Alan, about all you can do is pull it out and look. I know my repro tictoc has a pot, though I never needed to turn it. Steve (farm boy) put a post up a while back when he adjusted his, but I think his car is a 67.
Tachman sounds like he knows what he is doing, but with just 2 posts, both here in this thread, we don't know him yet.
For sure, don't go near that thing with a metal screwdriver. Electronics won't work if you let the smoke out.
correct, all the repops have a pot to adjust. the repro pcb is used on camaro, chevelle, etc. i have a ton of them in here (can't repair). what happens is the zener diode goes on them and it takes out the intergrated circuit (IC). since taiwan or mexico used generic parts, there are no part numbers on the chip to find a replacement. so the solution is to buy another repop! has any one seen classic industries 1970 ls-6, l-78 chevelle repro tach. the yellow line is wrong. yellow shoud go from 5700-6500 and red 6500-7000. same as the L-78 1970 camaro. heres the story about the big block square port heads and the history
1. 1969 back, hipo's used a 6000-7000 redline and yellow from 5700-6000. why? the valves on the heads had 1 spring a 1 dampner.
2. 1970 and some 71's had the yellow from 5700-6500 and the redline from 6500-7000. why? valves had "2" springs and a dampner, raising the reline to 6500 rpm. viva: less valve dropping when busting the torque on the rat motor.
this, of course, applies to the 7000 rpm tachometers. different story on the late 69 and 1970-72 z-28 tachometers. hope this helps.
many say there were no 1971 ls-6 cars made, but not true. they were 454-425 hp, but about 60 were made. any body have the facts on this one?