Electric Fan and Speedo Help.

[72MARIO]

Well I got 700 miles on the truck this weekend. I have a few small problems.

The speedo needle bounces. under 60 MPH Why ? Cable or speedo ?

3:73 /700R in 4th and 3000 RPMs - what speed ? I was around 70 MPH is that right ?

My eletrice(sp) fan comes on at 185 off 170. It's a painless kit. The truck runs right on 180. But the fan comes on and never trurns off cause it cant get down to 170. I have a 160 stat. 4 core rad new pump. Should I change the switch to a 195 on 180 off ? Can I get it ? I just dont think the fan should be running whne I am on the highway. I would rather it run at 195 with the fan off. It is a brand new everything. Motor tranny diff. Could it be just a bit tight ? It was also like 34C today.

Any Ideas ?


I think thats all thanks for any help.

[kelsfine69]

I can give my 2cw

Needle bounce is probably cable, pull it out and Clean it, then lube it up.
Next fans. they wont shut off on the highway because the sender is in the engine right? I found one from.... I think Flex-a-lite. the sending wire goes in the rad and you mount the ajustable box next to the rad and wire it up to the fans. That way when your crusin down the highway the rad cools off and the fans shut off. Around town. It keeps my mill at 180

[pjmoreland]

Gear Ratio = Engine RPM x Tire Diameter x .002975 / Speed / Transmission Ratio
Speed = Engine RPM x Tire Diameter x .002975 / Gear Ratio / Transmission Ratio

Speed = 3000 x 29 x .002975 / 3.73 / 0.7

Speed = 99 MPH

Something is not right. Maybe your tach isn't accurate. What's the diameter of your tires? Maybe you weren't really in 4th gear. Was your torque converter clutch engaged? If you were in 3rd gear, then the calculation looks a lot better:


Speed = 3000 x 29 x .002975 / 3.73 / 1

Speed = 69.4 MPH

I have a 700R4 in my truck, and my tachometer reads slightly over 2100 RPM when I'm driving 70 MPH.

[tomatocity]

My eletrice(sp) fan comes on at 185 off 170. It's a painless kit. The truck runs right on 180. But the fan comes on and never trurns off cause it cant get down to 170. I have a 160 stat. 4 core rad new pump. Should I change the switch to a 195 on 180 off ? Can I get it ? I just dont think the fan should be running whne I am on the highway. I would rather it run at 195 with the fan off. It is a brand new everything. Motor tranny diff. Could it be just a bit tight ? It was also like 34C today.

Any Ideas ?

Check with Wes. He has the electric fan stuff nailed.

[69 longhorn]

I run a pair of 14" fans on a homemade shroud, behind a 4 row copper/brass radiator. The fans are said to pull 1350 cfm ea. They are controlled by the same Painless setup you have (on 185/off 170), & the eng has a 160 stat. They cycle off/ on just about right on, & have been keeping my 383 cool in the mid 90's F temps here in Illinois. What size fan, or fans are you using? Also, are they mounted on the front or rear of the radiator? L

[72MARIO]

I have a 16" fan single i think is the size it behind the rad. It kept the truck cool 195 during the 20 minutes at 2000 rpm. 40 C that day. I just think it should be a bit warmer. Mabye I neeed another fan to help out.


Could the 2500 stall I have be the reason the rpms are higher ? I also do not have the lockup hooked up. 28" tall tire.

Thanks for the help.

[jay6891]

Lockup not hooked up. Man hook that thing up before you burn that new tranny. My first 700r4 I didn't hook it up and it lasted about 4 months. Tranny guy said it was because of: 1 heat, and 2 something about these trannys that without the lockup hooked up the pump is what is running the tranny not the direct lockup between engine and converter. Pump goes bad, tranny goes bad, day goes bad. I have had my new one going on 4 years now and STILL hits as had as new.

[72MARIO]

How does your truck launch off the line ? Sounds like a similar setup that i have in the 67. I will hook up the lock up soon just need a toggle switch.

[jay6891]

Launch, what launch. Up in smoke. I can hold it in first gear running about 25 mph. Hammer on it, hold it till 6500ish, second hold it 6500ish, third. Smoke, smoke ,smoke. Pleg leg rearend though, gotta get that posi in there.