electric fan cfm question

[TENDRIL]

lol i guess what i meant by that was its probably ok to bring your timing to 12-14, depending if you have a weber or not, with regular driving, and if you start to hear pinging try higher octane gas, or retard it a bit 

[spdcrazy]

no I don't regularly bring it to 5-6k. sometimes on a pull but not on the reg. I am not good at hearing pinging, idk why, but it isn't something I've ever been good at recognizing. yes I have a weber, however its the Chinese junk copy and doesn't hold a constant fuel ratio. soon to be changed.

[datzenmike]

i'll work some more things out, however, without changing the counterweights in the el dizzy, i'm limited to about 8 at idle without over advancing at the top end. do you think this is a big enough prob to have the weights modified?

 

Why would you need to modify the mechanical advance weights? If this is the stock distributor and not modified you have nothing to worry about. Set to 12 degrees (at least)

[spdcrazy]

I don't recall the number but I was told there is a max advance at high rpm. 32 or 36? Something like that.

 

And after thinking about some earlier comments, no I don't think there is a problem with my coolant system. I had no problems before with my mechanical fan. Only change is the electronic fan

[datzenmike]

About 32 degrees total. That's the initial static 12 degrees set with the light at idle, plus the 20-22 degrees mechanical which should be all in by about 2,500-3,000.

[spdcrazy]

Yes. So the Datsun mechanic did just that. 32 degrees total at high rpms. (Wasn't looking at my tach personally, he was) and set the timing. Which had my idle at something like 8.

[TENDRIL]

8* is not right, that is below stock and even worse for a Weber, better fuel efficiency,  more power advance it a bit 

[spdcrazy]

But them I'm over advanced at 3k on up. So.....

[TENDRIL]

lol, its not a big deal weather or not you keep it or advance it, just trying to give you info for future reference at this point, you are going to keep it at 8* and that's fine its just not factory   

[spdcrazy]

I'm with ya. I'd rather advance it, but I don't want to over do it. Either way, this isn't causing my overheating.

[spdcrazy]

And I much appreciate your help by the way! Always learning something on here

[TENDRIL]

http://www.davidcmurphy.com/olddat/620tech2.htm

[TENDRIL]

I'm with ya. I'd rather advance it, but I don't want to over do it. Either way, this isn't causing my overheating.

 

 

agreed!  :lol:

[DanielC]

An engine running retarded timing does not run cooler. it runs hotter.  More fuel is used, and instead of the energy in the gasoline being used to move the truck, it is just dumped out the radiator.

 

If your mechanic did not disconnect the vacuum advance to the distributor, that will change the amount of timing you see with a timing light.  

[datzenmike]

Running retarded means the hot expanding gasses arrive too late and the piston is quickly descending and accelerating down the cylinder. The hot air can't push effectively on it and chases the piston. Two things happen. The gasses transfer heat to the cylinder and exhaust ports and the water jacket around them and you have to run the engine harder to produce the same power.

[spdcrazy]

Thank you both, i understand what it is doing. But the fact is it still wasn't running hot before! So while I want to fix this, I can't just re time it. It'll solve the idle timing and mess up the high rpm timing. And again. With timing set like it is, I was NOT having problems with temp when I had my mechanical fan. Only when I swapped for ele.

[scooter]

I run the biggest flex a lite pusher i can in my car, and it seems to cool well. When i put an l20b in the 620 i had it also ran cooler than the l16. Dont know why.

 

I had the clutch fan sieze on it, so i removed the fan and put a big maradyne fan on it, holy hell that thing was loud, and pushed alot more air than the flex a lite.

[spdcrazy]

See that was my thoughts as well, but my small fan is as big as I can fit. I think it's just now pulling enough air. I'll build a shroud and that should help out, also want to get my timing spot on as well

[datzenmike]

Once moving (depends on engine/weight/rad....) vehicle speed will be enough to push air through the rad and cool it. Electric fans only come on in town, parked at idle or if waiting at a stop light long enough.

 

A shroud only helps the efficiency if a pull fan. If a pusher fan a rear shroud does nothing.

[spdcrazy]

Agreed. I have a small puller so a shroud should help my idle temps

[datzenmike]

Yes.

[jesusno2]

I think sometimes those big radiators can actually make cooling worse. If you think about it that giant chunk of aluminum is alot of mass. Once it gets hot it takes alot to cool it. If you pay attention to newer cars with aluminum radiators they are often thin with lots of air flow passing through them

[KoHeartsGPA]

yes i'm using a factory gauge. the electric fan is controlled by a 185temp sensor located in the lower rad hose, and it seems to kick on and off with the middle of my factory gauge, so I don't have exact numbers but it seems to match up.

 

 

while i'm driving it seems fine. my truck didn't have a clutch to begin with so it was running very very cold on the highway with my big radiator. system has been flushed multiple times recently as well

Move the sensor to the top of the rad, the heat will always be higher at the top, this will allow for the fan to kick in sooner, that might be your entire issue, I have 2 9in pushers and once those babies kick in the temp drops in a hurry, mine are 1250cfn each.

[spdcrazy]

I googled around and the general consensus was the lower hose because if one was low on coolant, you'd still get an accurate reading on the sensor. While in the upper hose you might not. Does anyone have any thoughts on this? Is my googled knowledge in accurate?

 

I'm also thinking your TWO fans are huge in comparison to my one 750cfm fan. But again im willing to try a change if anyone can help me out on the thinking

[datzenmike]

The water is hottest at the top where it comes in directly from the thermostat. All the temp senders for fans I have seen are on bottom of tank and some are even in the return rad hose. This give the rad a chance to cool rather than turning the fan on too often.