well we got the truck back together last week, and was thrilled to see that the truck fired right up again. It ran for about 30 seconds and then started to surge in RPM's. It ran up to about 2000 r's and settled in there for a bit and then gradually started idling down until it settled in at 600 r's. no loping but my omnipresent white smoke is still with me to some extent. Not like it was before, but still killing snow skeeters. I let it run for a while and charge the batteries a bit and then shut it off. tried cranking again and sure as heck it fired right up again no problems.
I'd like to address the issue with the white smoke though. I've done several searches here on the issue and it seems the consensus is if it smokes just live with it. However I tend to want o be a perfectionist and so we'll try to get to the bottom of it.
- what we know........... we have adjusted the injectors to preliminary setting of 58 in lbs for first start up, after seeing a marked improvement, we took it for a test drive. seemed to have decent power again, maybe not quite tweeked the way it should have been, but I was more worried about putting too little fuel into the system on initial startup, making it hard to start.
Anyway we get back from the test drive, and I asked my brother how much smoke, what color, etc etc. he says "black on acceleration, white with little or no load" so I set up again and give the injectors 7"lbs more. "black smoke gone, still plenty of white smoke" In my notes I noted a distinct drop in HP. So, anyway we are still interested in getting rid of the white smoke. Engine Temp is running 150 or so on all runs so cold engine isn't the cause. So we set the injectors back at 58" lbs. power returns! still some black smoke but not like it was when we brought it home from Sparta. fuel filter is changed, tanks have been drained and new #2 fuel (actually it is blended) has been added. I check all the old fuel hoses for leaks as the searches here have suggested, we still do not have new hoses on yet, but none appear to be leaking either, also there is no need to prime the engine before starting. It fires right off with just a little preheat and about four revolutions with the starter. If I prime the system it fires within the same no. of revs.
-Now for my questions....... 1) I have read here that some have been experimenting with adjustment of the fuel supply pump, has anyone actually had any success with slight advancement of the pump or retarding the pump a bit? 2)will fuel supply pressure to the heads affect how much fuel is actually entering the engine or can it be forced into the cylinder on say for example the exhaust stroke, if the pump pressure is set too high?
3) I've read here a bit about the NHC-250 having pistons that had three rings instead of the newer pistons with four, I'm assuming one was an extra compression ring or something of that nature. does that make a difference? My compression in the cylinders is up to par or so I'm told so I'm thinking compression is not at fault here. Just wondering if that extra ring could be some of the difference?
I will get more pictures up soon to show you guys/gals what kind of smoke we are getting.
as well as some more pics from the repairs.