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#1
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Mopar purple cam question small block 360
i have a 360 sappose to be stock i have a 430/450 mopar purple cam is this the biggest mopar cam you can use for stock and do you have to degree this cam? or just line up the dots? or would it be better to degree it what is the rpm range on this cam i dont have the cam card for it and which intake should be used thanks
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#2
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The rest of the combo will define how big you can go on the cam. What does your car weigh, stock converter or high stall or stick, gear ratio, and heads used all play a part to selecting the cam.
The cam you mentioned is a good street cam. Should pull to about 5000 rpm in a 360. Use a dual plane intake. In other words if the rest of you drivetrain is stock then yes this is about as big as you would want to go. It's always a good idea to degree in the cam to get maximum power. We rarely used to do it but anymore seems stuff is massed produced so fast the timing sets can be off enough to cause significant power decrease. I've seen 2 timing sets mis-marked. One was one tooth off and the other was 2 teeth off. The one that was 2 teeth off was a Mopar performance set. The other a no-name brand. |
#3
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i got 2000 or little over stahl and 3.92 gears 750 holley vac sec 3 inch exhaust dumped at the axle 75 dart sport pretty light car 904 trans so does this cam need degreed or just line the dots up what do i set the timing at?
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#4
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A dot to dot alignment will do OK, even more so when the cam is small.
If you wish to extract every last bit from the cam, degree it. It really isn't that hard to do. It may take some time to do. But it's really not hard. When you degree in a cam, size and build depending of course, there could be as little as a mere 5-10 HP (and/or torque) gain on mild builds. More on beefier builds. I myself would do it. A degree wheel is cheap and it just takes a little time to do. (I like taking all night and drink coffee and talk about nothing myself with freinds or the wife, but hey, thats me. LOL ) |
#5
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Rumble is right. With your mild setup it's not absolutely necessary but I always do it cause of the 2 timing sets I've seen that were marked wrong.
Set the total timing to 34 degrees. Also use a lightweight spring kit so the total is in by about 2200 rpm. Your car should run real good. Sounds like a good combo. |
#6
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Mind telling us what carb you're going to run? Run an Edlebrock Air-Gap intake(dual plane) so you won't die on the bottom end.
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#7
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Looking at the basic combo you listed, stall/gears/carb in an "A" body. I would say cam timing can be preety nice for the street. Let me ask you, what size tire are you running. This would help in a suggestion on a max size cam that you could run WITH drivabilty. Off the cuff, in an example, A Comp Cam of 280 is a good power maker that would fall in the perameters. The MoPar purple 284 is as large as I would go. Chose your cam based on cruising RPM. Since you allready have a approx. 2000 stall, that wold leave room for a decent cam like I listed above, to be used without major problems. Intake suggested....RPM or Stealth. Walkercolt suggested a Air-Gap RPM. While I have this intake myself and like it a real lot, have your carb be an electric choke model. The intakew doesn't warm up very fast at all and will cause driving problems when it gets chilly out. The regular RPM or Stealth do not have this problem. |
#8
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intake
ill have to look at that intake again its a weiland no air gap nothing special and so i should curve my distriputor with a 2,200 kit? and set the tyiming at 34 what rpm do i have it idling at when i set the timing? i have vaccume dist and holley 750 vac secondarys man choke ill get back with you on which intake i got so that cam i have will work best with the edelbrock air gap rpm best?
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#9
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A recurving will help. What exactly it should be at ....well, it is a bit of a gray area to me at this point. Having it all come in (Timing) early is desired though. Discontect the vaccum hose to the distrib and plug it. Run the engine @ 2,000 rpm and set the distrib @ 34* and lock it down. A note on cam choice. There like opinions. Eveybody has one and they all think there right while thinking everyone elses stinks. To chose a cam, follow these basic guide lines; Select cams operating range on what you will cruise in. Example; 65 mph @ 3,000 rpm w/27 inch tires. Get as much lift as you can. Lift is directly related to HP increases. If your head stall @ .500 lift in the air flow capacity, theres no real reason to use a cam with .600 lift. Street cams for performance cars are normally found to be ground on a 110 centerline. Going smaller helps top end punch. As well as brings it on a tad quicker, but, it starts to get to be a pain to tune while at idle. (Very choopy idle) If the cam is ground on a 112 or larger, the idle tends to smooth out and power isn't as strong. It comes on slower and you'll wait longer. (A few hundered rpms.) It also doesn't tend to peak as high in HP. It's not mandotory to seek a grind that takes max advantage of the .904 lifter. It helps, but all has to be very good to see any real gain from this advantage on a street ride. It's better to error on the small side! Having a cam custom ground can result in a few more ponys or lbs. of torque for a minimal cost amking the worth while to check out. (It also sound real cool saying that in a crowd.) |
#10
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#11
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This is only true to a point. When the airflow stalls, theres a level of stall. As in, does it quit flowing and take a nose dive or just level out. Quickness of the valve opening is near absoulte mout.
In example a comp cam of 1 grind and then the next size up isn't lifting the valve quicker to make a measured difference in power. It is a minimal difference. A change in rockers and/or a move to Magnum heads and /or combined with a agressive ramp make a difference. And not a whole lot. Hitting the sweet spot twice and sounds nice, but it's not all crack up to what you think it is. Heres why. When the valve goes past peak flow, the flow rate slows down. Going back to peak flow on closeing events, the air/fuel have to pick up speed again to achieve the flow rate. But it won't. It has to overcome the mass of the charge in the cylinder first. By then it's to late. This is for ports that fall hard after peak flow. Still, even if the past peak flow only dip slightly, it still has to have good ram effect enuff to keep it flowing in. All above is such a minimal thing. But YOU missed it and therefore look stupid. Remember, I'm on you. because you asked for it. |
#12
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OK Fish.
Put your desktop dyno and your magazine down for a sec, and think about what goes on INSIDE the motor (and not in your superchevy magazine). For one, INSIDE of the engine, the fuel/air mix is not moving at a constant velocity. EXPECIALLY in the intake port. (DOY?) now Back to 4 stroke 101 When the piston is going down the cylinder fast, it makes a incredible vacuum. You may also have figured out that air has mass and velocity, so, considering the "flow drop from too much lift" you speak of happens near the middle of this "vacuum" made by the piston,(or where teh piston is traveling the fastest) the "velocity" over powers the "flow drop from too much lift" you see from your flow bench and the 28 inches of water that the flow was measured at. (the reason is becasue the vacuum made by the piston, along with the velocity from the moving air, is creating WAY more force through the intake valve than your measly lil flow bench and your magazine numbers. I didnt ask for it, you decided to give it on your own. |
#13
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:lolup:
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Flow bench operate at a pressure drop to test the heads performance. Which is very different in the real world. And very different on any engine. Since it will change from engine to engine given so many combonations. The head will allways flow well, but the carb intake cam will change the performance of the engine. The head will only work with whats it is given. Quote:
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#14
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Ahh, the pissing contest thread again. Oops, I mean - oh, never mind. Anyway, for 73roadrunner's info, that cam's specs (Mopar catalog) are: P4452759, 221-228 duration at .050", 44 deg. overlap, 110 centerline, 430/450 lift, 1200-5200 RPM power band. I have one in my 9.0-1 360 with a TQ, iron manifold and Hedman headers, in a 3600 lb. Mirada with 2.94 gears and it works fine on the street. I'd think your Dart with 3.90's could use more cam. Just my 2 cents. (1 .875 US)
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#15
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#16
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OK, in my opinion, if you have and want to stay with the stock valve gear, do a compression test on a warm engine. Take the readings with a fully open throttle. If you get 150 PSI average, you probably have a 9 or 9.5 to 1 engine. I'd probably stay with that cam until you feel the need, and then consider just how many $$$ faster you want to go. Meanwhile, go enjoy - it'll be pretty entertaining with those gears!
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#17
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#18
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Anything to argue eh? |
#19
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You make yourself look silly all by yourslef. I just like setting you up to fall, which you do well all by yourself. |
#20
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The cam is fine. You could go larger with your 3.91:1 gears and stall converter, but you will have a rough idle and loose some low end torque.
I always degree in my cams, but I have the tools. The big advantage of degreeing in the cam is you will know exactly the installed position. Doing the "line-the-dots-up" method will work, but you won't know how far off the cam is, and if the engine dosen't perform correctly you may think the problem is the cam, and not that it may be several degrees off from where it should be. I have installed several cams and it's fairly common to be 4-6 degrees off when you just line up the dots. |
#21
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well that cams gotta be better then my stock cam thats in it now
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#22
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Don't know what your 360 came out of, but the numbers for a 1980 pass. car 360 4bbl are: 252 deg. duration at .002 lift (200 @ 050?), 33 deg. overlap, and .410 lift. Earlier might be better, but yes the 2759 cam is considerably better - quite close to early 340 specs, actually.
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#23
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the motor is a truck motor from what my uncle said and he put a stock cam in it becasue he had that purple cam in in and said it wasnt running right with it so i think he probably didnt set it up good cause he didnt use a degree wheel thats why i wanna put it back in should work
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#24
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OK, I would think any truck 360 (except the 78 L'il red express) wouldn't have any more cam than a car. Might be wrong, so check the year of the motor. See the post re:340 engine i.d on this page - and let us know what year it is. Somebody here will have the cam specs. Also, do you have a set of new lifters for it?
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#25
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cam
yeah the 430/450 cam that my uncle pulled out i have new lifters so when i out it back in do i have to pump the lifters up before i put them in or just put them in? i also checked the compession when the engine was hot it was 130 psi so what do you think the compession ratio is?
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#29
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Concur with the Alaska Kid. If you have some assembly lube ( and it's handy to have around, buy a big tube if you don't have any) slather lots on the cam lobes and lifter feet, and flush the oil and filter after an hour or so of operation. Cheap insurance, since you don't know how long the cam and lifters ran before, and probably don't know which lifter ran on which lobe.
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#30
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Ditto everylast word.
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