lets start with what i have
1967 F250 300 inline 6, with about 90k on the engine (was dads work truck, the motor was rebuilt.)

so about 3 months ago I found that I had a few push rods bent and rocker arm studs were starting to pull from the head after i tried starting the truck after about 2 months of sitting.

I pulled the head, got new studs, got new push rods and proceeded with the rebuild of the head.

I made sure the rocker arm studs were re installed correctly, bought new push rods, did a valve job along with a bathing of the head *( took it to my local head guy and he has the washer)

Put it back together, changed the oil, filter , flushed the fuel system, filled that tank with new fuel, and started her up....it ran excellent , like it hasn't ran that good in years.

From the on, I vowed to at least start it each weekend , to keep it from bending push rods again. it doesnt get driven much as its now just a parade truck, so maybe a 100 miles a year.

Just the other day it went out to start it, heard two pops and a ping, started up and felt like it was running on 4 cylinders. Pulled the valve cover , low and behold, bent 2 push rods and pulled a stud from the head, one push rod bent so bad i couldnt pull it from the hole. I actually had to pull the head to get it out.

Now the fun part. Pulled the head off, and pulled the valves out. The exhaust just slid right out smooth as silk...but... the intakes were gummed up and stuck..after a couple of taps with a rubber mallet and some silicone spray they came out and had the look of about 10 coats of varnish on them along with the intake runner just shiny with it. Also the valve stem was tacky like glue.

here is my questions.

1) What would make the extreme "varnish" build up happen? When ever i start it and let the truck run, I make sure it gets warmed up before I shut it off.

2) How do i prevent this from happening again? I will take all recommendations into account and summarize my own actions.

3) Could this be a result of getting TOO much fuel. When it runs it doesn't smell like its rich, nor runs that way, a plug reading shows a slight richeness but brown on the tips. The reason I ask this is because I am wondering if my carb is leaking by and down the intake runners during storage. Plus there is a question with my Fuel pump, but, that is for another post at another time after investigation.

But, before everyone starts answering, here is a list of things that were recommended to me and some I am going to do regardless.

A) Run synthetic oil. THIS I AM GOING TO DO ANYWAYS. Due to the cleaning nature of the synthetic oil this would keep the guides clean of gum. But, oil has to get in the guides first for this to happen ....so...
B) Pierce the oil seals (as they are really only rubber umbrellas) with multiple holes using a hot needle, thus allowing some oil to get into the guide instead of relying on just the fuel for lubrication.
C) Leave the oil seals off the intake valves. If its just going to get a small amount of use the worst that will happen is some smoke during initial firing of the engine.
D) Leave ALL the oil seals off ....same reason as stated above.
E) Be sure and run Heet, or Gumout fuel additive to keep this from happening. I WILL ALSO BE DOING THIS REGARDLESS.
F) Add a 10oz bottle of synthetic 2 stroke oil to a full tank of gas. I've heard of this, and may try it, it couldn't hurt, but unsure as the result when it comes to the valve stems and guides.
G) Always add Marvels Mystery Oil into a full tank of gas on older 60s vehicles . I have heard this, and my dad did it, but thought it was silly...well...anyone got a glass of milk to wash my feet down with.
H)In case the carb is leaking by, and mine well may be, install a shut off valve between the fuel pump and the carb. When getting ready to shut it down after a warm up, shut the valve off and let the carb run dry. I WILL BE DOING THIS FOR SURE.

So the parts list I have obtained to fix everything is as follows
Crane Cam push rods
Comp Cams threaded rocker arm studs
head,intake/exhaust gasket.

And I have all the tools to install the threaded rocker arm studs, after I tap the holes im going to take it back for another bathing.

So, I am looking to all my peers on here for your help , suggestions and advice, especially if you have battled this issue also, please tell me what you did to conquer the sticky valve situation.

Thanks again
Webslinger

 

Start using a product called Sta-bil in the gas tank. Not sure on the spelling. It is bad gas causing it. You see, on the intake stroke the valve opens. When that happens part of the valve stem comes out of the valve guide. This valve stem is right in the path of guess what? Yep, the air and bad gas goes right around/past it. When the valve closes back up in the head it takes a coating of the bad gas with it right back up in the valve guide. There is your sticky varnish. Put new valve guides in it. Run it more. Non-use is worse than a good beating.

 

Well, i dont need to replace the guides because clearnce and play are still within tolerances and i would have to have the head drilled out to accept installable guides. The guides in there now are just the iron machined into the head then knurled.

I do like the idea of the Sta-bil and i do believe that is the correct name.

Still looking for some more inputs, especially concerning the valve seals.

 

BTW, Welcome to FTE!

I wouldn't do anything as described above. Seals are there for multiple reasons. And still work to this day. Don't take offense, but I think you are over-thinking this. IMHO put it back as originally designed with the seals. The MMO not a bad idea. I am a big fan of the stuff. Also Lucas brand additives and a product called Seafoam. The main one though is sta-bil. 300's are as tough as a Sherman tank. I'd keep the seals intact.