Problem with T&D Roller Rockers and Pushrods.

[blackshoebox]

My mechanic just called me, and we are having an issue with the the intake pushing rods bending when installing the cam sensor and priming the motor. The roller rockers are T&D 1.65 rockers that I bought from a board member. However they are older style rockers, but are suppose to be 1.65 ratio. We were using the same length pushrods I was using with stock 1.55 ratio rockers, but it appears the pushrods had 20-30 thousands taken off since the motor had been decked in a previous rebuild. So the pushrods were not exactly stock length. My question is, is there any explination for only the intake pushrods bending, and not the exhaust? My mechanic has suggest that possibly the exhaust rockers were 1.55 and the intake rockers were changed to 1.65 to get more lift. He told me this was an old practice, but since the rockers are older style, we are not sure.

I know that I will need a good set of adjustable pushrods, however I am try to determine, if the rockers are true 1.65 ratio all the way accross, or if they have 1.55 on the exhaust rockers, or there is another reason that only the intake pushrods bent?

Thanks for your advice in advance...

[TurboDave]

Ask him how the rockers are marked.
Also ask him what he set the pre-load at.

[blackshoebox]

Originally posted by TurboDave
Ask him how the rockers are marked.
Also ask him what he set the pre-load at.

The rocker shaft says t&d on it, and each individual rocker says E on top corner of the rocker.

The preload was set @ 0 and then a quarter turn. Once the motor was primed and some of the oil began to put pressue on lifter, only the intake pushrods bent and the exhaust ones remained fine. All the pushrods were the same length, which were used with stock 1.55 ratio rockers.

[musclecar neal]

No need for adjustable push rods. Have your tech determine the correct pushrod lenght for the engine. Are the valve stem heights the same or all over the place? If a push rod is bending 90% of the time its from piston to valve contact unless they are cheap punp rods with stout springs. It could also be coil bind. Sounds like you need to check piston to valve clearance first. then get the correct lenght pushrods and don't buy adjustables.

[TurboDave]

Originally posted by blackshoebox
The rocker shaft says t&d on it, and each individual rocker says E on top corner of the rocker.

The preload was set @ 0 and then a quarter turn. Once the motor was primed and some of the oil began to put pressue on lifter, only the intake pushrods bent and the exhaust ones remained fine. All the pushrods were the same length, which were used with stock 1.55 ratio rockers.

If they're all labeled E then they're all the same ratio. I'm sitting here at work wracking my brain trying to remember what ratio "E" actuall is though

I'd certainly agree though!! Check the valve stem heights! all the same? Coil bind problem?

[TS6]

So you're saying that the pushrods are bending when he tries to prime the motor? As in the oil psi is actually forcing the lifter plunger up hard enough to bend the pushrod? Wow! More than likely your pushrods are too long, I seem to remember a good TR builder telling me that 90% of the time roller rockers will require shorter pushrods. It was true on my motor, and I was staying with 1.55 ratio. HTH

[blackshoebox]

OK, guys it turns out that the rocker was not clearing the retainer properly. I guess there is some machining required on the older style 1.65 t&d's to help with this issue.

As for the length of the pushrod, it appears the length will be fine, since the pushrods were already shorter due to the block being decked with a prev. rebuild.

Thanks for all the input.

-Alex

[Chuck Leeper]

Be sure to follow the adjustment instructions.. If the adj screw is too far out of the rocker, it will block the passage that the oil takes to oil the rocker....
The p rods for stock rockers and T&D's are not the same...
Check w/ an adjustable checker p rod to see where the roller tip is riding on the valve.

Also, do not do the grinder trik on the under sides of the rockers.. That will create serious stress risers and the rockers can break. Have a machinist mill the clearance and use a mill cutter w/ a significant radius on it..BTDT....

[TransAm WS6 420]

I think you should junk the whole thing and give it to me

[J Banning]

Originally posted by blackshoebox
OK, guys it turns out that the rocker was not clearing the retainer properly. I guess there is some machining required on the older style 1.65 t&d's to help with this issue.

That's interesting.

What part of the retainer was not clearing... the top or the side? How much maching did you have to do? how much is too much?

Thanks,
-Banning.

[REDS HOT AIR]

retainer hitting shouldnt bend the pushrods

being that he was trying to set the cam sensor does that mean a timing chain was just put on ?