I have a 91 RS. It was a 305 TPI. (I am old school. My last Camaro was a vintage 67 with a 302. All stock.) I installed a stroked 383 in my the 91. Why? because I can work on it. These newer motors, fuel injection are way to advanced for my old school brain. LOL. Anyway, stock heads, moderate cam, Holley 750. I am running a Summit HEI Distributor. Wires are new and plugs are in good shape. She runs low 12s. When I accelerate hard, she misses just a little. As if she is breaking up a bit and I know that is costing me power. This happens during street driving where I get on it a bit. I also notice that this happens more on cold days where she runs under 180 degrees. Also she backfired two times when I passed 5,100 at the track. Don't worry, I know better than to run her with that happening. She is off the track until I solve this.

I think I have two problems:

First: I think my distributor isn't up to the job. It's a $159 Summit HEI, nothing fancy. It is relatively new, but I'm wondering if stiffer advance springs are in order or if an MSD will help solve the lower RPM problem by controlling timing advance better. On the other hand it may not be timing advance at all. It's very suttle and most people wouldn't even notice it. She idles real nice and I recently adjusted my valve lashes so I know that's good. I'm open to ideas!

Second: I'm pretty sure I am floating my valves past 5,100. That I understand how to solve. Either new performance heads or stiffer springs.

Now here's why I think it may be ignition related. Back when I had my 67 RS (way back in 1970. I told you I am old school) that car did exactly the same thing. That car had a stock distributor with stock points and springs. A dual point would have solved that back then as I think I was floating the points.

Well, thats my dilemma. Any ideas?
Thanks
Dave

 

Floating valves has to do with your cam and duration too, not just springs. What cam do you have? I think Comp (crane maybe) tells you when the valves will start to float with different specific cams, so you may wanna look up the grind number.