The Camaro Club (UK)

Interesting article:

http://www.superchevy.com/how-to/additi ... on-timing/

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Good articles on Super Chevy.
http://www.superchevy.com/how-to/46178/

So I went ahead and changed the vacuum port from ported over to full. As my car doesn't have emissions (no A.I.R system injecting air into the exhaust) according to that article, it means that there's no benefit in running ported, as ported is designed to help keep the spark very close to TDC so that when the exhaust valve opens, the mixture is still on fire and the air being injected helps give a more complete burn. As a result, power is lost and also idle temps are higher. Therefore, I changed to full vacuum and as the article stated, my idle rpm went up, as there was an increase in power.

Didn't notice much of a difference in idle temp, perhaps it took a minute longer to get to operating temp. Then again, I had changed the thermostat out from 160 to 180 so that's skewed the results. The electric fan does come on less frequently now, before it was on and off every 15 seconds. Then again, this could be to do with the thermostat.

Need to check the timing now as i've no idea what it's set to. It does idle nicely and start nicely.

What's a good starting point for timing? Manual shows 4 (or 6) BTDC but that's emissions based. Also, as RPM at idle has now gone up, should i reduce the rpm? It used to be about 550 at idle, ran nice and smooth. After changes, at first it was about 950 but not it's about 850.

Guessing this will also turn into a carb tune? It does run a bit rich (i can still smell unburnt fuel on my clothes )

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It depends on your distributor really and what total timing you end up with.

Good ballpark is 10-12 degrees at idle (with vac advance disconnected and blanked). It certainly livened mine up when I did this, mines running 12 at the moment with a full MSD dizzy. You can keep dialling in more until it starts pinking, then dial it back a little, as a general rule of thumb. I want to add a 6AL box at some point as well. I changed all this when I ripped off all the old Calofornia smog gear.

I may try moving vac port as well after reading these linked articles!

Rich fuel smell also sounds familiar! Mines been on the rolling road and is apparently set up spot on, but always smells rich to me!

Thanks for the info, that's helpful!

On my 3rd gen the timing was 4dg btdc but it had an AIR system so that explains why it was so late.

10-12 sounds better, it gives me something to start with

When blanking off the vacuum line, i'm guessing that it would a case of blanking off the inlet to the distributor? Or blanking off the carb side of the vacuum?

From what i've heard it's better to have slightly richer compared to slightly leaner, as it lowers the chance of valves overheating (richer mixture apparently helps with cooling the intake valve).

Cheers!

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You need to plug the carb side, otherwise you have a vacuum leak!

Cheers, that makes sense - I feel stupid now!

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