Well went to old town this weekend in orlando and took the turnpike. Well running at 77-80mph on my 93 cummins speedo was really only 68-70mph and a good bit of throttle keeping it around that speed, what's going on?

Also at that speed the egt's were about 850-900, tranny was 150 and boost was 6-8psi.

 

CUMMINS just in case ya didnt know.....


its a common problem on these old dodges to have non working or odd working speedos....

 

Speedo will be off if you have a different size tire than stock... EGT's due to rpm's maybe? 3-speed auto and 80mph (at least the truck thinks so) with stock gearing is a bit high I'd guess.

 

Its got the stock 245's size, its a 3 speed with od.

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My fualt for the spelling tired last night.

 

Yeah at 80 with the 3 speed auto your turnning some RPM. The speedo I don't know. How do you know your running 80? have you had someone pace you to check? I know that with teh stock gov spring my truck would not fun over about 70-75 with my foot on the floor.

 

Well I do have Overdrive. The speedo read 80 and my dad in front of me was doing about 65-68mph. We went to old town in orlando for the weekend this past weekend.

 

I forgot you did have OD

You could just have teh wrong gear in the tranny. I'm not sure which one you should have.

 

The overdrive may still be a little deep on the gearing if you have low (4.10 ish) axle gears with stock size tires. Just a thought.

 

its a stock rear axle and its a 2wd truck.

 

If i remember correctly the end of teh speedo cable that goes into teh tranny has a little plastic gear on it you can swap to make your speedo match different tires and gears. Do you know the history of this truck? Could it have been swapped in the past?