Since it was a little warm today...(a balmy 45 degrees) - I decided to start getting the Z ready for spring. I decided to change my blower pulley to the smallest pulley available for the blower I have, which is 2.8". This "should" give me around 7 to 7.5 pounds of boost.

Prior to this, I had a slightly bigger pulley on it and was only running 5 to 5.5 pounds of boost.

Back then, I had the car dynoed, and the guy found out it was detonating in the upper RPM range pretty badly. I had set it myself to 34 degrees at the time and I couldn't hear it detonanting at all, but the dyno results proved otherwise - which kinda scares me...

The total mechanical was backed off to 32 degrees and that took care of it.

Considering the extra couple pounds of boost now, should I back it off a 2 more degrees to be safe - or even more? Or is it strictly a "trial and error" thing?

I'm also dealing with a Unilite distributor now, and the timing curve seems very conservative. It's not all in until 3000 RPM's....I seem to think my last distributor had it all in by 2200...does that seem reasonable, or again - is it a "trial and error" thing?

The engine is a iron headed (Dart 200cc) 9.1:1 compression engine. Premium only...which is 92 octane around these parts. I'll be adding Don's headers and a Multi-spark boost retard also. (just in case I actually hear it detonating) I'm hoping for even mo' powa!!

Any tips or advice appreciated...

 

every engine combo is different... you just have to play with the timing and fuel to see what your specific combo likes

 

Yeah I know it'll have to be dialed in, but I'd like to know where a good general safe starting point is. Trying to get everyone's take on how aggressive or lazy the timing curve should generally be, and what I should limit total timing to w/7 pounds of boost...at the very least, I gotta drive it to the dyno.

 

I would set it to 26˚ until you know how much boost you're actually going to make and to make sure the a/f ratio is safe at the new boost level. There's no point in being too aggressive before it's tuned on the dyno.

 

Appreciate the reply calebzman....I already have an idea of how much boost it's going to have with this pulley since I've had it on breifly before. Should be around 7-8 pounds.

But this time around, I'm changing headers to Don's 1-3/4 primaries, and going with a bigger carb, from a 650 to 800 cfm. I plan on these changes as being my last for a while since I have plans to throw a few mods at my other car (Challenger).

I plan on going to dyno with the Camaro again to see if the numbers improve even more....I suspect they will (or should).