changing VALVE SPRINGS on the engine while its in the car

[grumpyvette]

now most shops will rotate the cylinder to TDC and install an adapter for an air hose and pump a steady 100-130psi into the cylinder to hold the valves closed, but theres frequently clearance problems with headers and the adapters or hose and since you need to wack the valve retainer with a plastic hammer at times to get them free.......

yeah, IVE use air pressure frequently, BUT IVE NEVER TRUSTED air pressure ....and HATE paying rental fees.....if you don,t have the adapters or compressor,ETC. Ive usually prefered the old method of manually turning the cylinder to bottom dead center and removing the spark plug, then inserting about 10 feet of 3/8" cotton rope into the cylinder(TIE A KNOT in the end to prevent it from falling ALL the way in) then spin the engine MANUALLY (NOT WITH THE STARTER) to as close to TDC,as the crank will spin. this compresses the rope into a wad that supports the valve physically preventing its movement, down into the cylinder, once the valve springs replaced , you rotate the cylinder to BDC and remove the rope, proceed to the next cylinder

 

BTW I vastly prefer these

 

http://store.summitracing.com/partdetail.asp?part=PRO%2D66784&N=%2D114082+115&autoview=sku

 

to these

http://store.summitracing.com/partdetail.asp?part=MAN%2D41830&N=%2D114082+115&autoview=sku

 

but if you use an air compressor youll NEED these

http://www.tavia.com/cat15.html

[MONGO510]

Hey Grumpy, good info! I have used the air process scores of times and never had any problem. One trick is to place a socket over the valve and tap it with a hammer. Not to hard or the keepers may come off. Just hard enough to unseat the retainer. The spring will then easily compress and disassembly is easy. I will put the rope trick in my toolbox for future use!

By the way, I can't for the life of me figure out how the first tool would be used. I have used the second type before as well as others.

[DaleMX]

I do the TDC thing on the LS1. No rope needed. It's a snap to do. Just use a soda straw in the spark plug hole to bring the piston up and change the springs. I never tried it on a SBC, but it works on the LS1.

[John Scott]

No offense grump,personal experience speaking, but the rope can get tangled in the cylinder, and then the heads come off,...a major PITA. If you can't pull your heads in the engine bay, the engine gets pulled. Air compressor fitting can be modified, or easily made to fit even the tight headers on my engine. I cut down an SK tool with a hack saw and jambed a rubber hose in it. Been using it for years, 60 seconds to modify. Also simple to make with the insulator knocked out of a sparkplug. A light tap on the stem with a rawhide hammer frees up sticky locks. At least with my engine, with piston at TDC if air pressure fails the valves only drop a little before contacting piston. You don't need compressor on the whole time, only removing or ready to reinstall. Pull the valves back up and pressure holds fine. I change out my valve stem seals way more often than I'd like, and I've gotten really fast at it. After experiencing the nylon rope incident, a little 3/4 hp air compressor set at 100 psi, IMO is the preferred way. John

[grumpyvette]

now I thought about that (THE ROPE GETTING TANGLED )and worried about that at first, but in thirty plus years and dozens of engines Ive never had it happen ...yet,(maybe IM lucky).. but then Ive never used nylon or anything but 3/8' cotton rope, and its fairly stiff it tends to coil in the cylinder bore, while Im sure its possiable Ive never had it happen...YET.

Like I stated < IVE used BOTH air pressure and ROPE, both have advantages...AND potential problems

[John Scott]

now I thought about that (THE ROPE GETTING TANGLED )and worried about that at first, but in thirty plus years and dozens of engines Ive never had it happen ...yet,(maybe IM lucky

..or maybe it was just my bad luck.