Thread: ZZ4 350 stutters on acceleration...cold weather?

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Hey 65cayne, thanks for the reply.

Yikes ...I have to think where my hands were last under the hood, Im always doing something in there...I do remember moving the HEI wire to another location the day before, Ill have to go back and double check to make sure thats ok. I know for sure its getting 12V, I tested the new spot right out of the fusebox with my trusty voltmeter.

Anyway I pulled the plugs and changed them all. They looked a nice tan color except one plug was rather black, but not too bad, and I thought for sure that was the problem (thinking maybe it was carbon fouled). Put in all new plugs, but problem persisted. Perhaps a bad plug wire is to blame? But those are new too...Ill double check for strong spark tomorrow.

Car idles great at 700 rpm, no problem there. Runs great after 2,000 rpm. Also runs fine if I ease slowly into the throttle from idle. But stutters/surges alot if I slam on the gas from idle. This occurs from 700 to about 2000 rpm, then pulls like a scalded ape.

When you say not getting vac advance, what exacly do you mean? I have the vac advance can on the distributor disconnected and plugged as per advice of many posts ive read here about the ZZ4. with it attached I was getting something like 50 degrees total and couldnt get the darn thing to idle right.

Thanks for your input, gives me more to think about. Maybe someone else has more ideas, cant wait to spend my weekend under the hood...again.

Good luck with the holley, it seems to be a good carb.

Originally Posted by 63BoxNova

Hey 65cayne, thanks for the reply.

Yikes ...I have to think where my hands were last under the hood, Im always doing something in there...I do remember moving the HEI wire to another location the day before, Ill have to go back and double check to make sure thats ok. I know for sure its getting 12V, I tested the new spot right out of the fusebox with my trusty voltmeter.

Anyway I pulled the plugs and changed them all. They looked a nice tan color except one plug was rather black, but not too bad, and I thought for sure that was the problem (thinking maybe it was carbon fouled). Put in all new plugs, but problem persisted. Perhaps a bad plug wire is to blame? But those are new too...Ill double check for strong spark tomorrow.

Car idles great at 700 rpm, no problem there. Runs great after 2,000 rpm. Also runs fine if I ease slowly into the throttle from idle. But stutters/surges alot if I slam on the gas from idle. This occurs from 700 to about 2000 rpm, then pulls like a scalded ape.

When you say not getting vac advance, what exacly do you mean? I have the vac advance can on the distributor disconnected and plugged as per advice of many posts ive read here about the ZZ4. with it attached I was getting something like 50 degrees total and couldnt get the darn thing to idle right.

Thanks for your input, gives me more to think about. Maybe someone else has more ideas, cant wait to spend my weekend under the hood...again.

Good luck with the holley, it seems to be a good carb.

An H.E.I. really needs 12 or more volts to operate correctly.

What brand of plug wires are you running an have you messed with the carb?

Originally Posted by 63BoxNova

Hey 65cayne, thanks for the reply.
But stutters/surges ....Good luck with the holley, it seems to be a good carb.

I would look at the carb first. You might want to change the power valve. See what's in it, probably a 6.5 if so, and if it is good ( check by sucking on it, place your tongue on it and see if it lets go or if it holds) go for a 8.5. If it doesn't hold vacuum, replace it with the same one that was in there. When cold weather hits, you need more fuel. Also, does the intake have exhaust travelling through it to warm it?

Originally Posted by TyphoonZR

I would look at the carb first. You might want to change the power valve. See what's in it, probably a 6.5 if so, and if it is good ( check by sucking on it, place your tongue on it and see if it lets go or if it holds) go for a 8.5. If it doesn't hold vacuum, replace it with the same one that was in there. When cold weather hits, you need more fuel. Also, does the intake have exhaust travelling through it to warm it?

He say's the engine idles great.
If it where a blown power valve it would idle up and down.