.576 lift with 1.7 rockers /forums/images/icons/shocked.gif

I'd have SERIOUS doubts. No way I'd bolt that one in without checking!!!

 

The X303 has a base circle lift of .33875. Times a normal rocker of 1.6 = .542. Now if you use a rocker of 1.7, you now have lift of almost .576. That is a lot of lift. If you want to keep the 1.7 rockers, you might consider the F303 cam which would net you .544 lift. While the lobe angle center is a little more forgiving, it has a little more duration. BTW, these are fairly hot cams, unless you've changed gears and raised compression, it might make the car hard to drive (low vaccume) and lose power (bleeding off cylinder pressure) plus that stock computer might have a fit. IMHO, a better selection might be the B303. Of course it is your car, have fun

 

I have AFR heads, they have the valves in the stock position.
I'm running a .565 lift cam with 224@.050 lift. The valves had the minimum clearance. My lobe centers are kinda tight at 106 deegree. I don't think the x cam will work without flycutting with the 1.7 rockers. Maybe some 1.6's

 

I am running this motor in a 65 mustang with a carb. I will not have power brakes or power steering. The car has 3.50 gears with a 5-speed trans. I will check the clearence of the valves. If there is no chance of it working then why buy it but there seems to be a good chance that it will work with 1.6 rockers. I do have a friend that wishes to trade me his 1.6 rockers for my 1.7 rockers so that is an option for me if needed.

 

Just clay the pistons and check, you can make a solid
roller lifter by removing the circlip and flipping the little piston
over, makes it a much easier then having the hydro lifter adding variables. Porting the heads (if stock) would help
a cam of that type work MUCH better.

 

Avoid the 1.7 rockers on a hydraulic roller cam unless it is a low lift,non aggressive profile.Hydraulic roller cams are nice,but they have limits.A profile such as the one you mentioned requires substantial spring pressures to avoid valvetrain separation(float)at higher rpms.Hydraulic lifters will bleed off under these circumstances(although cam manufacturers don't want to talk about this)and valve timing variations will result and you'll have no way of detecting this.Any 5.0 dyno test you read will limit rpm to 6000-6200 for this reason,even if the head, cam,combination is capable of producing more power at a higher rpm.Hydraulic roller lifters are very heavy,and combined with aggressive lobe profiles,high valve spring pressures,this can overwhelm the hydraulic capability of the lifter.Using a 1.7 rocker amplifies all of these limitations and makes for a very unstable valvetrain.This is especially true of hydraulic roller retrofits,since they have a smaller base circle and make the lobe profile even more aggressive.Do the machine work for valve/piston clearance and try a solid roller cam & lifters.This eliminates all these limitations,will rev far beyond anything else,and make more power through the whole rpm range,and improve idle quality and vacuum.Good luck

 

Interesting. I can spin my F303 Roller Cam up to 7000rpms, no problem. I think a lot of that power is in the heads, though. I think those 5.0 graphs you saw were based on a stock cam, which has a much lower redline. I agree a solid cam would be a much more efficient power maker.

 

Would I be better off keeping the E303 cam with the 1.7 rockers that I have or going to the X303 cam with 1.6 rockers? I am one who likes the sound of a good thumping motor and I would like to have the better of the two set ups that would give me the sound and performance. If I was not starting out with a 13,000 mile bottom end I would have the solid lifters and and all the other requirements in the motor to run the X303 set up with 1.7 rockers. Thanks all for your help and input.

 

I don't mean to sound like a know it all,but spinning that parts combination to 7000 is risky business,especially when using 1.7 rockers.There is valvetrain instability and if you dyno'd it,you would find that horsepower & torque drop rapidly after 6200,even if it will rev higher.A solid roller will outrun the hydraulic by 30 to 45 hosepower at this rpm level.I would limit a stock short block to 6500,absolute maximum,irregardless of how many guys say they get by with it.That is,unless you have an unlimited budget.Try a solid next time.I bet you'll like it.

 

I would run the X cam with 1.6's,but still check valve piston clearance & degree the cam,to be safe.Let us know how it turns out........

 

I usually shift at 6500 when I get on it day to day but it'll climb right up to 7000. That's with 1.6 rockers. It's just a street motor, a daily driver. Hopefully I'll build a solid lifter roller cam motor in the future, once, as you say, I build the bank account up a bit. /forums/images/icons/cool.gif

 

Is it possible to install the solid lifters on the X303 cam? I do not remember the spring pressure of the springs on my heads but can have them checked. I had a solid lifter cam in my 460 motor. The specs where .710 lift and 314 duration and I loved it. I hope to have the motor running by this spring. I will keep every one posted on the out come. Thanks again for all the input.

 

The lash must be limited to .004 because the hydraulic is ground without a clearance ramp on the backside of the lobe.If you run it any looser than .004,it will pound the valvetrain to pieces.I would'nt recommend it.......