Exhaust manifolds to coat or not to coat

[Bill Balkie 24172]

Hello ,
   I am in the process of replacing my exhaust manifolds . I have a leak at the gasket so I purchased another set of manifolds just in case the manifolds on the car now need work . I want to have a good set to be ready so I do not hold the shop up while I am looking for a set . My question is should I consider plating or coating the new Manifolds ? And if so what is the best way to go ? I see products that you brush on and other services that are plated on ( ceramic ) My objective here is simple I want a good set of manifolds  that do not leak . However  should I take advantage of the time to get them coated for a cleaner look . 

Thank you ,
         Bill

[savemy67]

Hello Bill,

Show or Go?

When I point my temperature gun at my '67's exhaust manifolds, the gun indicates temperatures approaching 400 degrees F.  That is a lot of heat.  If I recall correctly, Cadillac did not put any sort of coating on the exhaust manifolds of its modern (post '48) V-8s (feel free to disabuse me of this if I am incorrect ).  My guess is that Cadillac wanted the heat in the manifold to dissipate as rapidly as possible.

Ceramic is certainly a permanent solution as far as a clean look is considered.  I painted my exhaust manifolds with VHT (very high temperature) paint, but I am not completely satisfied with the result.  However, the paint is thinner than a true ceramic coating, so I know that I am getting reasonably good heat transfer from the manifold to the surrounding air.

True ceramic will be thicker than paint, and will slow down the dissipation of heat from the manifold.  How this affects the underhood environment of your car, and things like the choke, heat riser, intake manifold, coolant temperature, etc., will be a function of how you drive your car.

A true ceramic coating should involve the manifolds being heated to 800 - 900 degrees F. so that the ceramic fuses with the metal.  This is how the old iron bath fixtures were coated with ceramic, and why my 79 year old bathtub is still white.  Today's ceramic coatings use materials similar to true ceramic, but the application process is different (and in my opinion, less authentic).

Today's ceramic coatings are more similar to paint than to true ceramic in how they are applied, and in how they bond to the manifold. Modern ceramic coatings are spray-applied to the manifold and adhere to the metal via a polymer binder - similar to how paint adheres.  Just like may other products marketed in the U.S., ceramic coatings are called such, but they may not actually be such.  However, they will look good.

I encourage you to do your own research, and keep in mind what the function of the exhaust manifold is, and whether you want Show or Go, or something mid-way.

Respectfully submitted,

Christopher Winter

[Jeff Maltby 4194]

A pint of gray brush on worked fine on my 49 exh manifolds that you can touch up as needed, though not factory correct being bare metal. Spraying the intake with high temp flat black, followed by cad blue, will hide the center manifold runner area that always burns off to bare metal that rusts.

[Bill Balkie 24172]

Hello Christopher and Jeff,
     I am always looking to improve my car . But when it comes to second quessing the Engineers that designed these cars back in the 50's i do have limitations . I have no problem with Electronic Ignition , Radial tires Etc,Etc. Heat transfer seems to me inportant .  If i intended to put my car in a musem and was only considering looks i would go with Ceramic . Right now i am leaning towards very high temperture paint . Jeff what kind of paint did you use ?
  Thank you very much .

Thank you ,
         Bill

[76eldo]

I have used Eastwood manifold grey after glassbeading the manifolds.
The engine is sitting on a stand waiting to go into my 60 Seville. I have not fired it up yet so I can’t say how it holds up but it looks really good.

[Bill Balkie 24172]

thanks Brian ,
      I wonder if any body else has used the  Eastwood Grey . Maybe they can tell us how long it last and if they are satified with it ? I hope all is well with you Brian . Hope to see you soon at a show .
  Bill

[Ralph Messina CLC 4937]

Hi Bill,

I've used both Eastwood's and Hirsh's manifold paint with great success. Start with a clean (bead or sand blasted) surface and paint with a brush. The paint will air dry. It cures fully when the engine is run and the manifolds are brought up to temperature. The finish held up as long as ten years with only minor touch up for shows.

HTH

[INTMD8]

thanks Brian ,
      I wonder if any body else has used the  Eastwood Grey . Maybe they can tell us how long it last and if they are satified with it ?

I did on my 59.  After 6 years and 10k miles still look great.

[Jeff Maltby 4194]

I forget which brand I used but it looked great.

[Caddy Wizard]

I have used the brush-on paint to rather good effect many, many times.  Hirsch or Eastwood. 

For the absolutely best results, I have sent manifolds to a place just south of Atlanta for a baked-on finish (Performance Coatings. http://www.headercoatings.com/pages/Motor_Sports


For me, I use the brush-on stuff for a "driver" and baked-on finish for a "show-driver". (I never build trailer queens...)


Attached is a picture of a show-driver with the baked-on finish.

[35-709]

How do you like the F.I., Art?  Would you do it again?  Has it stood up well?

[Caddy Wizard]

In my experience, the 2-bbl Carter carbs on the 331 engines are great combinations.  They perform very well, with few problems, and are not terribly prone to vapor lock.  On the other hand, as the engines became more powerful in the mid-to-late 50s and the carbs went to 4-bbl units, the carbs start having trouble with reliability and vapor lock.  Probably a certain percentage of the time the issue is with today's fuel (ethanol being added causes lots of trouble), not so much with the carb itself.  But you can't always avoid ethanol, so it is what it is.  EFI pushes the fuel into the engine, instead of sucking it into the engine, so vapor lock is more or less impossible with EFI.


For cars with the 2-bbl Carters, I would not do EFI again.  Yes, the EFI worked very well, but the Carter 2-bbl works pretty well too such that the "juice isn't worth the squeeze".  On the other hand, I really like EFI as a replacement for a 4-bbl.  Indeed, I am doing that now to my 55.  But I would never do it again for a 49-51, I don't think.


EFI is pretty easy to do.  Worst part about it is that the carb was designed to idle in the 400-500 rpm range and the transmission coupling was designed to allow slippage at those low speeds.  Anything above that and the transmission wants to transfer power from the engine to the wheels.  The EFI doesn't really like to idle below about 500-600.  So you end up trying to set the EFI idle as low as you can and even then it is a little rough to go into and out of gear.  So dropping it into Dr or R from N is harsher with EFI than with a carb.  But it starts instantly, reduces fuel smell at the tail pipe, gets better gas mileage, will NOT vapor lock, and gives great driveability.  Most difficult technical challenge is attaching the TV rod to the throttle body in a way to perfectly mimic the position on the carb linkage so that the Hydramatic performs the way it was designed.  One just has to be careful to get this right -- not hard, but you do need to pay attention to this little detail.

[Roadmaster75]

I used POR-15 gray exhaust manifold paint on my 49 Willys-Overland Jeepster.
Heddman headrs on the Buick V6.  Did it in 2000.  Still rust free after 8000 miles.

[35-709]

Thank you, Art.  Off topic I know.
Geoff N.