360 with purple cam

[Fletch]

I have a 360 that I am putting into a 37 plymouth. It is going to be a cruiser. The engine has been rebuilt - bored .030 over with Keith Black pistons, Edelbrock performer intake manifold, plus some other goodies and a purple cam which is said to be 284 duration .484 lift(P4120231) or maybe it is a 280 duration .474 lift (p4452992) - I have a reciept with that # on it. I bought the engine from someone already rebuilt.

Question - I do not want a radical idle for this cruiser and I am unable to find tech info to tell me the cam duration at .050" lift for either of these cams - that would give me some indication of what I have. Are these cams too much for what I'm looking for and if so, what is the downside to putting a stock cam back in?

[wallyghs]

I'm in the process of building my own 360 and gave some thought to the .484 purple shaft. Idle should be fairly lopey and u'll have to turn some RPMs to make real power but it will make a fun engine. What kind of compression are you running and what sort of induction? I think i'm going to go larger than the .484, I'd like to make power from around 2500-6200 or so. If you're not looking for gobs of power and would rather have a nicer idle then better cams can be had(again, depends on compression). Don't go back to stock, go with a more modern grind that will give you better power and idle. "Racer Brown" cams come highly recommended. See the phone directory in the Performance Forum(stickied at the top).

Good luck


BTW-these are more street rod cams than long distance cruiser cams.

[340duster1]

I have the 280 .474" cam in my street driver duster. It is quite lopey and only draws about 10" of vacuum at 900 rpm. The idle sounds cool but is a little rough. If your are going to use either of those cams I would suggest a higher than stock stall converter and some 3:55's or 3:91's for gears.

[deadhorse66]

Yeah, ditch the purple nurple regardless--you can get a better idling cam without compromising too much performance. Do like wally says and call Racer Brown. All you have to do is give them a rundown on what you have, and what you want to do with it and they will send you the cam that best suits your needs. The only time I would use a Purple shaft would be if I wanted something with a lopey idle and not much else--there is much more modern and high quality/better performing stuff out there. By the way, if you don't mind setting valve lash every now and then, I would suggest a solid lifter cam package, if you do mind, or you don't want to buy the rest of the stuff to go solid, just keep the hydraulic, but from what I hear good hydraulic lifters that stay pumped are hard to find these days.

[TimL]

Hey there, I just finished a very strong 360 , with a .040 bore, cc'd, milled 040, ported and polished, bowls and runners, I'm using a .484 lift at 276 duration advertised, dialed in on a 108 cntr line, and it idles fairly smooth, will get "choppy" round 800 rpm but becomes managible around 900, what your probablylooking for will be around the 270-280 duration, and will have a very nice sound and still give you the torque and horse power your looking for, it's not just the lift that gives you the sound or horse power, it's also how long the valve stays open and closes, on both intake and exhaust, that makes the power, you can pack it in , but if you can't evacuate it out , your in trouble.So I would look at duration as well as lift to solve your problem, look at weight of your vech., where you want your power to come on, and for how long rpm wise, rear gear ratios, they all need to be insync, to achieve the power your looking for,as well as the driveability.



Tim Lawrence

1 nasty 360
1 high school present 68 Dodge SuperBee
1 440 marine block 9.90 challenger
1 1976 Dodge Cornet Sleeper BB

[340duster1]

TimL - what pistons did you use for .040"? Were they std bore 340 pistons?

[rumblefish360]

If the cam you want is a 284 duration unit, chose it with a wider centerline. The MoPar 284's narrow center line is good for reaching peak power faster. The 284 with the 112 centerline will idle better and provide a wider, longer power band.
A custom grind would do bgetter. Racer Brown or even Comp or Crane can do this.

[Fletch]

Thanks all. I'm convinced I want a wider lobe seperation - probably 112 degrees. I'm still trying to nail down my compression ratio. As near as I can tell I start out about 8.4:1 stock. It's been bored .030 and has flat top KB pistons. I do not know what the freeboard is in the cylinder with the piston at TDC. To add to the fun, my heads have been milled - not sure how much but the shop labeled the job "street comp". The shop is no longer around. The guy I bought the engine from said the comp ratio was about 9.5:1 which seems reasonable but I plan to find out for sure.
The vehicle is about 2900lbs (37 plymouth) and I'm going with a 727 automatic and 3.23 rear.
Does Racer Brown have a web site? I've been unable to pull it up.

[wallyghs]

Check the phonebook stickied at the top of this page. not really a website.. just call 'em.