pushrods

[Bbeachmobile]

i thought the hemi preditor had 1.3 rockers and i was told that i need to upgrade to chrome-moly pushrods with the f-275 cam well they havent bent yet so well see im sick of dumping money into this engine and it runs pretty damn good the only thing i want to do is make a new exhaust

 

[Bbeachmobile]

HF212 preditor HEMI
ARC rod
billet flywheel
6 degrees adv.
dynocam F-275
stock PUSHRODS
25ex and 27int stock size stainless valves
stock flattop piston
.020 in the hole
head milled .022
lightly polished
pz26 mm slide (re jetted with kit from hotrodminibike)
1"x1/2"intake
3/4 "exauhst pipe
plan is to match the exhaust to the intake 1 inch stainless pipe

 

[youngengines]

The hemi does not have 1.3 rockers.. they are 1 to 1 (or very close). I set my pushrod length by making sure the adjustor is riding on the valve tip, or lash cap, correctly.. and I check the actual lift at the valve. To me, proper geometry should give me the correct lift at the valve.

 

[SnakePliscan]

Been gone, but back with new info. I'm putting a dyno 356 cam in a predator hemi and this is what my valve train geometry looks like. As i rotate engine i can see that at zero lift or center line on cam i have full contact between lash cap and tip of adjuster. When i rotate crank to full lift of cam which is .3555 the tip of adjuster rolls up on the very edge of the adjuster buts stays in center of lash cap , no moving the to edge of cap. i have 1:1 ratio rockers and are using stock push rods that are 5.560" long. Still think after reading everyones input i may need to shorten push rods, comments ?

Good question, first we started out talking about shaving the head and or top of the block and how that effects the geometry, well with a stamped rocker that sets lash at the fulcrum you will have a problem, the Hemi on the other hand adjusts lash at the tip, the fulcrum is fixed. A better way to go in some cases. and probably will work better when shaving the head.
As for adding just strait up lift the contact at the valve stem is going to move farther, how much of course is directly proportion the to how much more lift your adding, by the sounds of it the Hemi has pretty good geo and we can add quite a bit more lift and its not a problem.
As for push rods they will have they own frequency under operation just like a guitar string, how crazy that gets and when mass is going critical is dependent on cam design, spring pressure and RPM.