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MG MGA - Rocker box paint

The inside of my rocker box (valve cover) is quite horrible. There are places where the original paint is OK, some where it has worn off exposing blackened metal underneath, and some places where there is hard crud that will likely take the pain with it if removed.
My feeling is I should sandblast it clean and apply epoxy primer, such as PPG Omni Au. I think it would be bad to leave it unpainted, also bad not to clean it thoroughly. Any idea what was the original oil-proof paint, or any other suggestions.

Also, what does the 1/2" pipe from the cover connect to ?
Art Pearse

Do you mean the pipe that connects the valve cover to the air cleaner?
Without the hose joining the two items you will be drawing dirt into your valve gear and crankcase.


Mick
M F Anderson

Art, I would be surprised if the inside of the cover was ever painted. If the paint lifted, and I suspect it would, the paint residue would contaminate and block the oilways.
The pipe is connected to the similar pipe on the forward carb, with a short length of rubber hose. It vents the crankcase into the fuel stream.
Barry
BM Gannon

The pipe only vents fumes from the crankcase into the air cleaner while the car is stationary with the engine running, or the engine has recently stopped.
When the car is moving the draught tube on the side of the engine draws filtered air from the air filter into the valve gear, then the crankcase, then out the draught tube.


Mick
M F Anderson

Thanks for the info on the vent tube. I couldn't see any connection to the manifold.,
There definitely appears to be paint, as in the sump. Light green in colour.
Art Pearse

I'd clean it out and hit it with a scotch brite pad to get rid of the old paint. It's going to be coated in oil, so I wouldn't think paint would be necessary to prevent corrosion. Don't hot rodders paint the inside of their engine blocks to ensure the oil a faster trip back to the sump?
Mark J Michalak

Here is the paint your talking about Mike,Eastwood has it.
http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=2297&itemType=PRODUCT&RS=1&keyword=glyptal
I wouldn't bother either just clean it good.
gary starr

Art,

Don't forget the advice given by Steve Gyles in a previous post. Mount the air cleaners the correct way.
Upside down filters will block off required holes in the SU's.

See image this post and the next.

Mick


M F Anderson

Art,

Attached is an image of the corresponding holes in the SU.


Mick


M F Anderson

I have never seen the inside of a rocker box painted on any MG. As Mark says, it will get coated with oil, that's all it needs. The coating sometimes used on the inside of blocks is Glyptal, used for a smooth return path of the engine oil. This isn't necessary for our cars IMO. I think its also used on new cast blocks to keep core sand and other cast iron bits from coming off the cast surfaces and mixing with the oil circulating in the engine, which would be a bad thing of course. I doubt there's any of this happening with our 50 yr old blocks.
G Goeppner

Well, there is definitely a green coating of something in the cover and sump. I will sandblast the cover and keep it oiled.
BTW, I have 2 spare valve covers, chromed but peeling. If anyone wants them, it would be shipping only cost.
Art
Art Pearse

I have seen an MGB block that apparently had Glyptal or some equivalent applied from the factory. It was from a 1974-1/2 BGT that had extremely low miles, around 15,000 IIRC. It had somehow made it to the rural Alaskan town where I grew up, developed some mechanical trouble, and then sat in the weeds for many years until it was bought by my high school shop teacher around 1991 or so (still kicking myself for passing on it). Since it had sat for so long, he tore the engine down as a matter of course. It was amazing how clean it was inside, and consistent with the low miles on the odometer. And there was definitely this paint on the inside cast surfaces of the engine, almost certainly from the factory. He cleaned it up, and reassembled with new gaskets and rings, and did little else to it other than repainting the exterior.

Damn I wish I had bought that car.
Del Rawlins

Mick,
You refer to Steve's prvios post, what was it titled?, and do the comments apply to all air filters/carbs, or are they for specific ones?
Nigel Munford

Nigel,

I don't think that you will ever find the original post. These comments often appear in posts with quite unrelated titles.
Basically Steve said that he had problems with the way his engine ran. He found that he had the air cleaners on upside down. The photos I posted earlier in this thread show the problem. All SU's require a vent to allow air to enter the area below the piston, otherwise the suction above the piston would not be strong enough to lift the piston.
Some SU's have the vent as shown in the photos. Other SU models have different vents in other locations. You just need to be aware of the requirement for a vent somewhere.


Mick
M F Anderson

Thanks for that. The reason I asked was that I replaced my exhaust manifold earlier this week. I have done about 30 miles over the last couple of days without any trouble, but today the car has been backfiring, and not firing at all. I suspect something electrical, but as I had the carbs off the other day I thought it might be linked.
Nigel Munford

Nigel

I have mentioned the gotcha a few times. It only really applies to the rear filter and carb in the standard MGA setup as the front filter box has the vent pipe to the rocker box and will always be fitted with the pipe up wards. Mick has already posted a couple of my images. They are also on my website 'Odds & Sods' page: http://www.mgaroadster.co.uk/odds_and_sods.htm

When talking to Bob West some time ago he mentioned that a lot of his customers with 'carb' problems have the rear box on upside down! So it's quite a common error.

My original post was 'MPG Normal' on 3 may 07: http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=2007050319515324249

You will see that I had been suffering poor MPG which I guess is one of the symptons. Also, because blocking the holes delays piston movement, it means that performance, particularly accelearation, is affected. In cruise, I guess the piston will slowly take up the correct position.

Steve
Steve Gyles

This thread was discussed between 18/03/2009 and 22/03/2009

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