zz4 tuning battle update

[mikeorwan]

As many of you are aware its been a real battle getting my zz4 "385 fastburn" running well. A few weeks back I got help with carb tuning and that made a very significant difference. However the bottom end performance up to 3800 rpm or so still really sucked.
The past week or so have been strongly suspecting timing/timing curve issues as I read about similar issues by mining the web and here.

Today I installed a complete MSD ignition system- 6AL, coil and dizzy. Locked out the dizzy and set timing to 38* @ 2500 rpm. Boy did it make a difference!! She's like a new motor from idle to 4000 rpm:yes: :D.

Finally I'm starting to feel I got the motor I paid GM for. Think she's ready for the track now and final tuning efforts there...hopefully soon!!

[ALLT4]

Wonder what was wrong with the old dizzy that the several shops you had it at couldn't find. In any case it's good to hear you've finally solved it, oh the joys of Hot Rodding.

Yeah, now you can finally start dialing it in knowing everything is pie R square.

[Jeremy77nova]

It's good to hear your on track again. MSD makes so great Ignition products.

[Lgian]

I also struggled with a low end /snap accelleration stumble when I first installed my sons 385 fastburn. I was able to get rid of nearly all of the stumble with a larger squirter (38) and a different pump cam. I suspect the HEI is still holding the car back. I have had performance problems with HEI ignitions in the past, one in particular I remember would start to retard the timming after 4500 rpm. We had it in and out of the distributor machine a dozen times and even changed the module before I gave up and went with a dual point back in the day. I am not ready to throw in the towel yet on this one but I could use a little fire wall clearance anyway.

[mikeorwan]

As I searched and read it seems tuning troubles with the fastburn version of the zz4 are common, much more common than the 355 horse version without the fastburn heads. Go figure...:turn: