Do people have words of advice? going from CC 978 to 977 so the only change will be higher spring pressure.

I know it is always best to check install height but if it was shimmed before, do I need to do it again?

do I need to change locks or reuse?

How do you keep the valves from falling down? I don't have air.

Thanks,
Ben

 

The first time I did a spring swap I didn't have air either. We used really soft cloth rope and filled the combustion chamber with it through the spark plug hole then rotated the motor so as to compress the rope enough to hold the valves in place while the springs were gone. I don't recomend this unless all else fails as it is very time consuming as you can only really do one cylinder at a time and it takes a while to feed the line in the cylinders, not to mention the lack of space in your engine compartment.

My recommendation would be to take it to a friends place that has air and do it there.

 

If you rotate the engine until that piston is at the top of the cylinder it will not drop.

 

95BlackHawk:
The moderator "Shoebox" has a page on this. About 40% down on the page there is a table that details which cylinders are at TDC and when. "http://shbox.com/ci/valve_spring_swap.html"

 

I used the top dead center method, worked just fine

 

FWIW, don't be afraid about 'dropping' a valve. The stem isn't even long enough to be completely lost in the cylinder.

I used the TDC method.

 

Yeah, the TDC method sounds alot easier. We did the string trick about 18 years ago back before I knew much about cars and we were doing what ever we could think of to get things done. BTW, the string method also works for a piston stop to torque a crank bolt LOL.

 

I've seen this posted before but I question it's accuracy. How'd you come up with that?

Jake

 

First, visually inspect each and every spring, especially the new/out of the box ones. Use a magnifying glass if your eyes have the mileage mine have.

It's always best to check EACH and EVERY spring for it's seat/open pressure before installing it on the head. Pressures can vary, even those in the same box.

"Old Racer's trick" I learned from AFR many, many years ago is to put each new spring in the protected bench vice. Then bring each spring to coil bind. This relieves surface tension and allows the springs to better maintain seat pressure so that they don't lose the 10% or so loss new springs generally experience.

Some new springs may already be mechanically stress-relieved, so I suggest checking with the spring seller and even AFR.

Also, follow the start-up/cool down procedure for new springs.

Skipping any of those procedures could negatively impact on the effective life of the spring(s). I always pay 'attention to detail' when screwing on these suckas. "Do it once; do it right" is my motto.

Jake

 

I am guessing because the stroke is 3.48 and the valves are like 5 inches long. They may not drop down into the cylinder but it isnt going to be easy to get them to come back up unless you are able to get ahold of the tip of the valve.

 

I've got a pair of 96 LT1 heads sitting beside my fireplace so maybe I should use those and measure to see how far the valve stem sits above the top of the valve guide.

Then how much the stem tip extends above the retainer. It'll be just above 2" is my guess.

Now I'd have to calculate the clearance between the top of the piston (at tdc) and the amount the valves are recessed into the combustion chamber. Then I'd add to that 3.48"

I'd need to know the length of the guides and we know the guides stop deep within the valve bowl and don't extend all the way to the deck of the head.

Now I'm wondering if it's worth all the work??? LOL

In any event, once the stem disappears into the guide it would be rough getting it back out. Doable but rough.

My thinking is "An ounce of prevention is worth a pound of cure".

Jake

 

Absolutely.

I'm certainly not advising to just let it drop! It's nothing a strong telescoping magnet can't pull up.

In case it does happen to anyone, it's retrievable. It's worth running out and getting a 10-dollar magnet versus pulling the heads because you think all hope is lost.

 

I like all the advice.

I will use the TDC method and call CC to see if they have been "relieved". I like the idea of checking each one. Makes sense.

Ben

 

If you're referring to the TDC method in setting the lifter preload, that could cause you a problem with your cam. At TDC both of your valves would be in over-lap meaning the lifters will be on the lobes' ramps and not on the base circle.

By all means, when you call CompCams about the springs also ask about the preload procedure. All of their literature recommends the IC/EO method.

Jake

 

The TDC method should only have the valves in overlap 50% of the time otherwise you would be firing your sparkplug with both valves open.