joscorstjens
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| posted on 26/7/10 at 11:05 PM |
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cam changes requires different timing?
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?
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blakep82
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| posted on 26/7/10 at 11:13 PM |
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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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MakeEverything
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| posted on 26/7/10 at 11:16 PM |
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quote:
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
Only the valve timing...
By changing the cam, youre changing how the fuel and air enter and exit the combustion chamber and changing the compression ratio's.
Spark doesnt change with the cam either, youll need to adjust this by megasquirt with a timing light to calibrate.
[Edited on 26-7-10 by MakeEverything]
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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blakep82
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| posted on 26/7/10 at 11:20 PM |
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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
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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snapper
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| posted on 27/7/10 at 04:42 AM |
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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.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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snapper
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| posted on 27/7/10 at 04:58 AM |
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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
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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joscorstjens
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| posted on 28/7/10 at 12:30 AM |
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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.
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