road car cam for my 318

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str12-340

str12-340

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I have a 318 in one of my Darts that is mated with a 42RH 4 speed OD automatic, and has 2.94 gears. 8.5:1 compression, Edelbrock Performer intake and a 650 AVSII. It is a long distance road trip car. I believe that the current cam is not serving me well - 17mpg on the road, lack of vacuum for power brakes at low RPMs, rough idle especially when in gear. When in overdrive with the lock-up converter engaged:
45 mph - 1550 RPM
55 mph - 1700 RPM
65 mph - 1850 RPM
75 mph - 2000 RPM
(all numbers approximate with relatively small tach and my 54 year old speedo (augmented with a GPS))

I'm looking for suggestions for a different cam. There used to be a ton of "mileage cams" out there in the late 70s/and 80s but I don't see them advertised these days. The one in there now is advertised for 1800 to 5000 rpms, so a lot of my driving between 45 and 65 mph barely gets into the range when I'm out on the road doing miles. I would like to boost the gas mileage if I can, and provide more vacuum to the booster for stop and go in town driving.
 
so you're saying no 3/4 race cams then?

a stock 360 2bbl would probably work great for your application, 410/412 252/256 (for the earlier 71~74 and then 410 252 single pattern after). the melling 23103 specs out at 410/412 with 198/199 @ 50, though their advertised shows 278/282-- which i don't believe for a second-- on a 110 which is perfect for the use you're looking for.

i like the purple shaft P4452755 if you can find one. it's .405/.410 240/248 yes, i know it's smaller than the 360 2bbl cam but it slap *** works in a 318. with the performer and small heads and reasonable carb it's gonna make a ton of low end and pull vacuum while idling like a sleeping kitten.

a little more spicy, the howards street force 1 would be a good choice. 420/430 and 259/267

if you're okay with comp's units they have a tremendous offerings of XE and DE cams that are right in the wheelhouse for what you're looking to do.
 
Sounds like a good tune is all that is needed. You might get better mileage with a seat of 3.23s as well because the engine will be in its sweet spot at cruise speed . I just got 18.8 with my Barracuda and it has a 221/229 cam with .550ish lift , 800 AVS , 904 and 2.76s. And I can smell the excess fuel in the exhaust so Im sure it’s running rich .
 
What is the current cam?

That light car with those gears should get 25 MPG highway without OD.
 
str12-340 said:
I have a 318 in one of my Darts that is mated with a 42RH 4 speed OD automatic, and has 2.94 gears. 8.5:1 compression, Edelbrock Performer intake and a 650 AVSII. It is a long distance road trip car. I believe that the current cam is not serving me well - 17mpg on the road, lack of vacuum for power brakes at low RPMs, rough idle especially when in gear. When in overdrive with the lock-up converter engaged:
45 mph - 1550 RPM
55 mph - 1700 RPM
65 mph - 1850 RPM
75 mph - 2000 RPM
(all numbers approximate with relatively small tach and my 54 year old speedo (augmented with a GPS))

I'm looking for suggestions for a different cam. There used to be a ton of "mileage cams" out there in the late 70s/and 80s but I don't see them advertised these days. The one in there now is advertised for 1800 to 5000 rpms, so a lot of my driving between 45 and 65 mph barely gets into the range when I'm out on the road doing miles. I would like to boost the gas mileage if I can, and provide more vacuum to the booster for stop and go in town driving.
Click to expand...

What are the current specs on your cam? Go to answer is: get a custom cam. Racer Brown and others. You may be able to regrind the one you have since you are going smaller. I used to get 25 mpg+ steady cruising with a 340 cam and a TQ in a 273. Using a vacuum gage helps to teach you how to drive for mpg.
 
I will say there is something to be said for an aftermarket power/mileage cam grind. I had one in a 250 straight six in a gmc pickup. It knocked down 17 mpg in a 4000 lb pickup empty or even loaded with a ton of scrap iron (I hauled 100 tons over 6 months) consistently and it had plenty of balls doing it.

I would call your preferred cam grinder, tell him your combo and your goals as to mileage and performance.
 
Comp XE250H, but I've heard comps quality has gone downhill considerably in the last 10-15 years. Might be better finding someone else who can grind you a similar profile
 
What cam is in it now? And how is the timing curve/vacuum advance set up? You already have the mileage maker package if it has a stock cam in it and a vacuum advance distributor. You just need to tune for it.
 
There should be several cams who's range says something like "idle-4500", or "1000-4750".
 
With 8.5:1 compression you want a short short duration cam like what @RustyRatRod suggested or you will have no dynamic or cranking compression and will suck for a street engine. You also want a small LCA (like 106 degrees) if still the stock heads. I would call Ken at Oregon Cams and get a 2016 grind at 106 degrees. My opinion.
 
current cam is a Crane 15005
adv. duration - 272
.454 lift
1800 to 5200 rpm

Not the right cam for my use...
 
I'm with @ch1ll on this one. I always recommend calling your chosen manufacturer (or several if you want options) to see what they suggest. If their website has a downloadable cam recommendation form, print it and fill out as much as you know before you call. Those guys design cams for a living. They'll provide better results than crowdsourcing, whether it's a custom grind or something they regularly stock.

After that, look into your timing. As the Borscht Belt comedians used to say, "Timing is everything." At part-throttle cruise you want a ton of it (often 50+ degrees). The more timing it likes, the more power it makes. The more power it makes, the less you have to open the throttle to maintain the same speed. Juggling and adjusting vacuum-advance canisters can work wonders here without affecting your base and centrifugal timing.

With economy being of primary concern, your car is also a spectacular candidate for a 340/360 ThermoQuad. It's hard to beat a good spread-bore when your foot's not in it.
 
str12-340 said:
current cam is a Crane 15005
adv. duration - 272
.454 lift
1800 to 5200 rpm

Not the right cam for my use...
Click to expand...

That is not too far off... not a lot of duration (more than I would use on a 8.5 through, I would keep it well below [email protected]" duration) and too wide a LCA (110 degrees) for the crummy stock 318 heads (Vizard) but that should have a lot of vacuum.
 
str12-340 said:
I have a 318 in one of my Darts that is mated with a 42RH 4 speed OD automatic, and has 2.94 gears. 8.5:1 compression, Edelbrock Performer intake and a 650 AVSII. It is a long distance road trip car. I believe that the current cam is not serving me well - 17mpg on the road, lack of vacuum for power brakes at low RPMs, rough idle especially when in gear. When in overdrive with the lock-up converter engaged:
45 mph - 1550 RPM
55 mph - 1700 RPM
65 mph - 1850 RPM
75 mph - 2000 RPM
(all numbers approximate with relatively small tach and my 54 year old speedo (augmented with a GPS))

I'm looking for suggestions for a different cam. There used to be a ton of "mileage cams" out there in the late 70s/and 80s but I don't see them advertised these days. The one in there now is advertised for 1800 to 5000 rpms, so a lot of my driving between 45 and 65 mph barely gets into the range when I'm out on the road doing miles. I would like to boost the gas mileage if I can, and provide more vacuum to the booster for stop and go in town driving.
Click to expand...
2000 rpm at 75? Don't use a cam with any performance designed into it. With the OD and those gears most any cam but a stock spec one will be too much. (generally speaking)
 
Since I don't know/understand much about picking a camshaft, my engine rebuilder suggested this Melling:

Melling Cam SPD-20 (Specs).jpg


He said it would be a good choice for my ice cream parlor cruiser (.030 over original 318, LD4B intake, 1406 carb, MP electronic ignition, factory exhaust manifolds, FlowMaster 40s, 2 1/4" pipes, A904, 3.55:1 sure-grip 741 case 8 3/4" rear end with P245/60R15 tires (15" X 7" WheelVintiques Rallye wheels).

I've never checked the gas mileage, so I can't share any information on that point.
 
str12-340 said:
current cam is a Crane 15005
adv. duration - 272
.454 lift
1800 to 5200 rpm

Not the right cam for my use...
Click to expand...
woof.

for your app i'd want to be below 440 lift and sub 260 duration with a 110 or less CL, preferably with a split pattern to favor a little exhaust scavenging.

i think the AVS 2 is great carb, but as mentioned if you're looking to absolutely maximize cruise a small primary big 2ndary would be the move. or like a holley economaster (barf).

and timing. you're gonna need to figure that out too...
 
DartGTDan said:
Since I don't know/understand much about picking a camshaft, my engine rebuilder suggested this:

View attachment 1716318140

He said it would be a good choice for my ice cream parlor cruiser (.030 over original 318, LD4B intake, 1406 carb, MP electronic ignition, factory exhaust manifolds, FlowMaster 40s, 2 1/4" pipes, A904, 3.55:1 sure-grip 741 case 8 3/4" rear end with P245/60R15 tires (15" X 7" WheelVintiques Rallye wheels).

I've never checked the gas mileage, so I can't share any information on that point.
Click to expand...
that's a decent little cam for a run around. i've run that with a 1.6 rockers and it was a nice little mill with the added lift to that duration.
 
str12-340 said:
current cam is a Crane 15005
adv. duration - 272
.454 lift
1800 to 5200 rpm

Not the right cam for my use...
Click to expand...
Not the right cam for your combination for sure. The lift is not an issue but the duration on those Cranes can make them a little sluggish at low rpm.
 
ch1ll said:
I will say there is something to be said for an aftermarket power/mileage cam grind. I had one in a 250 straight six in a gmc pickup. It knocked down 17 mpg in a 4000 lb pickup empty or even loaded with a ton of scrap iron (I hauled 100 tons over 6 months) consistently and it had plenty of balls doing it.

I would call your preferred cam grinder, tell him your combo and your goals as to mileage and performance.
Click to expand...
You remember the specs?
 
DMC_78 said:
You remember the specs?
Click to expand...
No idea, I bought the truck from a guy that worked at a parts store called automotive and aircraft. The engine was rebuilt in house by the guys that ran the machine shop. After talking to them, they gave me some information on what parts they used, but not any spec’s.

The story goes like this after I pulled up to the machine shop garage door, hey how’s that thing running? Killer I said, its got balls. They said we rebuilt it a couple years ago during the winter when we were slow and bored to death. It’s got a power cam and flat top pistons.

Cool say I.
 
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