I'm about to change the cam on my Pinto to a more sportier one. Do I need to adjust the spark advance table in my megasquirt?

short answer yes.
don't know how though. by changing the cam you're changing how the fuelling and timing behaves, so your timing also needs to change

quote:

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Originally posted by blakep82
short answer yes.
don't know how though. by changing the cam you're changing how the fuelling and timing behaves, so your timing also needs to change

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^ ah yeah, what i meant about fuelling is sometimes the valves open longer, meaning more fuel/air in the cylinder.

anyway, yes, you will need to change the timing

What cam are you fitting?
What compression ratio are you running?
What rods and pistons do you have?
I am just completing a high performance Pinto build, I have some spark maps for Megajolt and I am very curious about your Megasquirt set up, perhaps we can exchange some information.

Just to clarify Richards point about the compression ratio changing, the static compression ratio is calculated in a way that does not take into account valve opening and closing points. A cam with more duration and overlap means that the piston will be further up the bore at the end of the inlet stroke before the inlet valve shuts, therefore the compression achieved will be down on standard. You need to up the static compression to make best use of the cam. Burtons use 190psi on a compression check meter as there ideal pressure.
It all changes as the engine revs and the cam performs so overdoing the static comp ratio can cause Det if you go to far.
Over 10 to 1 but no more that 10.5 to 1 static on standard pistons

Standard 2.0i so it is a Kent FR34.
Standard Compression.
Standard rods etc.

I would like to exchange msq data but am unable to post attachments.