That should be plenty big enough if the electric fans are well shrouded on the backside of the radiator to pull air through the rad fins. Is the PCM controlling the fans and if yes, what temperatures? My first fan is supposed to come on at 190 degrees F, the second fan is on at 210 degrees F and then both go off at 190 F.

Don't forget to deal with the steam line and the "Jags That Run" web site has plenty of different size rad hose adapters with that type of fitting for the steam line.

Are you using the transmission cooler in the Silverado radiator?

Rick

 

 

I've just started driving my 68 C10 LS1/T56 swap. I used a big Griffin universal dual pass radiator. Not real hot up here in MN about mid 80's and I run about 180 in traffic. I like the dual pass because it puts the inlet and outlet on the passenger side. Cleans up the radiator hose routing. For a fan I've used a single 16" Spal fan with great success. On my 73 Camaro LS3 swap (same radiator and fan) we got stuck in traffic while on the Power Tour. 3 hours to go three miles. Never overheated. Fan controlled by the computer. On at 205. Off at 195. I like welding a bung in the upper part of the radiator tank for the steam line. I have drilled and tapped the water pump for the steam line but if water pump dies out on the road you have to be able drill and tap the water pump. Jags that run does offer a hose coupler with a pipe tap fitting for the vent line.

 

Reference Material-The GM radiators that come in the 2006 & later trucks, that have the factory DUAL electric fan set ups ROCK! However, they are 35" (core width) wide and will not fit in a 1970 C-10. I know because I bought the fans, and radiator, only to find out that they would not fit. No loss-I put them into my sons 2002 Silverado.

On the '70 we took the old radiator out of my sons truck, which is 28" core width, then used a 2 speed electric fan off a 1997 Ford Thunderbird. We have the PCM set up to run both stages of the fan. The fit is perfect. The thunder-chicken fan is a perfect fit to that radiator height wise, but is not as wide as the core is. No problem, we were charging the A/C the other day and idling in 105 degree temps for over an hour it never got close to over-heating. The fan was cycling between low, and high, but the engine temp never exceeded 210. If it never over-heated that way, it should not have any issues running down the road. I think your '68 is dimensionally the same as my '70. The Thunder-chicken fan pulls a LOT of air.

You will have to run 2 relays to utilize the high, and low, speeds on the fan if using your GM PCM to control them. I can give you a wiring diagram if you would like. You will need 1 4 pin relay, and 1 5 pin relay. It's not difficult. If I can help you, please let me know. Also, factory 2002 Chevrolet Suburban upper & lower radiator hoses will fit if using the GM 28" radiator. You will have to cut them a little shorter, but they fit and look factory when trimmed to length. Forgot to mention that the plastic side tanks sit right on the factory rubber supports in the C-10! It's almost like GM knew we would be doing this swap.

 

Hey Kawabuggy, I'd like to see the wiring diagram if you don't mind - I'm just about at the point where I can use that to wire up my own radiator fans. Thanks in advance!

 

Great information guys! I'd like to see that diagram as well please!

 

 

my thought is put an 80e in there

 

I always run a separate trans cooler in front of the radiator so the cooling fan pulls air thru when the car is moving slowly and the fan comes on. I've used the "stacked fin" coolers. -6 lines to and from the trans.

 

 

The rule of thumb that I've heard is that for every 20* F drop in auto-transmission fluid temperature, transmission life is nearly doubled. Haven't tested that myself, & I don't recall where I heard that from, so take that for what it's worth. Also, I'm sure that it's possible to over-cool the fluid as well. Probably something that's worth researching before spending much time/money on it...

 

TruckDoug FOR THE WIN! The 80E is THE way to go. I build, sell, and install them here in Houston.

If you think the price is too high for a 4L80E, factor in how much you will spend over the next 5 years trying to get a 4L60E to survive any type of abuse. The cost to retain the 60E will surpass the cost to swap over to the 80E. But, you will be spreading out the cost of constantly swapping 60E transmissions over time, whereas an 80E conversion will take a substantial investment all at one time... But ONLY that one time.

 

Trying to insert a copy of fan relays.. Let's see if this works..
http://i125.photobucket.com/albums/p...n%20relays.png

 

 

I buy my 80e's from the u pull it junkyard for $200. if there are no chunks of the case in the bottom of the pan, it'll run. HD2 kit and throw the boost at 'em

 

 

 

I agree. If you're having transmission problems then spend your money there. Running cool doesn't matter if you can't drive it. I have been running a mechanical fan with a stock radiator and shroud in my '71 C10 for years and it doesn't overheat even with the A/C on. If it was good enough for the millions of Chevy trucks made then it's good enough for yours.