Help with cam choice for magnum 360 please
One thing to keep in mind is with the poor lifter to pushrod angle inherent to a SB Mopar you loose .020-.025" lift even with perfect geometry. I always heard that and last year I did a mock up with a couple different cams to see if it is correct and it is. My test used 2 different hydraulic cams with the lifter blocked so as not to loose any lift from compressing it. With roller cams the lifter to pushrod angle is even worse so you'll loose a little more. You really should measure your heads to see how much lift YOUR heads will accept as manufacturing tolerances vary. Turd might measure his at .500 lift max and yours may be .480 max or they might be .520 max. Can go either way. No matter what cam you use you should measure to determine what length pushrods you need because again manufacturing tolerances vary so much there is no way anyone can say that a certain pushrod length is the correct length.
I have a preliminary measurement from my shop that cleaned up the heads indicating a .570 lift - IIRC, I just can't find that slip of paper at the moment, but the easiest thing to do would be to re-measure them, both exhaust and intake.
As far as pushrod length goes, get me in the ballpark please. Stock length is 7.500 I believe? I understand I will need to check myself to be sure, but with a small base cam, how much longer than stock would I need to be, approximately? I at least want to order the right length adjustable pushrods so I can check/read the cam when I order it.
Another thing I noticed you mentioned using 1.5 rockers on your heads. The only way you can do that is to convert it over to Chevy style stud and ball rockers because all rocker arms made for Chrysler magnum heads are 1.6 or 1.7 ratio. At least all I ever saw advertised were and I went through that last year trying to find some 1.5 rockers for a set of magnum heads. They didn't exist then.
I am probably going to stick wtih the stock rocker setup for now. I do like the idea of converting over to an adjustable valvetrain, my buddy with a set of GT40 ford heads has the same pedestal setup as my magnum heads and I found these Crane stud/guideplate conversion kit for him
http://www.summitracing.com/parts/CRN-36655-2/ - looks pretty trick for $128 all in. Less than the machine work a shop would charge to drill and tap to 3/8 or 7/16 stud I imagine. I could then run a set of chevy self aligning rockers in either ratio, but that is not my plan from the get go.
I have been burned a couple times on E-bay so I'd be leary of ordering a cam from someone there. If the place is a legit business they should sell to you direct. If I were interested in the cam like you are I'd e-mail him and ask about buying it direct. Paying a business with a credit card generally gives you protection that you don't get on e-bay. E-bay claims you get protection through PayPal but don't believe it. I bought a part from a guy and payed with PayPal and the guy never sent the part and PayPal tried to collect it from him but he drained his account before they could collect so I was told tough luck.
I am also always leery of ebay but this guy comes recommended by a FABO member and has good feedback and had extended his 7 day inspection/return period to 14 days for me - which is why I want to get all my ducks in a row before I get the cam. I want to be ready to drop it in, degree it, read it, check lift, etc and not wait for summit or jegs to ship something - I like the price, I like his feedback, I like his policy and the numbers I get on Pat Kelly's calc look perfect for me - so I'll give it a shot; I just want to be prepared and ready.
A note on ebay/paypal. Your payment method, short of a bank transfer, can be protected through your credit card's fraud protection program if you use a CC to pay PayPal I believe. This particular seller offers a full refund policy and has a 320+ rating and is 97.7% positive, I read all the negatives he got, they were from dumb-sounding buyers with almost bogus complaints. He also takes Money Orders, so if you use a USPS MO you have the Feds to behind you (as much good as that is at the rate they move) - I'll take a chance if I can return the cam and get my money back if there is a problem.
I measured the retainer to seal clearance today and found the contacted at .524 lift -int @1.66 installed, however some exhausts run less than the intake might, fi..I measured some stock '974' heads I have and found .544 -int @1.68 & exhaust .444 @ 1.55 installed
I will re-measure my heads and check the retainer to seal clearance as well as overall lift and coil bind height.
Quick Question : what valve spring would/should I use with the regrind cam in question assuming a .480-.512 lift?
