1.6 rockers changes

[GTRS Fiero]

When changing to 1.6 rockers, is head work required?

[Raydar]

Not if you have a stock cam. If you have an aftermarket cam, it may make it necessary.

FWIW, The stock cam lift is .394/.410 (intake/exhaust). The 3.4 Camarobird cam has the identical specs.

Stock Fiero (or stock 3.4) lift numbers, with 1.6 rockers, are .415/.431. Still no danger of binding anything.

To expand on that just a bit...
The largest aftermarket cam that I would consider that does not require machine work is probably the Crane 260-1 (.427/.454).
If you have have a 260-1 and switch to 1.6 rockers, the lift numbers become identical to the 272-1, which DOES require headwork (.454/.480).

[GTRS Fiero]

I think I have a 252 cam and 1.52 rockers.

[Raydar]

I was going to do the calculations and hazard a guess, but I looked around and couldn't identify what cam you have.
A search of "252 cam" resulted in various results with lift numbers that were all over the place. So I dunno...

My own personal preference is to just install the cam that has the lift/duration numbers that you want (or that your heads will accommodate) and use the stock ratio lifters.
Changing the ratio can impart more stresses on the valvetrain components than they were designed for.

With that said, if I had a nearly stock cam, I would surely use them (and HAVE used them) if I didn't want to take the engine apart.
If you can come up with a manufacturer/part number for your cam, I can still have a look.

[GTRS Fiero]

My bad.  A 260 cam, 1.52 rockers.

[Raydar]

Ah. Don't do the 1.6s, without machining the spring pockets for clearance, or finding some springs that will work. You'll likely bind the coils.

The 260 is already a very good cam. One of the car mags, back in the day, made some minor changes to a 2.8. The 260 really made it happy.
I understand that it's also the same cam that came in the 3.4 GM crate motor.

[GTRS Fiero]

Well. The lobes on the cam may be damaged.

[Raydar]

I don't understand. Are you speculating that you may be having issues with your cam?

Or are you saying the lobes may be damaged if something binds? Most likely, you would bend the pushrods, and the "coil bind" wouldn't happen any more.

[GTRS Fiero]

I may currently have a damaged cam, as a result of the valves having been adjusted incorrectly.

[Raydar]

Got ya'.

I would suspect pushrods, first. But then, I can't see it, obviously. So you may be right.

Edit - Usually, if valves hit pistons, it bends the push rods. I've seen it numerous times. They're the weak link.

When our Odyssey's timing belt broke, and the valves hit the pistons, there were no pushrods to bend (since it's OHC), so it bent the valves instead. Cams and rockers were fine (although they were roller rockers. No lifters, per se.)

[GTRS Fiero]

Oh, the pushrods were destroyed.  The lifters, too.  That was fixed several thousand miles ago.

So, head work to change to 1.6 rockers, but it seems you recommend against that.

[GTRS Fiero]

By the way.  Your Odyssey.  Way more motivated than I am.

Usually, I sit and offer helpful advice, like "YOU'RE DOING IT WRONG!"  Lately, I've been noticing that, if I get a chair and some tools out by my car, open the engine compartment, then sit and stare at the car, less gets done.

Sometimes, I watch closely enough to require a change of clothes and a scrub shower.

The other day, I got motivated, for a bit.  There were red wasps that disputed occupancy of the rngine bay.  After a brief run, kerosene ended the dispute.

[Raydar]

By the way.  Your Odyssey.  Way more motivated than I am.
...

Other than the broken timing belt and an unknown number of lopsided valves, the Odyssey was in very good condition, albeit with a large number (215K) of highway miles, from many trips back and forth between west GA and Olive Branch MS. (Essentially, suburban Memphis.) It had always been carefully maintained. Broken timing belt notwithstanding. (It was on its second belt at 215K. One of our friends was pushing 280K on the original belt. I made her bring it to me immediately, after this happened.)

Anyway... Not running, I was told it was worth not much more than $500.
We didn't have the room, the time, or the inclination to part it out.
For probably less than $1000 worth of parts and head work, a few specialty tools, and a few evenings and a couple of weekends, it's running again, as well is it ever has.
We are about to put it up for sale. I was going to keep it as a parts hauler, but we already have too many cars.

So yeah... KBB was a huge motivation.   And I got some really good experience.   

[GTRS Fiero]

Experience.  That's the word for which I was looking!

Yeah.  So you took the engine apart far enough to get the heads off.  That takes me days of working for about an hour per day.

So, are 1.6 rockers a bad idea?

[Raydar]

...
So, are 1.6 rockers a bad idea?

Combined with your cam? Yes. Bad idea. Not enough clearance.

Combined with a "lesser" cam? They're a band-aid. Good for more lift, if you don't want to go into the engine.
If the engine is being built up from the short block, the engine builder should decide how much lift (and what other parameters) they want, and should choose the correct cam for what they want. (Heaven knows, they're out there.) And then use the 1.52 rockers. 

Edit - If you want to check your pushrods, you can back off the valve adjustment, far enough to rotate the rockers and pull the pushrods out. (I have seen a tool that will compress the spring, without screwing up the adjustment. But I don't remember how it works.) Make sure you put the pushrods back in the same hole they came from.
Roll the pushrods across a flat table top, or a piece of glass. The straight ones will roll smoothly. The bent ones will tick. The really bent ones may not roll at all.