Cam help please

[chuckstirrr]

I got a chance to buy roller rockers , shafts , push rods, all from Scorpion performance for $300 for my 400 motor , I want to run the old purple shaft hyd cam 509 lift , I ran some thing like this years ago in my small block 340 (same cam) but instead of roller rockers it was the old 273 adjustable rockers, it worked out with my small block , does any one for see any problems with my big block, and do I need to be concerned with rocker ratio 1.5 / 1.6 don't have a clue Please advise thanks for any help :confused1:

 

[lewtot184]

if you have stock heads there probably won't be enough retainer to guide clearance. a 1.6 rocker is going to put lift in the .540 range and that won't work with stock heads.

 

[chuckstirrr]

Thanks for the info, I hate to be a dumb dumb , the number 1.6 does this number go up or down or both ways ? and I assume this changes the height of your rocker, if these rockers are 1.6 i'll pull the heads and go ahead have valve job and heads surfaced then I assume machine shop will get me the retainer to guide clearance I need??

 

[rumblefish360]

The rocker ratio of 1.5 is 1.5 x's the cams lobe lift.
Changing to a 1.6 increases the lift at the valve. Pushing the valve open further than before can create a problem as mentioned above.
The 1.6 is an increase and can not be made to work as a method to decrease the valve lift.

The actual rocker size will vary from manufacturers.
If there are any issues with them, it will show up quickly when you install them. They can be but not limited to clearance issues with the valve spring or contact area of the roller tip on top of the valve.

I have not been there or done that with those rockers.

 

[Cranky]

There's a lot of info on the net on rocker geometry with drawings and actual pics of what things should look like and text laying out what needs to be done when installing high lift cams using factory castings. Modifications to the heads are important. Even the factory high performance books are a good source of info. Not trying to take away from help you can get here but imo, the more you learn, the more you'll understand what questions you might need to ask and the more you know will diminish the chances of messing up the engine. Setting up the valve train can be rather tedious and to me, it's easy to make mistakes which can cause a lot of damage. Also, when you install the cam, use a degree wheel to set it up. Don't rely on the dot to dot method.....

 

[chuckstirrr]

Thanks for all the help guys, just found out that the set up is 1.5 ratio I will still check out the online info and learn all I can about the rocker geometry and any Modifications to the heads that may need to be done, Thanks again to all you guys, you have been a big help