Rocker ratio change

[larrym]

Good day gents I recently broke a second stock rocker shaft this one was a TA HD, I had a freshly machined motor sitting at home so I assembled it and pulled my old worn out one, had to put a locking dipstick on it there was so much blow by... here is my question I had a buddy set me up with T&D 1.65 rockers I did my research and its a roller cam 212 212 with .503 lift so the change is to .535 by my calculations max lift on springs is .590 so that should be ok heads are ported with bronze guides and the pedestals are ready. How will these rockers affect my current tune up am I going to have to add fuel I fired it up yesterday and had 2 leads backwards on my LS coils lol started and ran on 4 cylinders I plan to take it out and seat the rings tonight just wondering about the tune I run an SD2 chip.

 

[Pronto]

That is very confusing. Did you build a freshly machined block with the old rotating assembly and have blowby now or was the old engine being pressurized so you puled it? Did you break the shaft on the old engine or new engine? Did you check clearances with the roller rockers? You first need to seat the rings. No WOT blasts. The tune (if it was to set to the 212/212 cam) should be close for seating the rings.

 

[BEATAV8]

It's a different engine, you'll need to re-do the VE table.
To seat the rings on a brand new motor I like to take it out and part-throttle it gradually to 10-12 psi of boost and just hold it there for a bit. go around the block and repeat. (my personal drag strip - a little stretch of road just outside the neighborhood)

Your old tune up should be able to pull that off without much fuss as long as it was good & close on the old motor, but you will have work to do.

 

[larrym]

Its a fresh short block all the way around new bearings rings freshly machined TRW pistons and stock rods and crank, same heads cam and lifters I was waiting until the old motor was beyond its service life, had it at the track and it broke the rocker about 3/4 track. Decided it was time to put the new motor together and use it. The roller rocker upgrade was a solution to breaking the TA shafts there was lots of room on the rockers from what I could tell rolling it over, the only thing I did not check was piston to valve clearance but it seems to run fine on start up. How would you seat the rings I thought getting on it a bit and adding boost was the best way? I have a pretty conservative tune it rich and not a ton of timing. I found the broken rock on the old motor and did a compression test 4 holes were 125 on was 110 the other was 150 that was what really made me decide to go to the trouble of yanking the motor.

 

[xlr8ngn]

Put a test spring in there and check that valve to piston clearance on intake and exhaust. It's a bit of work, but better safe than sorry.

 

[TurboWh1]

You may need different length pushrods as well to hit the window for preload.. Are you familiar with how to check and set that up? You should also check where the roller rocker tip makes contact with the valve. I had to do some some work to make that work on my 109 so the geometry was correct.

 

[TurboWh1]

Here is before and after correction on mine... Check the pattern otherwise you will destroy the guides in the heads.

 

[larrym]

Thanks I did check both pretty closely when I installed the rockers must have set them 6 times before I installed the motor. With .050 preload I barely had threads showing on the bottom of the rocker. The roller tip road on the center of the valve stem and all had good oiling when I primed it on the stand.

 

[TIMINATOR]

You have to read the instructions and be careful with roller rockers and preload.
There is only a small band where the oil passage in the rocker will line up with the adjuster screw and allow oil to the trunnion bearings. Too high or too low on the adjuster will restrict or entirely cut off the oil supply.
I measure where the center of the adjustment is and order my pushrods at whatever custom length is required.
This assumes that the engine was machined correctly:
Block BHJ square decked even on both banks.
Head deck surface dimension to the rocker shaft stand the same on both ends of the head, and equal to the other head.
Pushrod calculations done with the head gaskets you will use.
Intake and exhaust valve stem height on all 12 valves equal.
None of these things are a big deal with stock cams, rockers, and machinework, as factory lifters have about .120" travel, and will oil just about anywhere.
That's why I don't recommend roller rockers and high ratio roller rockers for stock engines and poorly machined rebuilds.
TIMINATOR