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1275 Vent Tube Question

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norcalnewb

norcalnewb

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I have recently replaced the 948 in my 62 Sprite with a 1275 from a 72 Midget. The PO of the 72 parts car I bought had been working on the car and had dismantled much of the emissions control on the car, although he was intending to put it all back on. He had replaced the SU carbs with a Weber down draft.

I have gotten rid of most of the emissions (all of it is going), and it doesn't appear I have a spot to run the crank case vent tube from the oil separator to either the Weber or the new intake manifold. Does anybody have any suggestions as to what I should do with this?
 
Jim,

You have 5 choices; one - run a tube from the timing chain cover to a catch can, two - put a filter on it with a short piece of hose to clear the fan, three - run a tube up to the side of the air filter and let the fumes be sucked back into the engine, four - weld a bung on the exhaust pipe below the manifold at an acute angle and let the exhaust draw the fumes. The only other option (5) would be to jury rig a PVC valve in the intake manifold and run a hose from the timing chain cover to it.
 
Isn't the added advantage to choice #5 that the vacuum created helps keep the oil from seeping out as you go down the road?

Walter
 
Jim, should you go the route of running the line to the exhaust as Biff suggests, make sure to install an anti backfire check valve between the oil separator and the exhaust.
Jeff
 
I believe that the exhaust vacuum method is discussed in depth in Vizard's book on tuning the A-series. He also stresses the importance of the anti-backfire valve.

Did the '72 1275 have the oil separator on the timing cover? My transverse 1275 is earlier and the connection is on the front tappet cover. Regardless of location, you can route the fumes from the oil separator to a Smiths PCV valve mounted on the intake manifold (the discharge from the Smiths goes into the intake manifold). If the engine is in good shape without too much blow-by this works fine and looks original.
 
Thanks for all the information. I will consult with Vizzard's book about the exhaust set up, as this appears to be the better option.
 
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