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Tips

1275 valve cover vent

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E

erstearns

Jedi Trainee
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Finishing up the engine and have one of the aluminum covers with the small vent hole in the cap. Anything to be gained by drilling out the cover and installaling a vent nipple and running a hose to the manifold or a vent pot?
 
There should be a flat spot on the front,left side of the valve cover. Drill and tap it for an AN fitting.Run your hose to either a catch tank or overboard. If you run to the manifold it will suck out oil that's still in the ground.
 
If you are running a stock engine with no big giant compression, 11 to 1 or more. Don't drill the hole. If you are running a 1275 be sure and vent the timing cover vent can to a catch can. I vent the timing cover to a small can mounted on the firewall above the engine. (Actually I use a remote brake reservoir) and run the tube from the bottom of the can on the firewall to the vent can on the timing cover. That way any oil that comes out as vapor drains back to the engine. I stick a small bit of fuel cell foam in the upper can to act as a filter too. Also you need to put a 5/16' hole in the lid of the catch can on the firewall to allow things to breathe. I use this setup on all my racecars. Some of them run 14 to 1 or a little more. I use the vent on the valve cover and the timing cover in the racing stuff.
 
Vented cap is more than enough from the valve cover on street engine, as long as you using the timing cover and/or direct crankcase vent. The A series engine does have alot of room to get crankcase pressure up to head, especially the 1275, the pushord holes being the only source, and it is pretty occupied by other components blocking crankcase gases.

If you seriously vent the valve cover, you better have a good baffle, and for darn sure if you pulling vacuum off the carbs, which I was never a fan of. MGAs for example have a vent tube on the stock valve cover directly above one of the rocker arms, and it always been a issue with them pumping oil out there, so when I build a MGA motor I make a baffle in the valve cover to stop that issue.
 
Thanks, I think the only work done to the engine is a mild street cam. Will use only the vented cap and run the timing cover vent to a pot.
 
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