Reply With QuotePush rods of any quality at all just don't fold up and bend. They bend because they hit things. Leak down and then go in there and see whatcha got...left. Don't run anymore.
Leak down..not compression test.
We'll..I made a huge mistake...Ran some bad gas...462 12lbs of boost from a banks turbo set up and ran it..I spun it up to about 6800! I heard a some spark knock shut it down...It knocked only under load! Gettin on plane! Broght it home drained the gas..put in 110! Ran it same thing...under load a knock! Pulled the plugs #5 had some pepper on the plug! Pulled the push rods
on that side and some are very slightly bent...The exhaust on 7 is bent a lil more than the rest! I mean I roll then and barely a wobble...The boat didnt backfire, idled fine..I gave it a lil romp and the knock got worse! I shut it down! Would detonation cause pustrods to bent or did I over rev it and Hit valves?? Tommorrow I am gonna try a new set of pushrods and check compression! All of the plugs look good except 5 and it is slightly grey with some pepper! The oil pressure is good and the motor seemed to run fine untill load!?? If I floted the a valve or valves...can it be done without smoking them or should I pull her down Now! The springs in the book say they are good to 6500...and I rang it up a few times this year to 7000 2nd to third gear...not knowing eeeek! Any advice would be appreciated!! I know...Not the smartest way to learn!!
Push rods of any quality at all just don't fold up and bend. They bend because they hit things. Leak down and then go in there and see whatcha got...left. Don't run anymore.
Leak down..not compression test.
I'll second that!..
I Finialy Got The Pictures
Even though the valve springs will support 6500 it doesnt mean the cam profile will. Forced induction will allow an engine to rev past the limits of the camshaft profile. Not knowing the cam you are running, I dont know if that is the case , but a possibility.
Fiat is right, pushrods don't just bend. My guess is you tagged some valves with the pistons.
My .02
In the event anyone is following this thread, this late post might be of some use.
boost pressure has the effect of decreasing the intake valve springs ability to close (seat) the valve, because of the boost pressure behind the valve, especially in a marginally adequate situation. It's a fine line between controlling the valve and not killing the cam with excess seat pressure, if a non-roller is used.
Good luck Scott W.
pushrods can JUST BEND
If the engine is spark knocking the combustion pressures will be enormous.
Ever break an exhaust rocker arm or the stud.
Guaranteed way to bend the intake push rod.
I have done it a few times.
There wasn't any VTP contact.
The valve can't or doesn't want to open under extreme cylinder pressures.
What you also may have done ( most likely cause ) is that you overreved your valve springs and the valves floated and tapped the pistons.
The cam profile will not cause bent valves or push rods.
But weak valve springs will do it every time if you go past their ability to close the valves in time.
Dentz,
When you say you ran some bad gas do you mean regular or premium pump gas ?
I've been pretty successful this year at running 93 octane pump gas with 13 lbs boost.
With the water / air intercooler the intake temps are real low and that seems to be to be the biggest factor to resisting detonation.
On the Procharger website they make some wild / impressive performance claims from pump gas and they attribute it to the low intake temps.
I've seen in Turbo & Hi-tech performance mag where they successfully ran 23 lbs boost on pump gas premium in a 4 cylinder engine.
Tinkerboater,
I hollered and waved at you when you were idling by party cove at the Hardy Party weekend last month. Did you see me ? That was the wildest party scene I've ever seen up there.
Mark
pushrods can JUST BEND
If the engine is spark knocking the combustion pressures will be enormous.
Ever break an exhaust rocker arm or the stud.
Guaranteed way to bend the intake push rod.
I have done it a few times.
There wasn't any VTP contact.
The valve can't or doesn't want to open under extreme cylinder pressures.
What you also may have done ( most likely cause ) is that you overreved your valve springs and the valves floated and tapped the pistons.
The cam profile will not cause bent valves or push rods.
But weak valve springs will do it every time if you go past their ability to close the valves in time.
this is more what im thinking...
The high pressures from detonation can only occur when the valves are shut (else the gas would simply leak out). If the valve are shut, the force of the detonation should be transfered into the head via the valve seat. So, I don't see how detonation could bend a push rod.
Sounds like something else like a valve floating at the high rpm that hit a piston that bent them. Hard to say, lots of stuff could bend the push rod - lots of stuff except detonation!
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