hoosierdaddy

I'm installing a cc503 cam and crane 1.6 rockers in an ironblock (96 impala) LT1.
Question- Crane shows "offset left and offset right" in their product pictures on the internet. I assume I need to install a pair (one left and one right) on each cylinder?
Question 2- do I use stock length pushrods?
Question 3- do I adjust the rockers like the LT4? 18 ft. lbs. ?

HELP!

crazyhorses

iTrader: (1)

I think you can use the same pushrods, and I would adjust the rocker arms by going off of valve lash. I adjust mine with the motor running, I go went half turn more once I tighten enough to make the clicking sound is go away. Then I was told they may be too tight, so I'm going to readjust valves by goint > 1/4 turn past 0 lash.

JPH

iTrader: (2)

You should NOT be using an offset rocker on an LT1. Those rockers are designed for afterarket heads, with altered int/exh valve centerlines. You should be using part #10750-16 or #10759-16 I do believe for your application. Adjusting rocker preload, I would recommend O lash and 1 full turn, and if you have an aftermarket lifter, such as Crane, Comp, etc.. consult that manufacture on how much preload they recommend. Pushrod length will probably use stock length, but if you had had alot of engine work and head work done, milling, etc.. I would measure to be precise.

Joe

s346k

iTrader: (4)

it's a stock longblock motor. stock lifters, pushrods, heads have never been off the engine. the rockers came on it, apparently they worked fine for the original owner as this was a complete pullout; engine, trans, everything.

the engine runs fine, but is making noticeable valvetrain noise. so you're recommending 0 lash and 1 full turn? this is with #1 TDC? then rotate 180* (#6 TDC) and do the remaining valves the same way?

JPH

iTrader: (2)

Pick a cylinder. Watch that cylinders exhaust valve. When that cylinders exhaust valve is closed, and then just starts to open, stop and adjusts that same cylinders intake valve. You can tell this by taking all of the slack and up and down movement of the rocker on the valve stem(no more clicking), then you will mark the polylock at 12 o'clock, and turn it 1 FULL turn. Then, continue rotating the engine clockwise untill that same intake valve you just adjusted, opens up fully, then starts to close. When it's about 3/4 of the way closed, stop and adjust that same cylinders exhaust valve. Use the same method I told you about for finding O lash, then go 1 FULL turn.

s346k

iTrader: (4)

hmmm ok. i don't recall reading or executing this method of adjustment. naturally, neither of the other methods we tried worked properly haha. thanks for the help, we will try it tomorrow.

JPH

iTrader: (2)

Got it from David Reher(Reher Morrison) years ago. Its the only/best way to do it IMO. Good luck.

Joe

96capricemgr

iTrader: (1)

Maybe you should be asking about springs and whether the iron HEADS will accept that lift.

Far as the "iron block" comment and offset rockers etc., makes me wonder if you should put this project on hold. All LT1 blocks are iron as covered you were picking the wrong rockers etc. you are going to get yourself in a heap of trouble if you don't slow down and learn a lot first..

BALLSS

with the higher lift provided by your new cam and 1:6 RR I encourage you to get chromemolly PR's, even the thicker wall. It will help eliminate "wobble" in the PR. 7.2" is stock length. Most likely that will work with your new cam but you can buy a $12 PR check tool to measure.....you would have to know how to use it though.

As Caprice Mgr. points out you need to set up the valve train right or big problems will soon follow.

Valve lash can be done with the #1 @ TDC doing 1/2 of the associated valves and rotate engine 360 degrees and do the other half. This method is described in the FSM or Haynes service books. The individual method described in this thread is more precise per cylinder. IMHO 1/2-3/4 turn after zero lash is good....but you need to know where "zero" lash is. It is when up/down movement of PR is a zero....not spining PR until you feel resistance.

You need to replace the valve springs or you will be very dissappointed with performance. crane 10309-1 is a plug & play spring kit for iron heads.

s346k

iTrader: (4)

pretty confident that the installed 918s will have no trouble handling that lift. also "pretty confident" that the heads will have no problem with that cam and those RRs. last i checked, there only a few thousand people running this combination of parts. it appears the rockers were torqued to lt1 stock rocker specs. after doing some digging we figured out what happened. at this point, it is as simple as loosening everything and following the guidelines for the crane golds.

on a side note - for not knowing anything, this guy did a hell of a job swapping this lt1 engine and 4l60e transmission into a 72 el camino. everything is bolted in, wired up, and it looks phenomenal. he apparently doesn't know his *** from a hole in the ground because something very simple got overlooked. thanks for the high quality advice on the heads and springs. he only made 43748279 other successful modifications to the chassis, drivetrain, engine, transmission, wiring, fuel system, ignition, and gages, he should just sell the whole project and go to lincoln tech.