97 k1500 5.13 swap and speedometer is all over the place!!!!

[Michaelknight]

BTW my truck has a built 383 with carb and 4l60e if that makes a difference

 

[kennythewelder]

And it worked for the 97 pcm? I just input my tires and ratio?

My truck is a 97. I went from 342s to 373s. So I put that info in and then my tires are 275/60/15, so I also put the height of the tire in, and then I did a Denali cluster with a 120 MPH speedometer swap so I adjusted the tire size to make it read the rite speed. Yes the Jet programmer I have will do all of this and more. Performance tune with 3 settings, transmission shift points and firmness, and you can set top speed limiter and RPM limiter. It also will clear CEL and does a live data sensor read. It is not a huge difference in engine performance but is noticeable. A big difference in tarns shift firmness. The trans shifts much quicker, but not to the point of real hard shifts. A live tune is always most effective, then a mail in tune, then a flash tune programmer. I am happy with my programmer. It is nice to be able to make adjustments any time I want to.

 

[Michaelknight]

Have you seen the people talking about it frying their ecus? How do I avoid that. And with mine being carb the only thing I'd need it for is the speedometer adjustment and trans functions with my 2400rpm stall converter and corvette servo

 

[kennythewelder]

Oh, and yes, the 120 MPH speedo reads correct, and yes I have had it over 110 but havent ran it over 120 yet. Although before I did the swap, and the 373s I had my truck to 5200 RPMs in OD. It was as pegged and took a long time to get back to 100 MPH where it could read the speed. My best guess is somewhere around 140 MPH. My truck was screaming. That was several years ago.

 

[Michaelknight]

So how do I keep from frying ecu? That's all I've been reading is people frying the computer

 

[kennythewelder]

Oh, didn't catch the carb thing till just now. In that case, its a whole different story. I think they make some kind of adaptor for this but I know nothing about it.

 

[Michaelknight]

Well I'm still running stock ecu for my 4l60e and I still have OBD2 so could I use it to adjust speedometer?

 

[kennythewelder]

I think so, but in that case, all you need is the transmission, speedometer reset tool.

 

[Michaelknight]

Ok so that's in that scanner?

 

[df2x4]

IMO get in touch with someone like Black Bear Performance, Nelson Performance, PCM4Less etc. Don't spend money on one of the Jet/Hypertech handheld programmers. A real tune is the same price and you can adjust much more.

Going to a carb setup surely means you've given up on some sensor that is making the stock PCM unhappy in addition to your gear swap.