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I've changed the oilpump today ( one part i forgot to change after changing the cam)
And ran into some trouble. I know the oil pump tube is a press fit in the oil pump itself, but im pretty sure mine is just too big to fit.
The pump I had was the standard ( high volume afaik) pump that came with goodwrench crate engines.
Bought a melling 55a as a replacement.
Don't want to get under that car again today, does anyone know if there are indeed different oil pump tube sizes ?
Guessing I'll just order a new pickup tube then, or does anyone know the drill size for the bigger one?
You can drill out just make sure everything thing is properly cleaned before you re-assemble.
It is also common practice to tack weld tube after test fit to the pan.
Because those tubes are a press fit or interference fit, I would shy away from playing with drill bits. I believe there is only a 0.002 clearance between the two parts. Just buy the correct unit and cut your losses or return it. You sure don't want that tube coming loose or disaster will strike within seconds.
Some people put a drop or two of LockTite Blue on the tube. Others tack-weld and another option is a bracket for less than $20 that holds the tube at the proper angle. It bolts to the pump using two of the four pump bolts. Look for that at Jegs.
When you adjust the tube to the angle you want on the pump, take a open-end wrench that slips over the tube and carefully tap the wrench with a hammer to force the fitment.
Last edited by HeadsU.P.; Jul 6, 2018 at 04:28 PM.
Do you dissasemble the pump to tack weld it? Wonder if the heat of the drilling would damage the spring inside.
i can get it machined, dont know how big the interferance is between the 2 pieces though. The tube measures 18.70mm diameter
Never had one welded. But rumor is, use caution because of heat damage. I believe proper procedure is to disassemble the pump if you insist on welding.
You will never get the proper tight fit drilling out the port. You would have to have a drill bit 0.002 undersized for the pickup tube to stay in tight. If it leaks, your oil pressure gauge will let you know you have to take it apart and do it over again, correctly. This is a very critical area to get it right or a sudden oil pressure loss will cost you thousands in the end!
Last edited by HeadsU.P.; Jul 6, 2018 at 04:17 PM.
I would disassemble pump then machine it. You will probably want to ream bore after drilling to maintain press fit.
Loctite is another option but a single tack weld will make sure it will never come loose. The pickup should be test fit to the
oil pan before the weld or loctite. The pump must be thoroughly cleaned after machining because you don't want the metal chips
pumped thru your engine. One tack weld (spot weld) will not effect the pump due to heat being in a small spot. My engine also has 2 bolts from the pickup
to the pump body which helps with the loctite. All the racers I know do the spot weld as cheap insurance as Heads up pointed out anything coming loose
would be catastrophic.
From: At my Bar drinking and wrenching in Lafayette Colorado
Don't drill the pump - that's stoopid. Get the right pickup screen. Chances are good if you have the 3/4" pickup that it won't fit your Corvette oil pan anyway - The Vette uses a completely different shaped, and length, pickup screen than any other Chevy, and it's available in the 5/8" tube size.
Get the right part and don't screw around. Part number is 55-S3.
55-S3 installed on a Vette engine:
The standard Chevy pickup, and most of the 3/4" pickups, are a short-style pickup:
Also, most of the 3/4" pickups are for the big block engines, and won't fit the small block oil pan anyway. This is the Melling 3/4" pickup (77-S1) for Big Block only. You can bore out your pump to hack it in, but it's not going to fit your oil pan:
The 55-S3 is the correct 5/8" diameter, and longer to clear the Vette oil pan baffles:
You're seriously considering spending 2 hours disassembling and machining the pump when you can spend $15 to buy the right part? Your time is worth less than $7.50/hr..? Just put the right parts on the engine and don't act like Bubba. And use the right tools to install it.
Ofcourse I value my time. But its not a 15$ part of you have to ship it a few thousand miles. Also makes the difference between driving today or waiting another week.
The pickup I have looks exactly like the one in the pictures, just 3/4 instead of the stock 5/8. Got a 5/8 on order.how do you set the height? Measure the pan, then measure from the block face?
Or some placticine?
my oil pan is probably what comes with the crate engines. Its my only c3 so cant compare.
A sad ending of what was supposed to be a simple swap :p
I would at least add the $15 bracket, it is good insurance, and easy to install. Relying on the press fit, could be problematic, I have seen pressed ones come off. Not immediately disastorous, but your oil pressure will drop in turns or on the brakes.
Welding is the best option. If you weld it make sure they DO NOT BRAZE IT.
Ask me how I know? A well meaning friend, with less than perfect welding skills, brazed it, pickup came off, saw a few oil pressure dips, then a KA-BANG at 140 mph on the straightaway at Summit Point in my 70 LT1. I guess 6000 rpm oil pumps don't like small pieces of brazing inside the gears. Twisted shattered the oil pump shaft into 3 pieces. Motor was otherwise OK (after a thourough R & D cleaning)
The bracket is from Jegs P/N 23620. Fits Melling 55A with a 5/8" tube. $15 + shp. Put a drop of LocTite Blue on the oil pump cover bolts and the bracket clamp bolt.
Good to go.
Last edited by HeadsU.P.; Jul 6, 2018 at 04:25 PM.
Keep in mind that Chevrolet built thousands of engines with nothing more than the press fit of the pickup keeping it in the oil pump. That said, I use a ring of blue loc-tite and then hit it in a couple places with a MIG welder, AFTER I set the height from the bottom of the pan.
I cant believe you drilled the oil pump......never in 30 years have I seen someone do it. So since it is done...here is my advice. Take it off and throw it away. Get the right part as stated above by Lars and install it. If you aerate between the pickup tube and the pump you drilled for one second.....you will cook all of the main and rod bearings at WOT.
You may drive it now......but you will be parked for a LONG time later.
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Oil pump pickup tube sizes?
Twisted shattered the oil pump shaft into 3 pieces. Motor was otherwise OK (after a thourough R & D cleaning)
