1968 with 318 5.2 adding HP

1968fury3sedan

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I would like to add some horsepower without throwing a bunch of money at this engine.
Has anyone on here done this ?
if so what have you done?
any links or pics are appreciated.
 
"Speed costs money. How fast do you want to go?"

Seriously, what is it you are trying to accomplish?

You will always be limited in Cubic Inch capacity and to a certain extent breathing capabilities with a 318. Upgrading a 318 takes some time, effort and money to get the same results that swapping in a 360 would accomplish and likely easier and cheaper.

If you mean a little more 'oomf' from a standing start without a true goal of lowering quarter mile ETS, consider going to deeper gears like 3:55's or 3:91s The trade off is a certain amount of drivability and gas mileage.
 
A 4 barrel carb, and intake manifold, dual exhaust and a 340 cam will get you some more power without hurting drivability. 3:23 gears are a good compromise.
 
I wouldn't use a 340 cam. It really needs a loose converter to work properly. A 4 barrel, a faster advance curve in the distributor and dual exhaust will help a lot. And yes a 3.23 gear can add some zip without sacrificing much mileage.
 
Playing with the tune-up specs (base timing, etc.) might yield a bit more off-idle response, but as I recall, those engines were about where they needed to be, as built. If you want more "top end/passing gear" power, then the 4bbl would be the upgrade to do, plus 2.25" dual exhaust.

The 340 cam will be dulled a bit by the smaller valves in the 318, though. Smaller valves due to the smaller bore size, although the DC LA Race Manual lists how to install the larger valves and such (probably more money than it's worth on a street car!). I believe the car would have a 2.93 rear axle ratio, with the TF904 trans. The 904 takes less power to run than the 727 does, which lets more of what you have get to the road, BUT it might need some friction upgrades to live with more power, by observation, as mentioned in some HOT ROD Magazine articles back then, related to drag strip longevity.

For "more power", substituting a 360 in place of the 318 would be the best incognito route. Add an Edelbrock Performer intake with some sort of Edelbrock 4bbl or a Street Demon carb . . . plus the dual exhaust mentioned above. BUT all of that costs money and where do you stop spending money.

Play with the tune-up items and try to improve off-idle response a bit, but don't expect anything really significant out of it. But any little bit helps . . .

Enjoy!
CBODY67
 
The factory 340 cam works fine. It is not that aggressive and will work with his converter. You can get 4 barrel manifolds in good used conditions at swap meets pretty cheap. I do agree that more cubic inches would be better in a large C body but he may want to keep his original motor.
 
I would like to add some horsepower without throwing a bunch of money at this engine.
Has anyone on here done this ?
if so what have you done?
any links or pics are appreciated.
75 shot of nitrous, nothing cheaper. you should be perfectly safe. Cost you a couple hundred bucks.
 
Total cost with new and used parts is about $800. Intake and carb were used.
Summit headers (low buck un-coated) Comp Cam 268H-10. Matched valve springs with home valve job.
The usual timing chain,gears,gaskets,plug wires and such.Tune to your liking by setting up the distributor and carb.
Your price may vary.
IMG_2858.jpg
 
Small tube headers, exhaust, and small 4bbl will add some power but the smaller exhaust will create torque over HP. A ex-lover in the exhaust will help in that regard, also. Since this is a big, heavy car, if it doesn't already have them, as mentioned 3.23 gears will help.
As for a cam, I would use an RV cam which also adds torque over HP. Torque is what gets ya going.
YMMV
 
You gotta set yourself a budget and see what the 318 would benefit from... intake, cam, carb? Maybe higher compression a little..

I used to have a 998ccm 4cylinder in a mini. The thing had 35HP!!! 125km/h topspeed. This engine mainly needed to breath better with an intake, head with bigger valves and a smudge raised compression, headers and a cam. I do not know the horsepower that came out at the end but it was estimated to be around 48 to 50hp. My topspeed increased to 150km/h. Now all that cost money although I acuired used parts I spend 1500 to 2k on this but then think I almost doubeled the power.

Of course a V8 is bigger but the principle is the same, you gotta see where the bottlenecks are and generally having the engine breathe in and out better will make it run more efficient and thus make more power. Now, I am comparing appels and oranges because the 998ccm was a 7k rpm screamer that came to live above 5k. Thats where the airflow really helps.

If it was me, I would get an edelbrock intake, a cam that gives more low end torque than topspeed flow and a 4bbl. Lots of the power is in the tuning so dont just slap a carb on and be done, get an AFR gauge and tune the carb with it! Match the ports and clean up any casting flashing.

I have a 360 in my fury with roughly the same parts but an unknown cam and I can get the tires spinning in 1st gear pretty quick. My car also has hyw gears... i would assume the 318 would benefit from a shorter gear ratio and its probably happier at a little higher rpm! But again, tuning the advance curve and carb correctly is Key.

Check out the Enginemaster show on motortrend!
 
By observation, the "A" and "LA" 318s (and other family members) are down-right plucky little motors! As with anything at or less than 5.9L, it can be very easy to over-cam it and not know it. Probably something like 205 degrees @ .050" lift and .430"-.450" or so valve lift? Split duration and about 114 degrees LCA, too. At least roller-tip rockers or the full-roller rockers. With a 2.25-2.50" exhaust system and turbo mufflers. In other words, a "torque motor that rpms". With a Cloyes roller timing chain set.

Enjoy!
CBODY67
 
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