Push rod question (1 Viewer)

[IDave]

I'm reassembling an F155 engine and I'm at the pushrod point.

I've been taught always to return the pushrod to the same hole it came out of, like it's really critical, but I'm trying to understand why and how important this is. The FSM engine manual (well, 3 out of 4 manuals I have) doesn't address this issue either way. I have new lifters, but the old rockers and adjusters.

Does it really matter? What if I mixed some of them up?

 

[Degnol]

Dave, I think that only applies with reusing the old cam and lifters, so you can replace "wear-matched" parts.

Ed

 

[IDave]

Yes, but why? What is it that matches? Is it the top of the lifter and the bottom of the pushrod? The Lifter and the cam lobe? All three?


How do it know?

 

[Degnol]

Well........................yes, it is anything that had a wear pattern with another piece. The new parts will get to know and become intimate with one another and in the meantime, you will have some valve adjustments. See?

The cam humps the lifter, the lifters hump the pushrods, the pushrods hump the rockers and the rockers hump the valves. Birds and Bees stuff.

Ed

 

[nodaksn3]

I fumbled around with this on my first FJ40, an '81. After months of troubles with it, in the end, I'm not too certain how important it is, except most books recommend being careful to ensure the pushrods get assembled as they were originally. I think the most important thing is esuring they get adjusted correctly, something I never did with the '81. I've since learned. My advice: don't worry about it if you got them mixed up, but just get the gop set right. Ned

 

[IDave]

I.... I think the most important thing is esuring they get adjusted correctly...Ned

See, that's just what I don't get. I'm going to adjust the valve lash anyway, so wouldn't that make up for any variations from swapping the rods around?

 

[Degnol]

See, that's just what I don't get. I'm going to adjust the valve lash anyway, so wouldn't that make up for any variations from swapping the rods around?

Yes, of course! But the closer the mating surfaces mate, the less frequent the need for adjustments. You are Ace at adjusting valves so you should have no problem at all.
You're good to go.
Ed

 

[grant5127]

Really the idea of keeping push rods and lifters matched applies to engines with hydraulic lifters, where there might have been a need for over size or under size push rods installed.... most common on chevy or fomoco.........

 

[IDave]

Now that makes sense.

 

[Degnol]

Really the idea of keeping push rods and lifters matched applies to engines with hydraulic lifters, where there might have been a need for over size or under size push rods installed.... most common on chevy or fomoco.........

What happened to yer fooking sig line?
I don't know dick about lots of things.............especially hydraulic lifters.
I do know something about contact points, and I do not mean electrical anything

In my humble brain it is like new boots, they need to be broken in.




Ed

 

[grant5127]

What happened to yer fooking sig line?

I'm tired of lookn' at it...........

 

[Degnol]

I'm tired of lookn' at it...........

You know how much I liked it.........................I take that as a personal affront
Cokesacker!


Ed

 

[grant5127]

Cokesacker!

 

[rsbcruiser]

Now that makes sense.

Hi IDave, where are you at with your rebuild? I am going into my motor here real soon. I might have damaged it for reasons relating to the questions you are asking. i.e. I rebuilt with new lifters and new pushrod nuts but old pushrods. Tons oh problems, fried my valves, Will know for sure if it was the pushrods here real soon. I will post results on my expanding valva gap thread.

 

[Degnol]

I rebuilt with new lifters and new pushrod nuts but old pushrods.

What are pushrod nuts? I guess I am in trouble..............I left those out of my rebuild

Ed


(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.

 

[grant5127]

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.

if speed were everything, Rabbits would rule the earth.....hmmm.... where did that come from.......

 

[Degnol]

if speed were everything, Rabbits would rule the earth.....hmmm.... where did that come from.......

You remember that? Heh. So, how are your push rod nuts?



Ed

 

[rsbcruiser]

What are pushrod nuts? I guess I am in trouble..............I left those out of my rebuild

Maybe I am using the wrong terminology. The nut I am refering to screws into the rocker arm end. It has a little ball end that contacts the pushrod. If you reused your old pushrods also you are free and clear. I used new nuts, old rods, thinkin now maybe not so good idea on my part.

 

[grant5127]

Maybe I am using the wrong terminology. The nut I am refering to screws into the rocker arm end. It has a little ball end that contacts the pushrod. If you reused your old pushrods also you are free and clear. I used new nuts, old rods, thinkin now maybe not so good idea on my part.

I'm not buying this push rod theory you got going..... post a pic or 2 of the culprits in question in your expanding clearance thread..... inquiring minds wanna know.... I need a visual, if you know what I mean.......

 

[IDave]

What are pushrod nuts? I guess I am in trouble..............I left those out of my rebuild

Ed

Ya, me too! (MAYBE that explains something....)






rsb, I'm at the point where I have to put my side cover and oil pan and clutch housing onto the rebuild, which means I have to pull the engine with the cracked block out of the FJ40, cause that's where they's coming from, and there's nothing else left I can do....