318 build up

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JohnWayne

JohnWayne

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For a time now I have been thinking of changing my old 273 mill to a little more powerful 318 in my ´65 Barracuda.

The 273 was very low on compression, 6.5 in seven cylinders and 7.5 in one.

I was suspecting head problems and I swapped my stock 273 heads for a set of 318 with the 714 castings. Should be the same as 302.

My Barracuda came to live again and it feels like 50 horses stronger. The compression is now 7 on one cylinder, 8 on six cylinders and 9 on one cylinder.

That is not optimal, but much better that before.

But still, a newbuild 318 would be the game :)

I´m not a motorhead, but I´m going to do as much work I can manage anyway.

So therefore I would like your tips, ideas and thought about this.

The goal is a reliable, strong engine, not a race-engine. The transmission is a four speed A-833.

No parts are decided yet, but the 714 heads is going to be used.

A friend of mine has a 318 block (I do not no what year) and another friend has a 318 forged crank that I think would be good.

I hope you have may thoughts about this and are willing to share them with me.

Regards JohnWayne
 
Just curious......how did you arrive at those compression figures for each individual cylinder?
 
What about going with a 360. Cubes IS king. You WILL not regret that decision. quench/dual plane intake/600 eddy/early mag or 68-70 340 HP ex manis/mild home porting/mandrel bends. pretty much only needs the BM 10239 flexplate/crank bushing (torqueflite patty) and minor mtr mt mods. EDIT missed that he is in europe which would change parts availability.
 
Well, I too, often jump on the more cubes is better.However, this time, Im having other thoughts.
Those early Barracudas are around 400 lbs or so lighter than the 2nd generations. That means the equivalent of pretty much 40 cubic inches.So a 318 is almost equal to a 360.
Then theres the tire fitment issue. Not much fits back there.Certainly not enough for a healthy 360.
Then theres availability. John doesnt live in America,home of plentiful iron.
And then theres the budget. Stuff from friends is mostly free.
And finally, John said "no parts are decided yet, but the 714 heads is going to be used." Thats a pretty definitive statement.
So it looks like this is how it may be;
The 714 heads,the free 318 block, and the free forged crank.Thats a pretty good start.

The very early 318s had the same early 273 rods, so if this is going to be a lo-performance teener, you can use your rods. If your gonna abuse it, then a switch to the later bushed rods would be better.Those late318 rods have the same casting numbers as the 340/360 rods. However the 360 rods are a press-fit pin.The floating-pin 340/318 rods allow you to assemble the pistons onto the rods yourself, and makes later piston mods easier.
Next is pistons and rings. This is the place to spend some money. Now,again,we come against the budget.If you see more performance in the future, I highly recommend a zero deck. This allows for a tight quench,closed chamber head design which will really wake that teener up.To that end, I recommend a piston,tall enough to be machined down to be fit the decks, and thus making a zero deck engine.If the 714s are an open chamber design, then I would buy quench-dome pistons and carefully fit those in there. They can be machined down at a later date,to zero-deck for a closed chamber hi-perf head, if the opportunity comes up. And in the meantime, you can reap the benefits of sorta tight-quench and hi-comp. I dont know what octane fuel is available out there, so this will have to be engineered by you.
Its hard to get a decent Dynamic compression ratio from the teener with its smaller bore,short stroke,flat-tops, and open chamber heads. Knowing this, the Static c/r and the camshaft need to be carefully co-ordinated. Those two are very nearly married.If you allow the Dcr to fall too low, the off-the-line performance will also fall, and you will forever have to rev it up and slip the clutch to get moving. That gets old in a hurry.So to that end,get the Static c/r up, Then you can manipulate the Dcr, with the intake closing point, so that you can use the available gas.
To illustrate this; Say,you can get the Scr up to 10.8,then to get the Dcr down to 8.5 for 93octane gas will require an intake closing point of 65*ATDC. Thats a pretty small cam. And requires a pretty small TOTAL chamber volume of 67.5cc,also pretty small.(thats about a 60cc head,an 8.5cc FellPro blue, and +.005deck flat-tops ). I told you it was hard.
Here is another combo;The 57cc chamber head and the .020 gasket.
However this combo does not suffer zero decks. The piston would need to be dropped about .015 down, to get .035 quench(piston to head clearance).This would get you 11.25 Scr, and with a 70*ATDC point would net 8.5 Dcr This is about a 1 size bigger cam.
For me, I would just bite the bullet, and buy a custom cam.

The point is this; if the 714 heads are open-chamber, I think you are really limiting your build options. Both combinations here illustrated are with the early closed-chamber oem iron heads.
EDIT;This from MoparTim; "714 heads are closed swirl port head with factory hardened seats." So it looks like you are good to go.

Having said all that,John, Many guys have been happy with a 268Comp cam in a low-compression teener. At your curb weight, you could be too.
Im wishing you every success
So now you have, or nearly have, a compete long-block.
 
scooby67 said:
Since he's in Europe, the reading might be in BAR. 7 bar = 101 psi.
Click to expand...

Thanks Scooby. I think you're right. I ran a conversion real quick and that's what it appears. I missed that he was in Finland. Good eye.

Probably also why he is looking at a 318. 360s are probably hard to find.
 
...which also likely means his choices will be strictly budget limited. Shipping tariffs are terribly high.

Given the opportunity, best likely choice for slugs will be the KB flat tops (#167 I think) since they only require a minimal cut to the deck to achieve zero which will net you good quench and similarly healthy compression in your 318. They're also pretty light and should mate well to the lighter duty 273 rods (if that's the direction you choose).

If you can afford to put in some effort, churching up the heads will be where you can make really appreciable and felt gains. Just some modest seat, bowl, and port work will net you the spirited feel you likely want.

Just read on here...a lot. I'm pretty sure there's over 100 builds where people spruced up their 318s, and I know I've seen a couple folks on here from your part of the globe trying to do the same.
 
714 heads are closed swirl port head with factory hardened seats. MT
 
Thank you all for the concern of my humble tread. I´ve never tought I would get so many answers in such short notice. I´m very much obliged to you all.

The numbers are in bar, yes. I forgotten that you mesure in psi, sorry.

360 make more power, but are more rare here. 340 cost their weight in gold. 318 are almoust free. And I already got the heads (closed chambers swirl port just like MT sais). I think the 360 needs even better heads.

The octane here in Finland is 98 so I can have a higher comp.ratio.

The friend who has the crank also has a set of almoust new TRW L2329. What do you think of them?
 
How does Finland figure its octane ratings? Research Method or Motor Method? Like us using R+M divided by 2?

Bob
 
I think those will work very well with your heads and the available gas. Should make for a strong 318 as long as all the other parts match.
 
IIRC, his 98 is = to 93 here.

Build idea #1.

Replacement pistons (Badger) with a mild cam, 4bbl. intake 600 carb, small cam.

Build #2.

KB Hyperutecics with a zero deck height & a more agressive cam, headers.

Vauge descriptions I know, but more of a pathway to decide on.
What is the trans and gear ratio/tire size?
I know you said not race car build but sturdy & reliable is the course for the build. I'm just trying to get a deeper feel/understanding of where you want to be up.

To much cam kills a build. I'm wondering where (RPM) you want to end up at while cruising down the road.
 
He has some pistons listed. They are 4 eyebrow flat tops.
 
I would use your forged crank from the 273, it has the right pilot shaft for your 4 speed, plus it's stronger. You say your using the heads, so I would just do a re-ring kit for the rest (rings, bearings, oil pump, gaskets, timing chain, lifters and freeze plugs). I doubt you will need a new cam, although you can check. Pistons are not a "must", only a performance upgrade. You said you did not want a race car, so I would just do the basics and save money.
 
I have a nice forged crank out of a 66 318 out of a van. So not only 273s got the forged steel crank. MT

another indicator was it used a SB 727.
 
Mopar Tim said:
I have a nice forged crank out of a 66 318 out of a van. So not only 273s got the forged steel crank. MT

another indicator was it used a SB 727.
Click to expand...
Of course some 318's and 340's had forged cranks, but no need to go look'n if he has one sitting in his lap... especially one with the right pilot bearing....
 
At his level of build and target goal, a cast crank will be fine.
 
rumblefish360 said:
At his level of build and target goal, a cast crank will be fine.
Click to expand...
Agreed! You can spin a 318 cast crank to 7k all day. But don't the auto's and manual's have different size pilot bushings? Means his is a 4 speed, he will need a 4 speed crank or I believe they sell an adapting pilot. He asked the question "what other thoughts" about the 318 swap. I thought the forged 4 speed crank would be about the only thing....
 
The cast crank can be machines if need be.
A Dakota pilot bushing will do.
 
rgp266 said:
How does Finland figure its octane ratings? Research Method or Motor Method? Like us using R+M divided by 2?

Bob
Click to expand...

I must say, I have no idea. It´s first time a hear that is more than one method to mesure octane figures :???:
 
rumblefish360 said:
IIRC, his 98 is = to 93 here.

Build idea #1.

Replacement pistons (Badger) with a mild cam, 4bbl. intake 600 carb, small cam.

Build #2.

KB Hyperutecics with a zero deck height & a more agressive cam, headers.

Vauge descriptions I know, but more of a pathway to decide on.
What is the trans and gear ratio/tire size?
I know you said not race car build but sturdy & reliable is the course for the build. I'm just trying to get a deeper feel/understanding of where you want to be up.

To much cam kills a build. I'm wondering where (RPM) you want to end up at while cruising down the road.
Click to expand...


Today the car has a weak 7 1/4 rear but a 8 3/4 with lock waits in the garage. If I´m not misstaken it could be a 3.23.

What rpm when a drive 100 km/h (60 mph) I do not know. The wheels are 14" Cragar SS with 235/60 tires.
 
318willrun said:
Of course some 318's and 340's had forged cranks, but no need to go look'n if he has one sitting in his lap... especially one with the right pilot bearing....
Click to expand...

This is a long time project because the garage is occpied by my restoration of the Meteor ´59. Therefore I was planning to build the Barracuda-engine while driving the Barracuda, therefore a need two cranks. Otherwise I think the 273 would get the job done.

But where do I find the adaptors between the A-833 and the 318 crank?
 
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