I want to try to replace my valve seals before I drive my F-600 cross-country next week. I just had it stripped down to long block today, and when I fired it up, it started smoking. I think the cleaner I used to flush it out dried out the valve seals worse than they were.

I have a sparkplug air connector adaptor, but I dont have an on the head spring compressor tool.

anybody do it?

also valve stem diamater for a 79 370 ? I need to order seals.

on a side note, I installed a DOVE intake, and a 1411 750 cfm edelbrock AFB, and copper exhaust gaskets, its really smooth and quiet, I just wish it didnt go and take up smoking...

 

valve seals should only cause it to smoke on initial start up unless the guides are totally trashed in which case putting new seals on it won't help.
valve stem dia. should be 5/16, yes I have done it I made a compressor for the springs out of some flat steel, but you can probably get one from you local parts store some might even have one to rent.

 

I'm wondering if the intake set I installed isnt sealing well. its the tri-metal sandwich style (not my favorite) I hate to mess with it again, but I'm going to look at that in the morning.

 

I too am wondering if I might not be in for the thrill of changing out a set of valve seals. I have a 1990 Class "A" motorhome with only 37995 miles on it. The problem is not so much smoke, but I use 1 quart of oil in 50 miles, or in about 1 hour of time in city driving. I do get quite a bit of black soot against the house wall on start up and while I let the coach idle for warm-up.

I have excellent vacuum on the manifold. 19" at idle in neutral, and 16" in drive. I have picked up a small miss at idle in drive, but I think that I have a spark plug wire that is breaking down, as I got a good shock off of the passenger side valve cover last week when I was going to start working on it. Had to stop, due to some family illnesses.

I have a Snap-on compression tester that I plan on using, to check compression. If that proves out, I also will use that to charge the cylinder with air to hold the valves up after removing the schreider valve. Is there a special tool that I can purchase to compress the valve spring to get the keepers out, without removing the head?

Also, what are the best seals to use in a 460 EFI? In the past, I have used the 'mushroom' type on small block Chevies. Are these used on the 7.5L EFI?

Thanx:
"Doc"

 

the one I built for my own use looked something like this.


I have used the "mushroom" type too both work, and you can buy both from summit and most parts stores, maybe even some of the site sponsers I would check them out.

 

Unfortunately, I got my compression readings today and I am really bummed out.

Cylinders 1-7 have minimum 193 psi and maximum 200 psi. cylinder #8 only has 75 psi. I filled the cylinder with air from my compressor and could not hear air at the throttle body, or at the tail pipe. I pulled the PCV valve and had air and vapor coming out of the PCV point.

I am hoping that since this engine has set for a long period of time, that it is just stuck rings. The #8 plug was the only one that was oil fouled and the rest looked great, maybe even a little lean. #8 plug wire also had more resistance than the others.

I am trying some Marvel Mystery Oil over night to see if it will free up the rings. I have had this work for me in the past on motorcycle and boat engines. I only hope that it is not cracked rings or piston. This engine comes out through the bottom of the motorhome. UGGGH!

Sorry to get off the subject, just disappointed.

"Doc"

 

I feel your pain. this F-600 is the *easiest* truck to work on I've owned...(if you have a stepstool, and dont fall off and impale yourself on the hood latch)

 

I use rope pushed down the plug hole and the piston to hold the valves shut. This way is a bit slower than the compressed air, but I can stop for lunch and not worry about the pressure dropping and losing the valve down the bore. My compressor tool is a nail puller tool with a hole drilled in it for the top of the valve. Works, cheap, and slow.

 

I used the air pressure tool and the rental wedge thing, it was pretty easy.

all of them were really bad, its a wonder it didn't smoke really bad before the intake swap. it took perhaps 2 hrs, with a break for refreshments...

 

Just don't forget to stuff a rag or something in the oil return holes before you start. If your lucks like mine and you drop a keeper it will find it's way down one of them.

 

Tiremine, Good tip! It is usually the little traps that really bite you. I use paper towels stuffed in all oil return holes and around the pushrods.