Lower Dip Stick Tube Length
Guys, this past Wednesday evening with the help of a buddy of mine, we managed to crank the 265 engine for my '56 Corvette for the first time since being rebuilt. I only ran it for a couple of minutes as the body and radiator are not yet in place. I later checked the oil level to find it measuring a quart low. I had added 5 quarts to the system at the start. I added an additional 1/2 quart and ran it again for about 2 minutes. The dip stick still shows a quart low. I have the correct oil pan, oil filter canister, oil dip stick, and upper dip stick tube. The dip stick and tube are from Paragon. I was told by one source that my problem might be with the lower dip stick tube or lack thereof. I have since removed the upper dip stick tube and see that there is a lower tube in place. When I installed the oil pan there was no tube protruding beyond the block in what would be the crankcase. My question is should there be? If there is supposed to be a tube in that area, apparently mine has been broken or cut off. Does anyone have a suggestion for removal of the lower dip stick tube without removing the oil pan? I hope that some of you engine builders can chime in on my post and help me with this dilemma. Thanks in advance! Brooks Glover (2141)
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Re: Lower Dip Stick Tube Length
Brooks,
Lower dip stick tube in the block is 7 3/4" long. Upper tube fits into at the block. Not sure how the lower tube being short would impact what the dip stick reads. Dip stick is 19.48 from full to washer and 20.43 from add to washer. Upper tube for '56 2nd design is 8 3/4" long per 56 P&A.
Gary
....NCRS Texas Chapter
https://www.ncrstexas.org/
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Re: Lower Dip Stick Tube Length
Brooks----
To remove the lower dipstick tube without removing the oil pan do this: remove the upper dipstick tube. Find a self tapping screw that will lightly tap itself into the bore of the lower dipstick tube. Using the screw, pull the tube out. If this does not work, you'll need to remove the pan. However, it should work.In Appreciation of John HinckleyComment
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Re: Lower Dip Stick Tube Length
Gary and Joe, thanks for your reply to my dilemma with the lower dip stick tube. As to the oil level, what has been told to me is that the lower dip stick tube determines at what angle the dip stick will enter the crank case to measure the oil level. The same source also told me that it would also keep the dip stick from being hit by moving parts (crankshaft). It makes sense to me but I really don't know. I am still wondering if the lower dip stick tube protrudes into the crankcase or is it flush with the bottom of the engine block where the oil pan bolts on? Thanks in advance for your input! Brooks Glover (2141)Comment
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Re: Lower Dip Stick Tube Length
Brooks, tube is straight. Measure 7 3/4" down from the outside of the block and you'll see that it extends into the pan. Makes sense that it was keep it straight and away from moving parts. Gary....Last edited by Gary C.; September 20, 2010, 09:19 AM.NCRS Texas Chapter
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Re: Lower Dip Stick Tube Length
The lower dipstick tube does not ensure that the dipstick enters the oil normal to its upper surface. The lower tube continues the same angle that the upper tube is to the oil's surface, which is approximately 60 degrees. The lower tube is a straight extension of the upper tube. The tube protrudes into the crankcase to a point that is below the windage tray (if used).
If you are absolutely certain that your oil pan and oil filter are of the same fluid capacity as original, then I suggest that you fill the crankcase with the prescribed amount of oil and then run the engine until warm. Shut off and wait a couple minutes before checking the oil level. Dipstick tubes are not always accurate, and need to be trimmed. Usually less than 1/4", BUT NEVER TO THE EXTENT THAT IT READS ONE QUART OVERFULL.
If your friend converted the engine for use of a spin on filter, then that will affect the oil level by as much as 1 pint, depending on the size of the filter.Last edited by Joe C.; September 20, 2010, 09:49 AM.Comment
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Re: Lower Dip Stick Tube Length
Joe C., thanks for your reply to my post. I talked to the fellow who built the short block this afternoon and he told me that he did not install a lower dip stick tube. I don't know if the one in my engine block was cut or broken off. I am going to make an attempt using a self tapping screw to extract it. If that does not work, I will have to remove the oil pan and use a metal rod to drive it out. At this point I feel sure that this is why the oil level is showing to be low in spite of having 5 1/2 quarts in the crank case. I am waiting to hear from one of my Corvette buddies to see if he has a lower dip stick tube in his stash of parts that I can measure to see what size screw will work. I will let everyone know how I come out. I find it rather strange that 2 books I have that deal with rebuilding a chevy engine don't say a word about the lower dip stick tube. Thanks to everyone for your input. Wish me good luck! Brooks Glover (2141)Comment
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Re: Lower Dip Stick Tube Length
ok, is this required if the drft pan is used?David DawdyComment
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In Appreciation of John HinckleyComment
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Re: Lower Dip Stick Tube Length
I am not certain of this, but I believe that the lower tube was not used unless the engine application calls for a windage tray. The reasoning being that the lower tube ensures that the dipstick does not get fouled on the windage tray (which was a small hole which the lower tube goes through). If there is no windage tray, the dipstick has a clear passage all the way until it bottoms, with no danger of becoming snared on any internal parts.
The broken or missing lower tube that you envision will not cause the false reading that you are experiencing. The lower tube is inserted first, and is simply dropped in through the top. Its "lip" rests on the step in the block. IT IS NOT A PRESS/INTERFERENCE FIT...............it simply lays on top of the step in the engine block. The thickness of the "lip" is about 3/32". The upper dipstick tube is then driven into the same hole, from above. It bottoms against the "lip" of the lower tube, which is resting on the step in the block. The pressed-in upper tube is what holds the lower tube in place.Last edited by Joe C.; September 20, 2010, 11:36 PM.Comment
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Re: Lower Dip Stick Tube Length
Joe------
The lower tube was used on all small blocks from 1956 onward, regardless of whether they used an external baffle (windage tray), or not.
The lower tube ensures that the dipstick is "supported" and prevented from bending once inserted. Without the lower tube, there would be a more-or-less "willowy" dipstick which might contact other rotating parts and also provide an inaccurate level of oil in the pan. Note that the lower tube "supports" the dipstick almost to the "full" mark in most small block engine configurations.
By the way, I should have mentioned that while the lower dipstick tube was used for all Corvette small blocks through 1979, it was not used on all other small blocks. For other Chevrolet cars and light trucks, it was used for most, but not all.In Appreciation of John HinckleyComment
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Re: Lower Dip Stick Tube Length
Brooks;
I know this seems like an obvious question, but did you measure your dipstick. The P&A manual says 21 9/16 inches from washer to end of dipstick.
I measured the dipstick in my 56, and that is what I got.
Also, what is the measurement on your upper dipstick tube?Comment
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Re: Lower Dip Stick Tube Length
Ed, sorry it has taken me a while to get back to you. I have been working outside. I did measure the dipstick and it is the same as yours, 19 9/16 in. I am about to go out to find a 5/16 self-tapping screw and try to extract the lower dip stick tube. I will let you know how it goes. Wish me good luck! Brooks Glover (2141)Comment
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