I picked up a set of Sportsman II cylinder heads for my engine build. they didn’t come with rocker arms, and they’ve been milled down a bit. I don’t know how much they were milled.
I’m at a loss when it comes to valvetrain geometry. I know I can’t really just throw any rocker arms and just stock pushrods in this motor now. how do I go about measuring and finding what the best fit is going to be for pushrods? and when it comes to rockers, what is the advantage between 1.5 and 1.6?
They aren’t intended for use, but they’re adjustable so you can determine the length of pushrod you need to order. 1.5 or 1.6 is the rocker arm ratio, where if your cam lobe lift is (number outa ass) .370", your valve lift would be .555" with 1.5, or .592" with 1.6…its lobe lift times the rocker arm ratio…so 1.5 or 1.6…
well this is the cam I have… http://www.summitracing.com/parts/CCA-08-422-8/ , the pistons are stock for the motor, which is a '97. I haven’t had the heads off yet. but they should be flat tops with valve reliefs. and like I said, I have no idea how much the heads were milled.
---------- Post added at 11:40 PM ---------- Previous post was at 11:39 PM ----------
Get an adjustable pushrod to check for desired length and you are going to have to clay the pistons to be sure on if they clear. With that cam if they flow to .550 assuming stock is 1.5 I would try a 1.6 but you might have PTV issues hence the clay.
so a bunch of my parts came in today, major component: the cam. after reading the whole booklet that comes with the cam, I’m beginning to doubt my mechanical abilities on this one. simple things like headers, carbs, intakes and distributors I can handle no problem. but everything involved with degreeing a cam and all of the clearances that need to be accounted for; I think I might be better off having a shop put this one together. anyone have any solid recommendations that aren’t going to murder my wallet?
If it’s a mild cam you can simply plug it in straight up. If the heads have been milled a lot the intake won’t bolt up correctly. It MAY have to be milled as well. What cam did you get? Roller cam or flat tappet? If it’s something with under .500" of lift and less than 230@.050 duration you probably aren’t going to have any ptv clearance issues. Do the pistons have 4 valve reliefs cut into them?
defineatly find out how much the heads have been milled, may have to mill intake as well. what is your static compression ratio? might be a tad too much duration for dished pistons unless you have small chambers. compression = horsepower. the cam in my truck has alot of duration, however thats to get the dynamic compression ratio down enough to run 93. what is the rest of the combo going to be?
also, if you have to run 1.6 ratio rockers, its because you didnt chose a cam with enough lift. more of a bandaid in my opinion. :lol:
just curious, why the sportsman 2’s?
when i put my motor together i used the summit 200cc aluminum heads. they were $950 assembled on sale. they’re actually brodix ik200 castings, 2.02 intake 1.60 exhaust, 64cc chamber, with comp cams components, good for .575 lift and flow quite well. ive been extremely happy with the quality and performance, especially for the cost. not to mention alot lighter.
Brand new the sportsman heads have 64 cc chambers, but after milling I don’t know what it is. I bought the edelbrock performer air gap intake, and I’ve got just a holley 600cfm carb for now. I’m not quite sure what I’m gonna run for a carb yet. Im using the sportsmans because I got them fairly cheap from a friend and theyre pretty new.