went out today and re calibrated my speed o ( i did it twice ) and now with me at 3.70 rear gear ( stock , 4 door with 235 3speed on column original )
with a 27" tall tire ( 225/50/18 )
mph 60 70
rpm 2000 2400
by what i can tell .
does this seem right ? if you do it backwards it dont add up i think something is still off ??
i used that , thats how i know i was off .. how do i fix this , i had it on a dyno before i did anything i figured i was off about 5 MPH , now i dont know how much
Either your tach is wrong or your speedo is wrong.
If it's the speedo and the odometer is still working, drive a known measured mile and see how far off your odometer is and adjust your speedometer accordingly. Or use a gps to measure your speed against your speedometer indication.
i did use the speed-0 to measure 1 mile ( mile marker ) and it was real close driving at 60 mph so its gotta be the tach its one of those you can set for 4cyl 6 cyl of 8 cyl ,, its on 4 now its shows be idling at 600 i thought that was close ??.. i have a tom tom i can use ?
with mine being a 5.3 ( no distributor ) 8 cyl , i do have a wire coming form ecm what setting should it be ??
here is what i got from instructions
If your vehicle’s DIS ignition system has a tachometer output lead set the switch to the 4 Cylinder position for the 4 cylinder engines and to the 6 Cylinder position for the 6 cylinder engines. When connecting tachometer wires (see ELECTRICAL CONNECTIONS), connect the tachometer GREEN wire to the vehicle’s tachometer output lead.
thats what i always had , that stuff was in the car when i got it ,, its got a
3.73 rear gear
27 in tire
over drive is .7 i believe on a 4L60e
sorry about i had ( ) around that info
Here is what I use. Gear Ratio Calculator
No pretty pictures just proven math. You can easily see how different transmissions, tire change, or gear changes will influence your engine rpm.
At 70mph you should be at 2268rpm.
At 60mph you should be at 1944rpm.
yeah thats wht i got too , my tach is hard to read that fine of numbers ,,i have found a 3;55 with posi that i am looking at , i know it wont change much but i mainly want the posi
thanks
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Hot Rod Forum
2.2M posts
175.6K members
Since 2001
A forum community dedicated to hot rod owners and enthusiasts. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!