MOPAROFFICIAL
Oogliboogli
Open chamber 318 heads usually measure 68cc stock. 360 about 72cc, 340 x about 69-70cc
904 with revearse manual with 3:55 gears out backThat's a good plan. For a 100% street car a motor with more low end torque is more fun. What are you running for a trans and gears? That's another area a large cam can start to pile on parts.
im currently driving the car with a little wild 318 in it.. im just trying to get this motor built because the 318 is tired..Me personally? If it was already together and ready to run and that's the only thing stopping my from driving my car I'd drive it! Is it gonna be the best combo? No! Will it get you from point a to point b and back to a? Yes. If you absolutely are at a standstill and cant wait the drive it and upgrade the heads when you find them.
In that case I would probably just drive the tired 318 until I could find some 360 heads.im currently driving the car with a little wild 318 in it.. im just trying to get this motor built because the 318 is tired..
904 with revearse manual with 3:55 gears out back
2800 stallStock converter? If so a mild cam and your 360/318 head combo should be a fun combo.
On your 318 head, are the springs for your Comp Cam installed? That's another factor to consider, as they will need installed and set up.
so how bad will 318 heads kill a 360? the motor i have has a fresh rebuild on it,but the heads are 318 heads... cast number..4027163 i believe them to be later model smog heads as well.... im at a stand still until i find some 360 heads.. i'm running the comp xe274 h cam, long tubes, Weiand Stealth intake with eddy 4 barrel...
bottom end is just stock replacement
i have to work with what i got.. my money is slim pickens.... i just building a weekend cruiser.. not a drag car or street racer... im actually trying to sell the cam kit to get something a little smaller. i have and edelbrock performer i can pull off my 318 if need be
is a good start, but yur not gonna get away with 2.76 rear gears. Consider 3.23s as the absolute minimum2800 stall
Here's what I see;
The cam is a high rpm cam.
The heads are dead at 4500
The stock rebuilt bottom end is sub 8/1 Scr, the 318 heads might bring it back to 8/1. But it doesn't matter, because the XE 275H, will kill the bottom end anyway.
So what you end up with is an engine with a powerband from 3500 to 4500. But it's a cruiser so that might be Ok.
But something will have to be done with the marshmallow bottom end, and this
is a good start, but yur not gonna get away with 2.76 rear gears. Consider 3.23s as the absolute minimum
Yur not gonna like this combo much, cuz it's gonna feel as tired as your 318, until the engine gets up on the cam.
With 3.23s that will be about 34 mph.
Having said all that, the cure is a smaller fast rate-of-lift cam, with an earlier ICA. Leave the rest alone, and you will have a nice cruiser. Lessee,on an LA, Ima thinking a stock 360 2bbl cam if you already have it, Or up to a 262 if you have to buy one.
But I just gotta mention that a 318 2bbl cam would kick azz with that combo, in a cruiser.
Why am I so confident? Because I did that to a 340, back in 75 and that combo is my second most favorite cruiser combo ever! In a 360, it has just got to be even better.
so how bad will 318 heads kill a 360? the motor i have has a fresh rebuild on it,but the heads are 318 heads... cast number..4027163 i believe them to be later model smog heads as well.... im at a stand still until i find some 360 heads.. i'm running the comp xe274 h cam, long tubes, Weiand Stealth intake with eddy 4 barrel...
@67Dart273 how can you disagree with something I would do? Because I absolutely would do that!! That wasn't a recommendation I was just saying what I would do.
Haha it's all good I was just curious lolIf I did that it was accidental. Did I do that? Damned if I know how. I see there was an "undo" link so I guess I did!!
Partly/ mostly true; it is a combination of the late closing intake and the overlap that makes the sound.I'm already running 3:55 gears with a revearse manual. I am trying to find a smaller cam kit, but I also want something big enough to give me a good lopey or choppy idle and I was told the duration @50 has to be fairly high to get that.
I would love to run and isky cam. Shoot I could even run a solid lift if wanted. I have the 273 rockers and pushrods. But whay about the fable comp 268 I see about 80% of you tubers use?Partly/ mostly true; it is a combination of the late closing intake and the overlap that makes the sound.
But the late-closing intake also softens the bottom end, usually requiring a hi-stall to overcome.
And the overlap is a result of the long durations. Overlap can be exploited with headers to power up the midrange and over the top rpm. But these same headers can pull fuel charge straight across the pistons and into the headers at low rpm. And out the tailpipe the unburned gas goes. resulting in, you guessed it, terrible fuel economy at, city driving.
And the large amount of exhaust duration has to come from somewhere, so it gets stolen from the power-stroke, resulting in, you guessed it terrible fuel economy ALL the time.
Lemmee show you something;
Here is the Wallace predicting your cylinder pressure and V/P, at 500ft elevation, with that 274 cam;I upped the Scr to 8.2 to reflect the slightly smaller 318 chambers.
Here she is with the Comp
Static compression ratio of 8.2:1.
Ica of 64*, 500 ft elevation
Effective stroke is 2.79 inches.
Your dynamic compression ratio is 6.61:1 .
Your dynamic cranking pressure is 124.49 PSI.
V/P (Volume to Pressure Index) is 106
read about V/P here; V/P Index Calculation
Notice the pressure is 124.
Notice the very weak VP, about what a strong slanty makes. This engine needs a hi-stall and gears to be fun
So here is the 360 2bbl cam
Static compression ratio of 8.2:1.
Ica of56*,still 500ft
Effective stroke is 2.97 inches.
Your dynamic compression ratio is 6.97:1 .
Your dynamic cranking pressure is .................. 133.78 PSI.
V/P (Volume to Pressure Index) is .................. 121VP
Here we have typical MAGNUM 5.2VP
Next, lets put a 318 cam in it, with no other changes.
Static compression ratio of 8.2:1.
Effective stroke is 3.10 inches.
Your dynamic compression ratio is 7.23:1 .
Your dynamic cranking pressure is ..........140.55 PSI.
V/P (Volume to Pressure Index) is ........... 133
Notice the pressure has risen to 140 or plus 12.9%
Notice the VP has risen to 133,which is about where the fun starts.
I would not run less than ~124VP, for me, that is already pretty sucked out.
Next lets compare the cams as to all their durations, and I'll use the advertised numbers. First the Comp274, then the Mopar 360 2bbl, and then the 318 2bbl
>276intake/118comp/ 101power/286 exhaust/110LSA/54*E-overlap/Ica of 62*
>252 intake/124comp/116power/260 exhaust/112LSA/32* E-overlap/ Ica of 56
>240 intake/130comp/122power/248 exhaust/112LSA/20*E-overlap/Ica of 50*
Compare the power strokes; the more degrees you have in a cruiser, the higher the potential is to make good fuel economy.
Compare the Effective overlaps; the more you have, the greater the idle lope.
Compare the Ica's; The bigger the number, the later the intake closes and the lower the idle vacuum.
I like to add the compression degrees to the power degrees to come up with a number that helps tell me how suited to an application, a certain cam is. Among these from top to bottom the numbers are 219/240/252.
for your application, I know 227 is a good number, for both economy and cruiser-fun. but 227 is not on the chart.
No big deal cuz you have a 2800TC, so your bottom end can be a lil soft, cuz when you floor it, you will only be in the soft part for a second. So while I don't like 219 for your application; If you got to have idle lope, then of these three your Comp is the best choice.
why?looks like i just need to find a pair of 360 heads with 2.02 valves and maybe little smaller cam
i was going to private message you,but box is full. my ultimate goal for the 360 is to be at around 300-350 hp to the ground... i want something that is stronger and pulls harder than the 318... car weighs like 3600 lbs with me in it...why?
with 3.55s and an automatic; you will hit 44mph@5000, spinning all the way;
and 60mph at about 4000 in second gear. The 318 heads will be fine to 4000. Just put a small-port intake on it.
How much better will 360 heads be at 4000?
What good will a 68* cam be, that doesn't power peak until maybe 5000 with the 360 heads.
Ok sure, the 360 with 360 heads and a 268 cam will make quite a bit more absolute power.
But what counts is the average power, to the shutdown. Furthermore, to get that top-end power, the 268 cam gives up bottom-end power.
Street Cams are like sliding windows, about 1500 rpm wide. When you slide it up, you leave the bottom behind. The higher up you slide it, the more important the heads become, and the higher the stall-speed needs to be, to get away from the soft bottom end.
The proper way to use a 268 cam, which wants to power-peak at around 5000, is to gear the car to use second gear,to hit about your highest anticipated speed.
If that be 60mph, then you would need 4.56s, for 60=5200, now you have the potential to be quick., Now the 360 heads are a must-have. Now an overdrive transmission is a must have.Now the 2800TC is optional. Now your starter gear is 11.17 waaay killer, and street tires cannot deal with that, so you are driving on the two-barrel in first, unless you just like frying the tires.
But you could do the same thing in first gear with 2.76s and now 60=5300. But your starter gear is now a tad on the low side at 8.11, so the 2800TC is back on the table. And now, you no longer need an overdrive.
But if you work the formula backwards, you find that 60 mph requires a gear of 7.00@5000. The engine doesn't care how you get it. So in 1.45 second gear, you would need 4.83 gears. In 2.45 first gear, she would need 2.86s. So, as you can see, there is no way to satisfy the cam in either gear.
But what about at 4000? At 4000 the required gear to hit 60 is 5.11, so with 1.45 second gear, this requires a rear of, wait for it ........ 3.52.....lol. Badaboom!
Wait, you already got those. And you got the 2800TC. And the 318 heads are easily good to 4000. Soooooo, all you need is a matching intake and a 4000rpm cam.
Will it be as fast to 60mph as the 268 with 360 heads?
Since you can actually harness first gear with the smaller cam, and she hits 60 at the optimum rpm. I would almost bet money, that the smaller cam could be quicker.
But hang on, we're not done yet.
The cam does not hit peak power at a specific rpm, but rather, plateaus over a few hundred rpm. say 400. So if you had a cam that "peaks" at 4000, it will have a peak at say from 3800 to 4200. Furthermore, you can, work the heads to stretch the plateau out say another 200 to 300. So now that 4000rpm cam is actually gonna be able to be shifted at say,4500, which is about the limit of the 318 heads. So then, we could run the same percentage higher gear than 3.55s...... if you wanted to. Or you could run the next smaller cam, or you could extend the 60 mph top speed by the same percentage. Since 4500 is about 12% higher, this would be 67 mph.
Ok soooooo what cam is gonna power-peak in the ballpark?
That would be the 318 2bbl cam. But If you have to buy a cam, Then I would not use the Mopar OEM cam, because it has notoriously long clearance ramps that are designed to outlast the engine,lol. as are most oem cams. including the 360 2bbl cam.
So then, you could up-cam one or two sizes, with a fast-rate-of-lift- design, and not sacrifice bottom end torque. Or you could keep it the same which would pump up your cylinder pressure, making the potential for better fuel economy.
Already have long tubes and 2.5" with flows on the 318 in the car.The truth is that you can bolt all the 318 top end stuff onto your 360, including the cam; and the 360 will feel NOTHING like the 318 you just robbed.. No contest. For best results install a free-flowing dual exhaust or Big single. Headers on 318 heads with a 318 cam, IDK . I doubt you'll notice much, other than the racket,lol..
I have put the 302 heads on a few 360s. 2 were in A bodies. Totally stock 360. Both cars picked up about .5 in the quarter mile at the street drags. Kim
U Betch ya. On stock 360s. KimWait...... You put smaller heads on an big engine and ran faster