almost stock L03 i installed a sunpro tach. factory tach is a piece of crap over-reporting RPMS. there is a switch located on the back of the tach for a 4, 6, or 8 cylinder selection. when the switch is set at 8 cylinder it seems like its under-reporting. it shifts around 4-4500 RPM. is this about the RPM it shifts normally? if i set it at 6 cylinder selection it shifts around 5-5500 RPM. which is proper. it seems like the switch should be set for 8 cylinder, since i have a 305 which is a v8. it just doesnt seem accurate that it shifts at 4-4500 rpm at full throttle.

4500 RPM shift WOT sounds right for a stock LO3.

ok thanks. that just sounds so weak. 4500 rpm? ha my s10 blazer with a 4.3 CPI revs higher than that. what makes the difference between a small block with a 4500 red line vs a small block with a red line of 5 or 6000 rpm? is it all in the cam, valves, and heads? i think the L03 is a great engine from a reliablity and longevity standpoint, but from a performance standpoint it is a real piece of junk. people really start to believe that it revs much higher than it actually does with that terrible factory tach. were those tachs that bad when they were new? my factory tach would rev as high a 6000 RPM and i knew that engine would never ever rev that high stock. that engine really runs out of ideas after 4,000 rpms, not joking. i disconnected my factory tach. now it stays at 0, and it can stay that way, i much perfer that $30 sunpro tach, at least its accurate. how high can a built L03 pull?

Naw, the tach have a capacitor in them that degrades and causes them to read high. You can replace the capacitor, if you want.

Man, you really nailed it with your statement on the L03 motor! From a reliability/durability standpoint, it's the best running sbc I've ever owned. But when it comes to performance, there is none. Lol. There's really not much you can do to improve that either. The heads have terrible flow capability, even ported, and the ecm/prom setup really slaps the handcuffs on any mods. A lot of guys will argue otherwise, but I've done lots of reading on the TBI forum, and even the veterans on that board play hell trying to get the computer system to agree with more radical cams, better flowing heads, etc. With that in mind, I'm swapping mine to a TPI motor. The only thing that worries me is that it's my daily driver, and I just hope it'll be half as reliable as the old L03!