ford 390 big block over haeting at idle - Page 2 - Ford Muscle Forums : Ford Muscle Cars Tech Forum
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post #16 of 21 (permalink) Old 08-11-2019, 08:06 AM
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And you forgot first post where it over heated at idle. You clearly didn't read the article where it states that ported vacuum makes the engine run worse. Do yourself a favor and Google "tuning and vacuum advance 101" and read it. Especially where it starts off with "ported vacuum!"
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post #17 of 21 (permalink) Old 08-12-2019, 04:35 AM
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Re: ford 390 big block over haeting at idle

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Originally Posted by ethanknapp05 View Post
Let me ask y’all this:

Seeing as my 390 in particular is a fresh build (roughly 5k Miles) what could be the chances the head gaskets could be at fault or even the heads? I know nothing about the internals or the guy who put the engine together. Could gaskets be on wrong? Could the heads be warped?

These are not GT heads... do the GT heads have cooling passages that non GT heads don’t?
Ethan, the GT heads are just passenger car heads, no different and not even really a "thing" The only reason many people refer to them as GT is the exhaust bolt pattern compared to the same head in a truck. They run fine and with work can make power, but they are actually the lowest performing, totally normal head found on everything, so GT are stock heads. Not to mention NO FE head has any different cooling passages and if you had the headgaskets on backwards it would overheat all the time, you couldn't drive it. If that IS the case, then maybe, but doesn't sound like it.

As far as yours overheating, to be blunt, I see this all the time. "I took off the engine driven fan and now it overheats"

You have a 300+ HP engine driven fan and replacing it with electric fans with tiny motors. Electric fans are rated for 1000, 750, cfm etc, but that is free flow. Unless you get a real bad-ass setup (Lincoln, Taurus, etc, and wire them to a big relay with a good alternator, you won't get there. In electric fan speak, you need 4000-5000 cfm puller, with good bypass doors to match the stock setup

In the end, we all like the cool factor of electric, but it's never cheap, and it's hard to beat a stock fan or the Flexalite fixed fans with the bent tips, flex fans are noisy and crappy, in the end, I'd go back to what you had originally, or I'd go deep in a real set of pullers.

FYI If you are really set on electric, look in Summit at the ready made sets for pickups, they pull 4000-5000 cfm and if you have the wiring to feed it, they work pretty well

As far as the ignition, if anyone's engine overheats due to not enough initial timing and the starter cannot handle more, then the car needs a better starter/battery/etc along with likely a fan/pulley problem

The ONLY reason I would run manifold vacuum is because I couldn't run enough initial to dial in a very big cam for idle tuning. Basically you can start the engine then timing comes in for idle to allow you to close the primaries to stay on the idle circuit, that is a much different reason.

However in that case. I will also add, that I deal with this on early Pontiacs, manifold vacuum for a distributor is awesome at idle, and at WOT, but can screw with you in between. As you work the throttle in town, you often end up with it coming in and out as it drops and rises, it can feel weird. Not wrong, you can tune it, but can be odd until you get it where you want it. In my opinion, I stick with ported other than some very limited vehicles

70 Sportsroof, 427 FE/489 cid, TKO-600, 31 spline 4.10, A/C. modified Mass-flo EFI/reprogrammed A9L/CnC ported Victor.
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post #18 of 21 (permalink) Old 08-12-2019, 07:21 PM
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Ethan, the GT heads are just passenger car heads, no different and not even really a "thing" The only reason many people refer to them as GT is the exhaust bolt pattern compared to the same head in a truck. They run fine and with work can make power, but they are actually the lowest performing, totally normal head found on everything, so GT are stock heads. Not to mention NO FE head has any different cooling passages and if you had the headgaskets on backwards it would overheat all the time, you couldn't drive it. If that IS the case, then maybe, but doesn't sound like it.

As far as yours overheating, to be blunt, I see this all the time. "I took off the engine driven fan and now it overheats"

You have a 300+ HP engine driven fan and replacing it with electric fans with tiny motors. Electric fans are rated for 1000, 750, cfm etc, but that is free flow. Unless you get a real bad-ass setup (Lincoln, Taurus, etc, and wire them to a big relay with a good alternator, you won't get there. In electric fan speak, you need 4000-5000 cfm puller, with good bypass doors to match the stock setup

In the end, we all like the cool factor of electric, but it's never cheap, and it's hard to beat a stock fan or the Flexalite fixed fans with the bent tips, flex fans are noisy and crappy, in the end, I'd go back to what you had originally, or I'd go deep in a real set of pullers.

FYI If you are really set on electric, look in Summit at the ready made sets for pickups, they pull 4000-5000 cfm and if you have the wiring to feed it, they work pretty well

As far as the ignition, if anyone's engine overheats due to not enough initial timing and the starter cannot handle more, then the car needs a better starter/battery/etc along with likely a fan/pulley problem

The ONLY reason I would run manifold vacuum is because I couldn't run enough initial to dial in a very big cam for idle tuning. Basically you can start the engine then timing comes in for idle to allow you to close the primaries to stay on the idle circuit, that is a much different reason.

However in that case. I will also add, that I deal with this on early Pontiacs, manifold vacuum for a distributor is awesome at idle, and at WOT, but can screw with you in between. As you work the throttle in town, you often end up with it coming in and out as it drops and rises, it can feel weird. Not wrong, you can tune it, but can be odd until you get it where you want it. In my opinion, I stick with ported other than some very limited vehicles[/QUOTE]


Thanks. Spoke with my dad about it extensively. He’s an old FE guru but it’s hard to diagnose over the phone... he made a good point, “you bought it to drive it and enjoy it and it sounds like putting it back to stock for now is what it’s gonna take to get rid of the headache of worrying in traffic.” And he is right. Because otherwise this car is capable of being a daily driver. I think until I can go through it the way I want to, meaning rack and pinion steering, bigger brakes, manual tranny swap, aluminum top end etc... I’ll put it back to stock and save these parts and keep collecting until I can do it all at once. Because I haven’t enjoyed driving so much since I was 16 and I’m tired of having to keep an eye on the temp gauge.
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post #19 of 21 (permalink) Old 08-12-2019, 07:23 PM
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Sorry I didn’t quote that last one correctly... still trying to figure out how this particular forum operates on mobile platform.
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post #20 of 21 (permalink) Old 08-13-2019, 09:37 AM Thread Starter
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Re: ford 390 big block over haeting at idle

Me and my friend Larry are going to try a smaller water pump pulley I measured my water pump pulley and it measured 7" so that's means the fans spins at low rpms , with a smaller pulley the fan will spin much faster keeping the temperature down im going with a 5.400 dia water pump pulley, and we are going to check the timing and compression, and vacuum, but we have to get my Cadillac engine back in my caddy first, I will let you know in about a week


Thanks
Scotty
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post #21 of 21 (permalink) Old 08-18-2019, 05:46 AM
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Re: ford 390 big block over haeting at idle

Quote:
Originally Posted by mcpherson4055 View Post
Me and my friend Larry are going to try a smaller water pump pulley I measured my water pump pulley and it measured 7" so that's means the fans spins at low rpms , with a smaller pulley the fan will spin much faster keeping the temperature down im going with a 5.400 dia water pump pulley, and we are going to check the timing and compression, and vacuum, but we have to get my Cadillac engine back in my caddy first, I will let you know in about a week


Thanks
Scotty
Scotty, the pulley ratio is more important than the size, should be 1:1 (same size) or 1:something less (fan pulley is smaller than the crank pulley) Be sure to look at the correct groove too, sometimes Ford have multiple ODs on the crank pulley, compare the one that drives the fan

Ethan - If your cooling is better once you put the stock fan on, chalk it up to experience and realize that it takes a heck of an electric fan to do what a stock fan does. Like it or not to the hot rodders, the benefit of electric fans is power (during the drag race) and the ability to cool between rounds with the engine off, they are not more capable at low rpm or in traffic unless you buy monsters and have the room for them, and in those cases, they draw more electrical load. In the end, it's pretty hard to beat a good fixed fan.

One other comment, lets say you gain 7 HP with an electric fan, but the engine is 15 degrees hotter as it creeps up, although you would lose HP with a fixed fan, the lower temp allows more stable tuning and a more consistent performance, so it's all in the margins, you won't even notice. Last thing, 400 dollars in electric fans can make up that power if spent somewhere else too...

70 Sportsroof, 427 FE/489 cid, TKO-600, 31 spline 4.10, A/C. modified Mass-flo EFI/reprogrammed A9L/CnC ported Victor.
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