Ok so i think i found what i want to do with my 350 this winter. found this combo on a website:

-World Products Sportsman II 64cc heads
-Dart II Sportsman dual plane intake manifold <~~anyone know if this is made by world products?
-Comp Cams Xtreme Energy 268°, with 268/280° of duration, 224/230° of duration @ 0.050 in. of lift, and 0.477/0.480 in. of lift <~~is this a lumpy idle cam or is it pretty conservative?
-9.5:1 compression
-It claims to put about 375 MAX HP and about the same torque

Question- what ratio rockers should i use? and would it be ok/smart to use a CC q-jet ontop of this or would that just be plain stupid?
My first real engine build-up is coming over this winter!!!

 

i'm assuming that's at the crank? are those heads aluminum? the compression is rather low for a higher n/a power motor which is fine unless your running aluminum heads which prefer a higher compression.

good luck.

 

Yeah that's at the crank and the heads are going to be cast iron, mainly because of the money issue. would it be ok to use my q-jet though? thanks!!

 

Not exactly; it's made by Dart, which bought the remaining assets of World Products after they went through their debacle. Dart still makes some of the World products, including their more popular head models.

That is a moderately "lumpy" cam, certainly nit radical; probably about at the limit for comfortable power brake operation.

With those heads, you'll benefit significant'y from the extra folw of the higher ratio rocker. If you have to buy rockers anyway, get 1.6s. Use 1.45" valve springs on it, not 1.25" ones; such as Comp 986.

375 HP is a reasonable goal for that combo.

You probably won't get good results with the Q-Jet, at least not as far as low-speed driveability; their idle circuits are hard to tune with a cam that gives low vacuum. It should run fine at WOT though, although a Holley or Demon would likely outrun it.

 

not that it matters too much... but what would you guess my gas mileage would be at with say a 650 dp?

 

And should i buy those heads bare or with valves and springs- i would prefer the assembled one because of no experience with installing valves, but the springs it comes with are 1.25". would this work (well) or would i get valve float? should i just go for it and do the valves myself? (with the help of friends of course)
Is there any other alternative to getting the 1.6 rockers and still get decent (or the same) power?

 

Cr
With those heads you are probably looking at a CR of 9.75 or 10:1. To make sure you get a good amount of vaccum get a lobe seperation of 112-115. Remember as you have a shorter duration cam and higher valve rates you will get a better idle with faster valve acceleration which might result in a little less cam life.
Call the cam manufactureer and see what they have to say about your question in pairing. I think I accidentily posted this as a new thread. opps.

 

I currently have the xe268. It makes about 14-15" of vacuum in my 350. I had a cc quadrajet on it and I was running 9.4's w/ a set of 305 heads. I had some kind of high end problem. It felt like kind of a flutter. Now I put a demon on. I still make about the same vacuum but instead of having that flutter it was a more audible pop(I have an open element now so I think I may just be hearing it more). It seems that the problem mostly goes away if I set my valve lash, but comes back so I am having some sort of valve train problem. This last time I reset the valve lash it seemed to go away, but came back about 10 minutes later. This time it is even at idle so I am just letting it set until I figure it out. I would be interested to see what kind of power I make w/ the 305 heads before I put the sportsman's on if I can get whatever problem this is fixed. I have not ever had the motor running quite right up high so I dont know what times I should have run, but it always ran fine in the low rpms with the cc quad. I was getting 15 mpg in town.

Ben

 

I'm still kind of stuck on what cam to get. Now i think i may be leaning towards the XE262, but i really have no clue. would the XE268 still be good to drive on the street as my summer everyday driver? and if i got the 262 should i still get the 1.6's rockers and 1.45" springs? im pretty sure that im going to be assembling the heads.
thanks for the replys!!

 

The xe268 is definately acceptable for a summer every day driver. I think you will loose more lowend w/ those heads than that cam. If you go much smaller than that you are really going to loose out on the potential that those heads have.

Ben