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Old 05-05-2020, 03:03 PM
x33rs x33rs is offline
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I'll elaborate some more since mine isn't "as built" from the factory.

I built mine with intention to run pure stock per rules here
https://www.psmcdr.com/rules

I've done a few engines this way with a few liberties taken to keep them as nice street engines.

Without getting into all the details it's essentially for all purposes here, a stock DZ 302. The cam is "tweaked" a bit and compression is exactly 11:1. Stock heads, intake, carb etc...no porting.

We only experimented with stagger jetting to see what it might be worth. Looking at the intake runners, both front and rear from the driver side are longer, so it made sense to jet that side of the carb up. It was worth a pinch of power on mine. After going 2 sizes I tried 2 more and didn't find any more gains. So I stayed with the 2 size differential.
This shouldn't let any secrets out as it's really not all that hard to look at intake runners and figure out where more jetting might be beneficial. I've been stagger jetting BBC's for years with decent results so I thought I'd experiment on the little DZ and was pleasantly surprised.
On power valves I like the 6.5's front and rear. I've tried blocking the rear and going up 4 sizes in the back and even 4 sizes wasn't rich enough to compensate for not having the power valve. WOT AFR's went from 12.4 to 12.8. Still safe and ran fine but if you're trying to keep the same air fuel ratio without the rear power valve you might want to step up 6 jet sizes.
I ended up going back with the rear power valve but either way works well.
So as I mentioned I ended up with 70-72 front jets and that's because I spend most of my time running around at 5000 feet elevation. When I go to the track I'll likely bump that up to 72-74 or maybe more depending on the weather, but may just leave the back alone as I have WOT pretty rich as it is at this elevation.
Keep in mind this is actually primarily a street car, my wife drives it daily to and from work, I'm just a fanatic about tuning and I like my stuff to run. With this carb setup the throttle is crisp, clean and quick. I run a fairly aggressive timing curve as well, with 18 initial, 18 centrifugal, for 36 total, all in at 2600 rpm, and I have an adjustable vacuum advance with my own modifications welding the slot for a specific movement I look for that limits total vacuum advance to about 10 degrees, and it starts pulling around 6 inches of vacuum, done around 8 inches, so it's rather quick, again since I'm up at 5,000 feet the engine makes 3-4 inches less vacuum up here. Idles around 9-10 inches, where at sea level it's 12-13 inches.
This setup runs perfectly on our crappy 91 octane and has logged over 30k miles to date. Hope this helps.
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