I'm new to the board so excuse my lack of knowledge but i recently bought a 91 RS with an auto tran. I think it's a 700r4 but not postive. My problem is that if I am sitting at a sstop and i gun the gas pedal down to full throttle, or even 3/4, the rpms will launch up into redline almost instantly and then continue on past 7000 rpm. I let it finally hit what would be about 8000 rpms if the tach didn't end at 7000...

I highly doubt that my tach is reading correctly because I don't think my 305 TBI can handle 8000 rpm.... a little too high. I don't tend to drive it that heavily but even in normal driving it tends to shift at about 5500-6000 rpm from first to second and second to third. I find myself normally driving in redline but i don't htink having my heavy foot helps that either. Still, i have no really ability to take off on the line unless I romp off the gas, let it get up to about 6500-7000 rpm, drop off for a instant then romp on it again, forcing it over 7000 then into second. That just doesn't seem to healthy for the engine.

The only real option I could think of would be to change the tranny fluid but I am just wondering whehter anyone has any suggestions or is in the same boat as I am.

do you think that the tach might be off a little? i think you would know how high 8000 RPM would be screaming.....furthermore I can't see this engine taking 7000RPM shifts to well, or the fact that this car wouldn't pull above 4500RPM very well either. Check the tach first.

I agree. A 305 at 8,000 would explode in about a milisecond. This engine is good to about 5,000 max. Beyond that the valves will float and it would drop a valve and destroy the engine in short order. I would check to see if your tach is working correctly.

If there is indead a problem in the trans it most likely lies with the 3/4 clutch pack, which often burns up and causes the trans to not want to shift from 2nd to 3rd. If this is the case changing the fluid won't help, in fact nothing will short of a full rebuild.

How many miles are on the car?

BTW, you defiantely have a 700R4, it was all that was available in '91.

The car jsut rolled over 90,000 miles. I Kinda guessed my tach was off but wasn't sure. I've taken out my guages before to replace a light and looking at it, i couldn't see a way to check the tach. Also, my car idles at 1500 once warmed up but another odd thing is when i start in the morning it'll be at around 3000-3500 rpm and will be at those rpms in park and neutral but in reverse or drive it drops to about 2000-2500. I'm noy sure if this is normal or if it's the engine/tran.

How would I end up checking if my tach is reading wrong?

Take your car to any place that does tune-ups, and check your "trim package" against an instrument.

I wouldn't get too excited about what the trans appears to be doing in relation to that thing in your dash that sort of looks a little like a tachometer, until I knew for sure what the actual engine RPMs are.

Hooking up an aftermarket tach would be the best way. Also, some digital mutimeters have a tach function that would allow you to test it. All you need is 12volt+, ground, and a wire to the negative coil terminal, or the tach output on an HEI.

My friend's in school to be a mechanic so he's bringing over one of his tools to test out the rpms. we're gonna see how wrong the tach is. I'm hoping my idle isn't the 1500 that the tach tells me it is.... plus, i was listening to the engine earlier today and by the sound of it i wouldn't say it gets much higher than 5000 if i romp on it. i guess when you have the music playing and the tach suddenly jumps up to 8000 rpm, you kinda make up the sound of the engine and think it's gonna explode.

Mystery solved, using his meter, we determined that i idle at 600 rpm and when in park, the highest he could get the rpms was 3600, but on the tach that was banking in the black past 7000. So now comes the time to pick a aftermarket tach and install it.

I'll plug Autometer stuff all day long. They are the finest gauges I've eve used. They have a ton of tachs too. You can get a shift light or non-shift light model, as well as a myriad of sizes and finishes.

I love running my car hard and having that bright amber light zap me in the eye when it's time to powershift. It's awesome!

there is a AC delco Place in North Carolina, before I got my digital dash, I sent them my dash with a note saying that the tach and the speedo was out of wack... Reading too high on tach and reading nothing on speedo, I left my number and addy on the package then a few days latter I got a call and they asked me what type of engine did I have, then they went ahead and resetted the tach and speedo to match to my 3.1 and sent it back... cost------125bucks after shipping and handling

if you want I can give you there number and address, it's in Charlotte

I was looking around at the autometer tach and was wondering if the bases on them are stationary so you have to mount them on top of something or can i turn the base so that it attaches to something on the left of the guage. I wanted to attach it to the dash beside the lighter/defroster but didn't want to get into drilling up under the vents. Could i turn the base on the autometer (or any other suggested company) tachs to mount there?

The Autometere tachs won't swivel like that. It would be easy enough to make it work though. Just get a small piece of 1/8" thick aluminum or steel and machine a set of holes to mount the tach, and countersink them into the bottom of the plate. The use countersunk head screws and nuts to mount the tach bracket to the plate. The orient the plate the way to want it and drill mounting holes for the plate. By changing the angle of the holes for the tach you will be able to position it where you want, while still mounting it where you want.

So your tach is reading roughly double what it's supposed to? My old beater did that, too, I just got used to it and divided the gage reading in half whenever I looked at it...

If you want a low buck solution, just go to ebay and buy another stock 91 RS tach for probably 10 to 20 bucks. If you want to spend the money though, just leave the factory tach to its own devices and install the auto meter tach.

I just did a search on Ebay and found 3 on there, i didn't even think to look b/c i thought it would be next to impossible to find one. *** bless Ebay. The only question i have with buying another cluster is how would i increase the mileage so that it reads what i have on my car now? i wouldn't think it would be too easy b/c it would be too tempting for people to turn back their mileage.

You can always just swap the new tach into your existing cluster. However, you can fix the mileage on the new speedo. You can remove the number spool from the speedo, and with a little patience, you can get the numbers all rotated around to the right mileage. I've done it a couple of times on my 89 cluster. I switched from a 115 to a 145 mph speedo and wanted the mileage to be the same. If your existing speedo is the same as the new one, and still works right, I'd just put the new tach into your old cluster though. That's the easiest thing to do.

the onyl problem with my cluster is that both the tach and the speedo aren't right, the speedo won't read until i have stopped and started three or four times one i start the car up in the morning. i'm also a little worried about the fuel guage, but i hear they aren't worth anything as it is.