Oh dear God! 318 stroker

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Some crank counterweight clearancing required.

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408 swinger said:
Early 318 pistons used for the compression height. Skirts milled off to clear crank throws. Basically made a gen 3 hemi piston out it. Deepen the valve reliefs a little after machining tops down for street friendly compression ratio.
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What rods did you run in it and how did the balance crank me out? I’ve inquired about getting a 360 crank cut down to 318 mains and no one wants to touch it. They say that way of building strokers went away when good parts became available a long time ago. Honestly, it would probably cost as much as some of the cranks that are available to remove the .3 off the mains of a stock 360 crank.
 
I imagine if you were to use some of the lightweight aftermarket rods that it may be possible to turn some off the counterweights of the crank if you also lightened the pistons. You’re going to be deep enough in one of these types of of one off niche builds that you may as well go ahead and plan on spending the money to make the rotating assembly as light as possible. But don’t be surprised if someone who spent less than you did to run a four inch stroke 318 gaps you by a couple of car lengths on a run.
 
If you have an old truck 318-3 maybe 1968 casting...usually you can make a 340 out of these easily...truck ones back then were steel crank
 
Garrett Ellison said:
What rods did you run in it and how did the balance crank me out? I’ve inquired about getting a 360 crank cut down to 318 mains and no one wants to touch it. They say that way of building strokers went away when good parts became available a long time ago. Honestly, it would probably cost as much as some of the cranks that are available to remove the .3 off the mains of a stock 360 crank.
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Stock 273/318 floaters. The thin beam jobs. Crank was a leftover Mopar Performance piece from Chicago Connection. He inquired about machining a stock 360 crank and got basically the same reply you did. If I remember, no heavy metal used to balance crank. Holes drilled and counterweight shaved a bit.
 
For the OP... I can't help but to ask, what exactly is the intended purpose of this build and what heads are you intending on using?
 
Also, FWIW, we could have stuck with the factory compression height on the early pistons. They did come out of the hole a touch. With factory Magnum head gasket and head, I think ratio would have been 10 ish. The pistons used were very low hour marine units. This was a mostly used parts build.
 
A page and a half on a one hit wonder....
LOL.. :popcorn: ...
Welcome to the forum.., (if we ever see you again...)
 
Mtrhead said:
If you have an old truck 318-3 maybe 1968 casting...usually you can make a 340 out of these easily...truck ones back then were steel crank
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You may be surprised what you find thick walls in. I’ve got several 318 blocks that the core revision number is -3. One is a 1973 block out of a 3/4 ton automatic truck with a large B cast in the outside, another is out of a ‘75 half ton, and another is an ‘82 reman by jasper from a truck. All of them are thicker between the cylinders than a 1990 industrial 318 hydraulic roller block I have and also have blind head bolt holes. The late 318 block would take a 4.04 inch bore, no sweat. I could spend a week straight sonic testing this stuff and posting the findings here.
 
408 swinger said:
Definitely! We actually looked into using gen 3 pistons, but, couldn't come up with an easy/cheap way to make the pin situation work. Never really looked into different bushings. Small Block is .984 Gen 3 Hemi is .945. When we were done shaving the skirts, they looked just like a gen 3 piston.
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There are some Molnar late hemi rods with .984 pins that look like they could be usable in an LA with a little light machine work.
 
LOL... It'll be funny to see how far this goes and also which direction it goes LOL..
My last thread asking about an air filter is in a heated conversation about 3/4 cams right now LOL.
 
Before this goes off the rails because J Fag got involved, to the OP: Do it if you want to. It's your money, your project. Yes, what you want can absolutely be done. I have done it successfully. Because it's sentimental, cost and common sense be damned. There will be nay sayers. " Just do a 360 or a 340 or a 408 or a 390..... Blah, blah, blah....." Stay true.
 
slick69 said:
Hello I'm new here and this might be the end of me for even bringing this up but...... after a long search on the web I have not found what I'm looking for. I have a LA 318 that is sentimental to me so it is what it is. I am looking to stroke it 340-349 Cid. No more no less. I see a lot of stroker kits to get 390 but it's not what I'm looking for. I understand that this is a dumb thing to hash through but any help would be much appreciated!
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Why the 340-349 cu in spec?
 
I was originally intending to do a "Medioker Stroker" 3.58 stroke 318 for a light truck towing combination with an eye towards fuel mileage via a 3.08 gear GM HD rear and an A-999. But, I've finagled my way into a 5.9 Magnum so I'm curious what I may be able to accomplish with it along the same lines. Anyone out there ever put a 3.31 inch crank in one and bore it to 4.07 before? :lol:
 
Garrett Ellison said:
I was originally intending to do a "Medioker Stroker" 3.58 stroke 318 for a light truck towing combination with an eye towards fuel mileage via a 3.08 gear GM HD rear and an A-999. But, I've finagled my way into a 5.9 Magnum so I'm curious what I may be able to accomplish with it along the same lines. Anyone out there ever put a 3.31 inch crank in one and bore it to 4.07 before? :lol:
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Boy, you are a glutton for punishment! :)
 
Garrett Ellison said:
I was originally intending to do a "Medioker Stroker" 3.58 stroke 318 for a light truck towing combination with an eye towards fuel mileage via a 3.08 gear GM HD rear and an A-999. But, I've finagled my way into a 5.9 Magnum so I'm curious what I may be able to accomplish with it along the same lines. Anyone out there ever put a 3.31 inch crank in one and bore it to 4.07 before? :lol:
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I got a 40 thou 360 with a bum crank thought about installing a 3.31 crank before.


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Mopar 340 crank to 360 block Main Bearing Spacers. These bearing spacers can be used to de-stroke an engine in order to fit into a certain class of racing. They allow for better choices of connecting rod lengths and piston designs. The spacers fit into a 360 engine block allowing 318/340 bearings, rear main seal, & cranks to be installed. Requires line honing for final sizing
 
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Yes, I am somewhat familiar with the Hughes kit for that. I sold an early 360 for a friend to a friend here and it got converted with that, a ‘68 steel 340 crank, Molnar rods, and some dome TRW pistons. That’s one I’d love to duplicate!
More just joking around on the 340 magnum (well, as a tow motor anyway). It may be feasible with a set of replacement ‘73 style low compression 340 pistons, but closed chamber heads and above deck pistons with the current head gasket availability issues (probably up to .080 thick for the Magnum 9.58 deck height) can put a project like that into eternal limbo right now…
 
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Jadaharabi said:
Welcome aboard.
And it seems that the stroke it people have already attached themselves to your thread here. All they can think of is put a 4-inch arm in it. Personally I would say put a 360 crank in it check and see if it'll go to 4 inches on the bore and have a 360 that's my personal preference in this case. Once again welcome board have fun.
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That seems to get me where I wanna go.
 
slick69 said:
Hello I'm new here and this might be the end of me for even bringing this up but...... after a long search on the web I have not found what I'm looking for. I have a LA 318 that is sentimental to me so it is what it is. I am looking to stroke it 340-349 Cid. No more no less. I see a lot of stroker kits to get 390 but it's not what I'm looking for. I understand that this is a dumb thing to hash through but any help would be much appreciated!
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@Johnny Mac could likely give you some serious sage advice! Blue print has many motors here in FABO. While he is certainly not the only quality vendor on here he is one of the good uns!
 
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