I have an 89 RS with a 305 RS TBI and am interested in making a step up in the valve train. I am interested in 1.6 full roller's and i think perform makes a set to fit at a good price. I herd that i might have to grind into the hole in the head for them to fit, and i really dont want to do that. Can anyone tell me of a set that works with no modifycations, at a fairly reasonalble price, can sombody please shed some light on the subject???

 

What cam are you running.I think if you change the rockers to 1.6 ur pretty much gonna have to do a little head work on the stock iron heads.

 

Is that the case with the stock cam???????? I too am interested in the 1.6's, am not ready for a Cam change, or head work yet, but might do a rocker change.......Is there any dyno test on just a rocker change from 1.5 to 1.6 (No other changes) ???????????? I have searched for 1.6, but did not see anything like that....Thanks for any answers to this....Tom

 

This is the factory cam, and to answer some other questions yes there is enough room for piston to valve clearance and with 1.6's you wont max out your valve lift, i am just interested in getting 1.6's that i dont have to grind the head to get in smoothly. Like does anyone know if Summit one's fit or Jegs's 1.6's fit. i just dont wana grind into the head.

 

Samrs350, im with ya on this, I too want to do no grinding, just bolt in....I was asking the same question as you BTW.......Tom

 

And I want to eat my cake and have it too, and I want 500 HP and still get 40 mpg and never have a part break, and souls in Hell want ice water.

Seriously.... Think about it. What is "rocker ratio" anyway?

It's the ratio of the distance between the rocker stud and the valve stem, to the distance between the rocker stud and the push rod end.

The distance between the valve stem and the rocker stud doesn't change when you put a rocker on, does it?

So how does a rocker change the ratio?

The only way it can.... it does it by shortening the side toward the push rod. Now you've got the ratio of the same original distance on the valve side of the rocker, to a shorter distance on the push rod side; which gives you a higher ratio.

Where you have to grind, maybe, is the inside of the hole where the push rod goes through the head. Depending on how close the push rods already are to that side of their little hole, the change in ratio might shorten the push rod side of the rockers by enough to move the push rods inward toward the rocker studs enough that on your particular casting, one or more of the push rods will rub.

So, by the VERY NATURE of changing the ratio, the possibility of needing to grind is introduced. There's really nothing that can be done to change that.

In my own personal experience, it's about half-and-half odds as to whether grinding is necessary or not. It's determined by the precision of YOUR particular castings. So it's not really something that can be predicted. I've seen 2 heads on the same motor with the same casting date, where one head cleared just fine and all 8 on the other head hit. You just never know until you try it.

 

Well Sofa, thanks for the explanation...Yes, I do want my cake, and to eat it too...I was under the idea that certain brands would clear with no grinding, but I do see your point about the same model, different heads and all...I have had this problem with my SFC's, mine have clearance issues, my buddy who has the same car, and same SFC's does not have a problem.......Thanks, Tom

 

I am well aware of the geomoetry of a valve train i was just hoping sombody had luck with a set and could give a recommendation of what works good. that's all. I think i will try my luck with Perform's 1.6 set for centerbolt heads.

Thanks

 

Well no two castings are alike so some guys can get away with it...I being one of them. I'm running the comp magnum roller tips and didn't have to do any grinding. And hardend pushrods arn't to spendy either if your really worried about it. My biggest concern would be the condition of your springs. increasing lift is going to put more strain on them. I think I got an extra .010 lift but I mached a cam and spring combo to it.....helps me sleep at night

 

are roller tip better than full roller?

 

No.

The ones with only the roller tip, still have the stock style ball fulcrum. This is clearly not "better" than a roller-bearing axle.

 

Please explain...............Thank you..........