Broken 5.0 Pushrods

RockSnake · #1 (**permalink**) 01-01-2003, 06:48 PM

Nice day today, so I took the car for a drive. Comfortably crusing at about 1800 rpm, I broke a pushrod...about 1 inch from the rocker. I am hoping for some insight on any of the following questions:

(1) What might have caused a breakage such as this? I would like to not experience a reoccurence.
(2) Would hardened pushrods help prevent this kind of failure?
(3) With pedestal-mount rockers, are guide-plates recommended for hardened pushrods?

I am using the E303 cam in a 5.0 block, and 1.6 ratio roller rockers. The pushrods are stock Ford units

Thanks,
David

mustangmendez · #2 (**permalink**) 01-01-2003, 11:02 PM

D****
Are you sure you didn't over rev at anytime ?
Come on did you miss a gear?
E303 cam and 1.6 should be ok as far as clearance but it would be wise to ck where your rocker meets your valve stem tip .
It should start a little pass center and end up pass center .
Do you know if anyone degreed you cam in at 0 ?
Last but least what is your total advance timing set at ?
You may have to go to a special length push rod but it should be common .For the E303 cam is a common cam .I would go harden after all has been oked
T

Captain Speed · #3 (**permalink**) 01-02-2003, 12:08 AM

Most often overrevving bends pushrods. Maybe it bent on a previous run or was bent and bad from the start? Just a thought as I don't know any history of the engine.

ERA600hp · #4 (**permalink**) 01-02-2003, 05:37 AM

RockSnake

If you replace one replace all of them!!

It's possible that it may have had a flaw in making, that is if YOU din't over rev it!!

I bent 11 one time, several over Revs!!

Will be willing to help replace them if you need help!!

The Royal one

RockSnake · #5 (**permalink**) 01-02-2003, 07:25 AM

Thanks for all of the input. For the day in question, I was taking my wife for a "quiet" drive, and MIGHT have tagged 3000 rpm in one of my shifts. As to previous over-revs...that is a possibility, but I have a 5000 rpm rev-limiter in place.

Years ago, I worked auto-parts, and saw many bent pushrods...never a broken one. Hence my perplexity.

However, Mr. Mendez' comment causes me to think. I did experiment with extra advance on the timing...got a lot of pre-ignition, so I backed it off again. Maybe I did damage on that day that only showed yesterday. But then again, it was an exhaust valve (#4 cylinder), and I thought pinging usually hit the intakes.

Cobra #42 · #6 (**permalink**) 01-02-2003, 01:13 PM

Rocksnake, If I understand you have a 5K chip in your box, that engine should handle that with no problem, have you ever checked to see if the chip is working , cheap fix , replace the chip they do go bad. What about a mechanical over rev, you know shifting from 2nd to third and sticking back in first. Not that I would admit, but stuff happens. Only other things I would look for are loose rocker arms, loose studs, broken lifterand I have seen the stock three piece ford break were the small tips are welded on. Make sure you have the correct length, I would use one piece hardened from a good company. Call Keith @ 817-417-6699 You have a problem and it needs to be found, come to the Club Cobra on Saturday and we can discuss, db

aumoore · #7 (**permalink**) 01-02-2003, 03:23 PM

You asked a question
#3 With pedestal-mount rockers, are guide-plates recommended for hardened pushrods?

If you are using most pedestal mount rockers you will not need guide plates. If you are using guide plates and stock pushrods you may have caused the breakage yourself as the stock pushrods are not ment for guide plates.

Did you set the preload properly when you put the rockers in? With the FMS roller rockers you turn the cap screw down until you just feel resistance while spinning the pushrod with your fingers. You should only be able to further tighten the cap screw from 1/2 to 1 full turn. If more than one turn shims will be required.