I want more Hp for my 318

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brentwab

brentwab

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I bought a 67 Cuda and love it, except for the lack of power. The car runs great but I think I can take it in my Dodge mini van. It has a beautiful 318 with a Edlebrock Performer manifold, a 670 CFM Holley 4 barrel carb, dual exhaust, 8 3/4 rear end, and a TCI tran. Some day I may drop a new engine in it but for now I would like to install a CAM and/or headers. Does anyone have any thoughts or experience and is this a waste of time and money for a 318? What do you think I will gain, another 75 hp?
 
I Have a comp cam #268 477/480 I think that this is a great cam for the 318. ITwas a pure nightmare to install headers on my 1974 dart sport, dont know how hard it will be on your car, but once installed there worth it.
 
mild cam,and smaller carb will wake it up,I'd start with smaller carb....you'd be surprised....
 
I think that you might be running too much carb.
I am running a holley 4160 600 cfm carb, comp XE 256 hyd. cam, flat top pistons .060 in the hole, .028 head gasket, magnum heads with stock 1.6 rockers and beehive springs, magnum air gap dual plane intake and hooker comp headers and it pulls hard. Everyone that has seen and heard the car says "Wow! that's a 318". According to comp cams it should make 320 hp and 380 tq. Not to shabby for a crappy old 318.
What heads are you running on it? What pistons? Compression ratio? I would try and figure these things out before you buy any parts, because too much cam and carb will make it a dog.
 
If you still have the stock cam in it you will need something bigger to make real use of the 4bbl carb. I am running the stock 340 cam in mine and it works well but like others have mentioned there are better more modern grinds. You are probably leaving over 50 HP behind with the small stock cam. I think your carb is just fine as long as it's not mechanical. The secondaries will only open as far as air flow demands anyway. I run a 600 holley on an old streetmaster intake on mine and power much better then stock and MPG actuall increased too. Most 318's will pick up around 100 HP over stock with cam change, 4bbl carb and good exhaust with headers even using the small port heads. Also be sure your getting full throttle at carb, if the intake and carb has been changed and the linkage not modded or changed you may not be getting WOT as the 4BBL stuff is different from the old 2BBL.
 
i've heard that about the best thing that you can do to a 318 is head work. and not even going out and buying the $1000 heads as much as giving it bigger valves and opening up the intake and exhaust by porting and polishing. I read an article in mopar muscle magazine from quite a few years back and they made an easy 350 hp. from their 318. all they did to it was the head job a .30 bore and an aftermarket carb. and intake which you already have. If you were considering keeping this motor for a while i'd highly reccomend doing the head job. there's no way it can hurt. hope that helps
 
That 670 carb is a vacuum secondary carb, its not too big! I ran 650 DP with great results on my 318.

Its camshaft and heads holding you back / plus those stinky little exhaust manifolds if you aren't running headers. (oh those wimpy valve springs have to go too...might as well throw some 360 heads on with fresh HP valve springs) My little 318 with a 224 @ .050 cam sees 6500 rpms each day its on the road.

The SB mopars are really neat were the intake can stay on during a camshaft change. That be my first to do list / along with some headers. What gears are in back?
 
Actually on a 318 of this level headers only provide a couple HP improvement over stock manifolds. First I would check cranking compression, ignition timing, and jetting to make sure the engine is running as well as possible. If so then I'd recommend a cam change to a fast-ramp dual-pattern design like the Comp XE 256 or Lunati Voodoo 256/262. Either of these will raise torque all across the powerband and gain a LOT of HP at higher revs (probably at least 60, most likely 75).

What will really wake it up though is higher compression (new pistons) and better-flowing heads with big valves. Then you'd want to get some headers, and some better tires (ha ha).
 
brentwab said:
I bought a 67 Cuda and love it, except for the lack of power. The car runs great but I think I can take it in my Dodge mini van. It has a beautiful 318 with a Edlebrock Performer manifold, a 670 CFM Holley 4 barrel carb, dual exhaust, 8 3/4 rear end, and a TCI tran. Some day I may drop a new engine in it but for now I would like to install a CAM and/or headers. Does anyone have any thoughts or experience and is this a waste of time and money for a 318? What do you think I will gain, another 75 hp?
Click to expand...

I like that 268 comp mentioned below. Your compresion ratio is an unknown and probably low. If the engine is in good shape, I'd mill and pocket port the heads with that cam and install heders with a 2-1/2 pipe. The carb is fine, alot, but fine.

You have a 8-3/4 rear, but you never mentioned the gear ratio or tire size.

Between the cam and preped heads and headers, you'll gain the HP your looking for.
 
My friend runs that comp cam .477/.480 in his smog 318 with a set of 360 heads,dual plane intake,650 carb and headers..with very good results..of coarse he also runs a full manual v.b. and a 8 3/4 with 3.91's..:cheers:
 
If it's burning oil, don't bother until you can rebuild the engine. However, if it's not burning oil, I would suggest the Lunati 60401 cam with the suggested dual valve springs. Stay away from 360 heads for now as they'll just drop your compression. You'd be better off sending your existing heads to BJR for some porting and the required machine work for the dual VS.
 
For 75hp, I would install headers and up grade the cam..lol. The carb IMO is a little large, but if you can tune it I think it would be ok. What do you do with the car 90% of the time? What is the stall speed of the convertor you have? What is the gearing in it? Do you have power brakes?
 
I agree...Bigger cam and headers are a great start. The carb is fine...spend your money on parts you need (the carb can be tuned).
 
Something must be wrong with your 318, either the tune, or its low on compression, i just purchased my 2nd. 71 Swinger 318 car, it is bone stock with the original exhaust (hanging on the ground i might add lol), it has 89000 miles on it, got it running after sitting 3 yrs., i had to install a rinky-dink elec. pump, it has about 3.1/2 lbs. pressure, i will say it has balls being bone stock, i could only amazin how well it would do with an extra 80-100 hp. & some 3.91s, plus a 100 shot to boot. The last 71 318 Swinger i owned would roast the tire for a block, & that one huffed blue smoke 8).

I may have just talked myself into something:-D
 
JoeDust451 said:
Something must be wrong with your 318, either the tune, or its low on compression, i just purchased my 2nd. 71 Swinger 318 car, it is bone stock with the original exhaust (hanging on the ground i might add lol), it has 89000 miles on it, got it running after sitting 3 yrs., i had to install a rinky-dink elec. pump, it has about 3.1/2 lbs. pressure, i will say it has balls being bone stock, i could only amazin how well it would do with an extra 80-100 hp. & some 3.91s, plus a 100 shot to boot. The last 71 318 Swinger i owned would roast the tire for a block, & that one huffed blue smoke 8).

I may have just talked myself into something:-D
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Well I'm at twice your elevation so my 318 didn't have any balls, and perhaps the OP is at a higher elevation too. Since I bought the car ('70 Duster auto) I have not once been able to break loose a rear tire going straight.
 
If "someday" is next year, don't bother. If someday is a ways off... the 318 needs some compression - more than stock. The rule of thumb is 9.5 maximum static compression for pump gas, although the cam you choose has a bearing on that.

You could "do it right" and rebuild the engine, with higher compression pistons. That means a bore & hone. Stick a good oil pump in it while you're there. Obviously, bearings, polish the crank, etc as long as it's apart. The problem I have, though, is why not spend $300 or so and pick up a 360 to build if you're going to all this effort? The $300 would be peanuts compared to all the machine work and new parts.

The alternative is to do a quickie job, which is NOT all bad. Check compression and make sure it's consistent cylinder to cylinder. Pull the heads and take them in. Get some mild porting, fresh valve job, hardened exhaust seats, and mill .040 or so off the heads. That will bring the compression up a hair. Get a mild cam, a little four barrel, some headers, and call it good.
 
MOPEkidD-3 said:
Well I'm at twice your elevation so my 318 didn't have any balls, and perhaps the OP is at a higher elevation too. Since I bought the car ('70 Duster auto) I have not once been able to break loose a rear tire going straight.
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The 1 318 Swinger i mentioned was in Amarillo Tx., 3700ft. Alt., most times the DA was around 5K & it would still light fire under that back tire 8).
 
67 318 is supposedly a little higher compression than the later years. Supposedly.

A cam would definitely help, but I'd keep it very much on the small side. Too much will kill it, and anything aftermarket will be a huge improvement over stock.

If you install a cam, then headers would be a good upgrade, though they are an MF-er to install.

The vacuum secondary carb is fine. I ran a 670 cfm street avenger on mine to good effect.

Gears are a definite must. Minimum 3.27, more if you can deal with the high RPMs.

Torque converter would probably be the best bang for the buck upgrade assuming your trans can hack it.

Good luck

Steve
 
JoeDust451 said:
The 1 318 Swinger i mentioned was in Amarillo Tx., 3700ft. Alt., most times the DA was around 5K & it would still light fire under that back tire 8).
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Well that just makes me feel unlucky (lol). BTW what gearing and rear tires did that Swinger have? I've got 2.76:1 and 225/70R14 BFG Radial T/A's.
 
MOPEkidD-3 said:
Well that just makes me feel unlucky (lol). BTW what gearing and rear tires did that Swinger have? I've got 2.76:1 and 225/70R14 BFG Radial T/A's.
Click to expand...

Have no clue, but it did have a factory 8.3/4 one legger, i'de have to say it was 2.76 gears, don't know if it was haunted or what, i was very surprized at how well it ran at that Alt. being completely stock, plus doubling as a miquito killer lol.
 
Thax for all the info, this has got to be the best forum I have ever been a part of. Its great to get a bunch of ideas and information from people who actually seem to know what their talking about.

We ll it sounds like I need to start with a cam and headers and from several posts, headers look like they may be real fun.

On the other hand another post recommended putting in a new engine, that may be the better idea. I figure if I build a new engine, I can continue to drive the car until the engines complete and then just do a heart transplant.

I know someone asked about the gears in the rear end, I'm looking in to that question. The wheels are P245/60 R14.

Now I need to figure out if I should try and find a 340 so I can use the small block transmission or just move up to a 360 and change the transmission. I'm guessing I would also need to change the fuel line to a 3/8 as well.
 
As far as headers go, they all stink real bad except if you decide to pay some much bigger price tags for ethier Doug's or TTI headers, and there still a pain, but at least you won't smash 3 out of 4 tubes on the first speed bump.

The 340 and 360 are small block engines, they both use or can use etier 904 or 727 tranny's. Just realize that there is a big block and /6 trans and they can not be used on a small block.
(One few things I can't stand about a MoPar)

Just have the tranny build for the intended power level if your going to be makeing a bunch.'

The fuel line at 5/16 can actually feed a good bit of power. An upgrade to a 3/8th's line is probably not going to be needed, but a good idea if you start searching for big power. Stainless steel line is the only type I'd look at.
 
a 360 is small block so it will bolt to your tci trans. the 36o is externaly balanced so i think you need a different tq but thats it. i have a 360 in my scamp and i love it:) mine is 4 speed but it always squeels the tires around a turn no matter how lil throttle you give it lol its a beast and it is just bored .30 over with ported heads and a full rebuild running 10.5 to 1 compression. i had the shop build it so i dont know all the specs but i know i like it a lot:)
 
Thanks for the info, looks like I will start looking for a 360 this winter.
 
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