Have a couple of questions

[pokertramp]

1. I thought my speedometer was off so going down the highway today I kept it at 60 MPH and even went a little slower during the run. I went from mile marker to mile marker and I got 41 seconds, 43 seconds and 42 seconds on the stopwatch. How do I figure how far off my speedometer is?

2. I plan on putting a different rear in my car, it has a 350 engine I want to go with bigger gears but I still want to be able to go down the highway. Should I swap out the th-350 3 speed and put in a 4 speed transmission? Any recommendations?

3. When sitting in Boston traffic in the hot weather my temp goes up to about 240 degrees but once I get going again it quickly cools down to about 175 degrees. Should I swap out the single fan and put in a twin fan? I think it's a 4 row radiator was in the car when I got it.


I want to use the car as a daily driver and be on the highway to take it to the track when I feel like so if anyone can give some opinions on what combo I should go with, it would be appreciated. I run about 14.5 et at 100 mph, estimated, right now in the quarter mile it could be quicker or slower. It has the stock 7.5 with what I am guessing 273's. I was thinking 355's with a 700r4 trans. Am I close and will this help?

 

[megaladon6]

1) i use the odometer and mile markers. reset your trip at the marker and record what it reads at each mile. i prefer to do this for 5 miles if possible. or you could borrow a GPS and set it to display speed.
2)4-spd overdrives are great, especially if you're on the highway.
3)i'm assuming an electric fan? first, double check what kind of radiator you have. then see if the fan has 2 speeds, you may only be using low.
i prefer the 200r4 to the 700r4 due to the smaller drop from 1st-2nd and the better overdrive. either way 3.5's will be a nice aggressive gear with the RPM's around 2500 on the highway

 

[pokertramp]

1) i use the odometer and mile markers. reset your trip at the marker and record what it reads at each mile. i prefer to do this for 5 miles if possible. or you could borrow a GPS and set it to display speed.
2)4-spd overdrives are great, especially if you're on the highway.
3)i'm assuming an electric fan? first, double check what kind of radiator you have. then see if the fan has 2 speeds, you may only be using low.
i prefer the 200r4 to the 700r4 due to the smaller drop from 1st-2nd and the better overdrive. either way 3.5's will be a nice aggressive gear with the RPM's around 2500 on the highway

Thanks a lot. Yes it is an electric fan, looks like a cheep one the guy put in.
I will put a twin fan in at some point.

Where is the best place to get the transmission? I see new ones for about $1500+. is it a 200 r4 or 4r or do people go by both?

As for rear gears, I could probably go higher too if that's the case with the overdrive. Also should I build up the 7.5 or is it cheaper to get a better rear end say from a junkyard?


What cross member should I use? right now there is one welded in but it has to go, I don't like it. Is it the same as the TH-350 mount?

thanks again.

 

[dan2286]

If you are planning on running dual exhaust eventually go with the G-Force crossmember. Factory crossmembers will not work with duals unless modified.

 

[pokertramp]

If you are planning on running dual exhaust eventually go with the G-Force crossmember. Factory crossmembers will not work with duals unless modified.

Thank, I already got dual exhaust but the guy I got the car from welded in a cross member, made from square tubing. That means if I need to take out the transmission, I need to cut the bar out. I think he put it in too high so I want the whole car to be right before I take it to the track.

 

[midwestls]

200 4r I believe is right. 200r4 is just what we call it. Same thing, just easier to say. I know that my 200r4 has the same crossmember as the short tail turbo 400, as far as the 350 or the 700 I can't really say. Guy's? I'm pretty sure either way you'll need a different crossmember. Try http://www.crossmembers.com/g-body.htm there you'll get more specific application info on what interchanges with what.