Need advice/help with new Tachs that don't work with Thunderbolt Ignitions

Tin Pangas

Skipper
Aug 28, 2010
322
646
Norwalk, Ca U.S.A.
Name
Kevin
Boat
37 Tollycraft
I made the mistake of letting a so called marine electrician replace all of the guages on the flybridge. He can't gewt the new tachs to work and says it's cause the Thunderbolt ignitions take a special tach that is no longer made. He wants me to get new alternators so he can hook the new tachs up to them. There is nothing wrong with my alternators. I'm at my wits end.
I would like to find someone willing and able to do the job. Any advise is greatly appreciated.
 

bman440440

I am the one who knocks!!!
Sep 8, 2010
2,784
1,228
San Diego 92117
Name
B-MAN
Boat
Heisenberg(20' Maxum), Sip N' Slide (33' 2 deck w/slide) Ships & Giggles (32' double deck pontoon)
if he is trying to get you to do that he is trying for more $$ out of you... just hook the tack up to the negative on the coil and your good to go!
 

Tin Pangas

Skipper
Aug 28, 2010
322
646
Norwalk, Ca U.S.A.
Name
Kevin
Boat
37 Tollycraft
i saw that forum response and many replies of hook it up to negative on the coil. Problem is...my Thunderbolt coil is encapsulated in a switchbox (# 332-2986A22) and I just spent the day with Marine Electrician #2 and still couldn't get modern tachs to work. I can hook the ancient 'Thunderbolt tach' back up that reads inaccurately, but reads something where any modern tach just simply doesn't read. Should I just resign myself to buying new alts and hooking the new tachs to them?
I know that my fix is probably similar to the outboard fix of hook it up to the neg on coil but my inboard 454s have that switchbox. Any help here is tremendously appreciated. I would owe somebody bigtime if they could help me with this one!
 

kindafishy

I've posted enough I should edit this section
Jul 21, 2010
4,286
2,018
hemet/ca/riverside
Name
SCOTT
Boat
bayliner cierra express 2452 "RYLEE'S WAVE RYDER"
what thunderbolt do you have, year & hp. inboard/ outboard
 

kindafishy

I've posted enough I should edit this section
Jul 21, 2010
4,286
2,018
hemet/ca/riverside
Name
SCOTT
Boat
bayliner cierra express 2452 "RYLEE'S WAVE RYDER"

bman440440

I am the one who knocks!!!
Sep 8, 2010
2,784
1,228
San Diego 92117
Name
B-MAN
Boat
Heisenberg(20' Maxum), Sip N' Slide (33' 2 deck w/slide) Ships & Giggles (32' double deck pontoon)
you still have a coil on your motor don't you?? the negative lead on that is what you hook your tack to.
 

kindafishy

I've posted enough I should edit this section
Jul 21, 2010
4,286
2,018
hemet/ca/riverside
Name
SCOTT
Boat
bayliner cierra express 2452 "RYLEE'S WAVE RYDER"
or go full on redneck and use a timing light to provide signal to the tach.