valve spring installation
Thread Starter
Racer
Joined: Feb 2001
Posts: 266
Likes: 0
From: virginia beach, va.
valve spring installation
last time i had an article from chevy hi perf. magazine in hand. it outlined which valves (8) were fully closed at TDC. (rotor pointing to #1 in the distrib). then you were to rotate the engine one revolution to TDC (rotor pointing to #6) at which time the other 8 valves were fully closed. anyone know which valves at each instance? thanks, don
Burning Brakes
Joined: Oct 1999
Posts: 816
Likes: 37
From: Wilmington NC
Re: valve spring installation (66c60)
Don,
I want to apologize in advance, I sometimes read into peoples questions and then I make statements that don't mean anything and they don't help.
With that said, the #1 valves are the only valves that are fully closed when at TDC for the rotor pointing to #1. (Here is were I read into things) If you are adjusting the valves and you read a procedure that states you can adjust all 16 valves by setting the balancer to only two positions (8 valves per position) then the issue is that the procedure never stated that 8 valves are fully closed at one position and the other 8 valves are fully closed at the second position. Its just an easy procedure for adjusting the valves.
I do have that procedure that states what 8 valves to adjust but, it is at home. I assume someone else can answer that part before I get home tonight.
If you want to adjust the valves more accurately, then you should do #1 at TDC then adjust the balancer 90 degrees and then do #8. Then continue with the 90 degree rotation and adjust the valves in the order of firing (18436572). Understanding that TDC for #1 is not on the exhaust stroke.
Hope I didn’t waste your time.
GaryC
I want to apologize in advance, I sometimes read into peoples questions and then I make statements that don't mean anything and they don't help.
With that said, the #1 valves are the only valves that are fully closed when at TDC for the rotor pointing to #1. (Here is were I read into things) If you are adjusting the valves and you read a procedure that states you can adjust all 16 valves by setting the balancer to only two positions (8 valves per position) then the issue is that the procedure never stated that 8 valves are fully closed at one position and the other 8 valves are fully closed at the second position. Its just an easy procedure for adjusting the valves.
I do have that procedure that states what 8 valves to adjust but, it is at home. I assume someone else can answer that part before I get home tonight.
If you want to adjust the valves more accurately, then you should do #1 at TDC then adjust the balancer 90 degrees and then do #8. Then continue with the 90 degree rotation and adjust the valves in the order of firing (18436572). Understanding that TDC for #1 is not on the exhaust stroke.
Hope I didn’t waste your time.
GaryC
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,270
Re: valve spring installation (GaryC)
The '63 shop manual valve adjustment procedures calls for adjusting all 16 valves and TDC #1 and #6. This will work for a Duntov cam, or they can be adjusted at TDC, but these procedures will NOT WORK for the 30-30 or LT-1 cam.
At TDC of the firing stroke, BOTH the inlet and exhaust on on the ramps with the 30-30. With the LT-1 cam the exhaust is on the ramp. Assuming you know nothing about the cam profile and ramps, you can successfully adjust all the exhaust valves at 90 BTC and all the inlets at 90 ATC. This allows you to adjust two valves at each TDC position.
As far as pulling all the valve springs is concerned, you can probably follow the '63 valve adjustment procedure and pull the spring numbers corresponding to what valve to adjust at TDC #1 and TDC #6.
I prefer removing valve springs at TDC of each cylinder just in case a valve drops. It's really not that hard to bump the engine around in 90 degree increments.
Duke
At TDC of the firing stroke, BOTH the inlet and exhaust on on the ramps with the 30-30. With the LT-1 cam the exhaust is on the ramp. Assuming you know nothing about the cam profile and ramps, you can successfully adjust all the exhaust valves at 90 BTC and all the inlets at 90 ATC. This allows you to adjust two valves at each TDC position.
As far as pulling all the valve springs is concerned, you can probably follow the '63 valve adjustment procedure and pull the spring numbers corresponding to what valve to adjust at TDC #1 and TDC #6.
I prefer removing valve springs at TDC of each cylinder just in case a valve drops. It's really not that hard to bump the engine around in 90 degree increments.
Duke
Thread Starter
Racer
Joined: Feb 2001
Posts: 266
Likes: 0
From: virginia beach, va.
Re: valve spring installation (SWCDuke)
gary and duke, this is a valve spring job. after the springs are chanced in the manner i described the engine is fired up and the valves adjusted running. thanks, don
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: valve spring installation (66c60)
The position of the pistons doesn't matter when changing valve springs. The valves and springs are disconnected from the cam at this time and the valves will be closed. You will need to make an initial adjustment of the valves before starting the engine and the advice already given applies to that.
Thread Starter
Racer
Joined: Feb 2001
Posts: 266
Likes: 0
From: virginia beach, va.
Re: valve spring installation (Vetterodder)
can anyone answer the original question? this is valve springs. the idea is to change the 8 springs with minimal pressure in 2 steps. i didn't make this up. i've done it before and misplaced the information.
[Modified by 66c60, 9:19 AM 10/4/2001]
[Modified by 66c60, 9:19 AM 10/4/2001]
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,270
Re: valve spring installation (66c60)
I think your question has already been answered. Once the rockers are off you can change all the valve springs regardless of where the crankshaft is because all the valves will l be closed. The "two cylinders at TDC" applies to adjusting the valve clearance with some cams that don't have long ramps.
Changing valve springs is a matter of defeating Murphies Lay. I've suffered from brain fade and pulled springs while forgeting to hook up the air hose, but I circumvented disaster (and defeated Murphy) because I always set the piston up at TDC on that cylinder so the valve won't fall into the cylinder. With the piston at TDC the valve drop will be stopped by the piston, so you can just hook up the air and pull the valve back up to the seat and install the spring.
If you do this with the piston too far down the valve will likely drop into the cylinder requiring you to remove the head to retrieve it.
If you rotate the crank to 45 degrees before of after TDC, all the pistons will be halfway down (or halfway up, depending on your point of view), but they might not be high enough to leave enough stem to grab if you drop one.
Duke
Changing valve springs is a matter of defeating Murphies Lay. I've suffered from brain fade and pulled springs while forgeting to hook up the air hose, but I circumvented disaster (and defeated Murphy) because I always set the piston up at TDC on that cylinder so the valve won't fall into the cylinder. With the piston at TDC the valve drop will be stopped by the piston, so you can just hook up the air and pull the valve back up to the seat and install the spring.
If you do this with the piston too far down the valve will likely drop into the cylinder requiring you to remove the head to retrieve it.
If you rotate the crank to 45 degrees before of after TDC, all the pistons will be halfway down (or halfway up, depending on your point of view), but they might not be high enough to leave enough stem to grab if you drop one.
Duke
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
