Add hotter cam or Add hotter head ?

which swap nets the best ET ?

  • A better cam for the win

    Votes: 22 78.6%

  • A better head for the win

    Votes: 6 21.4%
  • Total voters
    28
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318willrun

318willrun

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Per sake of the discussion, let's say the car is a '72 Duster, 318 with and addition of 600 eddy carb on a performer intake and 2.25" duals ran out the back from the stock manifolds. The car has a 904, and 3.23 gears. All in good working condition.
*WHAT MOVES THE CAR QUICKER IN THE QUARTER MILE?
- A hotter cam, any cam and lifter kit you can buy or have custom ground.
- A hotter head, any head is the option including trick flows.
- no other changes to the car can be had.
 
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Cam is the throne of all the timing events that is so important to an engine. Heads are the throat leading to the lungs, and we all know what happens when you squeeze the throat, you get a hung lung.
 
Ok I'll say it,They work hand in hand.Need both.
BUT, Budget plays a big part.Thus many would cam first.
 
Darter6 said:
Ok I'll say it,They work hand in hand.Need both.
BUT, Budget plays a big part.Thus many would cam first.
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Lets say money isn't an issue. one shot at best ET. Could go custom ground head to match the rest of the set up, or get the best head possible for the car.
 
318willrun said:
Cam is the throne of all the timing events that is so important to an engine. Heads are the throat leading to the lungs, and we all know what happens when you squeeze the throat, you get a hung lung.
Click to expand...
Catch 22. If you can only do one, the right cam to match the rest of the combo will make a bigger difference I think. I had my heads done and kept the compression and cam relatively the same. It runs about like it did before. (seat of the pants dyno)
 
I would want more information to come to a decision,engine details.
Stock cam?
Stock heads?
 
Cam all day. I don’t see the stock cam getting much use out of the extra flow of better heads. Low compression, and the stock gearing/stall are going to limit your cam choice, but I think it will provide the biggest gain.
 
Cam

With the increased duration moving the RPM up closer to where you want it to compliment the rear gear and tire combo, the increased torque made will accelerate the car quicker off the line and down the track.

As cast, the stock heads are not taxed for there airflow.

The increased lift is also a plus even though everything remains stock. The OE heads valve job is not even really fully used with the stock cam. Maybe if the cam goes past .400 lift but I don’t remember all the OE 318 cam lifts. The valve job is most responsible for lifts to .400.

Going higher in lift actually uses the bowl area. In order to see the gain on paper you’ll need to research stock 318 head flow & take note of how it flows past .400. But here is where “More the Merry” comes into play.

Using stock head valve sizes, the math says a LSA of 107.67.
An off the shelf cam that has this “107” number is a Thumper by Comp. You can go 1 degree ether way and be hard pressed to see a difference worth mentioning.

Many years back the ‘79 - 318 (7.8-1 ratio measured) I fooled around with was in a ‘74 Duster w/a 904 & 3.21 gears on stock tires did make it into the 14’s while being seriously challenged by the stock tires, stock distributor and the OOTB untuned carb.

The cam was a Crane on a super wide LSA of 112 and the following spec’s.

216/228 - .480/.484

A move to a better cam and wider tires never came around.
 
I can tell you this much, from my families experience and others that I know that have done this.... putting stock good 340 heads on a 318 really... really wakes them up. !
 
318willrun said:
I can tell you this much, from my families experience and others that I know that have done this.... putting stock good 340 heads on a 318 really... really wakes them up. !
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I did stock 360 heads with a an erson 292 .441" lift on my 74 318 I had and it was a dog anything under 3,000 rpm but would come on strong until the valves floated at 5 grand
 
toolmanmike said:
Are you trying to start a riot? :poke: :lol:
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No, for sure no!! Plenty of that now !!! I will say from experience, that small chamber 340 heads on a 318 with just a 4bbl on top is a huge change in the performance of the car. I can also say, I've just cam swapped a 318 4bbl, all else stock, and found some pull on the upper end of the RPM's, but I believe from my experience the heads have made "more" of the difference. I was curious of others experience.
 
318willrun said:
No, for sure no!! Plenty of that now !!! I will say from experience, that small chamber 340 heads on a 318 with just a 4bbl on top is a huge change in the performance of the car. I can also say, I've just cam swapped a 318 4bbl, all else stock, and found some pull on the upper end of the RPM's, but I believe from my experience the heads have made "more" of the difference. I was curious of others experience.
Click to expand...
Why not both? Lol
 
Stock manifolds?, stock cam?, stock heads?, your screwed, I say option c= nitrous! :lol:
 
318willrun said:
I can tell you this much, from my families experience and others that I know that have done this.... putting stock good 340 heads on a 318 really... really wakes them up. !
Click to expand...
its was in the dc booklet under 13 second 318 build section
318 headers 2 1/2 exhaust 340 j heads 213 purple shaft torker 650 dp spray 3.23s 727 shift kit
1968 dart 270 i won alot of money with that setup paid for the car and all the parts plus more
the heads added bigtime reved nicely to 6200 really needed 4.10 gears but i loved top end racing then
4 wheel drums awfull@130 mph
one of the best sounding mopars ive had
 
abdywgn said:
Cam and kit, port stock heads and exhaust manifolds.
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yes, that works. But that is like saying "edelbrock heads, and send the stock cam out to get custom ground". Out of the parameters of the 1st post. Heads or Cam ? All else stays stock. You can match the springs with the cam recommendation.
 
not really. only money you are out is gaskets. or is this the "one piece at a time" test? in that case, cam and kit. do the heads in the next testing stage.
 
abdywgn said:
not really. only money you are out is gaskets. or is this the "one piece at a time" test? in that case, cam and kit. do the heads in the next testing stage.
Click to expand...
it isn't about money. It's hypothetical question. "Which lowers the ET more: A good head on the stated above car or a good cam?
 
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