The ignition is a Malory unit, I’m not at-all sure of its timing or stroke etc.
Ok, good. So let's ignore the horsepower potential for the moment and concentrate on the knowns.
You
MUST set the ignition timing. Period.
An engine can run hot even if it's a 150hp wheezer, if the timing is retarded. Or perhaps even too far advanced, but being too retarded is a known heat builder.
I do know it has a roller cam, but not sure of specifics.
May or may not be pertinent, but how does it run overall? Lopey idle or smooth? Bogging down when just getting rolling, or strong right from the bottom end of the rpm range?
It is an edldbrock carb, I THINK it’s a 550 double pump.
Could be wrong, but pretty sure there is no such thing as a double-pumper Edelbrock. That's a Holley thing.
But Edelbrock carbs are easily tunable and run very well on the street. Not the most fun off-road, but they do pretty well otherwise.
And 550 is way too small (I believe) for anything coming near 600hp. Maybe the lower end at 475 would work, but not much more I'm thinking.
Here again though, a smaller carb can be great for lower rpm running and idle quality and such, as long as the cam is not too large for it.
I do NOT know the year of the block or if it was for sure a boss, or if it for SURE came from a mustang, but it IS a Windsor.
Ok, good to know stuff. But unfortunately older 351's were well known to run hot when modified, especially with over-boring. But you say as far as you know it's not been bored? That's probably a good thing.
Tires are 35” gearing is 4:88.
This is a pretty good combination for lots of stuff. Should not be an issue in the vehicle running hot due to overloading the engine then.
What transmission are you running?
The truck has never been to a shop to measure hp, but was told that the build was targeted for it to be 475-600hp going off parts etc; I quote the 600 as a better safe than sorry.
Ok, fair enough. But that range is way too wide for anything reasonable to assume in tracking down an issue. There's a TON of stuff needed to add an additional 125hp to an engine with no increase in displacement or induction pressure (turbo/super charging in other words).
For now though, we really don't need to know the exact horsepower it has. But it would be nice to know how it runs otherwise.
Does it run very smooth? Engine is mostly quiet (other than exhaust)? In fact, what exhaust just for our information while we're on these subjects.
You see where this is going though. We need to know it all. Not just that you're running hot. We need to know all about how it runs, feels in your opinion, what other quibbles you might have with it, etc.
The electric is a pusher, mechanical fan is shrouded by a modified stock shroud, and only gaps roughly an inch at the top and bottom of fan.
Sounds good. What type of mechanical fan is it by the way? Some are decent, some are great, and some are next to useless when you're fighting an issue.
Otherwise half-way decent fans for a perfect running engine might actually be next to pitiful for a hot-running setup. In other words, it might be fine for some, but not for all.
An aftermarket aluminum flex fan like the hot-rodders use is a perfect example of this. A factory 18" heavy bladed high pitch fan is an example of a good one. A late model Explorer 5.0 is an example of an amazing mechanical fan.
I currently have no thermostat, but did run a 180.
I would put one back in. Did you remove it because you were trying to figure out the heating issue? While it can help sometimes, if you find it does not, then you should always put the t-stat back in.
In fact, if you were running a 400hp engine I'd say go to the high end and run a 195° thermostat. If you were really running closer to 600hp, through the use of high compression and other tricks, and running the engine hard all the time, maybe the cooler 180 or even the 160 t-stats would be called for.
But in this case, personally I'd run AT LEAST a 180.
I’m not sure what specific water pump I have, but is THAT the easiest way to get an extra bump, ie- more flow?
Yes.
To the more flow part anyway. It's anything but a guarantee of running cooler, but it's a step in the right direction if the other stuff does not pan out. It's been proven time and time again that more pressure inside a cooling jacket is only a good thing. Until it ruptures a radiator that is!
And high flow "can" sometimes equal a bit more pressure. Often just enough to quell the formation of hot spots and steam pockets inside the engine.
But if that's not your issue, it's a waste of time too...
If the pump in use is a known pump and has low miles on it, then I'd do other stuff first like check timing.
If it's an older pump with unknown mileage, you never know if it's worn out or not. The impellers on these things can go through some very strange metamorphosis. Some can last a million miles, and some will go 100k and be literally worn down to the nubs.
I would get a timing light on the thing first and foremost.
Paul
