Can any one help me ..I have a fresh 318 bored 40 over Keith Black piston (flat top) Mopar Perfomance purple cam and lifters adv duration 280/280 dur@238/238 lift 474/474 and 203 cast iron heads Not Milled fresh vavle job comp cam valve spring od 1.460 id1.060 seat load 124 lbs @1,800" open load 239lbs @1.250" coil bind 1.95"rated 308s/n new stock push rods and used stock rocker arms and shafts. Fel-Pro head gaskets. Less than 10 hours on engine and it pushed the push rod though #1 Exh rocker arm ball seat and bent #1 intake push rod and did same thing on # 7 cylinder all other cylinder seam to be fine carry about 50 psi of oil pressure all rocker arm are getting oiled ,No its not been over reved .. Haven't even driven car yet still in the process of restoring car ,Any help would be greatly appreciated :banghead:
Vavle train problems
- Thread starter fsteddie
- Start date
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OwdKasd
Well-Known Member
Might be a dumb question but is the Cam still in great shape? I know it's new. The reason I ask is because if the #1 Exhaust lobe was wiped or for some reason the Exhaust valve didn't open, Bam the Push rod will bend
Doesn't the lobe push up on the lifter to push the rod to push the rocker? If the lobe was wiped would it not push up the lifter to bend the rod? Or am I missing somethin'.
Snake
Mopar Nut
If its wipe very little movement is what he would have.
OwdKasd
Well-Known Member
When I had it happen, The exhaust valve would not open due to the wiped out lobe, Then there was way too much pressure in the Cylinder for the Intake valve to open and the Push rod bent. It happened twice to me. Bad Exhaust lobe but the Intake Push rod is the one that bent. However it was not a Mopar engine so It may work a bit differently.
I see what your saying.
pishta
I know I'm right....
bent pushrod or windowed rocker is one of 2 things in my history with breaking motors....either the valve hit a piston and punched the rod through the rocker (uncommon, more like just folding the pushrod) or the valve seized in the guide, ran the clearance too small and caused the lifter to fold the rod. Im betting on the valve guide being too small for the valve stem. Thats a bummer but pushrods are usually the least expensive parts to replace, sort of a fuse for your valvetrain, weakest link.
So Rob are you saying possibly that I could have fatigue rocker arm are do i need to get some kind of performance rocker arms
Unless something change time I installed valves into guild I push them back and forth very smoothly before installing springs
I did not inspect cam lobs as of yet ...Some one else told me rocker arms was my problem as they was used and I don't know nothing about them as came on heads when i bought them ..possible new valve springs have too much pressure???
Unless something change time I installed valves into guild I push them back and forth very smoothly before installing springs
I did not inspect cam lobs as of yet ...Some one else told me rocker arms was my problem as they was used and I don't know nothing about them as came on heads when i bought them ..possible new valve springs have too much pressure???
http://www.wyckoffchryslerparts.com/scripts/prodView.asp?idproduct=-2047
if you want to stay with non adjustable rockers...
if you want to stay with non adjustable rockers...
Bulldozer
free ice cream sandwiches
im using 273 adjustable rockers and pushrods on my 360 and i love them, especially for the money i didnt spend on aftermarkets.
breakstuff
Well-Known Member
Stock rocker arms can't take a whole lot of spring pressure. I've popped push rods through engines that had a few thousand miles and mild cams. Go buy the heavy duty stamped rockers or some adjustable rockers and call it a day.
breakstuff
Well-Known Member
Your intake valve isn't going to be held up by cylinder pressure, but the spent gasses would come barking out the carb though when the intake valve opens.
K.O. SWINGER
Meeting in the alley since 1976
ya I have used stock hd 340 rocker arms with some stiffy springs with never a problem I would look at other components bent valve ext.
OwdKasd
Well-Known Member
All I can say is that on My Engine, the bad Exhaust Lobe on the Cam caused the Intake Push Rod to bend...Twice.
All we could figure is that since the Exhaust Valve wasn't opening due to the rounded Cam lobe. This kept all the compression in the cylinder. Then when it was time for the intake valve to open, Bam.............Bent Push rod.
If You have a better explanation, then I'd love to hear it.
Probably not what's wrong with the Op's engine but something is Binding the Valve train. That's the only way a Push rod would bent. Stuck Valve or something else stuck. I mainly just was throwing out one more possibility to the obvious.
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