Re: Thoughts on Mechanical Fan Please
Fans... So many different scenarios that its difficult to say what's best in every situation... Its never truly "apples-to-apples"... Not only the local climate, but things like tuning (lean mixtures and ignition timing can cause overheating) along with the size and type of core (some cores are more restrictive to airflow than others, while some others may provide more coolant contact with the tube surfaces (needed for heat transfer) as well as water pump impeller design, flow and pulley ratios.
IMO, work with what you have first. Make sure its all properly working, before throwing it all out and starting over from scratch...
IMO, IF choosing a mechanical fan, then why NOT use a clutch version? And of course, an full-coverage (stock?) shroud. If you read through Scott's writing, he usually suggests the stock GM 7-blade fan and the Hayden HD clutch...
I have had cooling issues on various Chevelles over the years, and each one seemed to respond to different methods and parts selection.
Personally, I now replace the water pump with a well engineered "high flow" version (I have had excellent results using the EMP/Stewart Pumps), as well as a quality thermostat. naturally, a clean radiator helps.
My last Chevelle used the Flex-a-lite dual fan (#498?) with integral, full coverage shroud, with pressure relief flaps. It fit the Summit/Northern "direct replacement" aluminum radiator well, and with the Stewart pump, my cooling problems were solved. While my A/C wasn't functional, the condenser remained in place ( a restriction to air flow). The car typically would not go over 185 in traffic (using only one of the fans). If it did climb to about 195-200, then the second fan would kick on, and bring temps back down. I have seen temps up to about 200+, but that was with 100+ degree days stuck in heavy stop and go traffic (a few times at Hot August Nights in Reno), but the second fan always seemed to bring the temps down quickly) I was using individual adjustable Derale fan controllers and relays for the fans. On the highway, the temps would often drop below 175 (gauge sender in the intake manifold, NOT in the head).
I had indicator lights that lit up when the fans were energized, as well as a "calibrated" gauge (upon initial warm up, the gauge would rise to 180-181 degrees (on the gauge), and then drop when the Thermostat initially opened. once "warmed up", the temp stabilized.
So when people blindly state that electric fans are no good, I usually disregard further cooling "advice".
I also live in an area where I am not worried about freezing (maybe 15 nights a year with outside temps under 32 degrees, but my attached garage never gets that cold), so I ran straight water (distilled) with Redline Water Wetter for corrosion/lubricity. Water is a better coolant than "coolant" (at least than Ethylene Glycol). As a side benefit, I have had leaks before, and always hated the sticky mess that EG coolant made... Had a friend (hood-less car), that blew off the top radiator hose at a car show once... What a mess, as the coolant sprayed out on 4-5 other cars... Luckily, no one got burned...