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How hot do cast iron exhaust manifolds get? #165913 12/10/08 10:14 PM 12/10/08 10:14 PM
Joined: May 2005 Posts: 4,706 Florida BDW OP master
BDW OP master Joined: May 2005 Posts: 4,706 Florida	I painted my 340 stock exhaust manifold with hi-temp paint and it blistered as soon as I fired the motor up? I wired brushed off all surface rust, hit it with some Ospho, then painted. What went wrong? Last edited by cnxt; 12/10/08 10:15 PM.

Re: How hot do cast iron exhaust manifolds get? [Re: BDW] #165914 12/10/08 10:38 PM 12/10/08 10:38 PM
Joined: Jan 2003 Posts: 1,339 Detroit, Michigan fjr340gts pro stock
fjr340gts pro stock Joined: Jan 2003 Posts: 1,339 Detroit, Michigan	I measured mine with a laser pyrometer and they usually are in the 460-520* range

Re: How hot do cast iron exhaust manifolds get? [Re: fjr340gts] #165915 12/11/08 07:51 AM 12/11/08 07:51 AM
Joined: Jan 2003 Posts: 8,064 Arlington, Texas earlybee master
earlybee master Joined: Jan 2003 Posts: 8,064 Arlington, Texas	Quote: I measured mine with a laser pyrometer and they usually are in the 460-520* range They get hotter than that under load.

Re: How hot do cast iron exhaust manifolds get? [Re: fjr340gts] #165916 12/11/08 07:55 AM 12/11/08 07:55 AM
Joined: Dec 2004 Posts: 1,061 New Mexico D dmerc super stock
dmerc super stock D Joined: Dec 2004 Posts: 1,061 New Mexico	I did the same thing and get about 800-850 degrees at idle. I'm sure it goes way up under full throttle. I guess there are spray paints that will stay on but I've given up painting my manifolds. It's kind of like trying to keep the bottom of the car clean. If you drive it it's going to get dirty and natural colored manifolds really don't look bad at all.

Re: How hot do cast iron exhaust manifolds get? [Re: dmerc] #165917 12/11/08 10:28 AM 12/11/08 10:28 AM
Joined: Jun 2008 Posts: 3,916 usa L lewtot184 master
lewtot184 master L Joined: Jun 2008 Posts: 3,916 usa	the 440 in my '69 r/t varies from 550f at #1 cylinder to 650+f at #7 under very moderate driving conditions.

Re: How hot do cast iron exhaust manifolds get? [Re: lewtot184] #165918 12/11/08 10:37 AM 12/11/08 10:37 AM
Joined: Jan 2003 Posts: 42,714 Spokane Washington ScottSmith_Harms Mr Wizzard
ScottSmith_Harms Mr Wizzard Joined: Jan 2003 Posts: 42,714 Spokane Washington	Skip the paint. First you must remove and media blast the manifolds clean,then wipe them down with a liberal coat of clean 90 weight (yes, it's a nasty mess) wipe them off, put them on the engine, and run them until it all smokes off. It stinks to high heaven so be sure to do it away from your place. You can also cook it off prior to assembly with a propane torch, either way works about the same. The raw cast iron will take on a nice mellow brownish gray color and won't rust for ages, a light spot touch up with a wire brush and more 90 weight during the first year will keep rust at bay for many years, the results are pretty amazing.

Re: How hot do cast iron exhaust manifolds get? [Re: ScottSmith_Harms] #165919 12/11/08 12:26 PM 12/11/08 12:26 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: Skip the paint. First you must remove and media blast the manifolds clean,then wipe them down with a liberal coat of clean 90 weight (yes, it's a nasty mess) wipe them off, put them on the engine, and run them until it all smokes off. It stinks to high heaven so be sure to do it away from your place. You can also cook it off prior to assembly with a propane torch, either way works about the same. The raw cast iron will take on a nice mellow brownish gray color and won't rust for ages, a light spot touch up with a wire brush and more 90 weight during the first year will keep rust at bay for many years, the results are pretty amazing. That is so unconventional that I'm just going to have to try it but 1st I'm going to try some black barbeque grill paint. live every 24 hour block of time like it's your last day on earth

Re: How hot do cast iron exhaust manifolds get? [Re: ScottSmith_Harms] #165920 12/11/08 01:03 PM 12/11/08 01:03 PM
Joined: Oct 2007 Posts: 3,877 Oregon hooziewhatsit master
hooziewhatsit master Joined: Oct 2007 Posts: 3,877 Oregon	Sounds like the method (sans the 90wt ) to season a cast iron skillet. That should work great. -Dave If you ever find yourself in a fair fight, your tactics suck.

Re: How hot do cast iron exhaust manifolds get? [Re: RapidRobert] #165921 12/11/08 01:56 PM 12/11/08 01:56 PM
Joined: Jan 2003 Posts: 14,610 Not2farfromNashville, TN R Rug_Trucker I Live Here
Rug_Trucker I Live Here R Joined: Jan 2003 Posts: 14,610 Not2farfromNashville, TN	That is so weird Scott! Wonder if that would work on headers? I am tired of spraying Plasticoat white on the Hookers. Isn't there a coating that Eastwood or somebody sells? "The only thing to do for triumph of evil is for good men to do nothing" "NUNQUAM NON PARATUS!"

Re: How hot do cast iron exhaust manifolds get? [Re: Rug_Trucker] #165922 12/11/08 03:31 PM 12/11/08 03:31 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: Isn't there a coating that Eastwood or somebody sells? yeah but I dont know how good it is though live every 24 hour block of time like it's your last day on earth

Re: How hot do cast iron exhaust manifolds get? [Re: RapidRobert] #165923 12/11/08 03:48 PM 12/11/08 03:48 PM
Joined: Jan 2003 Posts: 42,714 Spokane Washington ScottSmith_Harms Mr Wizzard
ScottSmith_Harms Mr Wizzard Joined: Jan 2003 Posts: 42,714 Spokane Washington	In my own experience it works best on cast iron but many other metals as well. I didn't invent the method, Mike at Rcket Restorations showed it to a while back, works great for treating cast iron of all types when you want a more original appearance (as opposed to painted which is never "correct").

Re: How hot do cast iron exhaust manifolds get? [Re: dmerc] #165924 12/11/08 04:07 PM 12/11/08 04:07 PM
Joined: Jan 2003 Posts: 25,200 Upper Midwest M MoparforLife Too Many Posts
MoparforLife Too Many Posts M Joined: Jan 2003 Posts: 25,200 Upper Midwest	They get hot enough to cook on. If you are looking at an original look, leave them natural cast.

Re: How hot do cast iron exhaust manifolds get? [Re: MoparforLife] #165925 12/11/08 05:07 PM 12/11/08 05:07 PM
Joined: Aug 2007 Posts: 828 KS M MoparKansas super stock
MoparKansas super stock M Joined: Aug 2007 Posts: 828 KS	Calyx (sp? keeps them looking nice, but a little too shiny for stock cast iron. It also will rub off somewhat for a while. My brother has it on his car and hasn't had it bake off yet... http://www.calyxmanifold.com/

Re: How hot do cast iron exhaust manifolds get? [Re: MoparKansas] #165926 12/11/08 06:21 PM 12/11/08 06:21 PM
Joined: May 2005 Posts: 4,706 Florida BDW OP master
BDW OP master Joined: May 2005 Posts: 4,706 Florida	The 90w does sound unconventional! I might just have to try it. I'm still curious what happened with the paint. It started separating as soon I fired the motor up! It actually looked like there was a latex glove on it and was being blown up. For some reason the paint didn't even attempt to bond with the metal. Really frustrating. Last edited by cnxt; 12/11/08 06:23 PM.

Re: How hot do cast iron exhaust manifolds get? [Re: BDW] #165927 12/11/08 06:31 PM 12/11/08 06:31 PM
Joined: Jan 2003 Posts: 3,967 S.I. N.Y. 1MYTGTX master
1MYTGTX master Joined: Jan 2003 Posts: 3,967 S.I. N.Y.	FWIW I had mine Jet-Hot coated and have looked like this for the past 5+ years now...reduced the underhood temps as well 4872852-4-18-20073-54-45PM_0004_exposure_resize.JPG (635 downloads) 1MYTGTX

Re: How hot do cast iron exhaust manifolds get? [Re: 1MYTGTX] #165928 12/11/08 06:45 PM 12/11/08 06:45 PM
Joined: May 2005 Posts: 4,706 Florida BDW OP master
BDW OP master Joined: May 2005 Posts: 4,706 Florida	Looks nice, where did you have it done & how much did it cost? Thx

Re: How hot do cast iron exhaust manifolds get? [Re: BDW] #165929 12/11/08 09:14 PM 12/11/08 09:14 PM
Joined: Aug 2007 Posts: 902 Seattle, WA R rss super stock
rss super stock R Joined: Aug 2007 Posts: 902 Seattle, WA	Quote: I wired brushed off all surface rust, hit it with some Ospho, then painted. I'd bet it has something to do with the Ospho. Probably hadn't fully cured so you had some moisture trapped under the paint that bubbled once you heated them up.

Re: How hot do cast iron exhaust manifolds get? [Re: rss] #165930 12/11/08 10:35 PM 12/11/08 10:35 PM
Joined: May 2005 Posts: 4,706 Florida BDW OP master
BDW OP master Joined: May 2005 Posts: 4,706 Florida	Your probably right, but it might have something to do with cleaning it with easy-off oven cleaner initially. I thought I rinsed it well, but maybe not enough? After letting them dry for a day I then used a wire bush on a drill to clean it up further. I then put on the Ospho. Manifold actually sat then for a week at this point(I had to go out of town on business). After painting, I set it out in sun for 2 days. But it must have been some sort of trapped moisture, that paint didn't last 10 seconds! Last edited by cnxt; 12/11/08 10:37 PM.

Re: How hot do cast iron exhaust manifolds get? [Re: BDW] #165931 12/11/08 11:50 PM 12/11/08 11:50 PM
Joined: Jan 2003 Posts: 1,339 Detroit, Michigan fjr340gts pro stock
fjr340gts pro stock Joined: Jan 2003 Posts: 1,339 Detroit, Michigan	I had mine coated. The inside with a thermal barrier, and the outside with a cast iron gray coating. Cost about $150 for the pair. www.automotivemachine.net did the process.

Re: How hot do cast iron exhaust manifolds get? [Re: RapidRobert] #165932 12/11/08 11:53 PM 12/11/08 11:53 PM
Joined: Nov 2004 Posts: 25,050 Texas GoodysGotaCuda 5.7L Hemi, 6spd
GoodysGotaCuda 5.7L Hemi, 6spd Joined: Nov 2004 Posts: 25,050 Texas	Quote: but 1st I'm going to try some black barbeque grill paint. ..dont even waste your time. 1972 Barracuda - 5.7L Hemi, T56 Magnum 6spd - https://www.facebook.com/GoodysGotaHemi 2020 RAM 1500 [img]https://i.imgur.com/v9yezP9.jpg[/img]

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