the block completely and set out to reassembled everything. I checked tolerances as directed, checked tolerances as directed some more and o yeah, did I mention checked tolerances? It really isn't that hard to do if you have the right tools, measuring instruments and most important of all, PATIENCE! I took about a month to completely assemble it, working on it a few hours a week. No stress was my motto when going about it. I had plenty of time and a warm garage to work.
You don't know how happy I was when I laid all the new bearing inserts, lubed and torqued everything down, that it spun very freely and smoothly. So, flash forward to the moment I go to turn the key last weekend to see if all my hard work paid off. It fired right up, no leaks, no overheating, oil pressure was over 40 psi at start up and would rise and fall with engine rpm! The hotest it got was about 160. I did a few happy jumps and shut her down after about 15 minutes. I won't be able to give it a true test until I can get her out on the lake, but I think it should be fine.
It sounds very different now too, which was a very nice side effect to this project. It is very racey sounding and it revs very easily. Sounds mean. I didn't have time to tune it, set timing or anything. That will be the next thing that I will do.
All in all, I would do it all over again and it was fun performing everything on my own. I learned alot and I think I am going to rebuild that 94 Cobra motor I have and turn it into a marine engine as well. Possibly sell it. We will see. Anyone in the market for a 302!
If you want to ask me questions about things I did not include or you want to know about, just ask. I'll try to answer your questions as best I can. I'll post pictures of my build from start to finish as soon as I can get them off my camera.
Long time lurker, recent poster. Have a great day!
A couple of years ago I bought a remanufactured marine long block from a good source to repower my 84(pics have been posted of it here before). The engine itself was fine and has worked very good for 100 hours, however a mistake I stupidly made prevented 3 of the cylinders from sealing properly. Essentially it overheated on break in, good for the cam, not so good for the piston rings.
Long story short, I installed the raw water pump on backwards, so instead of pulling water in, it was pushing water back out. Once I installed the pump, the right way, the temperature came down and it seemed to settle in. It made good power, but I was consistently oil fouling 3 plugs over the course of a season. I knew what the problem was and I knew I would have to fix it eventually, so I decided to go ahead and bite the bullet this off season and tear it apart, rehone the cylinders and re-ring the pistons. I figured I would replace all the bearings as well too, since I would be in there anyway.
Once I got the engine apart and could see what had happened, it basically confirmed what I had originally feared. Glazed cylinder walls, caused from overheating. I checked out the bearing surfaces and they a looked brand new! That was great news! The block is essentially at the end of it's serviceable life as told by the overbore at 4.060, which is fine on a 351. I knew the deglazing wouldn't take too much material, if any, and I was going to use a good set of Sealed Power file fit rings to fit them to each cylinder perfectly. By the way, the cylinders had almost no taper to them what so ever, even more good news! So the honing began. The cross hatch pattern was not as difficult to master as I thought it was going to be with the honing stones. Actually very easy and fast. It was nice when I was done to see the cylinders look brand new.
I figured since I had it apart, I would also put a set of GT-40 heads and some nice FRPP roller rockers from my 94 Cobra on it I had lying around. Took the heads to a machine shop to clean and inspect, valve job, mounting holes drilled to accept 1/2" head bolts and brass freeze plugs installed. The heads checked out, so all was good.
Once I had everything I needed, I cleaned the block completely and set out to reassembled everything. I checked tolerances as directed, checked tolerances as directed some more and o yeah, did I mention checked tolerances? It really isn't that hard to do if you have the right tools, measuring instruments and most important of all, PATIENCE! I took about a month to completely assemble it, working on it a few hours a week. No stress was my motto when going about it. I had plenty of time and a warm garage to work.
You don't know how happy I was when I laid all the new bearing inserts, lubed and torqued everything down, that it spun very freely and smoothly. So, flash forward to the moment I go to turn the key last weekend to see if all my hard work paid off. It fired right up, no leaks, no overheating, oil pressure was over 40 psi at start up and would rise and fall with engine rpm! The hotest it got was about 160. I did a few happy jumps and shut her down after about 15 minutes. I won't be able to give it a true test until I can get her out on the lake, but I think it should be fine.
It sounds very different now too, which was a very nice side effect to this project. It is very racey sounding and it revs very easily. Sounds mean. I didn't have time to tune it, set timing or anything. That will be the next thing that I will do.
All in all, I would do it all over again and it was fun performing everything on my own. I learned alot and I think I am going to rebuild that 94 Cobra motor I have and turn it into a marine engine as well. Possibly sell it. We will see. Anyone in the market for a 302!
If you want to ask me questions about things I did not include or you want to know about, just ask. I'll try to answer your questions as best I can. I'll post pictures of my build from start to finish as soon as I can get them off my camera.
Long time lurker, recent poster. Have a great day!