7.3 Head Gasket Replacement-ARP Head Stud Install

[tbrumm]

Thanks, Al. I don't think the heads need a valve grind as there is only 108k on the clock now. I wanted to replace the valve seals and springs while I had the heads off, although they may not really need replacing. However, the truck used to sit a lot when the Air Force had it, so the valve seals may have hardened up over time. In any event, it certainly won't hurt to replacethe seals for longevity, and I already have them. I purchased a NOS OEM Ford valve grind gasket kit which has the valve seals, but no "sleeve" to install them over the ends of the valves. I wonder if a short piece of thin plastic tubing slid over the valve end would work? If I understand correctly, the only thing that tube is doing is keeping the seal from getting nicked up on the groove for the keeper.

 

[Knuckledragger]

If, I replace the No.3 intake valve with a new one, what needs to happen with the valve seat-anything? Does the new valve need to be "fitted" to the existing seat? Does the seat need to be replaced when installing a new valve. I have almost no knowledge in this area.

Since you are not going to take the heads to a shop, the easiest way to fit the valve to the existing seat is to lap it in. There is a product called "clover lapping compound" which has some carborundum powder in a greasy medium. Put compound on the valve seat or valve sealing face and push together. Turn the valve several times (by hand, no need for power) while keeping pressure on the seat and take it out to look. if there is a wear ring from the compound, it is ready to go. Clean off the compound very carefully, you don't want to reassemble the engine with any in there.

 

[tbrumm]

Thanks, Knuckledragger. I am still thinking I am gong to have to take the heads to a shop. I don't have the knowledge or experience with regard to replacing that one valve and making sure the valve to seat fit is correct. I understand lapping the valve to the seat but have never actually done it. The Ford service manual also states "Interference fit of valve and seat should not be lapped out". Manual also says "Fit of valve and seat should never be lapped out with lapping compounds" The manual talks only about grinding the valve and seat with grinding wheels dressed to the proper angle, and then checking the fit with prussian blue. It also states "If blue is transferred to the center of valve face, contact is satisfactory". Guess I better start making calls to some other machine shops.

 

[riotwarrior]

See there ya go....get prussian blue and check dor yourself.

BTW

DO NOT MIX UP VALVE LOCATIONS KEEP ALL VALVES IN THEIR ORIGINAL SPOTS...USE AN ENGRAVER AND MARK THEM FOR EACH SPOT IN THE HEAD...OR USE A NUMBER STAMP SET BUT DO NOT MIX THEM UP

BTW I erred on instructions....insert valve place capsule over tip place seal in seal driver slip over valve and set to head...my bad sorry

 

[tbrumm]

I have the replacement valve (NOS OEM) ordered and it may get here as soon as Saturday. Once it arrives, I will check the valve to seat fit and see what I find. I already have the prussian blue on hand. Maybe I get lucky

 

[BDCarrillo]

However, the truck used to sit a lot when the Air Force had it, so the valve seals may have hardened up over time.

Sorry! Lol... we're tough on diesels... short runs, wet stacking, excessive idling, and low speeds...

Check those valve guides while you've got the heads out

 

[tbrumm]

The new intake valve arrived in the mail today.

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Removed the old valve, cleaned up the seat and brushed a LIGHT coat of prussian blue on the seat.

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Inserted the new valve in the head, held it against the seat with light finger pressure and turned it.

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and this is what I got-a nice even thin coat of blue approximately in the center of the valve face.
Too bad the camera didn't focus well for this picture.

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Sure looks to me like this new valve will seal against the seat, but what the heck do I know

 

[Matt_INW]

And a new motorcraft thermostat while you're at it.

 

[DaveBen]

You can lap the valve to the seat. All auto parts stores have lapping compound and the tool to lap the valves. It is a stick with a rubber cup on it to engage the valve. Just place the compound on the valve and turn it back and forth using both hands. This is what the pros use.

 

[riphip]

To see if valves are seating, turn heads over (head posts if you have them) so the face is level & pour small amount of gas or diesel on them in a pool. If not sealing, liquid will leak into intake or exhaust port.

Rick

 

[tbrumm]

Thanks for the help guys. I dropped the heads off to the machinist this morning. God only knows when I will get them back as he is swamped with work. In the meantime, I have a ton of other stuff to do on the truck, not to mention getting the block cleaned up and head bolt holes chased.

 

[riotwarrior]

Lapping an interference fit valve iznt really going to do much except expose contact surface and prussian blue does exact same thing....

I dunno bout interference fit myself ezpecially with known issuez of guide wear etc.

Going to think bout this one for a while...pretty slim margin for contact and cooling....wowzers

 

[tbrumm]

Well, the machinist finally has the heads done! That is the good news. The bad news is that he had to surface both heads. One required removal of 0.003" but the other required removal of 0.007". I warned him that about the tolerances stacking up on these engines and to think carefully about resurfacing the IDI heads. He doesn't think this is any big deal but my stomach is queasy now. What do you all think? Should I be worried? Haven't picked the heads up yet.

 

[IDIoit]

measure the recess of the valves, if they are in spec, you should be good to go!

 

[tbrumm]

Thanks, Brian. My stomach is bit less queasy now. I will check that out after I get the heads picked up. I am also concerned about the pre-cup "recession/protrusion". I think spec. only allows a couple of thou. on that iirc. I will have to look at the spec's in my manual again. I printed all the spec's out and gave 'em to the machinist when I dropped the heads off.