Best 318/x-head /hyd cam combo

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OL DODGE

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So I planned on building this 318 in my Dart;I have the x-heads getting new stock valves,double springs,etc. I bought a new MOPAR 508" cam from Hendricks but upon opening the box found the brand new cam broken in 2-right about dead center!!!!!! This got me thinking that it may be a bad omen. For a street /strip would I be better off with my COMP .477/.480???? I have 4;30 gears , Hooker street headers with 2 1/2" dual exhaust.
It's a 2 door, no a/c,no carpet, manual brake car, 650 Holley double pumper, manual valve body 904.
The idea is to go mid 13s don't care about the MPH or the MPG
I haven't had it to the track with the present 360 heads because the guides are worn so bad that with the oil smoke coming out of it ,it looks like it 's Ford powered(Fords and oil-they either leak it or burn it) .
 
CC is to big. On the x heads. Lower compression = not good.
 
X2 on the compression. IMO I would say that the 2.02" X-heads are a bit more than the 318 needs. I'd recommend milled 1.88" J-type heads or 1.88" valves in 302 heads.
 
Since your rebuilding the 318, you'll need to grab a quality piston. Low compression can be an issue. It is not the end of the world. The bigger the cam the more compression you should have to operate the cam as intended.

You list the lift of the Comp Cam, but not the duration.
(Problem)

If your looking to up the compression for the 318, look to the KB line of pistons. They have slugs that can be used at zero deck height in Hyper or forged.

When it comes to the cam, the Purple cam has a duration @ .050 of 248*'s.
You now can look at other cam companies offerings in this duration range.
 
As stated those heads might be a little too much for a 318,my buddy runs a "smog" 318 with that comp cam and 1.88/1.60 heads headers manual shift 904 3.91's he's gone 13.75 in a '70 dart..the Mopar cam coming in 2 pieces might be a good omen their cams have never impressed me..
 
The duration of the Comp Cam is 268/280 advertised or 224/230 with a lobe sep of 110.
You guys bring up excellent points. My intent right now is for a motor to get me going quick again until i can afford a stroked 360 which is $$$$ down the road at which time i would sell the x heads. perhaps i haven't done enough homework -thinking this through and all. Some people say that bolting up x-heads will increase the compression ratio because of being closed chamber as opposed to the open chamber 360 heads that i have on there now. Hence the reason for the .508 cam. Thoughts??????
 
OL DODGE said:
The duration of the Comp Cam is 268/280 advertised or 224/230 with a lobe sep of 110.
You guys bring up excellent points. My intent right now is for a motor to get me going quick again until i can afford a stroked 360 which is $$$$ down the road at which time i would sell the x heads. perhaps i haven't done enough homework -thinking this through and all. Some people say that bolting up x-heads will increase the compression ratio because of being closed chamber as opposed to the open chamber 360 heads that i have on there now. Hence the reason for the .508 cam. Thoughts??????
Click to expand...

All 340 and 360 heads were open chamber and on the big side, including the OEM X heads - casting # 2531894. Indy has the aftermarket LA-X for shaft mounted rockers and MA-X for Magnum 318 and 360 replacements. Both are closed chamber. Maybe those people were talking about the LA-X when they said it would bump up compression. OEM Magnum, 318 and 273's had smaller chambers.
 
That's why I suggested the KB slugs for zero decking with the open chambered head.
I wouldn't worry an inch over having to much head with those X heads.
Though I suggest a bit more cam, a good bit. Look at a cam of at least 230*'s @ .050 or larger to run in the mid 13's.

My cam pick would be the Lunati 304A3 (AKA 10200313)
276/284 (231/239) - .514-.536 on a 108/102
2800-6500 rpm

What intake, stall converter do you have?
What size tires?
 
Are 340 heads too large?, I agree the not needed for mild build or semi built if willing to port.

The 318 head was originally designed for 273 45 cid smaller, a 318 closer to 340 size especially after a rebuilt.

He's willing to gear it, as long he's willing will to bump up the CR too.
 
Considering he first choose the Purple 292/509 cam with its duration of 248*'s @ .050, the cam he listed is more than just a little small. I listed a Lunati cam a bit closer to what the Car could use to run 13's to work better with the smaller cubic inches he has and the 4.30 gears. (A bit tall on gear IMO. Might need a tall tire.) With that cam, he is jut missing 2 things. Decent compression that is fixed by the zero deck height slugs in which the KB's go a long in fixing and a 3000-ish stall converter recommended by Lunati.

The 340 heads flow approx. 220 at max lift and is IMO a little shy of what he could use.
Between the 4.30 gears and the hi-stall of the converter, he will get moving quick. The engine will use up a lot of that head quick.

At this point, I feel that porting the 318 head is not cost effective over a preped 340 head. In which he could reuse on the 360 later. It would be my route to take and at least bowlmport the 340 head if not take it a little further. Yes! Even for use on the 318!
 
Presently I have a factory 73 Cast iron 340 intake-the heat risers are NOT blocked off.
I'm running a stock converter right now-the oe dart manual said stall was between 1800-2200 which WAS ok with the Comp cam BUT with the 508 cam I realize would not be nearly enough.
The rear tires are Radial T/A s 245/60r14 on Magnum 500s(14x7) i'm putting a taller 15 size on soon. Haven't settled on diameter yet and do not plan on moving the springs in just yet. On the street the 14" tire/4:30 gear is fun but impractical for the track.
The frame is tied(US Car Tool) and the battery is in the trunk.It hooks up nice on the street
The Holley has 69 jets up front/82s in the back and a 5.5 power valve. squirters aren't touched.
So at this point if i run the X heads with the cam I have(477-488) it may have the flow head wise but the cam won't optimise the flow and without more compression this is an excercise in futility?
So add compression bigger cam taller tire and looser converter
 
BTW, Hendrick sent me an e-mail saying to send back the MOPAR cam .
We'll see how this plays out with them-at least they are trying to make it right from their end. If it works out I will let others know.
As far as all the other advise goes, I really appreciate the input.
As I get older I realise that i'm a big dummy!
 
Ol'Dodge, that's what I would do.
If you want to use the smaller Comp Cam, the stock converter, intake and the rest of the combo will work well togther. The gear is way tall for the engine combo. And that would be the thing to change.

Low compression is not the end of the world. Better to have a good flowing head and low compression rather than the reverse.
 
rumblefish360 said:
Ol'Dodge, that's what I would do.

Low compression is not the end of the world. Better to have a good flowing head and low compression rather than the reverse.
Click to expand...

This exactly!!!! We have never put 360/340 heads on a 318 and lost performance, ever!!! Milling the heads ,040 is what I like to do, and nope, I did not mill the intake. Bolted it on and the bolts lined up better! Forget the cork end gaskets on the intake, use a thick bead of RTV
 
Well I got one for you.
Both times I put X-heads on LC 318s, with the dead stock 340 cams, I lost a ton of torque down low(sub 2400ish). Sure it made more on top. Sure I had passing power. Sure it was a dog below 2400ish. Sure the cure woulda been a higher stall converter and more gear.
The point is it lost torque down low.When the Dcr falls into the basement, so does drive-ability. You are then married to stall, gears , or a diet. Woulda been cheaper to fix the compression right from the get-go. JMHO.

EDIT.
OK, one of these was in a 71 Monaco.With a 2200 stall convertor and 2.94s. Not the best comparison. But the right one to bring out the torque loss. And that car wasnt nearly as fat as it looked.
 
^^^^^^^ usually when you add bigger cams, more flow heads, you will loose a little off the line. But I will tell you this, my experience is doesn't make it a bad driver at all. Traction was still a problem, and that was with stock converter and 3.21 gears.
 
318willrun said:
This exactly!!!! We have never put 360/340 heads on a 318 and lost performance
Click to expand...


I did 76 truck 318 with 340 cam, 360 heads intake and 305 carb, stock single exhaust, it definitely picked up a bunch of power. My cousin put his dads duster 4 speed back on the road with smokey 318 bottom end with his dads fully ported T/A heads, LD340, 750 and some cam laying around, sounded pretty healthy, it worked really good especially when he swapped 3:23 to 3:91 that really woke it up. Plus he needed to fix the 340 short block on his late model so he just swap carb and intake on the his duster 318 and kept up with the pack.
 
AJ/FormS said:
Well I got one for you.
Both times I put X-heads on LC 318s, with the 340 cams, I lost a ton of torque down low(sub 2400ish). Sure it made more on top. Sure I had passing power. Sure it was a dog below 2400ish. Sure the cure woulda been a higher stall converter and more gear.
The point is it lost torque down low.When the Dcr falls into the basement, so does drive-ability. You are then married to stall, gears , or a diet. Woulda been cheaper to fix the compression right from the get-go. JMHO.
Click to expand...

Dead stock 340 cam or a Purple upgraded cam on a 110?
Other cam manufacturer used?

Reason I ask is that the OE 340 cam is still a pretty mello bump stick. I have never heard of anyone complain of its use in a 318.
 
I just got a replacement cam from Hendricks today in the mail-they really went out of their way to warranty the Broken cam-I am very impressed because of the time that had passed since I bought it. They took care of it including shipping and will do MOPAR business with them again. (today is Feb. 27th- I sent the defect back on Feb 23rd)
 
With either cam, install the 4.30s. Then you won't have to weat the convertor...
 
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