jessed

Have a 350 with vortec heads with upgraded springs to handle up to .490 lift, 1.6 ratio comp cams self aligning roller tip rockers, and cam with .442 lift. I have adjusted the valves following Lars paper, Tried adjusting with the motor running, even had another mechanic try, with new pushrods of course, and still bend most of the push rods. I bought the engine minus the heads and intake from a builder who had it running with some stock 350 heads. He told me that the cam was degreed 4 degrees advanced.Could this be the problem?Is it any different with the vortecs or 1.6 roller tip rockers? any help would make my life easier. Thanks, Jesse D :banghead:

jessed

Also I did drill the whole that the push rod passes through for the higher lift rockers.

71coupe

Two possible problems: Valve guides on Vortecs may be too tall or spring coils might be stacking
Hope this helps.


[Modified by 71coupe, 2:02 AM 4/19/2004]

pillowmeto

:confused: got me
they handle .48 stock, maybe something is binding
This might seem stupid, but are you sure you have the right size pushrods

MAtt

jessed

ttt

john V. zemba

Just a thought a friend had same problem and found out the shop had the marks on the timing gears way off, just hand turning it bent the rods

LemansBlue68

Check to make sure your valve springs aren't coil binding. Also check to see if you don't need to have your valve guides cut down a bit to accomodate the higher lift. I've heard that stock Vortechs don't work well with high lift cams without cutting the guides down. Check out Comp Cams website. They have a real good write up there that explains how to check to see if your valve train geometry is correct. If your heads or block have been decked significantly you may need shorter push rods.

If you're bending pushrods due to valve timing that means your valves are kissing the tops of your pistons i.e. you got more problems than just bent pushrods--you're gonna be replacing valves too.

TedH

I'd set the timing straight up as a starting point. The 1.6 lift on the .442 cam is approx .472. My thoughts are the springs are still too short and are bottoming, the pushrods are too long for the combination or perhaps the cam isn't a .442 lift cam. Verify the pushrods are correct for the cylinder head being used. I would also verify the cam lift since it appears you bought the engine minus heads and intake.

Fevre

:iagree:

Here is an article on upgrading the vortec heads for higher lift.

http://www.chevyhiperformance.com/te...ort/index.html

jessed

ttt

neverendingproject

did you change to screw in studs?

jessed

no screw in studs

71coupe

As stated above, the guides/bosses are too tall in Vortecs for anything over .450" and must be machined down. A easy fix might be using 1.5 rockers.
Good luck
:cheers:


[Modified by 71coupe, 9:40 PM 4/19/2004]

djgrelli

I have Vortec's on my 78 with 1.5" rockers. I'm using a .460 lift cam. The stock vortecs will accomidate a .480 lift cam. I would definitely check the lift of the cam. Of course I bought everything as a kit from Pace Performance and everything was matched. Just my 2 pennies.