The GM Manual that comes with this engine says set timing at 32 degrees max total all in by 3,000RPM. 32 Max just sounds a little low for an engine like this. Anybody have any comments about that or why would be this low. I thought 34 - 38 total was more common but not sure what makes the ZZ383 differenent? Anybody know?

What have those who have this engine found to work well?

Thank you :thumbsup:

32 Max just sounds a little low for an engine like this.

What's 'an engine like this'? Why would GM recommend that timing?

A carefully engineered balance of torque-producing bottom-end power and horsepower-inducing Fast Burn cylinder heads combine for the ZZ383/425’s stellar performance statistics. The Fast Burn heads have large 2.00"/1.55" valves
and specially designed chambers that draw in lots of air and fuel, burning the mixture quickly and completely.

Maybe a cylinder head that burns the mixture very quickly will produce peak cylinder pressure at the proper time by not lighting it so soon.

It's been my experience that most stroked engines (small blocks) tend to require less total advance. Most iron head 383's like 32-34 total...

Ineresting - maybe the "fast-burn" heads are they reason. O.k. what about carbs - what kinda carbs are you guys running? Do you think I'd be leaving some power on the table by using a Holley 670 Avenger Vac Secondary or would a 750 be better suited for better 1/4 mile times.

The suggested carb is a 750..

http://www.crateenginedepot.com/ZZ383-Crate-Engine-425HP-12498772-P764C2.aspx

The 670 might enhance throttle response and help with low end power. If you know what you are doing with the 750 you can get that low end power out of it and there is upper rpm gains to be had. I use to run a 780 (list 4346) on my 383 and found the lower end picked up with the 670. If I had about $500 to blow on a carb I'd be looking at something like this http://cgi.ebay.com/ebaymotors/Holley-0-82750-750-CFM-Street-HP-Vacuum-Sec-Carburetor_W0QQcmdZViewItemQQcategoryZ33550QQihZ00 4QQitemZ140166499862QQrdZ1QQsspagenameZWDVW

I have essentially that motor, but with a bit more cam.

GM says 32-34 total, so that's what I use. I assume it's because of the chamber design. It runs very well.

For a few years I ran a Holley 650 DP. (4777-2) It ran GREAT. I don't race it.

Recently switched to a Holley HP 750 DP. It still runs fine, but I don't notice gobs more power or anything.

68RS-SS,
Please excuse me for "borrowing" your thread, but I have a related question I'm hoping I can get a little help with.

I also have a 383 I had built for my '67 -- with all the go-fast parts and upgrades. Project HP is 470+.

A few years back I picked up an Edelbrock 850 cfm Q-Jet carb and I plan on using it on this engine. I'm concerned somewhat that this carb is going to be too much. So, I contacted the good folks at Edelbrock and they said that one of the benefits of the Q-Jet (and also the reason it has so many moving parts) is that the secondaries stay out of the picture unless the engine demands the extra airflow -- and that I shouldn't have any problems.

I'm not convinced but I'm no expert on this, so I thought I pose the question here. I'd appreciate it if anyone has thoughts on how the Edelbrock 850 cfm Q-Jet will work in this situation.

Thanks.

Vacuum sec and on demand carbs will only provide the fuel the engine asks for... Chevy put 780 cfm carbs on a 302 cu mill and for that reason. That on demand QJ will be very forgiving on your engine...

Thanks Dennis!