Welcome to the Corvette Forums at the Corvette Action Center!

Rockers tightened but trouble!!!!!!!

S

Stryker_78

Guest
Well I tightened up my rockers on my L-48 because they were quite loose. How much play should they have? I did the pass. side first. All went well.(BTW I posted on here a few days back about smoke coming out of my passenger side vavle cover. Thsi is now gone since I tightened the rockers)
Then I did the driver side and when I started the car, it started backfiring up through the carb and the idle is very erratic. I shut the car off quickly. Is it possible that the rockers are now too tight? Maybe one or more is a bit tighter than the others? I torqued them but not exactly sure what the proper setting should be for the torquing. Can someone help me out here with this one. :)



Scott
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Scott,

What procedure did you use? If you go too tight it will back fire as the valve is hung open.

There are two ways to do this in my opinion. One, cold set method. You pull both covers. Rotate the engine to #1 TDC at the compression stroke. If you have any g.m. or equal manual, it will take you through a series of the valves that are dead closed at that point (8 at a time). I like to back off the nut, spin the push rod with my fingers, and slowly tighten the nut. When I feel the pushrod get tight where I can't just spin it, I try to wiggle up and down. If no wiggle, then I go 3/4 additional turn. The G.M. manual will suggest up to 1.5 turns after zero lash. Then you rotate the engine 180 degrees, and do the other set of 8.

Second method is most likely more accurate for a worn engine. Pull both covers. Get some tin foil and fashion little squares about 2"x3" or so, and make them so they can from over the top of the rocker arms (like a little molded hat). Fire up the engine (make sure she is warmed up). One by one, remove the little hat (the hats keep the oil from getting all over the engine bay), and back off the nut until you hear it clicking. Then, tighten slowly until the click stops, then go 3/4 additional turn. Put the little hat back on that one and move on to the next. The order means nothing when choosing this method, just as long as you get them all. You might have to start and stop several times to avoid the engine just running with no valve covers while you are setting up for the next valve.

Either one here will get you on track. I would go back to the driver side and do a cold set the best you can first so that you get them loose enough to quit holding the valve open.
 
W

wolf_walker

Guest
If you have a spare set of valve covers you can cut a strip out of the middle of them to access the rocker arm bolts, that works alright too. Harder to hear them, but it works...
 
S

Stryker_78

Guest
Thanx for the advice guys. I will try 69's second method.:)
Nope, no second set .......yet..LOL. Gonna trash the stock ones I have and go with a chrome set. Oh, my vavle covers are baffled. Wierd to see that......:)


Scott
 
Joined
Jan 1, 2002
Messages
7,246
Location
Washington, Michigan
Corvette
'67 Marina Blue Convertible
Torque has nothing to do with it - you need to follow the proper procedure, or you will have exactly the situation you describe. Follow the process 69MyWay described for loosening/feeling zero lash/then tightening 3/4-turn, but do it as follows, starting at #1 TDC (both #1 valves closed, rocker arms even with each other - if they're not even, you're at #6 TDC). Pull the plugs to make it easier to turn, and make a mark on the balancer exactly opposite the existing index line (to show 180 degrees).

At #1 TDC: Intake 2-7, Exhaust 4-8
Turn 180 deg.: Intake 1-8, Exhaust 3-6
Turn 180 deg.: Intake 3-4, Exhaust 5-7
Turn 180 deg.: Intake 5-6, Exhaust 1-2

This procedure will set them all, right on the money.
 
R

RalleyRed

Guest
Scott,

I was wondering how you made out.

Hopefully all went well.

Rick
 

maxrevs85

Well-known member
Joined
Dec 17, 2001
Messages
709
Location
Eaton Rapids, Mich
Corvette
!985 ,blue coupe, 4+3 Z51
The best mehtod I have found for adjusting lash is, Put #1 @TDC, both intake and exhaust will be closed. rotate the pushrods with your fingers and and tighten the rocker until you feel resistance, do both rockers.Then go 1/2 to 3/4 turn more. then rotate the engine 1/4 turn (90*) and follow the firing order at each 1/4 turn of the crank. Firing order is 18436572.......in other words #1 TDC,adjust int & exh . rotate crank 1/4 turn ,adjust #8 int. & exh. .turn crank 1/4 turn and do both int. & exh. on #4....etc.etc.
Be sure to varify you are on the compression stroke on #1 !! :)
 
R

Ryan

Guest
ONE OF THE BEST WAYS TO LEARN ABOUT THE SETTINGS AND TORQUING YOUR CAR IS FROM THE HAYNES SHOP MANUAL BOOK.
THERE YOU WILL FIND ALMOST ANYTHING YOU NEED TO KNOW ABOUT REBUILDING YOUR ENGINE OR BRAKES,ETC,ETC...

YOU CAN BUY THIS BOOK AT "ECKLER'S"

GOOD LUCK!

RYAN
 
S

Stryker_78

Guest
Well I tried Johnz's method and the car is worse now then ever.LOL..Not Johnz's fault. I think I am not quite getting TDC on #1. The car backfires now and stalls as soon as I put it into gear. The rockers don't seem to be too tight whatsoever. :(
I am at a loss. Anyone want to buy a car??????..........LOL


Scott
 
W

wolf_walker

Guest
What kinda harmonic balancer you got on there? It could be off.
Are you manualy checking that your at #1 TDC?

If your not makeing any progress, try the messy running method.
But it sounds like you have some other problem. If you try that be sure to back them off till you hear a good click click click, then tighten down as posted above.
 
S

Stryker_78

Guest
New Harmonic balancer 2 years ago.
Should there be oil coming up through the rods?

Scott
 
W

wolf_walker

Guest
Oil through the rods? If you mean pushrods, yes, that's why there hollow. That's why it makes such a mess with the valve covers off if you have good oil preasure.. ;)
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom