Speedo Head Question
Thread Starter
Member
Joined: Aug 2001
Posts: 367
Likes: 1
From: San Diego, CA
Car: Firebird
Engine: 383
Transmission: 700R4, lots of Mods
Speedo Head Question
Hell all
I have is a '89 Firebird 305, the transmission and rear end have been calibrated for my stock Speedo which is 120 Mph, if I put in the 140 Speedo will I reading the correct speed? if not what will I have to do to correct it. Or can I just buy the 140 Mph gague overlays and I will be ok? Any information will be greatly appreciated.
Thanks
Brad
I have is a '89 Firebird 305, the transmission and rear end have been calibrated for my stock Speedo which is 120 Mph, if I put in the 140 Speedo will I reading the correct speed? if not what will I have to do to correct it. Or can I just buy the 140 Mph gague overlays and I will be ok? Any information will be greatly appreciated.
Thanks
Brad
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Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
No other changes are necessary to make the 145 mph head work other than swapping the head itself.
Thread Starter
Member
Joined: Aug 2001
Posts: 367
Likes: 1
From: San Diego, CA
Car: Firebird
Engine: 383
Transmission: 700R4, lots of Mods
if I dont replace my 120 MPH speedo head and buy the 140 MPH overlays, will this work? or must I have the 140 MPH speedo installed with the 140 overlays to make everything work good?
Joined: Aug 1999
Posts: 19,282
Likes: 103
From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
As I understand it, speedometers are geared for their specific speed so an overlay with a different 'face' would not read correctly.
JamesC
JamesC
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Joined: Sep 2003
Posts: 6,127
Likes: 11
From: conway, s.c.
Car: 1989 Iroc-Z
Engine: 5.7L TPI
Transmission: 700R4
Originally posted by Apeiron
No other changes are necessary to make the 145 mph head work other than swapping the head itself.
No other changes are necessary to make the 145 mph head work other than swapping the head itself.
So this chart wouldn't apply to making the speedo work accurately? Moderator
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Originally posted by Trickster
So this chart wouldn't apply to making the speedo work accurately?
So this chart wouldn't apply to making the speedo work accurately? Trending Topics
Supreme Member
Joined: Jul 1999
Posts: 1,593
Likes: 3
From: out of my mind; be back in 5 minutes....
Car: 1989 Firebird Formula
Engine: Internal Combustion
Transmission: Completed
Axle/Gears: ones that turn.
The gearing might work if he figured ut the percentage of change needed to read properly.
With the Firebird electric speedo, he'll likely have to swap over the circuit board attached to the head as well.
With the Firebird electric speedo, he'll likely have to swap over the circuit board attached to the head as well.
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