Cylinder Head Issues

Greg Reimer 7376 · 02-15-2015, 08:26 PM

Anybody out there had exhaust valve seat issues in SBC heads, circa 1968 whereas a cylinder or two,or 6, show very bad leak down numbers-35-65% just like a motor with a bent set of exhaust valves, only when the motor gets pulled and the heads taken off, no bent valves are found,only to see a very rough,almost deeply rusted corroded seat in the head? My Chevelle sat since August, took it out to run it before Winternationals, it ran OK but down about a mile and a half per hour in the 1/8th mile.When I loaded the car up the Saturday before Pomona, I heard a couple of low cylinders, so out came the leak down gauge with bad results. I thought I might have tagged a valve in the water,but no bent valves or any marks on any of the pistons showed up,just the seat damage.Could it be a chemical corrosive reaction between the iron head,the stainless valve, and the residue in the fuel? Just thought I'd ask.

Mike Semeniuk · 02-16-2015, 12:02 AM

Greg, I was told the metal in the seat area of some older heads was porous and susceptible to seat rusting. C11 also attracts moisture and causes rusting in combustion chamber unless you use Marvel Mystery Oil or something to fog the engine when sitting betseen races.

Greg Reimer 7376 · 02-16-2015, 10:53 AM

Thanks for your reply. I'm going to finish tearing the heads down and see just how bad the seats are.I'm prepared to replace all the seats with hard seats if necessary.The car had been run on mostly C-12 with a dash of 76 Union premium as well. (not at a NHRA race with that mix).If you ever saw an engine that had been run on propane, valve seat erosion is a problem on such a dry fuel.I've seen the Marvel Mystery Oil treatment, it may become the new norm around here.

Greg Reimer 7376 · 02-22-2015, 07:37 PM

Well, seems like we're not alone. I talked to a racer with a 305 '85 Camaro, he had the same problem affect one set of his heads. They are touching the valve seats, repairing the pitting, and going back together with whatever they need. Seems that the practice of lubing the engine with Marvel oil or ATF is going to be a new practice. Ever see a light rust haze on cylinder walls when opening up an engine ?

Kevin Panzino · 02-22-2015, 09:52 PM

I too always wondered about C11... The residuals from combustion seem to be terribly hygroscopic.... I've seen rust on almost every part post-combustion, but nothing on the intake side... Its not the fuel itself, it appears to be after its burned....

If I know I'm not going to run the car for a while, when I pull it in the garage, I open the hood, then kill the fuel pump and work the throttle on the carb while I spray in the oil, and keep the Revs up until the float bowl is dry and the engine dies. This has alleviated all of the issues. The white smoke and odor of this operation wafting up through the house is not at all appreciated by the wife however....

terry1 · 02-23-2015, 08:16 AM

Not to hi-jack the thread,but, is it common practice to turn off the fuel pump when fogging the engine?
Also the "mystery" oil is a MYSTERY to me up here in the white north.
I can get a "fogging" oil from a lot of suppliers but not mystery oil!!!!

Larry Hill · 02-23-2015, 08:39 AM

I fog the engine down at the end of the race.

Rsmith38 · 02-23-2015, 09:08 AM

Google Marvel Mystery oil for info. This has been used for many years - on the dragster we pulled the plugs and used a squirt bottle to oil the cyls, then turned over by hand. I remember Dave L. on his ramp truck fogging the Camaro after loading to head home.

Mike Semeniuk · 02-23-2015, 06:18 PM

Terry,

Canadian Tire did sell Marvel Mystery Oil out here in the west not sure if they still do. There is also a CRC aerosol product the motorcycle guys use but then you would have to pull plugs and spray the cylinders. Might need to go south and buy a couple of cases of Marvel. I bought 3 cases 6 years ago and only have one can left.

Rich Biebel · 02-23-2015, 07:56 PM

Cast iron rusts very quickly and always has. Your headers allow moisture/condensation to get in their especially when the exhaust valve is off it's seat.

Hold the carb wide open after a race and use MMO or ATF or WD-40 and crank the engine over to draw the stuff in past the carb.

I used to use a rag to absorb the gas from the carb accelerator pump.

Stuff rags in your open headers or find a plastic cap that fits..

Plastic Caps from various pipes might work....they protect the threads on new pipe and once you have the right size.....they work perfect....

Exhaust seat/valve rust was always a problem.....

02-15-2015, 08:26 PM	#1
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,110 Likes: 164 Liked 646 Times in 207 Posts	Cylinder Head Issues Anybody out there had exhaust valve seat issues in SBC heads, circa 1968 whereas a cylinder or two,or 6, show very bad leak down numbers-35-65% just like a motor with a bent set of exhaust valves, only when the motor gets pulled and the heads taken off, no bent valves are found,only to see a very rough,almost deeply rusted corroded seat in the head? My Chevelle sat since August, took it out to run it before Winternationals, it ran OK but down about a mile and a half per hour in the 1/8th mile.When I loaded the car up the Saturday before Pomona, I heard a couple of low cylinders, so out came the leak down gauge with bad results. I thought I might have tagged a valve in the water,but no bent valves or any marks on any of the pistons showed up,just the seat damage.Could it be a chemical corrosive reaction between the iron head,the stainless valve, and the residue in the fuel? Just thought I'd ask.

02-16-2015, 12:02 AM	#2
Mike Semeniuk Junior Member Join Date: Aug 2004 Location: Sherwood Park, Alberta Posts: 99 Likes: 19 Liked 6 Times in 2 Posts	Re: Cylinder Head Issues Greg, I was told the metal in the seat area of some older heads was porous and susceptible to seat rusting. C11 also attracts moisture and causes rusting in combustion chamber unless you use Marvel Mystery Oil or something to fog the engine when sitting betseen races. __________________ Mike Semeniuk 632 GTMA

02-16-2015, 10:53 AM	#3
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,110 Likes: 164 Liked 646 Times in 207 Posts	Re: Cylinder Head Issues Thanks for your reply. I'm going to finish tearing the heads down and see just how bad the seats are.I'm prepared to replace all the seats with hard seats if necessary.The car had been run on mostly C-12 with a dash of 76 Union premium as well. (not at a NHRA race with that mix).If you ever saw an engine that had been run on propane, valve seat erosion is a problem on such a dry fuel.I've seen the Marvel Mystery Oil treatment, it may become the new norm around here.

02-22-2015, 07:37 PM	#4
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,110 Likes: 164 Liked 646 Times in 207 Posts	Re: Cylinder Head Issues Well, seems like we're not alone. I talked to a racer with a 305 '85 Camaro, he had the same problem affect one set of his heads. They are touching the valve seats, repairing the pitting, and going back together with whatever they need. Seems that the practice of lubing the engine with Marvel oil or ATF is going to be a new practice. Ever see a light rust haze on cylinder walls when opening up an engine ?

02-22-2015, 09:52 PM	#5
Kevin Panzino Senior Member Join Date: Oct 2002 Location: Pittsburgh Posts: 520 Likes: 245 Liked 550 Times in 106 Posts	Re: Cylinder Head Issues I too always wondered about C11... The residuals from combustion seem to be terribly hygroscopic.... I've seen rust on almost every part post-combustion, but nothing on the intake side... Its not the fuel itself, it appears to be after its burned.... If I know I'm not going to run the car for a while, when I pull it in the garage, I open the hood, then kill the fuel pump and work the throttle on the carb while I spray in the oil, and keep the Revs up until the float bowl is dry and the engine dies. This has alleviated all of the issues. The white smoke and odor of this operation wafting up through the house is not at all appreciated by the wife however.... Last edited by Kevin Panzino; 02-22-2015 at 09:55 PM.

02-23-2015, 08:16 AM	#6
terry1 Member Join Date: Sep 2006 Location: Moncton, N.B. Posts: 276 Likes: 24 Liked 24 Times in 13 Posts	Re: Cylinder Head Issues Not to hi-jack the thread,but, is it common practice to turn off the fuel pump when fogging the engine? Also the "mystery" oil is a MYSTERY to me up here in the white north. I can get a "fogging" oil from a lot of suppliers but not mystery oil!!!!

02-23-2015, 08:39 AM	#7
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,274 Likes: 1,632 Liked 9,434 Times in 1,952 Posts	Re: Cylinder Head Issues I fog the engine down at the end of the race. __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817

02-23-2015, 09:08 AM	#8
Rsmith38 Member Join Date: Mar 2011 Posts: 186 Likes: 0 Liked 28 Times in 15 Posts	Re: Cylinder Head Issues Google Marvel Mystery oil for info. This has been used for many years - on the dragster we pulled the plugs and used a squirt bottle to oil the cyls, then turned over by hand. I remember Dave L. on his ramp truck fogging the Camaro after loading to head home.

02-23-2015, 06:18 PM	#9
Mike Semeniuk Junior Member Join Date: Aug 2004 Location: Sherwood Park, Alberta Posts: 99 Likes: 19 Liked 6 Times in 2 Posts	Re: Cylinder Head Issues Terry, Canadian Tire did sell Marvel Mystery Oil out here in the west not sure if they still do. There is also a CRC aerosol product the motorcycle guys use but then you would have to pull plugs and spray the cylinders. Might need to go south and buy a couple of cases of Marvel. I bought 3 cases 6 years ago and only have one can left. __________________ Mike Semeniuk 632 GTMA

02-23-2015, 07:56 PM	#10
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,275 Likes: 25 Liked 510 Times in 200 Posts	Re: Cylinder Head Issues Cast iron rusts very quickly and always has. Your headers allow moisture/condensation to get in their especially when the exhaust valve is off it's seat. Hold the carb wide open after a race and use MMO or ATF or WD-40 and crank the engine over to draw the stuff in past the carb. I used to use a rag to absorb the gas from the carb accelerator pump. Stuff rags in your open headers or find a plastic cap that fits.. Plastic Caps from various pipes might work....they protect the threads on new pipe and once you have the right size.....they work perfect.... Exhaust seat/valve rust was always a problem..... __________________ Rich Biebel S/C 1479