Ignition Timing Advance or Retard The Why's and How's

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8541Hawk
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Re: Ignition Timing Advance or Retard The Why's and How's

Post by 8541Hawk » Tue Jul 19, 2016 7:51 pm

I think I still have a print out of the HRC map around here somewhere. I'll try to dig it up for you guys, if not I'll post up what I remember as even that might be a bit of a help for a good starting point :thumbup:
To err is human, to forgive is divine. Neither, however, is Marine Corps policy

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8541Hawk
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Joined: Sat Jul 21, 2012 4:21 am
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Re: Ignition Timing Advance or Retard The Why's and How's

Post by 8541Hawk » Tue Jul 19, 2016 7:51 pm

Oh and good write up Carl :thumbup:
To err is human, to forgive is divine. Neither, however, is Marine Corps policy

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freeridenick
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Re: Ignition Timing Advance or Retard The Why's and How's

Post by freeridenick » Mon May 21, 2018 11:32 am

VTRDark wrote:
Tue Apr 22, 2014 8:53 pm
Image
The above Diagram shows the Point of Valve Open and Closing times
I'm triple checking my cam timing before I button everything up and start it up. Am I right in thinking this diagram is a view from the right-hand side of the engine (clockwise rotation) but the degree valves would be from the left?

I other words from TDC on the compression stroke everything is closed. Next time round to TDC the exhaust valve has nearly closed and intake is just opening. At which point, and this is the important bit, if the above is the rear cylinder coming back to TDC on the exhaust stroke, the front cylinder is on its way up to TDC on the compression stroke.

Right?

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VTRDark
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Re: Ignition Timing Advance or Retard The Why's and How's

Post by VTRDark » Mon May 21, 2018 3:00 pm

Oh man that's getting the old eltrodes vibrating in my skull :lol: That diagram is one cylinder and does not matter which one or which stroke as they are all the same but at diffrent points of rotation on the camshaft. The outer circle is the Inlet valve and the Inner circle is the exhaust and rotation is clockwise. That diagram is a basic diagram that shows valve opening and closing times.

To work out Cam Timing and how one cylinder relates to another on diffrent strokes you need a more detailed graph. Something along the lines of the following:

Sample Image (note this is not a VTR)
Image
Source
rear cylinder coming back to TDC on the exhaust stroke, the front cylinder is on its way up to TDC on the compression stroke
With the rear cylinder moving towrds TDC on the exhaust stroke the front wont be travelling in the same direction. The pistons are not travelling in sync with each other.

Image

This thread is aimed more torwards Ignition Timing not Cam Timing and it's important to not confuse the two. I was going to do a thread on Cam Timing but never got around to it. That's a lot more complicated and would reguire degreeing and taking measurments of both inlet and exhaust cams to draw up a graph and then to try and explain things in technical and laymans terms.
==============================Enter the Darkside

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