rosie Posted June 26, 2011 Share Posted June 26, 2011 gets you out from under my feet anyway!:kiss: Quote Link to comment Share on other sites More sharing options...
R Cubed Posted June 26, 2011 Author Share Posted June 26, 2011 Set the engine as it should be.. don't try and compensate for octane difference... the engine will run fine on the gas we have now set up for the gas they had then (gas in wwii was 70 octane... now everything is 85-87+.. much better fuel). If you want to tweak the timing... hook up the vacuum gauge and shoot for whatever setting gets you the highest vacuum reading... then back off 1-2inches (on the gauge). That should set you at optimum timing... but may need to be retarded as you drive it a little. It does say in the book to alter timing to compensate for different fuels I seem to remember someone saying that you could bring the timing towards TDC until you get pinking and then back it off a few degrees till it stops is this good practice ? I will also try the vacuum gauge method and see how that performs. Ultimately this seems to have reduced the noise so I am now going to hold off the strip down at the moment. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted June 26, 2011 Author Share Posted June 26, 2011 Richard, Reading what you have posted, it seems you are too far advanced, if you reckon it to be about 10 degs BTDC, and it would have been even more advanced if you had to remove a bump off the points. This is the point I was making in an earlier post. So, is the knock still there? It seems to have reduced the sound lots so I am going to hold off the strip down until I have carried out some more "tuning" and done some road runs this week. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted June 26, 2011 Share Posted June 26, 2011 It seems to have reduced the sound lots so I am going to hold off the strip down until I have carried out some more "tuning" and done some road runs this week. You need to do some basic checks with the distributor. Make sure the advance mechanism is working correctly, could be siezed in one position, check for wear in the bushes too. Then set points correctly and set timing to the book initially. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted June 26, 2011 Author Share Posted June 26, 2011 You need to do some basic checks with the distributor. Make sure the advance mechanism is working correctly, could be seized in one position, check for wear in the bushes too. Then set points correctly and set timing to the book initially. The distributor is new old stock and was in very good shape when I fitted it about 4 years ago, no play in bushes and also regularly greased via greasing knob. centrifugal advance mech is working fine and free to move against the springs, when released the rotor arm returns to the start point, so no play there, this is why I changed the old one, bushes worn and springs stretched. Will start by setting timing to spec and work from there. Also I noticed when cleaning and gaping plugs, all were quite a dark straw colour would this indicated they were running a bit hot, suggestions please ? Quote Link to comment Share on other sites More sharing options...
Sean N Posted June 27, 2011 Share Posted June 27, 2011 Book says 5 deg btdc, the truck itself seems to idle better at about 10 deg btdc !! If you try to set timing by ear you will always tend to make it over advanced. Advanced = firing earlier, retarded = firing later, so as you retard the ignition the timing of the spark gets closer to TDC, as you advance it gets further from TDC (assuming you're on the correct side of TDC!), i.e. the further left the ball the more advanced. Quote Link to comment Share on other sites More sharing options...
deadline Posted June 27, 2011 Share Posted June 27, 2011 I would advance a little, higher octane fuels burn slower and need more time to completely combust. Running at book figure will be fine but you will get more power and better economy with it advanced a little but probably only 2 degrees over book. That's a negative, Ghostrider. Octane rating has nothing to do with the burn rate or energy capacity of gasoline. It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Low octane fuels will knock or detonate at a much lower temp/pressure than higher octane fuels... that's why the compression ratio of a CCKW is like 5 or 6 to 1 while a modern engine is at least 8:1. My M35a2 is a 22:1 compression ratio. It can still burn gas, but its not recommended (due to other diesel engine limits like IP pump lubrication). As mentioned in another post.. advancing the timing will get you performance but can lead to knocking (the fuel ignites due to compression/heat rather than spark plug timing). That said... ignore trying to set the distributor for optimum performance... you want to get everything set to a known state. You may find out that one of your lifters and worn and may need to vary the gap to quiet the valve. With mechanical valvetrains there really isn't a one-size-fits-all method. You have to tweak each part. Hydraulic valves so that magically. We don't have those Quote Link to comment Share on other sites More sharing options...
Adrian Barrell Posted June 28, 2011 Share Posted June 28, 2011 I was aware what octane rating meant but believed that modern unleaded burnt slower than older, lower octane fuel. It may well do but it seems that is nothing to do with the fact it is higher octane but purely to do with the hydrocarbon makeup. So, advancing the ignition a little does improve things but is dependant on the chemical makeup of the fuel and a bit hit and miss! Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 3, 2011 Author Share Posted July 3, 2011 Bit of an update, set timing to the ball mark ( 5 deg BTDC ) upped the idle a bit so ticks over at about 800 RPM the Vac reading is now rock steady at approx 21" Hg engine seems to rev better and picks up quicker.. BUT the knock is MUCH louder and much more noticeable so have made the decision to strip down as far as necessary to find problem, still suspect No 4 as removing the plug lead removes the knock !!!! tappet clearances on all cylinders are all fine !! Will see what today brings. Can anyone come up with the torque settings for big ends and head settings and sequence of tightening ? Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted July 3, 2011 Share Posted July 3, 2011 (edited) Can anyone come up with the torque settings for big ends and head settings and sequence of tightening ? Oh, you won't be needing them for a few hours yet! :cool2: And where's Your manual? :readbook::nono:PM sent. Edited July 3, 2011 by N.O.S. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted July 3, 2011 Share Posted July 3, 2011 (edited) OK, looking at cyl head from cab - RH side (push rod side) has 7 bolts, number them (from front) 15,11,7,3,4,8,12 LH side has 8 bolts, number them (from front) 14,10,6,2,1,5,9,13 Big end cap bolts 40-50 foot lbs (not 59 as I typed in error....) Head bolts 60-70 foot lbs Edited July 5, 2011 by N.O.S. wrong figure Quote Link to comment Share on other sites More sharing options...
rosie Posted July 3, 2011 Share Posted July 3, 2011 :cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry: Not looking good guys, the big end was right at the very limit of going bang by the sounds of it! Cubed has a spare engine, which he put on a stand and turned upside down and wondered what all the dripping noise was only to discover he didnt check if the engine was empty of oil :nut: Anyway he is about to come in for a roast dinner so will get a low down on matters. Mega thanks to G506 for his help today and of course Mrs G506 for allowing me to cuddle babies all day!!!!!!! Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 5, 2011 Author Share Posted July 5, 2011 (edited) OK, looking at cyl head from cab - RH side (push rod side) has 7 bolts, number them (from front) 15,11,7,3,4,8,12 LH side has 8 bolts, number them (from front) 14,10,6,2,1,5,9,13 Big end cap bolts 40-59 foot lbs Head bolts 60-70 foot lbs Thanks very much, quite right wont need them for several days yet... :mad: Presume all main / big end and head bolts can be all reused ? Edited July 5, 2011 by R Cubed Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 5, 2011 Author Share Posted July 5, 2011 The strip down is going well, as ever daily work getting in the way of play. Anyway suspect poor old engine is well worn, big ends and main shells have surface cracking all over them and also very rough with some scoring although not down to any base metal, will post some pics when I get a chance. Also I think pistons are bad too as some of them when you push them up the bores towards the top of the head and then let go they slide back down the cylinders :mad: ( this is with the engine still in the truck ) Now I know the pistons are heavy but surely they should not do this with limited view the cylinder bores look unmarked though !!!!!!!! Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted July 5, 2011 Share Posted July 5, 2011 Big end bolt torque - I put 40 - 59, should be 40 - 50!!! (hit 9 instead of 0 by mistake :blush:). Suspect your rings might have just lost their spring? - expect a new set will cure this :-) Pistons must have clearance (a lot more when cold) so will slide down - only the rings provide any resistance. Quote Link to comment Share on other sites More sharing options...
Stormin Posted July 5, 2011 Share Posted July 5, 2011 Could just be that the piston rings are gummed up with oily deposits therefore not springing back out to grip the bore properly. Plenty of use in this condition can lead to glazed bores. As Tony suggest new rings are probably the best cure after a quick glaze bust. Just trying to remove the rings to clean up the grooves tends to lead to a few broken ones. Suspect they won't be too expensive for a set when added to the other parts you'll need. In for a penny in for a pound with these engine jobs. Always best to do the full lot whilst it's in pieces anyway than have to come back later the bit you skimped on. Quote Link to comment Share on other sites More sharing options...
deadline Posted July 5, 2011 Share Posted July 5, 2011 Unless at operating temp the rings should not be touching anything. IIRC the clearance is like .003 or something. Were you burning oil? Is the exhaust tailpipe black with soot? Bad rings will burn oil, not make noise. Seeing that your compression reading were all in the same ballpark that alone leads to no issues with the rings/valves. I HIGHLY recommend that you read this TM page: http://www.tm9-801.com/searchTM9/tm9_pages/229.pdf Your own compression tests were: First attempt No1 135, No2 130, No3 115, No4 115, No5 120, No6 120. Second attempt No1 130, No2 120, No3 115, No4 115, No5 130, No6 120. But you did not note if you reran the test with oil in the cylinder as per the TM link. DId you rerun the compression tests after you reset the lefter gaps? Nothing you are posting is flagging a cylinder (although the low compression tests are a hint, the fact that your vacuum gauge is 'rock solid' and you are not burning oil would rule them out. If it were me, I would Plastigauge main and rod bearings (visual inspection is nice, but in conclusive). Does not really require more than taking the oil pan off. Honestly I really think its a valvetrain issue. Old mechanical lifters are noisy and need constant care. Quote Link to comment Share on other sites More sharing options...
Adrian Barrell Posted July 6, 2011 Share Posted July 6, 2011 Unless at operating temp the rings should not be touching anything. IIRC the clearance is like .003 or something. Yes, 0.003 endgap, but if your rings are not touching anything, you need new rings! Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted July 6, 2011 Share Posted July 6, 2011 Yes, 0.003 endgap, but if your rings are not touching anything, you need new rings! :rofl::rofl:But we know what you meant, Deadline! Quote Link to comment Share on other sites More sharing options...
Stormin Posted July 6, 2011 Share Posted July 6, 2011 Yes, 0.003 endgap, but if your rings are not touching anything, you need new rings! Or a new engine Block. :rotfl: Quote Link to comment Share on other sites More sharing options...
rosie Posted July 6, 2011 Share Posted July 6, 2011 (edited) LATEST UPDATE The cubed one has just come in to borrow my permanent marker and said that all nuts and bolts have come off easily and he is about to remove the head which of course will reveal the pistons....................................................................................................................................... NEXT UPDATE Head off, all looks clean and cylinders look smooth!!!! Pistons are about to be popped, all this yelled at me as he raced in to grab his camera!!!!! Edited July 6, 2011 by rosie Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 6, 2011 Author Share Posted July 6, 2011 Well, had a good evening at it, head is off, the head bolts were all a little loose not as tight as I thought only had to pull a bit on a 16" nuckle bar !!!! All pistons are now out, cylinders are all nice and clean and shiny will do a honing job to rough up a bit, all pistons look good only a little wear on the near sides and off sides of them ( thrust faces ) tops not much carbon build up only a bit sooty black. rings all in tacked and free, oil cont rings also free and not gummed up ( will replace all ). Head gasket looks good too, only it has black sooty marking about an 1" wide between all cylinders both sides of it ( head bolts should have been tighter suspect ) most of the big end shells have marks and some bad pitting ( will replace all ) crank big end journals seem fine. How do the little ends work ? I have one piston where the gudgeon pin is free to move in the piston all the others are very tight in the pistons? The little ends are all ok no sign of play or movement. Going to hone all cylinders, replace all rings on pistons, and all big end shells and maybe a piston to get the gudgeon pin tight. Quote Link to comment Share on other sites More sharing options...
Pete Ashby Posted July 6, 2011 Share Posted July 6, 2011 I have one piston where the gudgeon pin is free to move in the piston all the others are very tight in the pistons? The little ends are all ok no sign of play or movement. Going to hone all cylinders, replace all rings on pistons, and all big end shells and maybe a piston to get the gudgeon pin tight. Which cylinder did the sloppy pin come from? Pete Quote Link to comment Share on other sites More sharing options...
deadline Posted July 7, 2011 Share Posted July 7, 2011 Ok, my English to American translator is having a bit of trouble with the description.. but I make it out there is a lose piston pin? Quote Link to comment Share on other sites More sharing options...
Stormin Posted July 7, 2011 Share Posted July 7, 2011 Sounds like possibly the oil feed to one little end has blocked up leading to gudgeon pin seizing in little end. This has caused it to rotate and wear in the piston instead which could well be the source of your noise. Check the oil ways in the crank for blockage and also inside the conrod if any. Quote Link to comment Share on other sites More sharing options...
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