318 build with XE268 AND 302 heads

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megavites

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Full disclosure...I'm new to Mopars.
I have a 318, good compression that I'm planning on using a set of 302 rebuilt heads.
I'm looking at the Comp cam XE268H.
Comp's website says this needs adjustable valvetrain. I thought I've seen others here run this
cam with the stock rockers.
If this cam needs adjustable rockers, what's a good "afordable" option?
I saw these...DODGE CHRYSLER 318 340 1.5 ADJUSTABLE S. STEEL ROLLER ROCKERS
Stock springs will be used for break in..comp springs for final assembly.
 
If this is basically stock, you may want to consider the XE262 instead. You are going from .373 and .400 to .474 and .480, so adjustable may be unavoidable with the 268. Comp also says a 2000 converter is ok. Ya need a lil more.
 
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Needing adjustable rockers for the 268 is news to me......
That cam wouldn't be my first choice.
 
more than stock. Holley 600, dual plane intake and headers, dual 2.5 exhaust.
Looking for the right cam for good low end torque. Just a stop light to stop light car.
I was under the impression that the xe268 was popular with 318's. It has a nice lope as well.
I was also looking at the Huges Whiplash, but the 302 head bring compression up to 9:1. Whiplash wants 8.5 or lower.
I'm open to cam suggestions. Not looking for top end HP, just bottom end torque and nice lope
 
The 262 is a much better choice if thats the case. When I first installed the XE 268 in my 360, once around the block and I realized The 3.23 was about to be 3.73. And a Coan 2500 converter. That fixed things, and I dont even have the compression you do. In a teener that cam will be a dog off the line. I had a 256/262 Voodoo in previously, that moved well stoplight to stoplight. I'm guessing you have a 904?


Another consideration without too much duration. It wont be lopey, but it will move you when you nail it off the line.
20-210-2 - High Energy™ Hydraulic Flat Tappet Camshafts
 
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megavites said:
more than stock. Holley 600, dual plane intake and headers, dual 2.5 exhaust.
Looking for the right cam for good low end torque. Just a stop light to stop light car.
I was under the impression that the xe268 was popular with 318's. It has a nice lope as well.
I was also looking at the Huges Whiplash, but the 302 head bring compression up to 9:1. Whiplash wants 8.5 or lower.
I'm open to cam suggestions. Not looking for top end HP, just bottom end torque and nice lope
Click to expand...
  • You don't know what the compression is unless you cc'd everything
  • xe268 is not the low end cam to choose, especially in a 318. If you put that in you 318, better have a better than stock converter and something of at least 3.23 gears.
  • Unless you get a cam like the Whiplash, then your request is kind of "off".
  • The "lopy idle" your looking for is usually found in cams moving the power band up..... kind of opposite of your "not caring about to end power, only low end torque.
 
I think The reason for the adjustable valvetrain is comp made their base circle smaller. They changed the suffix in (at least) their hyd flt tappets. When I called to ask why I couldn't get a certain part # that's what they told me. So now, not only do they grind them all on a 110 Sep angle, they all have the same base circle. Generic saves money!
 
318willrun.....
check out this vid of a 318 with the xe268..pretty nice idle
 
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Well, you don't necessarily have to spend that $$. I don't see why you could'nt just order custom length pushrods for a lot less $$.
 
megavites said:
Full disclosure...I'm new to Mopars.
I have a 318, good compression that I'm planning on using a set of 302 rebuilt heads.
I'm looking at the Comp cam XE268H.
Comp's website says this needs adjustable valvetrain. I thought I've seen others here run this
cam with the stock rockers.
If this cam needs adjustable rockers, what's a good "afordable" option?
I saw these...DODGE CHRYSLER 318 340 1.5 ADJUSTABLE S. STEEL ROLLER ROCKERS
Stock springs will be used for break in..comp springs for final assembly.
Click to expand...

I agree with the guys.
And IMO you should rephrase this opening post to query your application's needs. If you are a newbe I fear you are about to drown, in disappointment.
Putting a 268 in a low compression is the fastest way to blow an awful lot of money.
You cannot marry a lopey cam to a low Scr, a stock TC, and anything less than 3.55s.
So let's maybe start again . Here is a pattern;
I have a 73 Dart with a 318,an automatic and I figured out it has a 2.76 rear end. It seems a little sluggish.I'd like a little more performance out of it. It is a city only car and will only be rarely driven on the hiway for no more than 30 minutes atta time.I have $1000 to spend.What would you suggest.
>That is about as clearcut a request as could be possible, and makes the answer exactly one paragraph long, and instant results for you.
So now you try it.
 
AJ..Ok, I hear ya.
Hi..I have a 76 318. Planning to add 302 heads. will add headers and dual plane intake along with 2.5 exhaust.
Stock rear is a 2.76, but that will change.(probably 3.55) Auto 904.
I love the sound and specs on the XE268 cam. Any cam kit runs $400-$500.(springs,lifters,chain,cam)
I could spend under $500 on an adjustable rockers......IF that's what's needed for the XE268, but not a grand. If that's the case, then I need to go with a diff. cam.
I appreciate the input.
 
BTW, your static CR will be no better than 8.6 IF you have 318 flat top pistons, AND you use the Mr gasket 1121G head gaskets . If you have the 318 pistons with 4 valve reliefs and standard Felpro head gaskets, then your SCR will be 7.5:1.... I ain't fooling you. So that is why going with too much cam will suck.... the late closing intake of the longer duration cam will KILL the compression and it will indeed be a dog in the low RPM ranges. A rumbly idle will come at a very high cost to low end torque with your engine.

What were your cranking compression numbers? Is this a Magnum 318 perchance? (Not if you are looking at the rocker set that you linked.) If you have the heads off now, see if the pistons are flat top or have 4 valve 'eyebrows'.

Honestly, I would be looking a 256 to 252 duration cam from the Voodoo series for this thing and wanted good low end torque. I have run that kinda of cam before and it is where you want to be for torque and a stock torque converter. The 268 duration level cams are a compromise cam but you need some real CR to work with it well down in the low RPM's. Guys use it because they may drag race and they are spinning up the engines anyway and putting in a higher stall speed torque converter does not hurt that situation.

If you can let us know about the pistons and the present cranking compression, then better advice can be given. But all the advice so far is honestly on target for what you want to do with your engine.
 
BTW, 318willrun oughta be able to tell you about the adjustable rockers and the 268.. he is one of the kings of doing a lot with a little. 273 rockers ought to work OK too; different pushrods though.

Spend the $$ on some headers and the engine will sound great, 'specially whne you light it up, and it will help torque and power all across the RPM's. That is money better sent for sound AND performance.
 
megavites said:
318willrun.....
check out this vid of a 318 with the xe268..pretty nice idle
Click to expand...

yeah, I've heard 'em before. sounds nice. I've had 318's idle "rougher" than that. Shoot, throw an old MP 484/284 cam in. that will work with your valve train and give the noise you want. But throw out your low end torque request with it. I think that was the point I'm making.
 
Checking in as I am looking at a similar 318 build.
Reason for the 318;build...I did the exact same thing to a low compression 273. Comp 270S complete kit. Over cammed the damn thing. Has no bottom end.It now has LD4B eddy 1405. No bottom end.
Hope to not duplicate my stupidity on the 318 build.
Good luck!
 
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Me as well. 70 teen and I have a set of 302's, LD4B and a 600 Edelbrock. I have dual exhaust but would like a pair of 340 manifolds and some nice exhaust. Oh ya, 904, stock converter, and 3.23's. I might just put the intake and carb on it and forget the rest. From all I have read there is no magic bullit cam for teens.
 
I agree with the recommendations to use something lighter than the XE268 cam. I have that cam in my 69 Barracuda 340 4 speed, 3.55 gears, Eddy Air Gap, Eddy 650 Thunder series carb and Headers. It is a sweet cam, but it might be a bit much unless you are planning to match my other performance upgrades. BTW, you do NOT need adjustable rockers. My XE268 runs fine without them.
 
harrisonm said:
I agree with the recommendations to use something lighter than the XE268 cam. I have that cam in my 69 Barracuda 340 4 speed, 3.55 gears, Eddy Air Gap, Eddy 650 Thunder series carb and Headers. It is a sweet cam, but it might be a bit much unless you are planning to match my other performance upgrades. BTW, you do NOT need adjustable rockers. My XE268 runs fine without them.
Click to expand...
Nice cam for a 340. Too big for a stock, low compression 318 like the op has.
 
I don't have any issues with it in a 318, it sucks off the line unless I load the converter (needs gears).
 
Speaking of overcamming... 40 years ago, I once put a 300*+ duration cam in with a 7.6 static CR.... it was DEAD below 3800 RPM... I mean TOTALLY DEAD. The only reason I could race on it was that the engine was good to 8000 RPM all day long. (1.9L Opel, all forged bottom end, short stroke.) So I could rev the snot out of things, slip the clutch like nobody's business at launch, and get somewhere. But the 2:1 ratio of max to min usable RPM's really sucked for the racing I was doing with a manual trans; the drivetrain would fall off the lower end of the torque curve at the 2-3 upshift step; it was a real dog there and going uphill around 55 mph I was back and forth between 2nd and 3rd and not building any speed. Took me years to learn why... now the internet and a site like FABO is a great source for learning about this type of thing BEFORE spending the $$ on a disappointment.

But the sound of the high revving engine was good in way ... .everybody KNEW when the blue Opel was coming LOL! But I gave up a lot of finish positions with that thing.
 
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