How hot do you run? (1 Viewer)

Mark, can you provide more detail on the direct drive fan and the 4 core copper rad? I have a '77 2F and was looking for a replacement fan clutch that went bad on a trail ride. I had a trail fix with clamp and rubber hose that departed soon after I hit the hiway. At home, I put a 1/79 clutch on as earlier ones for my truck are discontinued (don't want aftermarket), but like the idea of a direct drive fan.

Thanks, Dan

Carb'd 350, stock 4 speed, 4 core CCoT rad, solid fan spaced 1/2 way out of custom shroud, stock SBC waterpump, 160*F tstat, 33's, 4;11's.

I run 160 on cool days below say 80*, 190 on hotter days (80-85) and cooler days on the interstate, and 210-220 for anyday above 85. When it's hot like it is now it goes to 210-220 and stays there. I have tried a huge multi-bladed clutch fan from a Caddy and it ran even hotter. The stock radiator is just inadequate, plain and simple. Pulled a small utility trailer with a pretty big fold-down gate that ascts like a parachute the other day to exchange my oxy/act bottles and it was 220-230. My engine builder told me 230 was the point at which to become concerned.

The fan pulls some serious air. You can feel it with your hands infront of the bezel and definitely behind the fan/shroud. My next step will be to increase the radiator area by going to some type of GM cross-flow design.

Well, at the risk of looking pretty stupid, I will provide a little story.

After 350 carbed-stock conversion with the toy 4 speed in my '78 40, heat would slowly build up going down the freeway. After about 30 miles or so, temp would be 3/4 of the way over (second mark on stock gauge). No problem when slowly wheeling.

So I had a shroud built for it. End of problems. Or so I thought.

A few years later on a long trip to Death Valley, started heating up on the freeway on the first morning. Same location on gauge. What the heck? Never went any farther up on gauge, but I could tell it was just wrong. And again, no problem while wheeling. Spent most of the trip on slow trails. Problem was there again on way home.

Not my daily driver so I parked it at home and pondered. I eventually installed a 5 row cruiser radiator. Think it came from SOR or Man-a-free. What the heck, had I forgotten that there was a time that it did not heat up using the 4 row radiator? I guess so.

The 5 row helped a little, but just delayed the inevitable.

Happened to need a smog check. Mechanic-tech sent me home before ever starting test with info that the rig had some problems. So I fixed them. Went back and he began initial check. Finally, he came over to me and said, let's take a look at the rig together. He had noticed a major timing problem. Reaching over to the dist. with the cap off he grabbed the mechanical/vacuum advance, he attempted to actuate the advance. Fully rusted up and did not function.

Mech said that he had seen this before. The 350 can be extremely unforgiving and sometimes you can not tell you have such a problem. Hmmm, maybe I should have known as it did seem like there were more incidences of stalling on the trails.

So, I would run a shroud, use a 4 or 5 row radiator, and make sure the dist. is operating properly. May not be the problem with yours, but sure was with mine.

Good luck.

I second Cat Scan's response. I know that on the air-cooled BMW engines that I regularly work with, timing is the difference between running hot and running within the normal temperature range. One thing that you may want to try also is flushing your cooling system. Scale can build up and in the engine and even the best intentions with the radiator, pump, and fan will be in vain.

Doug_S said:

I second Cat Scan's response. I know that on the air-cooled BMW engines that I regularly work with, timing is the difference between running hot and running within the normal temperature range. One thing that you may want to try also is flushing your cooling system. Scale can build up and in the engine and even the best intentions with the radiator, pump, and fan will be in vain.

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I am running 38* total advance on my carb'd 350 per my engine guru. Should I readjust to lower the temp and if so how much?

I was perusing some back issues of TT and the tecj exchange (Mark Whatley) recommends you use a high flow water pump and t-stat set-up. Check out Summit Racing for pages of pumps.

Kofoed said:

I was perusing some back issues of TT and the tecj exchange (Mark Whatley) recommends you use a high flow water pump and t-stat set-up. Check out Summit Racing for pages of pumps.

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Yes, I have read that also. From what I have read in TT and his many posts to the LCML he is not a big fan of a SBC in an FJ40 so I find his suggestions usually pointed. Don't get me wrong he is very knowledable and I respect that wisdom.

One must remeber that a high flow pump & t-stat can only do their job if there is sufficient cooling capacity in the radiator itself. Mine and others experiences show that a SBC will run hotter with the t-stat removed. The theory is that the coolant is traveling too fast and not staying in the radiator long enough to cool appropriately. The parts you mention will normally help an engine that overtemps at low speeds, not on the highway as I am experiencing. Overtemps on the highway mean not enough radiator cooling capacity/radiator area. I know this and am planning a larger radiator but I am investigating the total advance issue as it doesn't cost anything to try.

TBI 350/sm420/LC 3spd T-Case


I installed an aluminum radiator (26x19) and I am using the flex-a-lite electic fan with a 185 thermostat, and I run at 185 in any type of condition. the hottest it ever runs it about 195.

- Rico.

like a hundred billion gajillion and fivefillion gillion and like four degrees

350 with Griffin aluminum radiator, no shroud. Stays around 185 unless idleing around offroad then will climb to 200 until I flip on the electric kicker fan. Brings it back to 185ish. I plan to make a shroud one day.

In highway driving your consistantly burning more fuel than any other time. More fuel equal more BTUs of heat created. Radiator must have good water flow throughout AND be large enough. Air flow is usually taken care of buy the highway speed itself and not so much an issue till your city driving or crawling.

180 degrees under ALL conditions.
1997 5.7L Vortec (IAC disconnected)
Griffen aluminum radiator
Mark VIII fan

Vortec_Cruiser said:

180 degrees under ALL conditions.
1997 5.7L Vortec (IAC disconnected)
Griffen aluminum radiator
Mark VIII fan

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Ed,
Will you post pictures of radiator, mounting, shroud & radiator part/model number?

One thing to remember is that the more retarded the timing, the hotter the engine will run since the flame will be on top of the piston while the engine is beginning the intake stroke. The greater the advance means that you could be getting into a situation where the engine runs hotter, pings, and diesels when you turn off the engine.