Valve sticking on Roof head

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Model T Ford Forum: Forum 2012: Valve sticking on Roof head
Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Eagle Ida Fls on Friday, July 27, 2012 - 12:21 pm:

Number 2 exhaust valve started sticking after an couple hundred miles on my rebuilt Roof head. I had a new bronze guide put in just that guide and it started sticking after about the same miles. Number 2 and 3 exhaust valve share the same port and probably get hotter than the other two exhaust valves which each have their own ports.
While slowing down for stop signs it sometimes sticks but then kicks in if you increase the speed a little. I hand oil the valves both before and after short trips. If the valve sticks after starting I can rotate it with a wrench and it will free up. Have thought about an oil pump or a felt.
Any ideas for a permanent cure?
Rich


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, July 27, 2012 - 12:35 pm:

Guide could be too tight. Might correct it self with wear if you're willing to wait & put up with it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Friday, July 27, 2012 - 01:11 pm:

Being of a different, softer metal than the other valve guides (I assume), the pressed in guide might be expanding at a different rate than the other valve guides which, I assume, are not pressed in, or, if they are, they might be a different alloy that expands less so or are a slightly larger diameter. You might need to have the one bronze guide reamed to a slightly larger size to compensate for the expansion. It could be something as simple as introducing a little lapping compound into the guide and manually pushing the valve stem up and down within the guide until the stem revolves easily in the guide. Better to do too little than too much. You can always go back and do more but you can't undo what you have done. Make sure you remove all of the lapping compound and do not allow it to find its' way into the engine. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Eagle Ida Fls on Friday, July 27, 2012 - 02:02 pm:

Thanks for the ideas guys.
The new guide is the same material as the other guides which were put in 10 or so years ago. I assume the problem guide has worn some since it was new and didn't stick for several miles since it was installed.
I'm thinking it is carbon and have run kerosene and casteroil down the stems to clean them.
Rich


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Friday, July 27, 2012 - 03:19 pm:

As I suggested, being in the hot exhaust port both the guide and the valve stem expand from the heat to a point where they are not only tight, but are possibly too snug for any oil to get in to lubricate it. I would still suggest that to remedy the problem, the guide needs to be enlarged slightly to compensate for the expansion of the stem and the guide. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Friday, July 27, 2012 - 05:08 pm:

Richard & Jim - "Wild idea" that I just had that might just work. If you think it might be carbon in the guide as Richard suggests (and that seems likely as it IS an exhaust valve guide) you might just be able to clean out the guide with a bore brush from a gun cleaning kit. If no gun cleaning kit handy, any decent sporting goods store will have just the replacement bore brushes separately. A bore brush for a .22 caliber or .38 caliber gun barrel perhaps, and it's made out of brass or copper so as not to damage the bore of a firearm. Using that in your valve guide(s) seems to me like a good idea as it won't damage that soft bronze valve guide, but it would remove the carbon. And, if this works, you will NOT have enlarged the diameter of the valve guide with a reamer for nothing. Besides working the bore brush up and down in the guide, it wouldn't be too hard to adapt it to your cordless drill if you wanted to try a more "aggressive" approach.

Anyway, might be worth a try,.........harold

P.S. Hey,....Ted Ashmann would have liked that idea, huh?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach & Big Bear on Friday, July 27, 2012 - 05:33 pm:

When we used to replace the valve guides with bronze ones we knurled the inside of the guide and reamed it to .0015" but that was on modern oil pressure engines. The knurling helps the oil to stay where it does some good.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Friday, July 27, 2012 - 05:50 pm:

Frank - I never was too clear on this, but it would seem that there would be a huge amount of difference in how much lubrication (oil) would remain in an intake valve guide as opposed to an exhaust valve due to the heat. Does knurling actually cause some oil to remain in those hot exhaust valve guides? Just wondering,.....harold

P.S. By the way Frank, did you notice the post I added to the Long Beach Swap Meet thread near your post about how much time, effort and expense is involved with putting on that swap meet? Anyway, I mentioned that some time ago, you told me to take good care of that depot hack (or "shooting brake") that I bought from Pete's daughter Karen, as it's "a pretty special car". I actually think it's in better shape now than when I bought it; mechanically & cosmetically but I've only "redone" what Pete did and Louie Baglietto before Pete. Not sure who loves that ol' car more; our grandkids, me, grandma, or great grandma! Anyway, Pete would be pleased I'm sure as I've kept it EXACTLY as he had it, even the pin striping!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Cassara Long Island, NY on Friday, July 27, 2012 - 07:14 pm:

Guides are knurled and reamed to resize worn guides back to standard. New guides are reamed to size. If the valve is sticking it is 1) bent or 2) the guide is not sized correctly. Leaving it and letting it run-in will result in a damaged valve and/or guide. Pull it apart and check it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Richard Bennett on Saturday, July 28, 2012 - 04:44 am:

Richard, I have a permanent cure for you. Send me that troublesome Roof head and I will exchange it for a genuine Ford head. This head is guaranteed never to give any valve problems!

Just trying to be helpful, as usual.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, July 28, 2012 - 09:13 am:

I wonder if the guide is coming loose and moving with the valve some times causing it to hang up. Like John says I would not risk an expensive head like that. You ought to take it apart and fix the problem before something expensive happens.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Eagle Ida Fls on Saturday, July 28, 2012 - 10:25 am:

Thanks for the ideas. I'm still puzzled why it ran without sticking for so many miles. I guess I will take it apart and take a good look at it.
Rich

P.S. It was less troublesome with the stock head but the overhead is fun to have.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, July 28, 2012 - 12:24 pm:

There is at least one dealer of old Chevy parts on the planet. They sell a long, wide pad that goes over the valves to hold oil. It seems a bit overpriced at about $20.

Dunno if your Roof has a cover, but I mounted grease cups over the valve train of the Fronty, and squirt oil down there once in awhile.

I installed the PCV valve to draw oily air from the crankcase up into the cover. It seems to work.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthony Bennett on Sunday, July 29, 2012 - 11:17 am:

I'm not sure about your combination of guides and the age or clearance but in my limited experience if you use a "K-liner" to reclaim a worn valve guide they need very little oil to be happy.

I once had a similar problem with a BMC "A" series engine in a Mini. They used an exhaust valve that was I'm told a "nimonic" material and thus would expand very little with heat, at least when compared to a cheap replacement valve.

Might be worth considering;)


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