HEI upgrade options - street car 350

[Vettenick]

Adding an MSD can only benefit your vehicle. That being said, you need to go back to basics, because the MSD will not fix your issue. What RPM does this issue occur? What kind of fuel pump set up do you have. If your fuel supply is insufficient, your engine will tend to "float". When the issue occurs, does it seem to slow down, then pick up slightly, and then slow down again? Sort of like a mild bog.

 

[450bench]

Adding an MSD box to a street car with an already good running HEI won't do anything but cost extra money and create something else to go wrong.
Stock HEIs not revving past 4-4500 rpm is just plain bs.
I'd wager the op's issue isn't even the ignition. Timing? Maybe but probably not the distributor.

 

[G72Zed]

I guess it depends what a person views as a "street car", and what they are after, and there are advantages in certain cases, results vary greatly in this area.

It's not really a question of the HEI revving as much as it is loosing the "umph" past a certain rpm point in stock trim.

And your correct, it may in fact be a valve train issue, or timing combined perhaps with fuel delivery as i pointed out earlier.