318 driver - cam change or not?

-

1973dust

FABO Gold Member
FABO Gold Member
Joined
Jan 12, 2011
Messages
253
Reaction score
185
Location
Illinois
73 Duster 318/904/2.76 gear. Rear tires are 225/70-14's. Just have a 7 1/4 rear so no tire-burning. I am primarily interested in around town punch and am trying to decide if I want to change the stock cam or leave well enough alone. Engine bone-stock 74 318 with 40,000 original miles. I have removed smog devices and re-curved distributor 12 deg initial, 36 total all in by about 2800. I do have dual exhaust off of the stock manifolds and I have a Performer intake and a 600 Edelbrock carb. to install. I'm going to replace the timing chain when I do the intake/carb swap and the little voice keeps telling me "you're going to be there anyway so why not bump the cam up a little". I keep hearing horror stories of guys having cams go flat with the new oils and I'm just not sure how much gain I would get, considering how I drive. I also would prefer not to lose any gas mileage. Thanks in advance for the help.
 
I think with all the rest you've already done to it a mild cam swap would be a good compliment. Remember though, regardless of which cam you choose, to also get matching valve springs as well as new lifters.
 
Leave it alone. You can't do much of a cam change on a 318 without changing everything else. The 4 barrel and intake and a smooth flowing exhaust does the most for a stock 318.
 
Last edited:
i would of done the cam swap first, with a nice torque grind and have it advance it 4 degrees too build cylinder pressure up build more torque easy to move and better MPGs
 
I recommend changing up to an 8-1/4 before going any farther, unless you have a sure grip in your 7-1/4. You may find your style of driving becomes a lot more spirited with the extra power.
 
I don't think he's done it backwards at all. I think he's done it the smart way. A cam change is a pretty big job, so most people would put that off until all the bolt ons are done, which he's done. I think something on the order of the Edelbrock Performer would be a great choice. The old "204/214" @ .050 that everybody grinds. Stab it in 4* ahead and have fun.

...and normally, I would be the first to say leave it alone, but he's already done all the other stuff, so a cam change seems appropriate since he's obviously "looking for more".
 
The factory cam is super mild, even an entry level performance cam 250 will be a huge step up, and should give little away off idle, the largest I’d go with is around 260.
 
204-214 would be a big step backward with those gears- look at the seat duration
advance it or the 360 cam 4 degrees to get cyl pressure back and your gas mileage gets worse
op
take a look at the 318 cam thread stickie and find one with shorter seat duration and more lift
ps the 360 cam is also a step backwards
i'll t
post up your cranking compresson and let AJ run the numbers for you
273 at what checking height
lot of difference between a 260 crane and a 260 Mopar performnce
he's going to loose off the line with even a 256 comp
where he would also loose a little with a 256 lunati voodoo or the short howard he would make it up with the extra area
the 248 MP cam would be worth a look or find a later equilivant
still a lot of bucks
some say the best cam for a stock 318 is a stock 318 cam
here we are talking about stock gears and converter and compression
let's see if we can beat it all the way across OP's power band
 
204-214 would be a big step backward with those gears- look at the seat duration
advance it or the 360 cam 4 degrees to get cyl pressure back and your gas mileage gets worse
op
take a look at the 318 cam thread stickie and find one with shorter seat duration and more lift
ps the 360 cam is also a step backwards
i'll t
post up your cranking compresson and let AJ run the numbers for you
273 at what checking height
lot of difference between a 260 crane and a 260 Mopar performnce
he's going to loose off the line with even a 256 comp
where he would also loose a little with a 256 lunati voodoo or the short howard he would make it up with the extra area
the 248 MP cam would be worth a look or find a later equilivant
still a lot of bucks
some say the best cam for a stock 318 is a stock 318 cam
here we are talking about stock gears and converter and compression
let's see if we can beat it all the way across OP's power band

Ok, then you recommend him something. In fact, recommend everybody something.
 
An often overlooked cam on a bone stock 318 is a sealed power CS1006r. Single pattern, .420 inch lift, 204@ .050, 114 LSA. Tiny cam, rated for 1500-4500 rpm, this would work well with the performer or a Weiand stealth intake. An old Edelbrock streetmaster single plane rated from idle to 4500 would turn it into a real stump puller. Compared to the old TM77 sealed power ‘77-‘85 stock regrind of .394I-.420E and 196I-202E it’s probably the lowest step on the totem pole on the way up. But that’s just my $.02. With the performer intake I’d want to go a little larger on the exhaust duration, too, like the cam RRR proposed.
 
Last edited:
I would go with this cam if you do not mind the aggressive rate of lift
Howards Cams Hydraulic Flat Tappet Camshafts 711381-10
or this one if you do
Lunati Voodoo Camshafts 10200700
and these springs with either one
Trick Flow® by PAC Racing Single Valve Springs TFS-16901-16
and it would gain some power for sure.,As far as break in just make sure to use the tried and true parts you have (ignition/carb) and I would recommend a dedicated oil such as brad penn etc.
Yup that Howards camshaft should be a great runner, Howards has good cams, sunday morning cam swap should be done by dinner, lol hopefully

also try and find a 3.23 or 2.94 for 7.25 rear better gearing toward your driving habits, gearing has alot to do with MPG and with camshaft selection. you got to get it in the sweet spot in you rpm range, or else you would have a dog out of the hole getting less mpgs.
 
Last edited:
Have any of you guys that have recommended a cam actually used that cam with small 4 barrel, dual-plane, manifolds, and granny gears or just going by specs. I'd really like to know what to expect from someone's real-world experience. I don't even know if I'll feel a difference around town when I swap 2 barrel for 4 barrel carb. and intake. I've already got a decent curve in the distributor, one of the first things I did. Right now, I'm only running 6 deg initial and about 30 deg total as the stock 2 barrel is pretty lean, especially after adding duals.
 
You will be amazed at how much the four barrel and intake add to the combination. And with a properly selected cam even more so. Here is a good entry level grind for a probably high seven to low eight to one eighteen with your proposed mods. Mopar Hydraulic Flat Tappet Camshaft - Camshafts
 
Last edited:
Have any of you guys that have recommended a cam actually used that cam with small 4 barrel, dual-plane, manifolds, and granny gears or just going by specs. I'd really like to know what to expect from someone's real-world experience. I don't even know if I'll feel a difference around town when I swap 2 barrel for 4 barrel carb. and intake. I've already got a decent curve in the distributor, one of the first things I did. Right now, I'm only running 6 deg initial and about 30 deg total as the stock 2 barrel is pretty lean, especially after adding duals.
Sorry, I didn't read all the way through your first post. Sounds like you have the combination and it makes sense to install the cam with the intake off for a swap. You can search here for "318 cam" in the search box. There will be dozens of long threads about the subject. There is no magic bullet cam for a 318 but lately Mike Jones name has come up. He has a good mild small block cam that many recommend. You might want to give him a call and tell him your combination.
As mentioned, I would look around for a 8 1/4 or 8 3/4 rear end with at least a 3.23 gear. I changed my 2.76 to a 3.23 and picked up some pep and didn't loose any gas mileage.
 
I had what you had right back to the 2.76 gears. Short answer, in my opinion "yes" a mild cam is a good addition. One reason you may not have thought of is..............if you're the type of guy to second guess a decision. You'll continually second guess "not installing" the cam when you had the chance.
 
^^^THIS, all day and night long^^^ every time I’ve helped change an intake or do it without swapping the cam I always say after it’s done “Well, it’s a lot better, but had we put this or that cam in it would have gained that much more again.” It’s all about properly matched components. And as Mike says, 2.94 to 3.21 gears in a stronger rear end will make your car a lot more fun to drive.
 
And yes, I switched to an 8 3/4 with 3:23 sure grip gears. That was probably the biggest improvement. A daily driver that jumps when you want it to. But the differential change didn't come until years later. So enjoy the camshaft for now.
 
ok
sealed power cam is same as 204-214 already mentioned
compare all against Slantsix64's post above
Howards Cams 711381-10 - Howards Cams Hydraulic Flat Tappet Camshafts 110lca
Advertised Duration .006 255/261, .050 208 int./214 exh.Lift .479/.494,
(chevy 255/261 version for comparison Duration 255/261, Lift .410/.420,
sort like the 204-214)

the lunati slantsix64 mentioned is 250/256 .006, 208 int./213 exh. Lift .454/.454,
it has a 112lca but with the shorter seat to seat it closes the intake at about the same place as the Howards. Lunati has lots less overlap with the shorter durations and wider LCA combined
note that the Howard has an "intensity" (.006>.050) of 47 and the Lunati gets to .050 in 42 degrees (both open and closed sides so not perfect but you get the idea)(comp 268 takes 50, 260 48, 252 46)
Me I'd have Mike Jones grind me one with his motorhome lobe on the intake and let him pick the exhaust lobe and lca he get's even shorter actual seat to seat timings and about the lift of the Lunati but more duration at .275 than the others

either will outperform a 340hp cam or comp 268 in this application
 
Last edited:
Lessee you want around-town punch. And so far you have a smogger-teen with a 4bbl and dual exhaust.
But you are stuck with 2.76s and skinny 225/70-14s that won't spin. And probably a 1750 stall TC.
There is only one solution to this lack of punch; you need more low-rpm effective torque.
And there are just two ways to get it from the engine, and three more from the chassis.
As to the engine;
Stuck with the 1750TC and 2.76s, your only option is more cylinder pressure, and you will not get it with any bigger hydraulic cam. The solutions are higher compression pistons and or an earlier closing intake.
As to the chassis;
your options are; reduce the weight, increase the stall, and or increase the rear gear. And I recommend in that order.
As to weight; The 73 Duster is already a fairly light car, and has generous wheelwells which are gonna come in handy. There is not much in that car, for street, in Illinois, that you can sacrifice.
As to stall, I recommend a 2600 to 2800. I prefer the 2800.
As to gears; the sky is the limit but for a city car I recommend 3.73s or 3.91s preferred with the factory cam.

Now; if you do the stall and gears first............ then you can upcam, because the butter-soft bottom-end is bypassed with the higher stall TC. And with the bigger gears, whatever softness remains, is quickly overcome.
So in your case, you have to co-ordinate the TC and the cam,together at the same time... or just don't put a cam into it in the first place.
Think about it; the next bigger cam will move the power up about 200 rpm or 2 mph. With the 2.76s the power peak moves to about 52 mph. But the bottom end with the stock TC gets softer, that is to say more sucked out. Does that sound like a good solution? But guys just want to jump in with both feet, and grab a 262(or bigger)..... which is 22* degrees bigger than stock.. or 3 sizes. And so the powerpeak moves up ~600 higher than stock..... with the impossible to recover from, very soft, bottom end. Without going into the engine, there is only one bandaid for this condition, which is TM(TorqueMultiplication). And the starting point is a higher stall TC , like the same 600 at least; so 2350 at the minimum, just to retain the same low-rpm performance you now have. Bad deal in my opinion. Now with the 2.76s, and with the power having moved up 600 rpm or 6 mph; so now it is at 56 mph.
But you don't want just the same sucked out bottom end, so a 2800 is now the smallest to consider Stall, with a 3200 or more, a better yet solution with that 262 cam and 2.76s.
So you can see that this is becoming a balancing act, with lotsa money the solution.
Here's the deal; No matter how you look at it,your cammed up combo is gonna need a TC and gears anyway... so you might as well install them first, and maybe you will be so impressed with your smogger teen, that you will forget all about the cam idea. I can almost guarantee you this will happen with 4.30s and a 2800; cuz it did for me. And I'm crazy for smoking up the tires.
Grab a chair, I ain't finished yet.
Lemmee show you how this TM thing works.
Say your engine can make 150 ftlbs at 1750 at WOT, I mean let's just start there.
So then the TC is gonna multiply that, and the trans and the rear gears and by the time it comes to the tires, you might get;
150x 1.05x2.45x2.76 =1065 ftlbs of torque... which is pretty sucked out. Lets change the rear gear to 3.91s
150x1.05x2.45x3.91=1508, an increase of ~42%. That's pretty serious, but it will not sustain much tirespin. Ok so lets put the 2800TC in there. So this is about 1000rpm up higher on the torque curve, but with the stock cam,already on the downside of the curve, so I'll guess 240ftlbs Ok here we go;
240x1.05x2.45x3.91=2414ftlbs, now 127% more take-off torque, and now a serious tire-frier. You will need a Suregrip and much bigger tires to make use of that torque... and it's still the stock 8/1 smoggerteen with a 4bbl.
If you want to know; 150ftlbs at 1750rpm is 50 hp, and 240ftlbs at 2800 is 128 hp.

Now lets look at the engine;
Ok so here's what your smogger teen looks like with the factory 240/248/112 cam installed at split overlap or in at 110*
Static compression ratio of 8.0:1.
Ica of 50, 600ft elevation
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 7.04:1 .
Your dynamic cranking pressure is 135.08
PSI. .................. 135psi/111VP
V/P (Volume to Pressure Index) is 111
What's that mean?
Well the cylinder pressure is extremely weak, so it will or should run on the crappiest gas imaginable. But it sure won't make much power. And the 111VP supports that with a zero tirespin, sucked out number of 111. Read about VP in the link in BLUE at the bottom of the page.
The cheapest solution to this is to advance the factory cam.
With stock exhaust manifolds, the overlap is dead so that gives you the freedom to advance thechit out of that cam, with very little loss of top-end power..... which you don't need top-end power with hiway gears anyhow how cuz 4400 is 50mph at the top of first gear with your 2.76s and 26.4 tires. Pretty much EVERY performance hydraulic cam that you might put into it , is gonna give up a lotta "no spin"bottom-end torque that you are already lacking.... to get some power at 50 mph, that you don't need, cuz you said "around town punch"
Did I understand you right?
Ok so lets advance the cam to in at 104, that's a lot; 8* from straight up, but only 6* from split-overlap
Static compression ratio of 8.0:1.
Ica of 44*, still 600ft
Effective stroke is 2.96 inches.
Your dynamic compression ratio is 7.25:1 .
Your dynamic cranking pressure is 140.55
PSI. ....................... 141/120VP
V/P (Volume to Pressure Index) is 120
What does it mean?

Well, the pressure has risen 4.4%, but the big deal is the VP has risen 8.1%., Making your engine feel that much bigger or more powerful. Lessee, lets add 8.1% to the 50 ftlbs with everything still as it is right now; 50x1.081=54 ftlbs, an increase of 4ftlbs. That doesn't look like much but remember all it cost you was a gasket. But hang on; that's at 1750 stall; what about at 2800, for instance?
Well; 1.081x240=259 which is plus 19.44, which is now a big deal, because, at the tires this translates to
259x1.05x2.45x2.76=28.4 EXTRA ftlbs, for the cost of a gasket and the time (and the tools if you have to buy them).
But what if you combine that with the 2800TC and say 3.73s?
Glad you asked;
259.44x1.05x2.45x3.73=2489, lookitthat, this retime was worth more than one full gear change from 3.91s to 3.73s
But hang on, Do you really need 3.73s?
No! 2489ftlbs is plenty of ftlbs to initiate tirespin with those skinny 225/70-14s, both of them,lol, probably to 25/30 mph,I'm guessing... so you could probably get away with 3.55s, or for a healthy squalk, maybe 3.23s. Lets look at the numbers with 3.23s;
259.44x1.05x2.45x3.23=2073ftlbs and IMO yes it will for sure bust 'em loose, but the spin won't go too far. How can I say this? Because there is something I saved for you. At zero mph there is a hydraulic TM factor inside the TC which can approach 2/1. Let's say your proposed 2800 comes in at just 1.8 at zero mph. Then
259.44x1.8x2.45x3.23=3696 ftlbs at zero mph. This is why automatic equipped cars can jump off the line the way that they do. A manual-trans car would need a rear gear of 3696/(259.44 x2.66)=5.356 to match that with the same engine.
This less squealing is kindof good cuz the cops are attracted to squealing tires. So your 60fts might improve with the 3.23s, but the run thru the gears to redline might be a tad slower. Since people are practically giving 3.23s away, I would try it, cuz they make hiway cruising to be more bearable; 65= 2675rpm at zero-slip, in your case.

Ok now recall I picked the torque numbers out of a hat, so while they may not be accurate, IMO, I think the results will be similar. Why do I say that? Cuz I have installed more than a few 2800s and 3.91s or better, and even without the cam re-time, customers always returned smiling; and the bigger the rear gear the bigger the smile. 4.30s are awesome. Heck you can take two plug wires off and with 4.30s still have fun.

Ok last bit; If you must have a cam... wait until after the TC and gears are in.... and get a solid flat-tappet cam to try to retain a modicum of cylinder pressure. Solids, net size for size, will close the intake sooner to help with the cylinder pressure thing.... which helps with the VP, which with just a 2800TC, could be useful at the lower rpms, while for sure it will make more power everywhere else as well.
Ok done
 
Last edited:
Have any of you guys that have recommended a cam actually used that cam with small 4 barrel, dual-plane, manifolds, and granny gears or just going by specs. I'd really like to know what to expect from someone's real-world experience. I don't even know if I'll feel a difference around town when I swap 2 barrel for 4 barrel carb. and intake. I've already got a decent curve in the distributor, one of the first things I did. Right now, I'm only running 6 deg initial and about 30 deg total as the stock 2 barrel is pretty lean, especially after adding duals.
Yes, and most times a bigger cam with a mild stall, since you don't have a stall these cams (and anything close will work). The factory cam is not even performance for a factory engine hence the guys who do nothing more to the internals than a cam change and change the external intake/exhaust and pick up a TON of power. You might be surprised to pick up a mile or two on gas mileage as the engine will actually pick up efficiency with hp range. Just make sure you have the timing curve right as others have said and add a few degrees initial timing and get the carb right and it will pick up everywhere.
 
Have any of you guys that have recommended a cam actually used that cam with small 4 barrel, dual-plane, manifolds, and granny gears or just going by specs. I'd really like to know what to expect from someone's real-world experience. I don't even know if I'll feel a difference around town when I swap 2 barrel for 4 barrel carb. and intake. I've already got a decent curve in the distributor, one of the first things I did. Right now, I'm only running 6 deg initial and about 30 deg total as the stock 2 barrel is pretty lean, especially after adding duals.

Yes. I have used the cam I recommended in a 318 with Edelbrock Performer, Holley 600 and headers. I like it. Of course the resident guru shut it down so surely it was a dog.
 
-
Back
Top