Cooling Fan install

[bstandley1]

After a harrowing overheating episode on I-5 two weeks ago (stuck in a construction zone with no shoulder to pull off), I sprung for the 16" Spal puller fan that's 2.05" deep from the Fanman ($64 w/ free shipping). I've scoured the archives for installation tips and am in the process of fabricating some mounting brackets. Several of you guys recommended connecting the wiring to the existing pusher fans and increasing the amperage to 20 Amps which I'm planning on doing ..

Do have one question; does the factory wiring from Unique include a relay in the existing set up? I was crawling around under the dash, but with my extremely limited grasp of wiring, couldn't figure it out. Appreciate any insight.

Bob

[pgermond]

I wired mine right into the pushers (just spliced a hot lead into the harness where the pushers connect - same switch activates both). The only thing I did was upgrade the fuse to 20A, because the SPAL draws a lot of amperage. No relay or solenoid - works great and keeps everything cool.

Phil

427 Roadster, #4279436
Southern Automotive FE
3:31 and Toploader

Roseville (N.Cal)

[bstandley1]

I fabricated the brackets and installed the fan this afternoon. Tomorrow I'll tap into the pusher fans wiring and pop in a 20 amp fuse. Thanks for the input.

Bob

[pgermond]

Meant to include this in my prior post - http://www.uniquecobra.com/topic.asp?TOPIC_ID=489&SearchTerms=spal

Phil

427 Roadster, #4279436
Southern Automotive FE
3:31 and Toploader

Roseville (N.Cal)

[homer]

I have the same fan and wired it directly to the ignition switch -- the spal is always on and I use the pushers in stop and go traffic -- works great

[clayfoushee]

I copied Phil G. on the SPAL wiring, and have had no problems, and zero cooling issues.

Clay

'98 Unique #9299, 427FE side oiler (452.1-stroker), top-loader (close), 3.31 rear

Annapolis, MD

[bstandley1]

Thanks guys,

I just returned from the hardware store with 20 Amp fuses and a package of tap splice connectors ... should be operational within the hour.

Bob

[Jim Harding]

If I were doing this job, there are two things I would like to know first.....

1. What is the present wire gauge that is going to supply the 12 volts to the fan or fans?

2. What is the anticipated current draw (amps) that will be needed to run the fans. Add up the individual fans to get the total.

Too small gauge wire coupled with higher currents will result is something less than 12 volts reaching the fan motors. The wire will act like a resistor. It can get hot too.

Just sticking in a 20 amp fuse will not prevent a fire if the small gauge wire heats up because it can't handle the current demands.

A 10 gauge wire will safely handle 26 Amps. A single 12 gauge wire is just under the safety rating to carry 20 Amps. Anything smaller and you're looking for trouble down the road.

Most ignition switches I've seen will not carry the current demands of the car PLUS the fans. It will have a short life.

My recommendation would be to use a seperate 30 Amp relay to supply the fans... and also the headlights if they are also just connected to a simple switch.

Regardless of which way you decide to go, after your done with the installation, start the engine and switch on the fans. Take out your volt meter and measure the voltage at the battery. Then measure the voltage at the fans. A difference less than a volt is probably OK. If it's more, your wiring is not up to the job.

- Jim -

Jim Harding
La Plata, Maryland

1982 #3004
http://www.capitalareacobraclub.com/albums/album26/1aLeftside.thumb.jpg

[clayfoushee]

Hi Jim, I was a bit worried about what you just posted too when I made this change last December. I'm doing this from memory which is not as good as it used to be, but I believe the combined draw of the std. Weaver-supplied front pushers plus the SPAL 2.05" puller is 15.5 amps. Hence, the conclusion of most that a 20 amp fuse (upgraded from the 15a for pushers alone) would handle it.

Phil G. and I wired the fans to a separate switch (where the pushers already were), manual on and off. We could be wrong, but no one has yet reported a problem with this configuration. However, your test is a good precaution.......thanks.

Clay

'98 Unique #9299, 427FE side oiler (452.1-stroker), top-loader (close), 3.31 rear

Annapolis, MD

[bstandley1]

Jim,

Thanks for your insights ... My current draw on the fan circuit is 15.9 amps (7.4 for the pushers / 8.5 for the puller) and the wire from the switch to the fans appears to be 14 gauge. I will check the voltage drop over the weekend and start shopping for a relay next week ... better safe than sorry ... thanks again for your help.

Bob

[pgermond]

No problem...... been running it for a year and everything is happy [8D]

Phil

427 Roadster, #4279436
Southern Automotive FE
3:31 and Toploader

Roseville (N.Cal)

[Jim Harding]

Bob,

The 15.9 Amp load you calculated is just in the middle of the current capabilities of 14 gauge wire.

I'm posting a link to a pdf page from Pegasus... it has a copper wire spec table as well as some other stuff.

http://s2.pegasusautoracing.com/RefPage.pdf

In my other post, I took the average of the high and low to state what was safe to use.

Beneath the chart is a good explanation of how to determine the correct gauge, and how to apply ohms law to get the right answer.

- Jim -


Jim Harding
La Plata, Maryland

1982 #3004
http://www.capitalareacobraclub.com/albums/album26/1aLeftside.thumb.jpg

[bstandley1]

Jim,

Thanks for the link. I checked the voltage drop and I'm losing over a volt (1.3V) to the fans. I found a source on EBAY that sells 20/30 amp Bosch relays for $2.75 each with $3.99 shipping for two so I took the leap and purchased two for under ten dollars delivered. It seemed like cheap insurance. Thanks again for your help!

Bob

[Naumoff]

I wired mine separately and install the thermo switch for those times you forget. (Clay :D)
Same fan came with a relay.

Tony

Unique 427 #4279480 427s/o Nascar toploader 3.31 Jag IRS