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Compression stroke with no dizzy for reference.
I have no distributor and coil on plug. I don’t know how to don’t z1 compression stroke. I’m installing cam sensor. I need this info quickly if I want to get this done tonight so I hope folks are awake:)
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Brandon, one method is to look at rockers on cylinder #1 - the intake valve fully closes at the bottom of the intake stroke and then the compression stroke begins. Do you have a TDC mark on your crank pulley? If so, continue rotating the crank until the TDC mark aligns with the TDC mark on the fan housing (which is also the center line of the case).
If no mark on pulley, you can put a small, wooden dowel rod in the spark plug hole and watch it rise to the highest possible position (a homemade TDC locator) - then verify that the intake and exhaust valves are still fully closed. |
Thanks Ronnie I was hoping not to have to remove the valve cover. It sounds like it’ll be a little more involved. I may just go to bed.
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The end of the cam has no mark eh?
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Not that I'm aware of.
In order to not remove the valve cover (and what I do with aircraft in that situation) you can put a whistle in the spark plug hole (a tight fitting hose with a round whistle pushed into it) - as the piston comes up on the compression stroke, the whistle sounds off (doesn't sound off if either of the valves are open, so you know you're not on the compression stroke then), and then you can proceed to find TDC with yer homemade locator. |
That’s pretty sweet! I’ve decided to put my big boy pants on and just remove everything above the valve cover and look.
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Not going to do the work naked from the waist down, then - like you usually do?!?!
That whistle deal is really old school, but works great. |
I may have to do that. I can’t remove the lower covers I just put all my oil in the other day. Dammit
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You can probably leave the lower covers alone - just watch for the closing action of the intake rocker - it fully closes at the very bottom of the intake stroke.
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The only question I then have is at the z1 180 out is it open,closed or half way? If it’s z1 I know it’s closed.
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I don't know the answer to that right off, BUTT you can find TDC (Z1) for cylinder #1 and then rotate the crank 180 degrees and find out, bisch. :D
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I’m ya I guess. :/ haha
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I’ve decided that at too dead center, number 2 is at its lowest point or at lease the intake valve is open. I’m going to bed, if I’m wrong I’m sure Someone will tell me and I’ll move forward tomorrow.
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I didnt even check when I put in my cam sensor. It's adjustable in the settings on megasquirt anyways. Didnt work the first time so added 360* and it fired right up. I'm assuming you're doing this for sequential ignition/fuel?
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Yes sequential injection. I’m not running megasquirt and am not sure I can adjust that in electromotive.
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I'd have assumed there would be a mark on the end of the cam, and the replies here made me curious. A quick google search found this:
Freiherr Comments: Re finding 'compression TDC rather than Overlap TDC... I take out spark plug 1 and put a 2 foot long piece of fuel hose into the plug hole, then blow down it: if the cylinder is at Compression TDC the air can't escape, but if it's at overlap TDC the air leaks out via inlet & exhaust valves.. You can hear it through the intakes. This is a lot easier & quicker than using the other methods, and works every time. If you want to see the difference, try blowing down the tube in both OTDC and Comp TDC... The difference is reaaly obvious! NB Any hose will do, so long as it fits snugly into the spark plug hole & seals OK. I use a piece of fuel hose with a taper at the spark plug end taper was done on my cheap old bench grinder... https://www.pelicanparts.com/techarticles/911_static_timing/911_static_timing.htm A simple and neat method. |
That and the whistle seem plausible for sure...
I don't have a whistle so it looks like this is a winner. |
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Always a surprise when I see I've teed up a homer. Did i do it again?
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