CLAY72dart
Well-Known Member
How close is cutting a 318 at a machine shop to a natural 340. Trying to build the one I just got.
General 318-340 questions
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If you mean "boring it to a 340 piston", then you'll need to sonic test the 318 to see ... thin ice in my opinion
Professor Fate
Push the button, Max...
You have better luck with some year blocks than others, but only the sonic tester will tell you for sure.
And then there's always sleeves if all else fails...
And then there's always sleeves if all else fails...
I've heard early 318 blocks have more meat to go to at least 4.00". Why push it to 4.04" just for 7 more inches. Build a 333 and let er rip? No one will know but you and the machine shop.
Or.... look for a decent 360 core.
Or bore it .030 and throw in a 4" throw crank for a 390+
All you need are 318 pistons to work with 360 heads. See post #7 above. The rest is the same. Horse Power is in the heads, not the cubic inches.
Get it checked to see how thick the walls are but I see no need to go more than 60 over 3.97 x 3.31 = 328 it's just a hair under 4.00 bore and 12 cid less than a 340 a 3.5% difference, on a 350-450+ hp it ain't gonna make a big difference maybe powerband moved up a 100 or 200 or so rpm's and 10-20 lbs-ft.
Like she said "it ain't always the size of the bore."
Ant
Well-Known Member
The more metal removed, the weaker the cylinder walls become.
CLAY72dart
Well-Known Member
I’m looking to build it to 400-450 hp I should’ve wrote that earlier. I don’t care about size of the bore as much just thought bore size directly equaled more horsepower.
318 bore is more than capable to make 400-450 hp, rpm might be the problem, depending on you 6000-6500+rpm will probably be needed to make 400-450 hp
How well your rings seal makes way more difference than bore size!
CLAY72dart
Well-Known Member
CLAY72dart
Well-Known Member
I’m very unfamiliar with building motors.
CLAY72dart
Well-Known Member
Rings seal?
CLAY72dart
Well-Known Member
CLAY72dart
Well-Known Member
Also what exactly is a stroker kit?
TT5.9mag
Two atmospheres are better than one
I can tell by the questions you’re asking you are inexperienced and that is perfectly fine. We all are/we’re at some point. My best advice to you is to find a machine shop locally and get to know them. Ask them to mentor you through your first build. You will learn a lifetime of information and hopefully retain it forever. If that’s not acceptable for you search Amazon for books, search “how to build high performance mopar small blocks” and you’ll get some good reading material.
Here is a start
Amazon product ASIN 1613250126
Here is a start
Amazon product ASIN 1613250126
Thee are 2 ways to increase the displacement of an engine: one is larger diameter pistons, the other is putting in a crank with a longer stroke (how far up and down the pistons go). A longer than stock stroke in an engine is called a stroker. There are lots of well proven stroker kits out there and as mentioned earlier the 390 stroker out of a 318 is a popular one.
You probably should be shopping for a competent engine builder.
you should read the magazine articles I linked on post #13 there more on the sticky on the smallblock section, plus watch https://www.youtube.com/@richardholdener1727/videos give you an idea of what's going on.
here's 2 360 video, he don't have 318 but are similar
On the powerstroke the better the ring seal the more force applied to the pistons.
RED X ....Really??
That is not true. Small blocks are good to 6,500 -7,000 rpm, valve train, connecting rods and all. Rpm is usually limited by ignition, cam, valve springs. You want strong cylinders that you can seal with the pistons and rings. Next you want good heads, and for the power you want, you can do that with 360/340 heads. Don't get hung up on horse power numbers. 340's were giant killers and they were only about 300 horse power. If you do it right a 318 can be a blast to drive. Strokers require a big cash outlay for a new crank, rods and pistons. Strokers bring the rpm down by adding cubic inches. What car is it going into? What do you want your car to do?
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