Painting a new cylinder head

[29er]

There's been lot of great discussion lately relating to my current project: changing the head. I've got a brand new 5:5 Snyder's head coming that will need to be painted. Does it need any prep or primer before applying the Ford green top coat?

[Mike]

First send it out to a machine shop and have it Machine flat. Everyone I purchase has been warped front to back, then blow out all holes & clean with thinner and paint.
mike

[Mitch]

What Mike said

[tbirdtbird]

would suggest lacquer thinner, not paint thinner, unless that is what was meant. Paint thinner leaves a residue and is generally gonna cause trouble when it comes to car paints

Would also suggest spraying head down with Ospho (ACE hardware and others) , as a passivating agent. Then paint right over that.
I just blasted and Ospho'd a B police head to get it ready for paint the other day. Will post a pic of the passivated head later today,

There seems to be some confusion about using Ospho and other phosphoric acid agents. Some think you are supposed to wash it off with water. Not sure where that is coming from. BUT that is not what you want to do; you just removed your protection. The Ospho label states that if used on galvanized metal it MAY be washed off; but even then I am not sure why anyone would do that.

For small jobs I use a plant mister bottle; for bigger jobs like panels I use a garden sprayer

cyl heads.jpg

That battleship gray that you see is iron phosphate, which is inert. We then directly apply Baril, or Zolatone, or similar DTM (direct-to-metal) urethane. You will have to re-sandblast the head to get it off. I believe captdan on this forum also uses this process for his cast iron.

Tom W, that is a hi-comp head for my Stude M5 project; up 1.5 points from the stock head.
Time to load the gun.......

[Mitch]

i usually brake kleen it and paint.. but definitely get a skim cut.

[29er]

OK. I'll let you know whether it needs to be skimmed. Thanks!

[BNCHIEF]

Do not chance it just do it then you have peace of mind and head off would be problems. Correct head gasket and proper torqueing and re-torqueing.

[Tom Wesenberg]

I like to spray the bottom side of the head at least 1/2" in with a very light coat, so rust doesn't form at the edge.
The spray can paint is thin enough to not cause a problem.

[29er]

Good tips! There have been other discussions of the torquing and head stud selection issues that I've followed with interest.There were also threads on the head gasket selection. Interesting that Bert's doesn't even carry the so-called "premium" head gasket... the silicone one that is advertised with extra silicone bands around all water passages and does not require any sealant. In a recent phone call, they told me they've had problems with them so I'm going with the Best gasket. Tom's thought about painting the bottom side edge sound like a good idea. I'll let you know how it turns out! Hope I can get it back together in time for the 4th of July parade! Thanks.

[tbirdtbird]

ya, that silicone one was a good idea gone all wrong.......

[BILL WILLIAMSON]

Just scrub it with T.S.P. & spray on engine paint, it'll look GREAT.---- TOO much thinking will make your head hurt!
Bill Simple

[tbirdtbird]

TSP has gone the way of the EPA

TSP is still available. Get the original full strength one in the red box. The green label box is the neutered version. Red Devil. Lowes.

[BILL WILLIAMSON]

NOT in my Carriage House, I have enough T.S.P. to last me 'til I CROAK!
By the way, T.S.P. mixed with water, to a pancake batter consistency, is a SAFE, but SLOW paint stripper.
Bill Cleanerthanmostfolks

[Captndan]

would suggest lacquer thinner, not paint thinner, unless that is what was intended. Paint thinner leaves a residue and is generally gonna cause trouble when it comes to car paints

Would also suggest spraying head down with Ospho (ACE hardware and others) , as a passivating agent. Then paint right over that.
I just blasted and Ospho'd a B police head to get it ready for paint the other day. Will post a pic of the passivated head later today,

There seems to be some confusion about using Ospho and other phosphoric acid agents. Some think you are supposed to wash it off with water. Not sure where that is coming from. BUT that is not what you want to do; you just removed your protection. The Ospho label states that if used on galvanized metal it MAY be washed off; but even then I am not sure why anyone would do that

cyl heads.jpg

That battleship gray that you see is iron phosphate, which is inert. We then directly apply Baril, or Zolatone, or similar DTM (direct-to-metal) urethane. You will have to re-sandblast the head to get it off. I believe captdan on this forum also uses this process for his cast iron.

Tom W, that is a hi-comp head for my Stude M5 project; up 1.5 points from the stock head.
Time to load the gun.......

This exactly!

[29er]

So my head's hurtin' and Bill maybe right that I'm thinkin' (always dangerous) too much, BUT: Judging by tbirds pictures I guess it doesn't hurt anything to get Ospho on the bosses, in the threads or on the underside of the head where the gasket goes????

[tbirdtbird]

that is correct

I should add that many years ago this type of phosphoric acid treatment was available directly from DuPont as "Metal Prep"

[BILL WILLIAMSON]

I had forgotten about Metal-Prep, Auto Shop Teacher taught us about It, back in the '50s. We also used it over LEADED areas, for primer "GRIP"---
Bill W.

[29er]

'K. Thanks. Me and my brain are takin' the rest of the weekend off. Bill: Looks like a hot day down your way. Hope you and the dawg kin find a shady spot!

[H. L. Chauvin]

Just one (1) opinion.

After witnessing so many vintage automotive paint failures, my goal is to go through life preparing Model A parts and providing coatings on Model A parts once in a life time.

After looking at hundreds of painted Model A vintage engines in Model A's, and hundreds of painted engine in photographs "after" engines are at least five (5) years old, one clearly sees rust along the top of the block and the bottom of the head adjacent to the head gasket and many times peeling paint adjacent to same.

My engine, transmission, differential, and undercarriage was all prepared with all POR 15 products and finally coated with POR 15 products.

Not one speck of rust after ten (10) years and I think this coating could last at least another 100 years ....... if in doubt ..... just ask Mr. Purdy ..... one of the very few other Model A owners who learned years ago how to use these very special POR 15 preparation products and these very special POR 15 final coatings.