Author Topic: Ignition timing on farm tractors? Or any multi cyl engine..  (Read 738 times)

Offline Johnmcc69

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Ignition timing on farm tractors? Or any multi cyl engine..
« on: August 15, 2018, 12:58:52 AM »
A "remedial" question of basic engine operation I'm sure, but it's been a looong 
Day..
 I'm helping someone rebuild a 4cyl ihc (300 model) tractor. New cyl. Sleeves, pistons, brgs. Etc.
 Anyways..
 Found TDC on pulley, lined rotor up to #1 cylinder, a little backfire..close enough i thought but no run. Looked at it again at TDC & it was off 180. Retimed it to TDC, & it fired right up.

 Because of the Timing mark & rotor position & gear ratio how can it be you can NOT be at TDC & rotor @ # 1 cyl & not fire?

 It would seem TDC is going to fire #1 cyl. No matter where rotor is, as long as it's on #1 cyl. (?)

 Tired...

 John

Offline gbritnell

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Re: Ignition timing on farm tractors? Or any multi cyl engine..
« Reply #1 on: August 15, 2018, 01:19:00 AM »
John,
TDC comes up twice, once when the exhaust and intake are open (overlap) and once at the firing position.
gbritnell
Talent unshared is talent wasted.

Offline Johnmcc69

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Re: Ignition timing on farm tractors? Or any multi cyl engine..
« Reply #2 on: August 15, 2018, 01:35:29 AM »
That's kind of what I thought..had to ask...

 Thank you George, I really appreciate your answer.

 Thanks for helping me get this "inside my head". I spent quite a time recovering the ign. Wiring & making that work..coil w wire was hooked to headlight switch amongst other abornamies..

 Thank you very much george!

 John

Offline Brian Rupnow

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Re: Ignition timing on farm tractors? Or any multi cyl engine..
« Reply #3 on: August 15, 2018, 01:37:18 AM »
You have a 50% chance of getting it right. Best bet is remove sparkplug on number one cylinder and put your finger over the hole. Turn it over with the starter and when it tries to blow air past your finger it's coming up on compression. Stop the starter and use a wrench on the timing bolt to bring it up to timing mark.

Offline Johnmcc69

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Re: Ignition timing on farm tractors? Or any multi cyl engine..
« Reply #4 on: August 15, 2018, 02:36:14 PM »
Thanks Brian!

 Another issue we had after we got it running yesterday was that there was a (gasp)... Knocking in the lower crankcase. I'm sure I torqued everything right & the bearings are new with correct clearances... So, dropped the oil pan & found where a connecting rod was hitting a high spot (dent) in the rear pan area. Found out from the owner that this was not the pan that was originally on the tractor. The "old one" was in worse shape (so he says.....) So he got this one. I should have noticed this but didn't, it seemed like a pretty shallow dent. I guess there isn't as much con rod clearance there as I thought...

 I fixed the pan & will be installing it along with another new gasket this afternoon (I put a new one on before this, but it tore when we dropped the pan). Too bad, it didn't leak a drop when we had it running.

 Live & learn.....

 Thanks again for your help gentlemen!

 John

 

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