Tuning a DZ 302 - Page 2

**PxTx** · #11 09-02-2013, 01:32 PM

X2!

COPO PETE · #12 09-03-2013, 01:44 AM

NGK V power plugs work good. Usually run 7's.

#13 09-03-2013, 03:33 AM

Also keeping the carb absolutly clean of varnish and in tip top shape I have found is a must for peak performance.

Tony_H · #14 09-04-2013, 12:54 AM

Found the bushing that controls the amount of total timing was gone along with a couple of other little issues. Ended up with 14 initial and 38 total with the vacuum advance blocked off with a BB in the line. The Sun machine he ran it on was from the 60s. It was pretty interesting.

Plowman · #15 09-04-2013, 01:08 AM

That is so cool looking. Look's like he knows what he is doing. Good job.

**Salvatore** · #16 09-04-2013, 03:15 AM

its where you gotta be Tony!

**Kurt S** · #17 09-04-2013, 04:49 AM

38 deg total at what rpm?
You want that vacuum advance hooked up - remove the plug. And make sure it's connected to manifold vacuum, not ported vacuum.

http://www.camaros.org/pdf/timing101.pdf

Tony_H · #18 09-06-2013, 01:09 AM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kurt S</div><div class="ubbcode-body">38 deg total at what rpm?
You want that vacuum advance hooked up - remove the plug. And make sure it's connected to manifold vacuum, not ported vacuum.

http://www.camaros.org/pdf/timing101.pdf </div></div>

All in by 3200 RPM. That is a good write up and makes allot of sense. A Z28 has 3.73 to 4.11 gears and turns allot of rpms when cruising. I know your vacuum drops out under acceleration but when you are cruising at 2800 RPM with a load on it wouldn't the vacuum come up and add more timing causing detonation that you may not hear. With 11.1 compression and todays fuel I would be worried about that.

**PxTx** · #19 09-06-2013, 01:36 AM

Tony, you can place a temp vac gauge to verify this but the highest vac will always be with your foot out of the throttle. Light cruise with a slight load should not allow the vac advance to add enough timing to detonate with a proper tune.

My dad has always made a point with theze timing 101 articles to note that the vac advance needs to be limited to no more than 10 degrees due to the typical pump gas we have. I'm on my phone and don't want to go into details. Though engine tunes and config vary- they all act surpisingly similar in off throttle conditions (highest vac)..

Plowman · #20 09-06-2013, 02:52 AM

Having vacuum advance at light cruise will help with cylinder temp's to cool down. The cylinder at light cruise will be the leanest and cylinder temp will go up. Having manifold vacuum advance at 10 deg max at idle,with a "Hot camshaft",will help to have leaner mix at idle and won't load up. Also help's at cruise too lower cylinder temp by add timing.