Here's a question. How much air pressure do you typically need to keep the valves in place? At the same time, adding air pressure to the cylinder at TDC you stand a good chance of rotating the engine no? I guess I should block the engine from turning somehow?

 

How much PSI? I'm throwing 90 PSI should suffice out there, what say others?

Yes the engine can and likely will rotate some during the process. Having the piston at exactly TDC will reduce the chance. Being at the bottom of its travel would eliminate the chance.

If you need to walk away from the project at anytime with a spring removed, tie wraps around the valve stem will hold the valve up

 

Excellent tip about the zip tie! Thanks for that, you never know what might come up.

 

I’ll continue to vote for rope over air, but that’s just me. I am curious if folks are using fel pro seals as a replacement or another vendor or style of seal?

 

The rockers on these things are not adjustable correct? You just bolt them down to spec and you're good?

 

Yes they get torqued to spec but lube all of the friction points and only torque them down with both lobes of the cam on that cylinder on the base circle of the cam meaning no lift.

 

Right, so if I have the piston just about at top dead center there should be no lift on either of the valves correct? I guess, even if it's just a little before TDC or just a little after TDC I'll still have no lift on the valves (I think?).

 

The safest way to be certain of no lift is to have the cylinder you are working on TDC on the compression stroke. When a cylinder is on the compression stroke it's opposing cylinder is on the exhaust stroke and the the rocker arms on the opposing cylinder will teeter open/close as the crankshaft is moved a few degrees from BTDC to ATDC.

The opposing cylinder for #1 is #6, to determine this write the first half of the firing order over the second half like:
1 8 4 3
6 5 7 2
the numbers above below/each other oppose one another. The process could be started with #1 on the compression stroke and then the next rockers done sequentially following the firing order.

 

Here is a "How To" paper I wrote for the SACC magazine that was on a small block Chevy engine but might have some helpful information for your task.

 

Me too. Use compressed air

 

Here's a video where I did the first two. Replaced seals and springs. Used an air compressor. The keepers were stuck on all mine so I had to hit the spring (Not the valve) with a hammer to break em loose. First time I ever did this. First one took like 45 mins each one after took around ten. I used the L shaped tool. Hope this helps someone 71 Olds 350

https://photos.app.goo.gl/E49KUhJn7adEugu58

 

Excellent resources posted here! Thanks so much! What PSI did you use for the air supply?

 

Think it was 90. I rented a cheap compressor from the local tool rental place for like 24 bucks. Already had an oil pressure tester that came with an adapter to screw into the spark plug hole.

Once you do the first one the rest should be much easier 👍

 

This video is excellent by the way! I really learned something here.

 

So just thinking about this job once again. Now that I have my exhaust manifolds off the car, it's a good chance to tackle the valve seals which I have been procrastinating on and trying to think about every pitfall that could happen. Just wondering about the air you hook up to the cylinder to keep the valves in place. If I have the #1 cylinder at TDC and I introduce 90 PSI, the engine may rotate no? If it does, what do you do? Just roll it over by hand again until you get the #1 cylinder back to TDC?

 

Yes, having the cylinder at TDC is a safety net to decrease the chance of a valve dropping all the way down if compressed air was lost and when at TDC on the compression stroke both rocker arms will be in a position to be torqued in place.

 

So I just did cylinder #1 and I'm already running into a problem. Just wondering if anyone has any thoughts before I carry on.

Everything went perfectly up until I went to put the rocker arms back on. I still had the air hooked up, with the cylinder right at TDC, and as soon as I snugged up the exhaust side bolt the exhaust valve popped open and all the air started rushing out. I don't understand why the rocker is pushing down enough on the valve to pop it open when I just took it off with almost no air escaping. Nothing was changed here so I don't understand. I can actually watch the valves start to compress as I snug up the rocker arm bolts (not torqued yet). *edit* I double checked and I can see both intake and exhaust valves compress slightly as I snug up the rockers.

I rolled the engine around by hand back to TDC and I still have that leaking exhaust valve unfortunately.

Piston is right at the top of the cylinder and the rotor is pointing to the #1 plug terminal on the cap so there should be no lift happening here?

 

That is perfectly normal. When you took the pressure off the lifters the spring inside of them pushed the plunger to the top and it will stay there until the spring pressure pushes it back down or you start the engine. Dont worry about it.

 

Wonderful! Thanks so much for this. Puts my mind at ease. I admit sometimes I need my hand held with this stuff as I've never done anything like this before. No one prepares you for the stress of it!

 

I think I found the source of my oil burning problem. The #1 intake seal was obliterated and the majority of what I removed I just flicked on the floor as it was too small to pick up. Here's the larger bits anyway. Interesting how some are still fine.

 

Yowza!

These valve seals were toasted! These are the largest bits I could collect and the rest I just picked out and they went on the floor. I also removed quite a bit of rubber seal material from the oil return passages in the heads. Hopefully this cuts down on the amount of oil burning I've been experiencing (compression #'s were excellent, all 185+ psi ).

The tip you guys gave me to use the twist style valve spring compressor was a great one and it made the job go pretty easy. Thanks for all your help fellers!