Oil fill tube cap
Just bought a numbers matching 64 / L76 that enjoyed a frame-off restoration in 2005, including engine rebuild. If I rotate the oil filler cap 90 degrees clockwise it will "lock", meaning it becomes snug. Rotate it another 90 degrees clockwise and it is loose and can be lifted off. Essentially it will rotate 360 degrees. Unlike a radiator cap or common gas caps my oil filler neck does not have built in stops that prevent the cap from rotating beyond the secure position - it can be rotated further - a full 360 degrees. Is this normal for the oil filler cap? Should it be able to be rotated 360 degrees or should it stop after 90 degrees? It can be removed by turning it clockwise 90 degrees from the secure (tight) position.
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Ed -
Re: Oil fill tube cap
Edward,
Is there a cork seal inside? If it is missing, that most likely is your problem.
Hope this helps,
Marco -
Re: Oil fill tube cap
Edward, If you compare an original ol filler tube with a repro you will find that the cap orientation is not the same most of the time. But NOT all of the time as I have proven in my shop. Marco mentioned cork gasket. The thickness of it is the key.
Originals typically have a hole in the center of the cork gasket-Approx 3/4-1" hole ?. But not all of them.
Repro oil caps and repro oil filler tubes drive me bonkers here.
Caution: Most of the repro oil filler tubes are too fat. If you blast them in as it you may split the aluminum baseplate/intake.
Typically (always) I will put them duct tape on them about 1-1/2" up from the bottom. Then I will grind the Chrome off, etc.
Next step is I put the oil filler tube in my freezer for a couple of hours. Then I quickly install it with a heavy dead blow hammer.
To cut a hole in the gasket I use a big piece of copper tubing that I have sharpened. I put the gasket on a piece of scrap oak and then beat on the tubing to cut the hole out.
Look for an original oil filler cap. JohnComment
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Re: Oil fill tube cap
I bought one of the oil fill tubes from CC last year. Measured .012 interference. No way. I sent it back to them. The one I bought was for a 63 FI and in addition to the interference fit, the PCV port was set 1" too low which made it a dead interference with the FI balance tube. So that tube had 2 strikes against it. I cleaned up my original and used that. But I also bought the cap, and that fit perfect and only rotates 90*, so I kept that.
I bought several repro parts at the same time last year in addition to the oil tube and cap. I converted the 375 unit to full vacuum advance and also PCV, as my engine is 1962 was not set up for PCV. I did this with many thanks to Duke for helping me understand how it was configured. All the repro parts for the PCV system fit fine. I guess I just don't understand how some repro parts are probably as good as they can get, and still others are so dead wrong I don't know they can sell them.
-Dan-Comment
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Re: Oil fill tube cap
Dan Etal, It seems that some of the repro catalogs are advertising a 63 FI oil filler tube when in fact all they stock and sell is one from a Carburetor. It's exactly as you describe. On the car the 90 degree elbow is down further on the tube. I have sent pics of NOS oil filler tubes so the various vendors can compare my pic with what they are selling.
Only so much one can do. No way will the carb tube work on an FI. The two forward balance tubes angles would be all over the place.
I have given up on this situation. Sorry. JohnComment
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Re: Oil fill tube cap
John------
GM only SERVICED 2 oil filler tubes for 1963-65 FI applications. The first was GM #3834119. This tube was uniquely applicable to 1963 with L-84. The second was GM #3846102. This tube was applicable to both L-76 and L-84. The 3834119 was discontinued without supercession in August, 1978. The 3834119 was discontinued without supercession in February, 1999.In Appreciation of John HinckleyComment
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Re: Oil fill tube cap
Okay John, that explains it, and it makes sense. But if they cannot be made to work, why do they continue to advertize them for FI? If a supplier is tooled up to make the carburetor version, then is seems to me like it would not be hard to just move the fitting for FI applications, and while they are at it, they could fix the fitment problem too. So, what do you do if you are restoring 375 unit with the oil fill tube missing or damaged beyond repair?
I was fortunate with mine. The original tube was very dirty - no problem there of course, the inside had surface rust - an overnight soak in Evaporust took care of that. The chrome had some minor pitting, but I gently scrubbed it and then waxed it. You have to look real close to see the pitting.
But the real problem was the fitting was loose in the tube - it would actually rotate. I did not see any way I could buck the inside of the tube, so I used Loctite - retaining compound. That not only solved the rotation, but it also sealed it.
Anyhow, thanks for the education and explaining this and why these things are a problem. I hear you when you say there is "only so much one can do". I'm sure your effort fell on deaf ears.
-Dan-Comment
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Re: Oil fill tube cap
Bob------
Yes, there was also the one you mention. It was GM #3831528. However, it was only available for a short time in SERVICE. It was available from the start of production until October, 1963 when it was discontinued and superceded by the GM #3834119.In Appreciation of John HinckleyComment
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