Can I use my stock pushrods? 268H cam, stock rockers

[rang-a-stang]

I really don't want to buy new push rods right now. I am hoping that with the stock rockers I can squeek by with the stock push rods for now. Anyone running a 268H on iron heads, with stock push rods? I will probably get a pushrod checker to verify but I am wondering what others are using.

Also, any advice on cleaning pushrods? Soak them in oil eater and blow them out with compressed air?

[SC/397]

Measure the base circle of your stock cam and compare it to your new cam. If there is much of a difference, you will need new push rods if you are using non-adjustable rocker arms.
Did you have the block decked and or the heads milled?

I clean push rods out with brake clean. Make sure you don't loose the straw inside the push rod.

[rang-a-stang]

Sold and shipped my stock cam already. New cam is installed so it would be hard to pull it out and measure.

Block was not decked, heads were "surfaced". I guess with that many variables, I'll just have to measure and see.

So I guess I am probably on the hook for pushrods. Sigh.

Ok, that makes sense (brake clean). Hopefully that's all I need (along with a push rod checker).

[440sixpack]

Do you have bridged rockers or studs ? I would doubt your geometry will be off enough to require a length change from what you say but your preload will most likely be off.


I used stock pushrods but I had to shim my bridged rockers. I have used lock nuts on the studs for years but I've found them to be noisy even when adjusted correctly.

[babywag]

Carb cleaner works way better than the crap brake cleaner CA sells.
It really eats/dissolves the oily film/residue much better than brake cleaner.

[rang-a-stang]

Do you have bridged rockers or studs ? I would doubt your geometry will be off enough to require a length change from what you say but your preload will most likely be off.


I used stock pushrods but I had to shim my bridged rockers. I have used lock nuts on the studs for years but I've found them to be noisy even when adjusted correctly.

I have studs. (with locknuts)

Carb cleaner works way better than the crap brake cleaner CA sells.
It really eats/dissolves the oily film/residue much better than brake cleaner.

Good point. Our CA brake cleaner is a joke.

[babywag]

Good point. Our CA brake cleaner is a joke.

True...wasn't always the case but sure sux/isn't same stuff it used to be!

Brake cleaner didn't do squat on my dirty intake, carb cleaner made it spotless.

[SJTD]

For a while CRC sold brake cleaner in a green can and the original stuff in the red. Now they sell both colors and it's the same stuff. Acetone.

Used to be tricloroethelyne I think or maybe tricloroethane.

I used to be in the rocket engine test business. We used one of the above for hand wiping and the other to flush the engine after firing. In the early 90's AQMD or state or county or all three decided we were killing bugs or something so we switched to 90% isopropyl alcohol for wiping.

And you think acetone is bad?

Also had to closely monitor how much of the other stuff we didn't recapture during a flush until we came up with another process.

Carb cleaner is still the good stuff? I've always wondered if carb cleaner maybe wasn't as pure as brake cleaner and maybe had some oil in it.

[rang-a-stang]

I've been using a lot of oven cleaner on my parts lately (yes, even aluminum). It'll clean the carbon off pretty much anything but it destroys your hands if you don't have good gloves on (AMHIK). It comes out in a foam so it won't work inside push rods, though.

When using it on aluminum, it discolors the metal or worse. When I use it to clean aluminum, I don't let it sit long.

I once asked the difference between the red and green cans at the McParts here in Camarillo (one color was BOGO free, other wasn't). The guy behind the counter smirked, and said, "One is half the cost of the other".

[Ristow]

the stock AMC stud rockers were not "adjustable". you would need to swap the studs out for non shouldered adjustable style.



if your pushrods are incorrect length you can have problems so get it right.

[wiley-moeracing]

non chlorinated versus chlorinated, chlorinated works better and costs more but you have to be careful in a shop setting and used oil for recycling, makes it a hazardous waste when contaminated with chlorine.

[SC/397]

The last time I measured the base circle radius on the 268H it was .7040".
The stock one was .7320"
So there is a difference of .028"
Assuming that the heads were milled .010", your current push rods would be .018" too short.
I say try it but when you install the rocker arms check to see if the lifter plunger goes down (pre-loads) about .040"

[440sixpack]

I bet it's too much preload then.

Has anyone had good luck using the chevy studs and lock nuts ? I've done it for years even on hi pro 390's but no matter how I adjust them they're never totally quiet. I don't think I'd do it anymore I'd just get the right pushrods.


Smith Bros will make you anything you need.

[SC/397]

[quote=440sixpack]I bet it's too much preload then.

No. The base circle on the 268H is smaller than the stock base circle so the push rods will be short by .018" causing a little less pre-load.

[rang-a-stang]

I guess we'll find out soon enough! Machinist called yesterday and my heads are done. I'll pickem up Friday. Not sure when I will be able to get to installing them and measuring rods but it shouldn't be too long from now.