tach install and question

[jessejames620]

alright so i bought a cheap tach new for my l20b engine and hooked it up

black wire - ground

white - to the light

green - to the negative post on my coil

red - positive source with car on

brand i got was a Super Pro no shift light just basic..

so when i fired her up she smoothed on up to ~600-650rpm(manual T @ idle)

but when i rev'd her up to was seemed red line or near it she barely passed 1500rpm. let her idle, back to 650ish, shut her off, down to zero. didn't know what was up so i went 'n read some forums

there was something that caught my eye it said that a brand that (I DID NOT HAVE)but it said that some tachs are set to v8 from factory and that i might have to set it but the back of the tach was flush ill keep trying but just wondering if that might me it

set for a v8 cuz it makes sense that i was only getting about half readings off of a l4 thanks guys for any info/ideas

jesse

[freaky510]

yes some tachs are for v8 only. look inside?? is their a little switch? it might have 3 spots 4cly 6cly 8cyl

[moparvwfreak]

or like on some lower end autometers you might have to clip a wire to make it work on a 4 cyl.

[hoov100]

theres a counter sunk switch on the back that says 4-6-8.

[jessejames620]

ya for sure there was a switch on the back under the housing swaped it to 4 and works great even changes 7 different colors haha thanks guys