Hi I have a 67 Camaro, basiclly factory 327, 275 hp with the timing set to the book(7 degrees btdc) with factory a/c.. Summer is coming up and the last few summers I have had serious problems with keeping it cool with the a/c on, in 100+ temp. I have pretty much tried everything, I will list everything I have done/tried and hopefully you can help.
I have a 2 core 1-1/4 inch alum. racing radiator 27by18, with a fan shroud, mech. clutch fan and a 16 inch elec fan that 'pulls' approx 2000 cfm I just have a switch that makes the fan come on when I want it to, which is all the time :)which still isn’t hacking it, I have an over flow bottle,185 degree thermostat, no head gasket leaks or anything of that nature, good auto meter gauges that read correctly, it seems to do ok when I'm moving faster then 40 mph but when I have to sit for a little it overheats( the compressor gets to hot i guess and starts blowing out the back thus onto my exhaust manifolds creating great amounts of smoke :rolleyes: , but when I have the hood up it doesn’t seem to overheat as fast, it has the original factory a/c set up... condenser, compressor etc, but has been converted from r12 to 134a, my mixture is mostly water, I would say 80-20, 90-10... Any thoughts/ideas would be greatly appreciated, thank you very much

I would think you need more radiator. Even with aluminum radiator you should have at the very least a 3 row core and you could even go with a 4 row. You are sure to generate heat with what you have and the A/C. You might check your shroud and make sure it is doing the job. A front spoiler might direct more air up into your radiator area also.

alright, I do have a front spoiler and high flow whatever water pump also...forgot to add that

Was the A/C on the build sheet or was it dealer installed?

I am not sure what you call a racing radiator? The two row aluminum 1.25" tube design easily outperforms a three or four copper/brass/solder one, so that doesn't concern me, but I am hoping it isn't just a generic cheap alum radiator that usually has less fins per inch and/or a dual pass one that requires at least 8 times the pressure to sustain flow rates of a single pass?

Usually, systems that cool going down the road at a moderate or above cruising speed and won't cool at lower speeds is lacking one thing.....airflow.

I don't think your 16" fan is cutting it. I believe a larger fan such as dual Spal 11" units, MarkVIII unit and or check this page out http://www.derale.com/electricfans.shtml for Derale duals.

I believe you need at least 2700cfm to make a dent in the cooling, esp at the ambient temps you are running.

Also, changing out the fan with an upgrade in water pump will be a one-two punch. Stock water pumps just do not offer anywhere near the performance of a Tuffstuff or Stewart Components pump...esp at lower engine rpms. You absolutely need a pump upgrade if you have a multi-pass radiator.

Hope this helps.

What pressure cap are you running,and I'll assume it has a good gasket? As for the 80/20 or 90/10 mix... not good IMO. 50/50 will give you the best heat/cooling transfer. Might want to test your waterpump and see if its pumping at the correct pressure/flow needed.

The a/c came with the car in 1967, the alum radiator isn’t cheap I bought it out off the summitracing site, it was hi-efficiency fins 1-1/4 tubes etc, I put a hi-flow water-pump on it, and the water to coolant mixture, I live in Arizona and it never freezes out here smile.gif so my mixture is always 85-15ish... I always thought that water with just minimal coolant (to raise b.p) would cool better then a 50-50 mixture?
Thank you HOTRODSRJ for the site, would you recommend getting duals put on it with 4000 cfm? Does anyone have a 1st gen Camaro with a/c that might possibly tell me what they have/works on their car? Thank you
another thought I had was that maybe my a/c compressor and condenser isn’t up to par, and might be dragging my system down thus creating more friction/heat, I wonder if I were to get a new aftermarket system if that would help, any thoughts would be a appreciated

406 small block
Factory A/C
Stock pulley ratio (overdriven)
Edelbrock Victor waterpump
US Radiator 4-row 23" Desert Cooler radiator
Stock GM small block 23" shroud
GM replacement fan
Hayden thermal clutch fan.

With this setup it never budged 185*.

The new setup in the works is:

Same engine
C&R aluminum dual-pass radiator with oil cooler.
1:1 GM pulley setup
Mark VIII electric fan
No A/C

Testing to start in about 3 weeks.

You mentioned that your gauges are accurate. How have you calibrated them?

Actually I do have a 69 ragtop with air (vintage), 400+hp small block and Hotlanta traffic. Equipped with a aluminum PRC dual row 1" tube radiator, Tuffstuff hipo water pump (overdriven about 17%) and .....believe it or not a Derale 17" heavy duty flex fan and stock shroud.

This car never comes off the 180 thermostat cycling point either and we have operated it up to mid 90s. So, you can see that a mechanical fan could suffice too.

Any dual fan unit of at least 2700+cfm should do it for you. It's a matter of matching up what is best for your radiator size.

Good luck!

CarlC
"You mentioned that your gauges are accurate. How have you calibrated them?"

I have an infared temp sensor that I used to read the temp off the radiator...

the problem is the Mark VIII fan is to large for my 21-18 alum radiator and i cant find an elec fan that pulls more then 2200 cfm to fit my radiator....

Wait a minute? I have seen two radiator sizes here. One for 27" wide and the other 21". Which is it?

Check these pages out here for more choices http://www.flex-a-lite.com/auto/html/electric-fans.html

ps......your water/antifreeze mix is fine if you are running enough corrosion inhibitors. You are correct in that the higher water content the better the heat transfer.

Just read the label on any anti-freeze bottle.

http://www.sierraantifreeze.com/tech.html


SIERRA
Anti-freeze to water mix.


A-------W-------Boiling Point
40%-----60%-----249°F*
50%-----50%-----256°F*
60%-----40%-----261°F*
66%-----34%-----262°F*
*Closed System; 14 psi caps

If you use the propylene glycol-based "Sierra" coolant (instead of conventional ethylene glycol-based coolant), you'll give up 8-10% of your total heat transfer capacity right off the bat. We ran extensive OEM tests on that stuff (and the other brands with the same "pet-friendly" chemistry), which showed it to have 8-10% less heat transfer capability than conventional coolants, and specifically prohibited its use in products with narrow cooling system safety margins (Viper).
graemlins/beers.gif

JOhn.......you da man! Absolutely right!

what do you guys think, if i get two 10 or 11 inch elec fans that pull 2000 cfm each for a combine 4000 cfm that should be more then enough to keep it cool with th A/c on sitting at a light? this is my main concern i need it not to overheat at idle rpm's... thanks

What I was trying to show was the relationship of water to anti-freeze mix being 50/50 a better idea due to a higher boilover point, than 90/10.

True but I wouldnt ever let my car get that hot...

How is your vacuum advance set up, and is it working? If it's connected to "ported" vacuum, as most of the "smog" engines were, you have zero vacuum advance at idle, and it'll run HOT at idle and in traffic due to retarded idle spark timing and VERY high exhaust gas temperature, which gets transferred through the exhaust port walls into the coolant. First thing I'd do is 1)Make sure it's working, and 2) Connect it to full manifold vacuum so it adds about 15 degrees at idle. Inoperative or "ported" spark-connected vacuum advance is responsible for LOTS of idle/traffic heating problems, and can cause heating issues on the highway as well due to inadequate advance at cruise load. If that checks out, you either have an inadequate airflow situation at idle, wrong shroud, seals missing, or not enough radiator (in that order). graemlins/thumbsup.gif

Thank you for the excellent reminder about the vacuum advance!! I put a Holley Throttle Body Fuel injection on a while back. I just went out and checked the timing with the vacuum advance line hooked to one of the 2 small vacuum input tubes on the TBFI. At idle it was 10 DBTDC. I pulled the vacuum line and still at 10 DBTDC. When I finger felt the input tube on the TBFI I feel no vacuum pull at idle only after you speed the RPM up to above 1500 do you feel any vacuum. I pulled the big center input line and it has allot of vacuum at idle and attached the distributor vacuum advance line to that and the timing still did not advance.

Looks like for one thing I have a vacuum advance module problem and I need to understand or have someone help tell me why the 2 small input tubes on the TBFI don’t have any vacuum at idle?

Thank you