318 Cam Suggestions

[Airwolf222b]

Hello again everyone. Still working with my 73 Roadrunner with a 318. I'm looking at upgrading the stock cam. The engine runs great, but as per most folks around here, I'd like a little more power.

Right now I'm working with an almost stock engine with some bolt on upgrades. I've added,

PerformerCarburetor #1406 600 CFM With Electric Choke

EdelbrockPerformer Intake Manifolds 2176

HeadmanHeaders Ceramic Part # 78056
8.25 rear with 3.55 gears.
And dozens of other standard things like plugs, wires, ignition etc.

Next I'd like to look into a mild to semi mild cam. I don't really know where to go from here. I guess I'm asking if anyone has a smiliar setup with upgraded camshaft. How were the gains? Are you happy. Do you wish you would have left "well enough" alone? Which specific cam did you get?

 

[Cop car wagon]

Unless you bump compression, stay with a 252° duration.
Look in the RV selection by cam manufacturers.
Nothing worse than too large of cam making NO power.

 

[w.Hudson]

I've ran a hydraulic Isky cam in several 318's that made good power and sounded great

It was a 280 duration with .480 lift

Only drawback was to have it idle in gear it wanted more initial timing and at least a factory high stall converter.
I don't remember the duration at .050 but I do recall advancing the cam timing 4 degrees when I set the centerline.

 

[Cop car wagon]

Food for thought. Early pre 69 318 have a higher compression than 72 up.
The OP's 73 is advertised at 8.2, and probably lower.
A static compression test might answer alot.
My bet is cranking comp is 120 psi

 

[WileE]

I'd consider attention to the heads. Years ago, we'd go to X or J heads, but nowadays it would be the aftermarket to look at.

 

[Rebelrouser]

Hello again everyone. Still working with my 73 Roadrunner with a 318. I'm looking at upgrading the stock cam. The engine runs great, but as per most folks around here, I'd like a little more power.

Right now I'm working with an almost stock engine with some bolt on upgrades. I've added,

PerformerCarburetor #1406 600 CFM With Electric Choke

EdelbrockPerformer Intake Manifolds 2176

HeadmanHeaders Ceramic Part # 78056
8.25 rear with 3.55 gears.
And dozens of other standard things like plugs, wires, ignition etc.

Next I'd like to look into a mild to semi mild cam. I don't really know where to go from here. I guess I'm asking if anyone has a smiliar setup with upgraded camshaft. How were the gains? Are you happy. Do you wish you would have left "well enough" alone? Which specific cam did you get?

as others mentioned when picking a camshaft cranking compression is important. As the duration increases the dynamic or cranking compression goes down, too much duration on a low compression engine and you get a pig. I have been using hydraulic roller cams because you can go with a shorter duration with a higher lift and get big increases in torque without killing cranking compression. 220 duration with .520 lift and 110 center line installed at 106 is something I have used on a lot of street builds. Plus, they don't go flat. Everybody seems very happy with the results.

Your best bet is to buy a good engine program and start playing with different cams to see what your engine would like. I use performance trends engine analyzer. The program will predict cranking compression and lot of other stuff.

 

[RJRENTON]

Hello again everyone. Still working with my 73 Roadrunner with a 318. I'm looking at upgrading the stock cam. The engine runs great, but as per most folks around here, I'd like a little more power.

Right now I'm working with an almost stock engine with some bolt on upgrades. I've added,

PerformerCarburetor #1406 600 CFM With Electric Choke

EdelbrockPerformer Intake Manifolds 2176

HeadmanHeaders Ceramic Part # 78056
8.25 rear with 3.55 gears.
And dozens of other standard things like plugs, wires, ignition etc.

Next I'd like to look into a mild to semi mild cam. I don't really know where to go from here. I guess I'm asking if anyone has a smiliar setup with upgraded camshaft. How were the gains? Are you happy. Do you wish you would have left "well enough" alone? Which specific cam did you get?

First, define what "mild to semi mild" cam means? Second, what are your expectations, third, what is your budget, what is the intended use of the car?........just my opinion.....
BOB RENTON

 

[68-500]

Stock 340 cam should be a nice upgrade.

 

[496 polara]

3-8-Teen Dream

Something like the Comp XE256 (or similar specs/brand unimportant) with NEW VALVE SPRINGS will make a nice responsive package. Sure you can go one step bigger with the cam and find yourself wanting a better torque converter,then head work,etc,etc.

 

[jeepthrills01]

If you can still find one...the VooDoo 702 is a nice cam for a teener. I've seen them in the jungle.

 

[toolmanmike]

Hello again everyone. Still working with my 73 Roadrunner with a 318. I'm looking at upgrading the stock cam. The engine runs great, but as per most folks around here, I'd like a little more power.

Right now I'm working with an almost stock engine with some bolt on upgrades. I've added,

PerformerCarburetor #1406 600 CFM With Electric Choke

EdelbrockPerformer Intake Manifolds 2176

HeadmanHeaders Ceramic Part # 78056
8.25 rear with 3.55 gears.
And dozens of other standard things like plugs, wires, ignition etc.

Next I'd like to look into a mild to semi mild cam. I don't really know where to go from here. I guess I'm asking if anyone has a smiliar setup with upgraded camshaft. How were the gains? Are you happy. Do you wish you would have left "well enough" alone? Which specific cam did you get?

There are 7 pages (or more) of 318 cam threads over at FABO. Just use search and type 318 cams and click on the title option.

 

[Geoff 2]

There are better cams than the stock 340 cam because the factory had to compromise.
My advice: it is real easy to put in a cam that is too big. It is much harder to pick the 'right' cam that gives you the extra performance but not at the expense of drivability.

You have already picked, nice, complementary parts. I would use the Isky 270 Mega cam, works with stock c'ter. Isky makes great cams. Do NOT buy lifters, they are made of Capanium [ it is pure Crapanium though....]. Have your current lifters refaced if you do not want cam/lifter failure.

Remember it is 318, not a 418 or 518. Never going to be a world beater, so choose wisely....

 

[Airwolf222b]

Thanks for all the great suggestions. To answer a couple questions I guess I would like to see if I can get another 30HP or so out of it without any major work. I also know I've got a lower compression engine due to it being a 1973 so I'm just hnt sure what my best options would be. So I'm not looking for a drag strip car, but a little more fun to drive would be great. Right now it's a wonderful daily driver. But its "get up and go" wouldn't be much better than driving a honda or toyota. It's got plenty of power to get moving but nothing too fun if that makes sense. Budget would be somewhere between $1000-$1500.

I guess I'm asking, if you inherited this car today and wanted an increase in power and torque, what would you do?

 

[toolmanmike]

Thanks for all the great suggestions. To answer a couple questions I guess I would like to see if I can get another 30HP or so out of it without any major work. I also know I've got a lower compression engine due to it being a 1973 so I'm just hnt sure what my best options would be. So I'm not looking for a drag strip car, but a little more fun to drive would be great. Right now it's a wonderful daily driver. But its "get up and go" wouldn't be much better than driving a honda or toyota. It's got plenty of power to get moving but nothing too fun if that makes sense. Budget would be somewhere between $1000-$1500.

I guess I'm asking, if you inherited this car today and wanted an increase in power and torque, what would you do?

View attachment 1886450

View attachment 1886452

View attachment 1886453

It has all the what I will call the level 1 and 2 parts on it. (intake, carb, headers, dual exhaust). You may want to pull your distributor out and send it to @HALIFAXHOPS and have him recurve it. It can make quite a difference. What rear gear are you running? A 3:55 will wake it up and still allow you to highway cruise at a reasonable rpm. The next big addition would be cam and heads. The cam really needs to be matched with the heads or you will be doing that modification twice. There are thousands of cams out there and there is no "Perfect cam" The heads are for increased compression and efficiency. Closed, chambers, larger valves, and bigger smooth flowing ports will get you there. The only other way to build compression is with pistons. Unless you want to build the engine from the ground up, leave what you have in there.

 

[Unkle Krusty]

I asked Edelbrock what to use, and they suggested a Performer, which is the same name they call a lot of things. I have the same carb but with a manual choke, same manifold.
Electronic ignition. No mods to the stock exhaust until it fails.
If the stock cam has the fibre gears, I suggest removing it as soon as possible. Replace with a new double row chain and new gears. My heads are still stock, bout oil consumption has increased with the umbrella valve guide seals.
We are 6700 pounds loaded, and definitely needed more giddy up. I also put in a shift kit, in the 727.

 

[71Beeper]

Going to a 340 or 360 head requires more than just putting the heads on it.

Because of the chamber volume and port size on the 340/360 heads it will drop the compression ratio on your 318 by 1 point!
So if you have a 8.5:1 now, it will have a measly 7.5:1 with the other heads on it.....not good.

But if the budget allows a new set of pistons, then a head swap is a good thing. Zero decking is another option to up the compression.
I agree with the others here, with going with a 340 cam or one that's similar and switching the rear gears to either 3:23's or 3:55's.

 

[Airwolf222b]

I currently have 3.55 gears. when you say 340 cam are you talking about the stock cam out of a 340 LA Mopar and leaving my exsisting heads?

 

[DeltaV]

Budget would be somewhere between $1000-$1500.

I believe your stated budget prohibits you from using different heads.

 

[Airwolf222b]

I believe your stated budget prohibits you from using different heads.

I'm not sure exactly what they go for. I could do more if I had to but thats where I'd be comfortable.

 

[Airwolf222b]

Summit Racing SUM-6920 Summit Racing™ Muscle Car Replacement Cams | Summit Racing

Would something like this with my current set up work?