318 Bored .60 over...possible overheating?

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Varment

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My friend and I were placing the new radiator in my 68' Valiant for the new 318 I am putting in there and he asked about possible overheating issues with the engine being bored .60 over. I went online to research it a little and of course I am getting the "it will be fine forget about it"..."Oh my Gosh, you're going to overheat instantly" wish wash of answers. I decided instead of googling it and relying on a ratio of different answers I would post here about it in hopes that it would get me a little better answers.

Like I said in the title the engine is a 318 bored .60 over and I need to know if the stock cooling set up with a new radiator specified from a 1970 Plymouth Satellite with a 318 and a flex fan is going to be enough for keeping the engine at a decent temperature?

I am wanting the car to be a gas guzzling, noisy, daily driven grocery getter and I am hoping I wont be having to deal with temperature issues!

EDIT: I live if Northwest Florida...and the Summers get to be around 100 degrees sometimes...

Thanks,
Varment
 
I'm guessing that you didn't have the block sonic checked?

But, assuming your cylinder walls are thick enough to take a .060" bore and still be strong enough to take the piston loads, you shouldn't have a huge issue.

With most modern engines cylinder walls are pretty thin to begin with, they aren't acting like a huge heat sink. Yes, thinner walls will heat up faster, but they also cool faster too (less mass).

The bigger issue in cooling is HP. The more hp you make, the more heat you'll make, and the better your cooling system will have to be.

I'd venture that most folks that think their engine is overheating because of the "thin" cylinder walls aren't considering all the other things they did when they rebuilt their engine. Ie, they bored the engine .060 over, but they also raised the compression, stuffed in a bigger cam, carb, headers, etc, etc. And left the cooling system stock. The problem is not that the walls are .060" thinner, its that they added 100 hp without adding the cooling capacity to deal with it.

So, assuming your cylinder walls aren't razor thin, how much hp you added will probably be a bigger decider in whether or not you need a better cooling system. Most 318's can go .060" over without issue on a street car. There are exceptions of course depending on core shift etc, but the majority should be fine.
 
The 318 will take a .060" over punch and never look back. If it runs hot, it ain't cause of the bore.
 
very good answers here , with some great advice .

When you say that the radiator is specified for a '70 Plymouth "B" Body with a 318 , what exactly does that entail ? Is it a stock 22" - 26" width ? Is the motor a '70 & later with the aluminum water pump / right-side lower hose arrangement ?

Personally , I'm not a "fan" of Flex Fans , nor do I care for direct-drive fans . IMO , go for the 7-blade fan / fan clutch setup from Direct Connection ( or whatever they're called this year ... ) , and add a factory shroud from a , in this case , 1970 "B" Body .
 
you could always mount one of them electric fans in front of the radiator with a fan on both sides it shouldn't get hot
 
When I went to my local auto parts shop, the radiator I ordered was a re-manufactured one that fits a 1970 Plymouth Satellite. The reason I ordered using specifications of that is because the engine came out of that same car.

I may end up upgrading the cooling system because just about from the cam to the heads are not stock on the motor and my HP should be increasing quite a bit from stock.

Thank you very much for all the answers...Much more helpful!
 
the 2 fan idea can actually cause more turbulance than anything when front to back. if it were me ( since i already did it ) i'd invest in a summit racing dual core, all aluminum radiator, and an aluminum waterpump...i measured my frame rails and fabbed up brackets to go with the extra capacity all aluminum radiator, and threw on an electric fan for good measure...go with a lower T Stat too if you want...should help quite a bit.
 
you could always mount one of them electric fans in front of the radiator with a fan on both sides it shouldn't get hot
Click to expand...

I tried once with what I remember being 14" electric fans and I didn't have the room to fit them. With the water pump pulley assembly attached the fan would not fin in between the radiator and the pulleys. The engine bay originally held a slant 225 and I originally thought that there would be plenty of clearance thinking the 318 was shorter in length but apparently I was wrong.

It may have been the position I fabricated the new motor mount brackets. Because didn't the valiant come with a 318 option? or was the bay different in the later models?
 
johnnymac2k6 said:
the 2 fan idea can actually cause more turbulance than anything when front to back. if it were me ( since i already did it ) i'd invest in a summit racing dual core, all aluminum radiator, and an aluminum waterpump...i measured my frame rails and fabbed up brackets to go with the extra capacity all aluminum radiator, and threw on an electric fan for good measure...go with a lower T Stat too if you want...should help quite a bit.
Click to expand...

in my dart, the best way to get an electric fan in there is to stick it in front of the radiator as a pusher, i actually have 2 14 inch fans side by side mounted behind the grill. you'd need a pretty slimline elec fan (also avail from summit) to get it between the water pump and the radiator
 
nope. you'll definitely be fine. My 318 is punched 060 over and I beat the living hell out of it. lol But, like was mentioned, more power means more heat. upgrade the cooling system to cool them horses! :)
 
Mine is good expect for mid summer heat, which in mid 80's up here, lol

I found it cools off better with NO T-Stat. I run a 180 most of the time but come May to Oct I just remove the thing and motor runs around 170-180 if its 70 degrees or better outside.

I heard the old the water runs too fast to cool off with no T-Stat but real world it seems to help and costs NOTHING...more $ for gas money, lol
 
Thank you all for the responses! I am feeling much more comfortable with keeping it as it is for now, but I will definitely be watching the gauges a little closer when I start this beast up!

Thanks again,
Varment
 
I would venture to say most of those people who think it would overheat are Ford fans. The 302's had thin cylinder walls most of the time and would not take anything over .040. I have seen many 318's punched .060 over that never had a single problem. Beyond that though I would have the block sonic checked.
 
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