Swapping pushrods with a different motor?

[onetonjohn]

First off, I want to thank you guys for keeping me motivated on my little foot project. It's really easy to let months slip by without doing much, so thanks for that.

I read a thread a while back about copper side up on the pushrods, and made me think I didn't check this when I put mine in (I just put them back they way they came out). So I went out and checked one side today after work. I noticed several of the pushrods don't have any traces of copper left on either side. Several have a dot on the copper side, and one a dot on what looks like the non-copper side (crud).

Anyhow, in looking at them again and checking on a surface plate, noticed that one of the pushrods is slightly bent. This is off a 86 F350 6.9. I have an extra 89 7.3 motor and I"m wondering if I can pull a pushrod out of that and use it in the 6.9? I'm not building a race motor, but I did use ARP head studs, and I am planning to run a turbo with moderate boost levels to maximize reliability.

What do you think? Any input is appreciated.

 

[IDIBRONCO]

The push rods are the same between the two engines. You can swap them with no issues. The wear patterns on the push rod ends won't match which will shorten the life somewhat. How much probably depends on how much wear is actually on the push rods and the rocker arms. Be sure to check the push rods for excessive wear before you just install them in your 6.9. Although I don't remember the brand, the new push rods that we used in the shop that I used to work in didn't have copper on either end.

 

[onetonjohn]

Thanks. I'll swap out the slightly bent one for one that's straight.

 

[Randy Bush]

You want to make sure the pushrod end is nice and round not wore pointed, they don't oil right if so.

 

[aggiediesel01]

I believe the rockers are the same btwn 6.9&7.3 so you could keep the "wear parts" together by putting that rocker from the 7.3 in the 6.9 too thereby keeping the match.

 

[onetonjohn]

That's good point.

 

[snicklas]

Honestly, if the 6.9 still has the factory rockers, I would switch ALL the rockers, and you could move pushrods and lifters also. The factory 6.9 rocker design was weak and many have switched to the better 7.3 rockers.

 

[onetonjohn]

The rockers were all updated to the 7.3 style. So I'll probably just switch the ones I change to swap out bent pushrod.

 

[Randy Bush]

If the current rockers on the engine are not abnormally worn there is no reason to change for the replacement pushrods.

 

[Macrobb]

Yup; as others have said:
1. Pushrods are all the same length(and the hydraulic lifter takes up small variations anyway).
2. If they are round on the end(should be a nice ball), they are good.
Personally, I haven't seen any with worn ends or odd wear patterns; I'm of the opinion that the pushrods should outlast the rest of the motor; they certainly don't seem to wear.
3. 7.3 style rockers are better than 6.9 style ones(with the cast "loop").

 

[IDIBRONCO]

I think that the worst of the push rod wear comes from the engine being run low on oil.

 

[Frstdiesel]

I bought a used set of "new style" rockers on e-bay supposedly from a 7.3 and they came with a set of push rods.
The rockers looked fine but the push rods were longer than my original 6.9 push rods.
So I was wondering if the 7.3 rockers have the same ratio as the 6.9 rockers.

 

[DaveBen]

How much longer? A bit longer (thousandths of an inch longer) or much longer (1/4 + inch)?

 

[Randy Bush]

I think that the worst of the push rod wear comes from the engine being run low on oil.

I would have to disagree with that. Certain engines where bad for rocker wear , 350 chev, 300 fords with cast rockers. They all wear a certain amount just the nature of the style. IMO really has very little to do with being run low on oil. Bearing being worn and not allowing enough oil to be pumped to the rockers . Also on 7.3 and probably 6.9s the oil pressure valve in the filter head causes problems too.
It is always a good ideal to check the rocker and pushrod for abnormal wear. One should be able to blow through the pushrod and move the rocker back and forth like in the engine and the air flow should not stop. If it does pushrod or rocker is worn to much and needs replaced. Just what I have seen over the years rebuilding engines.

 

[79jasper]

Certain engines where bad for rocker wear , 350 chev

Is there a such thing as a 350 without valve-train wear? Lol


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