Coming home tonight I pulled onto the road which my subdivision is off of, and i see nothing but darkness, not a single car around. I figure what the hell, and decide how fast I could get my car up to.... kept the pedal on the floor and got it up to 140 before I let off as I was coming upon a bridge. Anyways, my question is what should my top speed be? I have a 350 TPI w/ 700-R4 and 3.73 rear....im assuming the speed limiter, if there was one, was disabled already. Btw im running 16x10 wheels w/ (i believe) 245/50/16 BFG Comp T/A's.
Thanks

 

Was the tranny still actually in OD or did it kickdown. I don't see anyone way of you goin 140mph with 3:73s and tpi.

Oh yeah, please be sure to be safe, a few members just passed recently from excessive speeds, I'd hate to see you as a sticky post too.

 

think it mighta kicked down... really didn't notice the tach at all, but i *think* it was getting up there - - i was more focused on the road...and i am definitely done for a while - - hell of a rush, but scary as fawk w/ everything whizzing by that quickly

and just out of curiosity, any way to get the tranny to stay in OD?? And KJ, im too tired right now to search for it...so

 

Got a ? for ya... Those gears aren't original, so did you ever change the speedo gear? If not , you weren't doin 140mph, prolly more like 110, which sounds a little more reasonable with 3:73s.


they do make a valve to stay in OD, get the police one, I hear it's better than the B&M one.

 

If you were in third gear with 3.73 gears you would have been turning over 6000 rpm at 140mph

 

I calculate 6850rpm in 3rd gear to do 140. Where did you come up with 140mph anyway? 3.73's aren't stock--your speedo could be way off. 16x8 wheels are stock. I've had mine to around 4600+(I try to watch the road) in overdrive--2/3 throttle an few times. 3.73's with 245/45 16's. She tops out in drive at around 110mph(5500rpm).

 

I did not put the 3.73 in so I cannot say for sure if the speedo was recalibrated...however, the previous owner who did all the modification either did it himself or had it professionally done - - even so, i still can't say for sure if he had it recalibrated at all..going to have to email him and ask him. Then again with those RPMs you guys are saying, it seems very doubtful that it was recalibrated.

One more question... i remember reading that if a speedo wasn't recalibrated it wouldnt be off by X mph, but rather X%...anybody happen to know the number??

LOL, either way, 110 or 140 is still fawking fast and scary as hell

*edit* .... just curious, what would 140 mph be in 4th gear?? Perhaps a kickdown valve was installed already.

 

Just got this back from the previous owner...

Yes. It matches up. We didn't do the work (the car came to us with a 3.73 rear gear), but we checked on the highway (you know the trick - drive at an indicated 60 miles per hour between mile marker signs on the highway - it should take 60 seconds), and it matched up.

Al

I'll try and get out and test it myself one of these days but do a series of different speeds (50, 60, 70, 80) then do the calculations to see if it is correct - - then again I trust what Al says.... anyways, i'm thinking there is a kickdown valve in it already... LOL, I guess next time I do it (won't be for a LOOONG time), I'll have to pay attention to see what gear it's in and at what RPM.

 

Sorry to say, but that guy i dont' know man. You can do 70mph in 3rd gear and you should be around 3730 rpms, depending on the height of your tire, there is a calc on the home page. But, I don't konw of any aftermarket valves that allow WOT in OD.

Yes the speedo is off a %, I was just estimating the mph.

I know I never changed the speedo, and at 55mph , mine says 70mph.
Also, this affects your odometer too, btw.

 

just use this, see if it matches up.

http://www.f-body.org/gears/

 

just used that calculator (thanks for the link) and it says 140 in 4th gear is right around 4800 RPM. Like I said before, I didnt see exactly what the RPMs were, but I remember seeing the needle right around that area on the tach. I'll go out one of these days and verify it at other speeds just to be sure

 

If you know someone that has a handheld GPS see if you can borrow it and check your speed that way. It should be fairly accurate if you keep it at a steady speed for awhile.

 

why dont u just go to a drag strip and run it, when u get near the end of the track look at your speedo and rpms then compare it to your slip and see if your speedo's off..

 

well i was out tonite and made a mental note of my speed and RPM in different gears, and everything matched up perfectly to the calculator...so it seems everything points to a correctly calibrated speedo.

And as far as the track, i'm planning on getting out there one of these weekends when I have some time, and after i stop my engine from burning oil.