Pushrod Confusion

Hg80Design · Aug 20, 2008

I believe I have a bent pushrod that needs to be replaced, but I have a very limited knowledge of actual engine building and or rebuilding.

What is involved in replacing these?

Do I need to remove the intake manifold, or can it be done by just removing the valve covers?

Should I go ahead and replace the springs and rockers at the same time?

Any help on this would be greatly appreciated thanks.

67rcks · Aug 20, 2008

if you have bent pushrod there is likely a reason why it is bended - valves seats, guides, worn cam lobes, bended rocker arm studs, and many others.

What is involved in replacing these?
new pushrod, stock length is OK when no mods are made to your engine

Do I need to remove the intake manifold, or can it be done by just removing the valve covers?
Through valve covers

Should I go ahead and replace the springs and rockers at the same time?
no unless they are damaged

Hg80Design · Aug 20, 2008

What about the rockers once they are removed, do I just tighten them back to stock specifications if I am reusing my existing ones?

Also if there any kind of gain using a rocker like this:

JEGS 20130 - JEGS Aluminum Roller Rocker Arms - JEGS

or

Engines & Components - Rocker Arms, Dmp 1.6 3/8 Stud Roller Tip - Early Model Classic Mustang Restoration Parts

If figure if I am doing this I want to do it right. Thanks again for any help.

D.Hearne · Aug 20, 2008

Hg80Design said:
What about the rockers once they are removed, do I just tighten them back to stock specifications if I am reusing my existing ones?

Also if there any kind of gain using a rocker like this:

JEGS 20130 - JEGS Aluminum Roller Rocker Arms - JEGS

or

Engines & Components - Rocker Arms, Dmp 1.6 3/8 Stud Roller Tip - Early Model Classic Mustang Restoration Parts

If figure if I am doing this I want to do it right. Thanks again for any help.

Before buying anything, you first need to find out what rockers you now have. Ford Used three styles in the life of the small block. The first type (62-mid66) could use the rockers you linked to, provided they fit the rocker studs you have (studs range from 5/16" diameter to 7/16" diameter) The second type (mid 66 to 76) are called "rail rockers" and you cannot replace these with the ones you linked to. The third type (1977 to 2001) are called "pedestal rockers" These also aren't compatable with those you linked to. Once you pull the valve cover and remove the rocker, you can then pull the pushrod (shake it as you pull it to break the suction the oil forms with the lifter) and measure the pushrod (measure an unbent rod for this) The rocker and the head date helps to determine what pushrods you'll need. (at least three different lengths used over forty years)
How they're reinstalled and tightened depends on what rocker and studs (if any) are used. Pedestal rockers are simply retorqued to 25 ft/lbs.

Hg80Design · Aug 21, 2008

I have a 71 302, so I am guessing buy the description you gave me I will be needing rail rockers. Can you recommend any good upgrades for this type. Thanks

jikelly · Aug 21, 2008

Um, you should take your valve covers off your 302 and verify what rockers you have on your engine.

It's easy, all you need is a rachet, a 3/8 socket, some gasket sealer (RTV), and a few minutes to play with it.

Do you know which cylinder the bent pushrod is in/on?

How did you determine that you had a bent pushrod?

I once had a rocker arm break on my 302 engine. I was crusing along the highway when there was a pop and then the engine started stumbling and backfiring. I could hear clanking on one side of the engine. Pulled the valve cover and found the broken rocker. I removed it and its pushrod, put the valve cover back on the car, pulled the sparkplug for that cylinder and drove the 40 miles home on 7 cylinders without incident.

Hg80Design · Aug 21, 2008

As far as I can tell its in the 5th cylinder or 6th cylinder area. I have a noise coming from that area of the engine. I fired it with the belt off, and was able to narrow it down to this area. I pulled the valve cover off and did a quick visual inspection and everything appears in working order.

The push-rod is my best guess so far. I had a friend who know way more about this give it a look/listen and he said it was most likely the push-rod. Told me to pull them out and roll them across a flat surface, to make sure they were in good shape. I have not made it to this because, I was unsure about the removal process and reassembly.

I have read that if you replace one you should replace them all. I figured if I am doing this it might also be a good time to upgrade my rockers. I have attached an image of the engine with the valve cover off.

ForceFed70 · Aug 21, 2008

Valve tick kind of noise? If so, I bet it's actually an exhaust leak/header gasket problem.

D.Hearne · Aug 21, 2008

Hg80Design said:
As far as I can tell its in the 5th cylinder or 6th cylinder area. I have a noise coming from that area of the engine. I fired it with the belt off, and was able to narrow it down to this area. I pulled the valve cover off and did a quick visual inspection and everything appears in working order.

The push-rod is my best guess so far. I had a friend who know way more about this give it a look/listen and he said it was most likely the push-rod. Told me to pull them out and roll them across a flat surface, to make sure they were in good shape. I have not made it to this because, I was unsure about the removal process and reassembly.

I have read that if you replace one you should replace them all. I figured if I am doing this it might also be a good time to upgrade my rockers. I have attached an image of the engine with the valve cover off.

Usually if a pushrod is bent enough to cause the motor to run rough, the rocker it's pushing on will be loose. As for having to replace all or none, that's not true. And yes, you should have rail rockers and positive stop rocker studs, if the heads are original and unmolested. To reinstall, all you'll need do is retorque them to about 25 ft/lbs---------same as the later pedestal rockers. I also agree with ForceFed70's suggestion, check that out as well. You might also check the spark plugs to see if any are loose, that too is a common problem.

Pushrod Confusion

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