Electronic Tach?

I would like to add a tach to my 'ole gal, but have heard bad things about adding an electronic tach to the distributor. I swapped out my dead 304 for a rebuilt 345 and it came with the gold box electronic ignition so I used it. I know they aren't the most reliable, but it's what I had at the time. I've heard that you can burn out the gold box by adding the tach. They are much less expensive and easier to find than a manual tach for that motor... Anyone had any experience with them? With the whine of the fan it's hard to tell where the rpm's actually are and I don't want to over work the engine, but I do want to maximize it's power range. Thanks in advance!

'71 Loadstar 1700
345 with a 5+2

I'm not sure why would would have a problem installing an electric tach, unless you wired it wrong, They don't "load the circuit" with any kind of load to cause a burn out of the control box.
Another option is a mag pic-up at the flywheel. All diesel trucks used this method for years. There are many options but you need to drill and tap the flywheel houseing (bell housing) 3/4" fine thread. The pick-up "reads" the ring gear teeth and uses that for RPM. The tachs themselves are often calibartable and there are "boxes" for those that aren't, to cablabrate them to the ring gear tooth count.

Thanks! I had heard rumors on some other sites - as well as an 'ole timer mechanic. I figured here was the best place to find out! I think I'm going to go with the electronic since it's easier.

Unrelated question: If I'm grossing 25,000 pounds with a 345, with a 5 speed tranny and a 2 speed rear... Which version of the transmission would you recommend for Loadstar? I pull a lot of hills and I'm trying to decide which gear ratio to go with if I do a tranny swap (see previous post about 3rd gear syncro out and blown front seal). I found a couple of transmissions - in the $300-$400 range and the parts to fix mine are going to be around $750 +labor. The last thing I want to do is heft a 200 pound tranny only to find that it's not the right one for me! Thanks again!

well, before you go buying different transmissons be aware that the often take different bellhouseing as the bolt pattern, clutch and input shaft may be differnt.
As to what trans, it is hard to answer anyway there are so many vairables.
Gradeablity (ability to start a load on a grade)
ratio splits (how much rpm drop between shifts
Rear axle ratio
tire size
load expectiations
grades incountered.
Anyway you cut it, you are going to be crawling up grades with 25K, it will not matter what trans, there just isn't enough power to keep up with traffic on a grade. you just don't want to run out of gears on a grade or end up twistig off a driveshaft or blowing a countershaft out the side of a trans.

If the trans was mated to an SV8 (266,304,345,392) there should be no problem regardless of the model truck it was in. As I posted in the other thread,there is very little difference in the IH 5spds other then 4th gear ratio.

As for the gold box and all the bad things you see about them,hogwash! They were just as good as any other system of the era. Most failures can be attributed to leaving the key in the run position without the engine running. Adding an electronic tach which hook up to the coil shouldn't be a problem.

I often grossed 30,000 pounds hauling grain with my little 304, four speed with two speed Eaton axle. Its true it will take a long time to build up speed and a long grade will slowly and steadily reduce my speed, especially with a head wind. Starting that load rolling In soft ground could be a little scary but on a grade, on solid ground, not a big problem. Not sure of my transmission at this time but I know first gear is plenty low.