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Topic: Changed LT1 6000 to LT4 8,000 RPM Tach

in Forum: C4 Electrical

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Changed LT1 6000 to LT4 8,000 RPM Tach (1/5)
3/4/14 9:36pm

396c4
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Joined: 12/7/2011
Posts: 219

I bought an LT4 cluster awhile back and finally got to changing the tach for the 6K that mine came with. In order to get at it, you have to remove the knee bolster and cover and drop the steering column to make room to remove the cluster held by 6 plastic screws with torx heads. I was expecting a plug but the cluster plugs right into the receiver. You can see white cross extensions on the back of the cluster housing that align the install via the holes in the receiver (in the pictures, one just above the receiver plug and one off to the right). Pops out quit easily.

Next remove the screws holding the clear plastic cover (mine had a lot more scratches than I had seen while in place but I had a new replacement anyway.) Next remove the orange LED display from the little red plug at the top, then the two screws that actually hold the tach to the cluster. It pulls up with little force, held only by the 3 contact posts in spring contacts.

Incidentaly, I wore rubber gloves to keep from finger marking it, brushed everything dust free and replaced the cover. You can see from the back shot what's required to replace the bulbs which are quarter twist once the back cover is removed. (LED's would be nice but another day.) Slipped back in so easily I was concerned the plugs hadn't meshed but turning on the key showed all was well.

Finished the replacing the other stuff to finish in about 1-1/2 hours. Seems like there are a lot more numbers now.

|UPDATED|3/4/2014 6:36:36 PM (AZT)|/UPDATED|

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Re: Changed to LT1 to LT4 8,000 RPM Tach (2/5)
12/4/13 8:56pm

cco
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Joined: 8/16/2013
Posts: 191

Trying to catch up on the forum here, but the new tach registers above 6k now but will your mods allow the engine to go higher, or was the change for aesthetics?
I too like the 8k tach but not sure I want to dismantle the dash to that extent to change it out.

C.

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Re: Changed to LT1 to LT4 8,000 RPM Tach (3/5)
12/4/13 10:07pm

396c4
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Joined: 12/7/2011
Posts: 219

I've done a "little" to get above OEM redline, most notably aluminum roller rockers, higher rev'g Comp Cams hydraulic roller lifters and LT-4 hot cam but I'm not pushing past 6200 until the new heads with bigger valve springs and titanium retainers are in place. Comp Cams told me the high rev lifters should be good for 600 to 800 RPM so I'm looking to 6500 as a practical limit. Still well above the old tach limits. Would like to get the Lunati hydraulic lifters but they are too pricey for the street.

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Re: Changed to LT1 to LT4 8,000 RPM Tach (4/5)
3/4/14 10:51pm

cco
Former Member
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Joined: 8/16/2013
Posts: 191

396c4 said: I've done a "little" to get above OEM redline, most notably aluminum roller rockers, higher rev'g Comp Cams hydraulic roller lifters and LT-4 hot cam but I'm not pushing past 6200 until the new heads with bigger valve springs and titanium retainers are in place. Comp Cams told me the high rev lifters should be good for 600 to 800 RPM so I'm looking to 6500 as a practical limit. Still well above the old tach limits. Would like to get the Lunati hydraulic lifters but they are too pricey for the street.

LOL, yeah now I've read up on your ride I can see the need for the LT-4 tach...Nice neat job.

BTW - where did you score the new tach?

Again, nice job -- that would take me longer but I believe I could git 'er done.

C.

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Re: Changed LT1 6000 to LT4 8,000 RPM Tach (5/5)
3/6/14 9:30am

396c4
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Joined: 12/7/2011
Posts: 219

I found my tach on Ebay put up by http://www.20thstreetauto.com/ They occacionally have more. Also, you will likely purchase the whole instrument cluster so you could just swap clusters although I'm not sure where the odometer reading gets stored. I decided to swap tachs and now I have some spare gauges.

Don't worry that the tach needle will flop all over when you tilt it, ie it's not spring loaded (which worried me that it was broken). It's not and works perfectly.

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