5abivt

I have had a few tachs and the first one was off by a few hundred rpm. a different one cured it. Did you try just plugging in the new tach to see if it was still off?

I didnt know there was a difference between the l98/Lt1 tachs

Kubs

Cool Thread! Good job!

Which tachs have the 7K mark on them? Are they just ZR1s, and do they plug in just the same way?

aklim

Will a 94 one work? I got a lead on one but the seller said it was 94-96

janarvae

Well, if you have a '90 or '91, you may want to stay within the color scheme of your year. The '92 and '93 LT1 instrument clusters and AC/stereo buttons still had the orange lettering. In '94, the lettering and gauges started using white lettering. I imagine a '94 would be plug and play too. The color difference was what made me choose a '92/'93 cluster.

janarvae

I knew that the old tach was WAY off because I connected my laptop to the car and saw the actual idle, as seen by the ECM. I didn't think to test it before installing it, but it would have been 10 minutes to take it back out with the new found experience I gained. I would much rather mess with the interior after working for close to 7 months on the engine and transmission!

There is a difference between the L98 and LT1 tachs! Check out the pictures above. The L98 was a lower revving engine than the LT1. So the LT1 hits the hash/redline marks at 5500, instead of the L98's 5000. The gauges also have more ticks or deviations, making them MUCH easier to read. Additionally, the LCD in the L98 displays the MPH on the bottom and fuel level on the top. The LT1 LCD displays the MPH on the TOP and the fuel on the bottom.

I know for sure the '91 ZR-1 has an 8,000 RPM tachometer. Someone in this thread said they just installed a ZR-1 tach in theirs.

Dale1990

I can't speak to all year combos but the 90 L98 and 90 ZR1 gauge clusters are plug&play compatible.

Besides the ZR1s, the LT4 also had an 8k tach, I believe.

I did have to swap LCDs in mine as the ZR1 cluster I bought from a forum member had a bad LCD (I knew this when I bought it). The LCD from my L98 panel plugged right in and worked perfectly.

aklim

How did you make sure the tach is reading right?

Kubs

Thanks! I am building a SB 408 on the side and it should have a redline of around 6,500 RPM but I want the interior to look stock and not have aftermarket gauges. I dont think it would look right.

aklim

http://cgi.ebay.com/ebaymotors/ws/eB...3AIT&viewitem=

2 more to go if you don't care about the color scheme.

aklim

How would you test it?

engle1147

http://www.apogeekits.com/tachometer.htm

aklim

I have a snap on timing light that has the engine speed light. That means you have to hook it up to test it, right? You can't bench test it can you?

RandyJ75

I have a question. You said that you cleaned all of the contacts in the dash and on the new cluster. Do you think that this fact alone could be the reason that the new cluster is working correctly? That cleaning the old clusters contacts and reinstalling it would bring the same results?

Randy

janarvae

All I cleaned were the bulb contacts. I doubt it helped anything except for my mild OCD. I think the problems with the old clusters lie in the resistors and capacitors going bad. At least that is what the fix is for other GM clusters of that era.

-Jonathan

janarvae

I don't know how to bench test it. I tested it after it was in the car. It would not take much time to remove it if it didn't work as planned.

janarvae

If I were you, I'd PM Ramrod92 and inquire about his '92 cluster for sale...Member WVZR-1 also has one disassembled for sale.

aklim

It would help if I didn't get a woody when I saw the cluster for $99.99 and bought it on ebay. IT is on the way here so I have to make it work as much as possible.

aklim

Anyone know how to bench test a cluster?

aklim

Got the thing today. Well, some of the warning lights like the Door Ajar is not in the right spot. For instance, the Door Ajar on the 91 is on the extreme right. On the 94, it is brake pressure. Guess I will have to sell it or trade it towards a fix.

janarvae

Are you saying you believe when the door is ajar, the brake pressure light will come on? Because between the '92 and '91, there were some lights switched around, but it has no effect on their function. The lights are all wired in correctly - the circuit board just translates the computer signal differently.

Now, if this is the excuse you need to get an orange one, then, right on!