Conn47D24 Posted February 24, 2019 Report Posted February 24, 2019 Today I have a question on the cycle of rotation / firing . Lots of threads but just to be clear I need some help please. I have the # 6 inspection plug out and have inserted a screw in rod ( old miller tool ). I rotated the engine with the starter and saw the rod go up and stopped. Using an inspection camera I can see the : # 1 cylinder - Exhaust closed , Intake slightly raised. # 6 cylinder - Exhaust slightly , Intake closed Question: What action is taking place next here ? Am I just BEFORE TDC or just AFTER TDC ?? Thanks all ! Clay Quote
Plymouthy Adams Posted February 24, 2019 Report Posted February 24, 2019 did you bother to see if your rotor was pointing to number one or number 6 on the tower...remember it takes two 360 rotations of the crank to get one complete cycle of all cylinders in a 4 stroke engine.. Quote
Conn47D24 Posted February 24, 2019 Author Report Posted February 24, 2019 PA I have the dizzy out and trying to get it set after rebuild. I am having tough time rotating the engine by hand and was wondering how close i may be to #1 being at TDC. plugs are all out but the 1 &1/8" socket keeps slipping off the crank hub. Do i need another touch off the starter or around again ? Quote
Plymouthy Adams Posted February 24, 2019 Report Posted February 24, 2019 IF on removal....you did not remove the oil pump....the base line is still an ESTABLISHED condition on your engine....you put in the distributor..it should fire up...if not, slightly lift the distributor and rotate the rotor 180 degrees....one of the two conditions will be correct..... Quote
Conn47D24 Posted February 24, 2019 Author Report Posted February 24, 2019 Think its too late for that. Engine was demantled completely for rebuild. Pump , dizzy both out . I am starting ( no pun) from stractch. If i continue the rotation a bit more from where I am now, does that close both valves in 1 & 6 ? From what I've read on other posts that's the condition I am trying to attain so I can set the oil pump and distributor. Is that corect? Quote
Conn47D24 Posted February 24, 2019 Author Report Posted February 24, 2019 Think its too late for that. Engine was demantled completely for rebuild. Pump , dizzy both out . I am starting ( no pun) from stractch. If i continue the rotation a bit more from where I am now, does that close both valves in 1 & 6 ? From what I've read on other posts that's the condition I am trying to attain so I can set the oil pump and distributor. Is that correct? Timing marks pictured is current position as I described above. Quote
thisoldtruck Posted February 25, 2019 Report Posted February 25, 2019 (edited) I would only pay attention to cylinder number 1. As mentioned, it takes two revolutions of crank shaft to complete cycle. So intake valve opens as piston drops, to let air/fuel into cylinder, then intake closes and piston starts to come back up. When piston is at top, that is top dead center and ready to fire that cylinder. Edited February 26, 2019 by thisoldtruck 1 Quote
maok Posted February 25, 2019 Report Posted February 25, 2019 8 hours ago, Conn47D24 said: I have the # 6 inspection plug out and have inserted a screw in rod ( old miller tool ). I rotated the engine with the starter and saw the rod go up and stopped. Using an inspection camera I can see the : # 1 cylinder - Exhaust closed , Intake slightly raised. # 6 cylinder - Exhaust slightly , Intake closed Clay If the #6 piston is near TDC then the above cannot be the case. Either #1 OR # 6 inlet and exhaust valves should be fully closed. You may not have installed your timing chain to the cam and crank gears correctly. Quote
Dodgeb4ya Posted February 25, 2019 Report Posted February 25, 2019 I thought it took 720 degree's of crankshaft rotation to complete one 4 stroke operating cycle Quote
thisoldtruck Posted February 25, 2019 Report Posted February 25, 2019 Basically he was 2 strokes away from TDC on cylinder number 1 and cylinder number 6 already fired and was in process of exhausting itself, so cylinder number 2 would be next in line for firing right at this stage. Whatever state number 6 is in, really doesn't matter because cylinder number 5 is next to fire after cylinder number 1 anyways. Quote
ptwothree Posted February 25, 2019 Report Posted February 25, 2019 Pull the #1 plug- Put your thumb over the hole and crank the engine till you feel compression pressure then stop cranking- look at the timing marks and pointer- rotate the crank till pointer lines up with "0". If the timing gears and chain are installed properly, you are now at top dead center compression stroke on #1 cyl. Install the dizzy with the rotor at 7 o'clock and there ya are. 1 1 Quote
Silverdome Posted February 25, 2019 Report Posted February 25, 2019 (edited) 14 hours ago, Dodgeb4ya said: I thought it took 720 degree's of crankshaft rotation to complete one 4 stroke operating cycle This is correct. 2 upstrokes consisting of a compression and an exhaust and 2 downstrokes consisting of a power and an intake. Each stroke is 180 degrees multiply that by 4 for 720 degress or 2 full rotations. Edited February 25, 2019 by Silverdome Quote
Dodgeb4ya Posted February 25, 2019 Report Posted February 25, 2019 Yes... two revolutions of the crankshaft... not four. 2 Quote
T120 Posted February 25, 2019 Report Posted February 25, 2019 (edited) I always keep in mind that distributor R.P.M. is one half of engine R.P.M....(engine R.P.M. 800 = distributor R.P.M.400) ? Edited February 25, 2019 by T120 Quote
Hickory Posted March 2, 2019 Report Posted March 2, 2019 Did this problem get resolved, I believeThe valves may be open if the timing chain is done wrong or the valve adjustment is wrong. With #6 @ tdc either #6 or #1 should have closed valves. I would check the valve adjustment 1 Quote
Plymouthy Adams Posted March 2, 2019 Report Posted March 2, 2019 16 minutes ago, Hickory said: Did this problem get resolved, I believeThe valves may be open if the timing chain is done wrong or the valve adjustment is wrong. With #6 @ tdc either #6 or #1 should have closed valves. I would check the valve adjustment THIS MAY BE INTERESTING..ON OUR WEBSITE.... Quote
kencombs Posted March 3, 2019 Report Posted March 3, 2019 20 hours ago, Plymouthy Adams said: THIS MAY BE INTERESTING..ON OUR WEBSITE.... That post asked a question that was not answered. Anyone have a comment on it?? Quote
Conn47D24 Posted March 3, 2019 Author Report Posted March 3, 2019 Thank you PA. Saw that and understand. My ? Was a little different. Next warm day i will rotate it further and evaluate. Hoping the chain is not off. Quote
Plymouthy Adams Posted March 3, 2019 Report Posted March 3, 2019 who is assembling this engine that at this point there would be a question as to timing off? I am a bit confused as to the order of assembly and the backing up I guess... Quote
Conn47D24 Posted March 5, 2019 Author Report Posted March 5, 2019 Hi PA, I did the assembly. Still haven't had time and weather to get out and investigate further. I'll try to turn it over and feel for compression at # 1. If this works out perhaps my doubts about the valves being fully closed is moot. then I'll get it back around to # 1 and set the oil pump and dizzy as per the manual and info here. The it's up to the Gods ! ? Quote
Frank Elder Posted March 5, 2019 Report Posted March 5, 2019 (edited) This is the life expectancy of your engine you are risking, if you are not confident enough in your abilities to find TDC Compression Stroke with it buttoned up remove both the head and timing chain cover and set it properly......this way you can "see" everything. If your are indeed at TDC and your marks line up on timing gears but your dizzy doesn't point 7 o'clock then you must pull it and try 180 test, if that still won't line up you must Clock the oil pump to ensure the dizzy points 7 o'clock presto everything is good. Button up and move to the next agenda.....all that peace of mind for the cost of a few gaskets and a little sweat equity......... Edited March 6, 2019 by Frank Elder left out cover 1 Quote
Conn47D24 Posted March 16, 2019 Author Report Posted March 16, 2019 (edited) Before removing the timing cover I want to ask this. After researching this site and Youtube , I have turned the crank further and now have # 1 top as indicated by BOTH the # 6 inspection hole rod, AND the position of the valves. I have watched as I turned the crank the valves closing with my video camera. That said, # 1 BOTH tappets move freely by hand. # 6 the Exhaust moves freely and intake will not. All 4 of these valves are closed yet this one tappet is never the less firm. Is this condition correct for TDC ? OR, should all 4 tappets be free ? Last call before I open this mother back up again. Thanks ALL Clay Edited March 16, 2019 by Conn47D24 Quote
ptwothree Posted March 16, 2019 Report Posted March 16, 2019 Forget about what's going on with #6...I think that is confusing you. What makes it go is the piston in #1 is at top dead center with both valves closed, pointer at '0' and the rotor pointing at 7 o'clock. With ignition, compression, correct firing order and fuel, it should fire right up. 1 1 Quote
Conn47D24 Posted March 16, 2019 Author Report Posted March 16, 2019 Great. Thanks for confirmation. Ill set oil pump and dizzy next. Quote
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