jagman Posted January 26, 2019 Report Share Posted January 26, 2019 I have driven my 720 about 100 miles after doing the valve seals. She still smokes (oil). Cyls 2 & 3 are OK but 1 & 4 are the oil burners. I have picked up another 720 with the same engine in it. Is there more that I should do to this engine or should I pull the engine from the junker and rebuild it to replace the one currently burning oil. Opinions appreciated. I notice that most of you guys are on the west coast. Are there any collaborators here on the east coast? Thanks Steve 1 Quote Link to comment
datzenmike Posted January 26, 2019 Report Share Posted January 26, 2019 There are only 2 sources for oil burning... the rings or the valve guides/seals being worn out. You've eliminated the seals so that leaves the rings. If you need to have the truck running and can't have it off the road for any time then get the junker engine and rebuild it at your leisure and pop it in on a weekend. If it's not critical to have it off the road then re-build what you have with the second engine as a second parts source. Ive done several 'hone and ring' builds and they were never that great. The cylinders are always tapered or oval worn or both. Only machining to the next oversize and new matching oversize pistons and rings made it a new engine. On a machined block you can use harder more durable chrome rings but on a 'hone and ring' best to use cheap softer cast rings that seal inconsistent bores. The last engine was $25 per cylinder but I expect it's much more now and there is a 2-3 week turn around. Then new pistons, gasket set and main and rod bearings. The head can be left as it is and if it's later a problem it can easily be removed (and rebuild) and put on for an additional $30 gasket.. 1 Quote Link to comment
bottomwatcher Posted January 26, 2019 Report Share Posted January 26, 2019 Give it a good compression/leak down test to observe the overall health. 1 Quote Link to comment
datzenmike Posted January 26, 2019 Report Share Posted January 26, 2019 You could, but burning oil is .... burning oil regardless of fair to good compression or leak down numbers. It could be helpful indicating the valve/valve seats are worn out and you have to decide if you're going to rebuilding this head at the same time or swap the other engine's head on. 1 Quote Link to comment
Stoffregen Motorsports Posted January 27, 2019 Report Share Posted January 27, 2019 If the smoke is coming from stuck oil control rings, there's a trick I have used over and over with varying results. Put a quart of ATF in with the engine oil and run it for a few hundred to 1000 miles. If the sludge is holding the rings stuck, the detergent qualities of the ATF can get in behind the rings and help loosen them up. It may actually smoke more with the ATF in there so don't be alarmed. Another quick fix is to pull the head and ball hone the cylinders from the top (without removing the pistons). This can give a little extra life to a worn set of rings. 1 Quote Link to comment
jagman Posted January 30, 2019 Author Report Share Posted January 30, 2019 After weighing the options you have presented, I spoke to my local machine shop guy and asked if he could 1. obtain quality parts for any overbore he may find necessary and 2. had the time to do the job. Both were answered in the positive. I will pull the engine from the junker and send the block and head out for a rebuild. When I reassemble this engine can I get rid of the gulp valve and the pipe to the valve? I would like to make the engine and controls as simple as I can. I will be using the Red Line Weber carb from the existing engine. There is no hurry. The weather is too cold for me at my age to do much outside right now. Next week it should be better and I can remove the front panels and remove the radiator and surround to give me room to pull the engine. Quote Link to comment
datzenmike Posted January 30, 2019 Report Share Posted January 30, 2019 Gulp valve? You mean the EGR? yes indeed. You can just remove the rubber hose from the carb to deactivate it. Or that and unbolt it, the pack pressure transducer (BPT) valve along with the EGR valve (but you will need to make a block off plate to cover the hole) and remove the SS EGR exhaust tube from the exhaust manifold. The hole on the exhaust manifold can be cleanly sealed with a metric? pipe plug. Quote Link to comment
DIY 1985 Posted January 31, 2019 Report Share Posted January 31, 2019 (edited) You could burn oil being pumped to the rocker shaft if the head gasket is toast? Edited January 31, 2019 by DIY 1985 Quote Link to comment
datzenmike Posted January 31, 2019 Report Share Posted January 31, 2019 On 1/26/2019 at 8:37 AM, jagman said: I have driven my 720 about 100 miles after doing the valve seals. She still smokes (oil). Cyls 2 & 3 are OK but 1 & 4 are the oil burners. I have picked up another 720 with the same engine in it. Is there more that I should do to this engine or should I pull the engine from the junker and rebuild it to replace the one currently burning oil. Opinions appreciated. I notice that most of you guys are on the west coast. Are there any collaborators here on the east coast? Thanks Steve The oil jet is between cylinders 2 and 3. It would be pretty damn hard to get past 2 and 3 to get to 1 and 4. Just sayin' It's the little hole with the red sealer around it. 1 Quote Link to comment
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