Coatings for cast iron exhaust parts

[Str8-8-Dave]

I posted this in the AACA "Technical" forum as well as here because Buick is not the only car manufacturer that used cast iron Marvel heat riser systems but the Marvel heat riser system I am working with for 1931 Buick is Pre-war specific so my post and question is repeated here hoping to get ideas from Buick enthusiast's experiences...

 

I've spent many hours restoring the Marvel heat riser system for my 1931 Buick model 8-66S, or at least resto-modding it to look and act authentically.  As I write this I have a copy of the Marvel Carburetor and Heat Control as used on 1931 Buick in hand which has good diagrams of the system including cutaways of the system in "Off/Medium/On" heat positions and the associated diverter and riser valve positions and for the first time in my lifetime have the riser, diverter valve and associated linkage all assembled on my desk and can see it work to match the diagrams in the Marvel book.  The riser casting that came with my project car came from a later Buick car that still used a Marvel TD series updraft carburetor but had slightly larger butterflies and is wider at the throttle shaft pivots by 0.375" which is why I say it is resto-modded,  I modified the throttle shaft to accept the articulated linkage that controls by cam and lever, positions of the large diverter butterfly at the exhaust manifold, the small tube butterfly in the riser directly, then controls the large butterfly in the exhaust diverter dependent on throttle position so that no matter which heat lever position you select on the instrument panel the large butterfly in the diverter goes vertical at wide open throttle to allow unrestricted exhaust flow at wide open throttle.  The other reason for transferring the linkage is so the warmup throttle appears correctly under the hood and works correctly from the steering wheel control.  I have modified parts that came with my car and made missing linkage parts, repaired castings and gathered all the parts that would make this system look so close to original you would have to know the heat riser casting number is not for 1931 and work just like it did when Buick made the car.  But alas, all the advice I get from other owners which I highly respect is gut the diverter valve housing (remove the butterfly) and block off the heat riser system internally to prevent heat and exhaust flow to the riser and protect it from burnout or breakage.  The advice also says the car runs better without the heat system functioning.  My experience has been a little different, the cars I've had never idle in  perfectly in cool weather until they get good and hot because you can't get perfect idle mixture adjustment.  The intake manifold on the early straight 8 is a big piece of iron not centrally located over the engine block.  It's a long way from the atomizing parts of the carburetor to the cylinders.  Some of the fuel air mixture condenses into drops and lays in the intake manifold until it gets hot.  So before it gets hot you have your choice on mixture, when the mixture is perfect for the inboard 4 cylinders, 3/4/5/6 outboard 4 cylinders, 1/2/7/8, are lean, when you adjust to perfect mixture for the outboard cylinders the inboard cylinders are slobbering rich.    

 

So here is my question.  Has anyone experimented with coating the inside surfaces of one of these heat risers to protect the iron from corrosive effects of exhaust condensate and acids? 

What did you use or have done to the casting?

Was the coating or process successful, I.E. no problems with burnout?

Buick was not the only car to use cast iron heat riser equipment so an owner of another make my have experience and I'd be very appreciative of hearing from owners of other makes. 

 

Thanks in advance...

Dave

 

Picture 1:  Heat off idle

Picture 2   Heat off wide open throttle

Picture 3:  Heat on idle

Picture 4:  Heat on wide open throttle

 

 

Edited November 16, 2018 by Str8-8-Dave
Correct puctuation- title (see edit history)

[Terry Wiegand]

Had the manifolds on my 1916 D-45 Ceramic Coated.  Finish Line Coatings in the Portland, Oregon area did them for me.  The cost was very reasonable.  They look extremely nice.

 

Terry Wiegand

South Hutchinson, Kansas

Edited November 17, 2018 by Terry Wiegand
GRAMMAR EDIT (see edit history)

[Hubert_25-25]

Jet hot coatings is supposed to be able to do what you are mentioning.  I took my parts to a local high temperature powder coating company.  They said it was good for 1200 degrees, which is better than regular powder coating.  I do think it is a ceramic coating.  I also figured maybe a little cheaper than using "Jet hot" as a brand name.  The actual heat riser on a 1925 Buick is painted, so I did not have it powder coated.  I did not remove the large butterfly, but is does still work, and I plan to leave it open all the time.

 

Edited November 18, 2018 by Hubert_25-25 (see edit history)

[Str8-8-Dave]

Wow- that manifold and diverter look great Hugh.  Thanks for your response and picture...

 

Dave

[Crazyfamily]

I’d love to see the correct color paint on each area/parts on the 1927 Model 27 so I can make sure it looks correct on our car.

[Hubert_25-25]

I have this side of a 1928 Buick Sport Roadster Engine that Larry says is pretty correct.  You can get the correct paint from Bob's Automobilia or Bill Hirsch.   My comment is that the firewall should be body color.  I will note that the oil can would have been cadmium or zinc plated and heavy polishing will make a copper oiler shine.   The fan is black.    I have this photo from Rod of the opposite side of a 1926 Buick.  The caps on the breather and oil filler should be engine color.  The steering box should be engine color.  The steering tube is black or nickle plated depending on the model.  Nickle plated for the sport models.  

 Hugh

Edited November 21, 2018 by Hubert_25-25 (see edit history)