First drive impressions, and some issues

[Guest Mr. Big Business]

Well, I finally got to the point of have a drivable car! Man, what a beast this thing is! (in a very good way) I'm running a ZZ4 with T56, and a holley 670cfm Street Avenger. (using holley blue pump, if that matters)

Acceleration in 1st and second is amazing, and will really put you back in the seats. I don't have the speedo hooked up yet, so I can't really comment on 0-60 or anything like that, but it felt very quick.

However, when on the freeway, 3rd gear is a dog. It feels pretty gutless around 2500 rpm's or so. When cruising in 3rd or 4th at around 60 MPH (based on traffic around me), it feels like the engine starts to run kind of rough, like it's not getting enough 'something' and doesn't have much power. (at least, not like it does from a start)

Any suggestions on what to tweak first?

 

Thanks,

Henry

[Pyro]

Sounds like it could be an ignition timing issue.

 

Check if the ignition advance is working correctly by using a timing light.

 

Also, make sure your vacuum advance line is on the right carb port. On a chevy, you should use the port that has NO vacuum at idle. This is one of the most common mistakes people do with an old chevy. If you connect the vacuum to the wrong port on the carb the timing will retard instead of advance during acceleration. A ford works in the opposite manner and therefore needs vacuum to the distributor at idle.

 

Then set your timing so you get 40 degrees maximum timing at 5000 rpm.

[Guest Nic-Rebel450CA]

Could be ignition, but I'd say probably mixture. Pick up one of those air-fuel mixture plugs that you put in where the spark plug goes and check your air-fuel mixture to make sure you are not too lean (or too rich). I think you can get them from JC Whitney, as well as most speed shops.

 

BTW, depending on what engine you have, what cam, and what heads, 2500 RPM can be quite gutless. It shouldnt really be that rough though, just wont make much power.

[rustorbust]

Also if your running a zz4 motor they are pretty thirsty. I dont think a 670 is big enough to feed it. It sounds like your running it lean to me. Try timing like other people said and if that doesnt help than try jetting it up a little, you might need to put a 750 or so on it.

James B.

[Guest Mr. Big Business]

Well, the answer turned out to be 'none of the above'. I only figured this out by dumb luck, because my neighbor wanted to look under the hood, even though it was dark out. That was when I noticed that my #1 spark ignition wire was just arcing directly to the block. Turns out the the sparkplug was cracked, so no spark in that cylinder.

I replaced that plug (after special-ordering those oddball AC MR43LTS's) and all of the wires with custom-cut Moroso wires. It runs like a champ now - smooth all the way from idle up to warp speed.