Engine temps with Vintage Air Installed

[65k10]

Okay,

It's summer and daily temps are 110 plus. I've got a 66 C20 with a 383/700r4 with a 4 core factory radiator (recently recored) with 2 12" electric fans. Without the AC on, stop and go traffic temps are in the 210-225 range (mechanical gauge in intake). With the AC on (and it's not blowing that cold), it gets to 235 before I panic and turn off the AC . On the freeway (without AC), temps are a steady 200. Using a factory serpentine set-up so I've got the correct reverse rotation water pump. Engine has a mild cam, long tube headers, aluminum heads and intake. 7lb cap on radiator, and it has never puked out any fluid. If the air temp is 95 to 100, I still see the same motor temps, but the AC is cold, cold, cold. I dropped initial timing from 12 to 9 and that has helped some, but definitely can tell performance has dropped some.

I feel that maybe the fans aren't doing the job and maybe I need to step up to something like the big 18" Lincoln fan. I built this to be my daily, but no AC in the summer is a disappointment. Any input is appreciated.

Thanks.

[MT65]

What is the cfm of your two fans, pretty sure you don’t have enough fan capacity….

[65k10]

I believe they were 1400-1500 each. I've double checked to make sure they are pulling and not pushing. They were on a shroud that I felt didn't seal very good, so I attached them direct to the radiator and it seemed to help.

[1971 GMC SHORTY]

Originally Posted by 65k10

I believe they were 1400-1500 each. I've double checked to make sure they are pulling and not pushing. They were on a shroud that I felt didn't seal very good, so I attached them direct to the radiator and it seemed to help.

You Need 3000 CFM Your Not Getting Enough Air Pulled through Radiator To keep It Cool Enough

[karlbenz]

I have two of these on a 383/th400. I made a shroud and sealed it up good. never gets above 180. I don't have ac yet.

https://www.amazon.com/30102038-Pull...s%2C180&sr=8-6

[nsb29]

I bought a pair a dual fans from Summit racing for my 65 their part number is SUMG4850 the fan measures 26“ x 15“ fit the radiator very well I have a three core radiator an LS motor vintage air towing a 16 foot travel trailer 90° weather AC blew cold I have the original gauge so I can’t tell you the exact temperature but it ran just a little over 3/4 of the way the same place it runs in stop and go traffic I highly recommend these fans in August we’re taking a trip to Southern California towing the travel trailer with the 65 that should put it to a test LOL

[65k10]

UPDATE.

My two 12" puller fans were pulling air thru radiator, but hardly any air flow thru AC Condenser. Added a 10" pusher fan to the front of the condenser. Not mounted all that well, just zip tied to grille. Got out into stop and go traffic (110 degrees today) and engine temp hovered around 220. would climb to 235 when stuck at traffic lights, but would come back down to 220. The biggest difference is the AC never complained -- ice cold the whole time. Will mount pusher fan direct to condenser in the near future. Probably need to upgrade puller fans as well.

[vin63]

Talking things over with the folks at Derale on my build (no belt-driven fan), they explained that a properly functioning shroud is essential with AC. It's also important to make sure that if in a pulling configuration, the fans are mounted so that the blades are operating inside the shroud. I run dual Derale HP 12" fans and mounted them so that they are halfway inside the shroud. My truck runs around 210-220 in traffic on 105 degree days with the AC running. Derale now makes integrated fan/shroud kits (I wish they had them back when I was building my C10) for standard-sized radiator cores, but they will also help with custom applications - Shrouded Power Packs: https://derale.com/product-footer/el...ual-powerpacks

[verdell]

Originally Posted by 65k10

Okay,

It's summer and daily temps are 110 plus. I've got a 66 C20 with a 383/700r4 with a 4 core factory radiator (recently recored) with 2 12" electric fans. Without the AC on, stop and go traffic temps are in the 210-225 range (mechanical gauge in intake). With the AC on (and it's not blowing that cold), it gets to 235 before I panic and turn off the AC . On the freeway (without AC), temps are a steady 200. Using a factory serpentine set-up so I've got the correct reverse rotation water pump. Engine has a mild cam, long tube headers, aluminum heads and intake. 7lb cap on radiator, and it has never puked out any fluid. If the air temp is 95 to 100, I still see the same motor temps, but the AC is cold, cold, cold. I dropped initial timing from 12 to 9 and that has helped some, but definitely can tell performance has dropped some.

I feel that maybe the fans aren't doing the job and maybe I need to step up to something like the big 18" Lincoln fan. I built this to be my daily, but no AC in the summer is a disappointment. Any input is appreciated.

Thanks.

I ran an iron head 383/700R4 for several years with Summit aluminum radiator and a '96 Mercury Cougar XR-7 big 2-speed fan on the low speed without ac and it never rose above 185. Summers here get above 100 too. I kept the same set up with my LS and Vintage Air but using the high speed as needed and it's still doing well. Maybe not moving enough air?

[Grounded63]

What temp thermostat are you running ? If your running a newer 195°+ thermostat. You may need to switch to something more conventional like a 180° or 160°.

[MikeB]

Switching from a 195° t-stat (if that's what you have) to a 180 or 160 won't fix anything unless the 195 isn't fully opening.

Might want to try a high-flow t-stat from Flow Kooler or Robertshaw. I have zero experience with electric fans, which fortunately I've never needed, even in North Texas. But if the OP is seeing 200° on the highway when ambient is 95-100°, that tells me the problem is not just the fans. I have to wonder about the re-core job.

I credit never needing electric fans to my use of aluminum radiators in my previous two project vehicles. One was a used Griffin in a 55 Chevy car with 350 and A/C, the other was an inexpensive single core in an 82 C10 with a 350 but w/o A/C. Some folks love to hate on both of those, but they worked great for me for several years before I sold the vehicles. Both had clutch fans and shrouds.

Good luck resolving the problem, and keep us updated.

[theastronaut]

If the AC isn't cold and the engine is running hot then neither the condenser or radiator are getting enough air flow.

A sealed shroud will help, without a shroud you're not pulling air over the whole radiator in traffic. Look for a shroud with flaps that open so the fans don't become a restriction at higher speeds.

How big is the condenser? A larger condenser with it's own fan/fans may help.

[forestb]

When I had my air conditioning installed they told me that for some reason they had to hook up the switch that turned on the electric fans to the air conditioning. I think they said it had to do with needing to hook up both to my thermostat. Because of this my electric fans turn on whenever I turn on my air conditioning. I have an 180° thermostat. I have never had a problem with the truck overheating or getting hot when the air conditioning was on. I don’t know how much this helps but it might be something to try.