AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,809
- Reaction score
- 13,117
Post #2 says it .
But I'll add that you need to make sure that your vacuum advance is working and pulling in at least mid-teens.
However;
I had one engine that did not respond properly no matter what I did.
I tore it down, put another .001 skirt clearance into her and opened up the ring gaps several thousandths, badaboom problem solved. So much so that , that I undid some of the previous mods that I had done in an effort to run cooler. I even installed a 195 Hi-flo, and reset the max Temp to 207*F, and that is what she has run ever since.
------------------------------------------------------------
Also; check your ignition timing. If the timing is overly-retarded, the heat of combustion will go into the cylinder walls as the piston is going down, and guess what is on the outside of the walls, lol.. Plus at certain times, the mixture may not finish burning in the chamber on the power stroke, and the piston may push the still burning mixture into the exhaust system. On it's way out, it heats the ports...... which are surrounded by water, so there goes more heat into the cooling system.
>>At idle, the timing is always retarded. It doesn't matter what you set it too, it will always be retarded. How much? well here's how you figure out what she wants. Set the idle to 750, then pull in some timing, say 5 degrees. Reset the idle to 750. Repeat until the idle rpm no longer increases, them back the timing off a couple . Now, read the timing. Whatever you get is what she wants. Don't be surprised to see a number at or over 30*.
Now, set your rpm to 2400, and again pull in timing/reset the rpm as before. When the rpm no longer rises, back it off a tad. Whatever you get is what the engine wants at that 2400rpm with no load on it. Don't be surprised to see a number over 50*.
Obviously, you cannot put a load on an engine set up like that, lest it detonate itself to pieces. So put it back where it started from. Then think about what you just learned and how to make use of the lesson.
At WOT/full load and not detonation limited , the 360 LA will like about 35* of timing after about 3600 rpm., plus/minus 1 or maybe 2 degrees. Unless you have alloy heads and on the street, then I recommend 34* . These numbers are pretty much set in stone so don't mess with them. But how you get there is entirely up to the engine, and the load on it. I highly recommend to start at around 12 to 16 degrees depending on where that puts the Transfer-slot to mixture screw synchronization, which is also more or less written in stone, at an exposure of square to slightly taller than wide. Once you set that, then you control the idle speed with timing and or idle-air bypass.
The point of all this, is that you get the combustion process contained in the chamber/and top of the cylinder, and all of the fuel burned up before it exits the cylinders. Thus you get maximum energy transferred to the crank, and minimum energy transferred into the cooling system. With electric fans, you cannot afford to get too far out of the groove.
My best advice, I don't care about anyone else's opinion, is to over-engineer your cooling system using; a 7-blade, hi-attack angle, all-steel fan; and then put a thermostatic clutch on the fan to control the temp within a very narrow range.
BTW; when you do this right, you don't need a mega-dollar rad. My rad is factory circa 1973, off a 318 Dart with A/C. Nor do you need to run the pump in overdrive. Granted my engine, by it's trapspeed, is only putting out about 430hp crank.
>>If you think the 7-blade fan is a power-hungry monster that certain Performance magazines say it is; lemmee ease your pain. What's more important to you; a few horsepower at WOT, or keeping your engine from melting down? With the T-clutch I can almost guarantee you that both you and your engine will hardly know it's on there. It will do all it's work at speeds under about 30/35 mph , then more or less freewheel, unless maybe you are working a roadcourse. And I gotta tell you, seeing the gauge at the same old spot EVERY time I look at it, no matter what lunacy I have just been doing, is worth every single horsepower it might rob from the crank.
Am I recommending you swap off those electric fans?
Well no, but;
sooner or later, you are probably gonna anyway.........., and when you do, pay attention; a clutched fan, on the street, is not the monster that some people will try to make you believe it to be. I'm not talking about FABO people; they're a good bunch.
But I'll add that you need to make sure that your vacuum advance is working and pulling in at least mid-teens.
However;
I had one engine that did not respond properly no matter what I did.
I tore it down, put another .001 skirt clearance into her and opened up the ring gaps several thousandths, badaboom problem solved. So much so that , that I undid some of the previous mods that I had done in an effort to run cooler. I even installed a 195 Hi-flo, and reset the max Temp to 207*F, and that is what she has run ever since.
------------------------------------------------------------
Also; check your ignition timing. If the timing is overly-retarded, the heat of combustion will go into the cylinder walls as the piston is going down, and guess what is on the outside of the walls, lol.. Plus at certain times, the mixture may not finish burning in the chamber on the power stroke, and the piston may push the still burning mixture into the exhaust system. On it's way out, it heats the ports...... which are surrounded by water, so there goes more heat into the cooling system.
>>At idle, the timing is always retarded. It doesn't matter what you set it too, it will always be retarded. How much? well here's how you figure out what she wants. Set the idle to 750, then pull in some timing, say 5 degrees. Reset the idle to 750. Repeat until the idle rpm no longer increases, them back the timing off a couple . Now, read the timing. Whatever you get is what she wants. Don't be surprised to see a number at or over 30*.
Now, set your rpm to 2400, and again pull in timing/reset the rpm as before. When the rpm no longer rises, back it off a tad. Whatever you get is what the engine wants at that 2400rpm with no load on it. Don't be surprised to see a number over 50*.
Obviously, you cannot put a load on an engine set up like that, lest it detonate itself to pieces. So put it back where it started from. Then think about what you just learned and how to make use of the lesson.
At WOT/full load and not detonation limited , the 360 LA will like about 35* of timing after about 3600 rpm., plus/minus 1 or maybe 2 degrees. Unless you have alloy heads and on the street, then I recommend 34* . These numbers are pretty much set in stone so don't mess with them. But how you get there is entirely up to the engine, and the load on it. I highly recommend to start at around 12 to 16 degrees depending on where that puts the Transfer-slot to mixture screw synchronization, which is also more or less written in stone, at an exposure of square to slightly taller than wide. Once you set that, then you control the idle speed with timing and or idle-air bypass.
The point of all this, is that you get the combustion process contained in the chamber/and top of the cylinder, and all of the fuel burned up before it exits the cylinders. Thus you get maximum energy transferred to the crank, and minimum energy transferred into the cooling system. With electric fans, you cannot afford to get too far out of the groove.
My best advice, I don't care about anyone else's opinion, is to over-engineer your cooling system using; a 7-blade, hi-attack angle, all-steel fan; and then put a thermostatic clutch on the fan to control the temp within a very narrow range.
BTW; when you do this right, you don't need a mega-dollar rad. My rad is factory circa 1973, off a 318 Dart with A/C. Nor do you need to run the pump in overdrive. Granted my engine, by it's trapspeed, is only putting out about 430hp crank.
>>If you think the 7-blade fan is a power-hungry monster that certain Performance magazines say it is; lemmee ease your pain. What's more important to you; a few horsepower at WOT, or keeping your engine from melting down? With the T-clutch I can almost guarantee you that both you and your engine will hardly know it's on there. It will do all it's work at speeds under about 30/35 mph , then more or less freewheel, unless maybe you are working a roadcourse. And I gotta tell you, seeing the gauge at the same old spot EVERY time I look at it, no matter what lunacy I have just been doing, is worth every single horsepower it might rob from the crank.
Am I recommending you swap off those electric fans?
Well no, but;
sooner or later, you are probably gonna anyway.........., and when you do, pay attention; a clutched fan, on the street, is not the monster that some people will try to make you believe it to be. I'm not talking about FABO people; they're a good bunch.
Last edited:
