Bore and Stroke a 318?

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RDupont01

RDupont01

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I am new to Mopar and have recently picked up a nice '73 Swinger that is running a 318. I was looking and it seems the fit on the 318 is tight, and with a 318 motor being cheap, I was thinking of picking up another 318, boring, and stroking it. Any tips or warnings or better ideas? Anyone know what I can bore it out to and some performance specs?
 
sonic check will tell you what you can safely bore it to, rumors are in the ball park of up to 4", stroking depends on your budget. A real cheap stroker is to take a 360 crank, turn the mains down to 318 size and shove it in the block.
 
If your going to buy another engine to stroke why not start with a 360???...
 
RDupont01 said:
I am new to Mopar and have recently picked up a nice '73 Swinger that is running a 318. I was looking and it seems the fit on the 318 is tight, and with a 318 motor being cheap, I was thinking of picking up another 318, boring, and stroking it. Any tips or warnings or better ideas? Anyone know what I can bore it out to and some performance specs?
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The fit on a 340 or 360 is not going to be any tighter in the engine bay. They are the same size and demetions of the 318.
 
RDupont01 said:
and with a 318 motor being cheap, I was thinking of picking up another 318, boring, and stroking it. Any tips or warnings or better ideas? Anyone know what I can bore it out to and some performance specs?
Click to expand...

Tip and warning...A 318 is the most expensive small block to stroke except the 273. Even though you start off cheaper with the 318, stroking turns out more expensive due to the piston selection being small and pricey.

Turning down the mains on a 360 crank is an expense you might not want ethier. On top of that expense, the selcetion of pistons (Yet again) is nill. You must be creative or pay the piper dearly for slugs.

Performance specs.
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I'm not sure what you mean by that.
 
Yeah I just saw a stroker kit and it alone was $1800. So what would you suggest on a more powerful motor, boring or not, stroking or not, that wont require fabricating the body? It seems pretty tight with the 318, thats why I thought I should stick to it.
 
Do your homework. Buying a crate motor isn't a bad idea. I put the cart before the horse and it's not cheap to build unless you own a machine shop. price it all before you start buying parts!
 
The only thing more expensive about a 318 to build than other small blocks are the pistons. Then of course, your also down on cubic inchs.

Again, as said before, all small blocks have the same external diamanetions, so a 360 will fit exactly the way the 318 does.

Now the question is, How fast do you want to go?

Also, is spending extra money on changing the rear gears & torque converter Ok for you or are we sticking with what ya got? (What is your gear ratio?)
 
RDupont01 said:
Any tips or warnings or better ideas?
Click to expand...
The 360 is a better idea. The extra expense of purchase more than offsets the cost of modifying a 318 to reach the same output level.
RDupont01 said:
Anyone know what I can bore it out to and some performance specs?
Click to expand...

Stock bore and stroke:
318 - 3.91 x 3.31
360 - 4.00 x 3.58

The machine shops I deal with are hesitant to take one of these block beyond +.030 without checking the bore center in the casting first. Now we're talking some extra $s for that.
 
If this is going to be a street car you could add 100HP with basic bolt on parts. Headers and a good dual exhaust, intake and 4BBL carb and a cam change will get you there and will not hurt fuel economy either if you drive it easy. Can get to 400 HP level with head change and larger cam if you up the compression and still be drivable but will take more gear.
 
The first thing I would ask is how much power are you looking for? Then you need to look at your budget and see what is available. Don't worry about the 318, 360, 390, 408 debate until you have a goal. Another big thing your going to have to look at is what the rest of the drivetrain consists of. Shove a 500hp engine in a car with a 7-1/4 rearend and your gonna have a nice piece of yard art.
 
I'm stroking a 318 because I got the whole short block for free, and because its different. It's really your call, there's not much difference power wise between a stroked teen and a 360 given the right circumstances. I'm using the Keith Black forged flat tops in my motor, they were around 400 bucks.
 
The real deal here is....when you go forged piston...the price is the same for stroking a 360/340 or 318.

The thing to consider that no one else has mentioned...is that you will need to remove more from the bottom of the bore for clearance than the 340/360 in the same situation, whoopie doo.
 
Exactly, so, if you already have the 318, and dont have the 360, and the motor mount, (And possibly the converter depending on what you are doing) you are money ahead using the 318....... And the different is 18 cubes.........

Probably more to find a 360, and a mount, and possibly a torque converter than the piston diff with hyper pistons.....

Ho hum.
 
A 230 at fifty cam would spin the crap out of an A body with decent street rubber at 390 inches, with a stock converter...............

Here's a question.........

When you buy a "balanced" stroker kit, does the 318 kit come internal, and the 360 come external? Or do they internal the 360, or external the 318?

My crank was balanced internal by the machine shop..........
 
The advertisement or description of the parts being used in the kit should say if it is internal or external. If not, enquire!
 
I cant see going through all the trouble of stroking an engine and still going external.....

But then again, if they don't make the crank heavy enough................
 
Most ktis when sold are internally balanced because it's the easiest way to do it without having the balancer or flex plate, or the offsetting weight figures to account for. External balancing is the "quick and dirty" way of doing it. It works to a point, but in terms of a 4" engine, one way or another you're working on the crank and many combinations will only require drilling, not Mallory. So if you're smart about parts choices the internal balancing is easier (and probably cheaper) than external, and it does what balancing is supposed to do.
 
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