1967 L79 Oil pan

[William B.]

Was looking in archives for info on correct oil an for a 67 327/350. Several emphatic posts about what is not correct so I got that....never a 6 qt. But, what is the part number for the correct oil pan? Could not find that in the posts in archives. Thanks

[David L.]

Re: 1967 L79 Oil pan

GM # 3820000 in Gr. 1.426.
This was a 5-qt. pan used on 1963-1974 Corvettes. It was discontinued and replaced with GM # 360866 which is similar in shape but uses the "thick" (0.41") front rubber seal.

All factory SBC oil pans made in 1974 and prior use the "thin" (0.22") front rubber seal. The 1975 and newer pans use the "thick" (0.41") front rubber seal.

The 63-65 Corvettes 327 w/SHP, FI used the 3820001 oil pan (6 qts.) which was discontinued in June 1970 and replaced with GM # 3956670 ("thin" front seal) which was then replaced with GM # 359942 ("thick" front seal).

[William B.]

Re: 1967 L79 Oil pan

Thanks David. Much appreciated.

[Michael H.]

Re: 1967 L79 Oil pan

GM # 3820000 in Gr. 1.426.
This was a 5-qt. pan used on 1963-1974 Corvettes. It was discontinued and replaced with GM # 360866 which is similar in shape but uses the "thick" (0.41") front rubber seal.

All factory SBC oil pans made in 1974 and prior use the "thin" (0.22") front rubber seal. The 1975 and newer pans use the "thick" (0.41") front rubber seal.

The 63-65 Corvettes 327 w/SHP, FI used the 3820001 oil pan (6 qts.) which was discontinued in June 1970 and replaced with GM # 3956670 ("thin" front seal) which was then replaced with GM # 359942 ("thick" front seal).

Dave,

How do you tell the difference between the two oil pans besides some kind of measurement ? The reason I'm asking is I have an oil leak between my original timing chain cover and my oil pan ( don't know if my oil pan is original or not ) so I'm trying to figure out if I should be using the thicker front seal to stop the leak, any thoughts ? I don't know what's been done to the engine over the years but I think its been rebuilt and the harmonic balancer has been replaced with a non-fin unit.

Mike

[John H.]

Re: 1967 L79 Oil pan

Dave,

How do you tell the difference between the two oil pans besides some kind of measurement ? The reason I'm asking is I have an oil leak between my original timing chain cover and my oil pan ( don't know if my oil pan is original or not ) so I'm trying to figure out if I should be using the thicker front seal to stop the leak, any thoughts ? I don't know what's been done to the engine over the years but I think its been rebuilt and the harmonic balancer has been replaced with a non-fin unit.

Mike

Mike -

You have to measure the front seal radius on the pan - there's no other way. With no gasket on the pan, either use a straightedge across the top of the opening or flip the pan upside-down on a flat surface and measure the distance from the flat surface to the seal surface on the pan. If it's 2-1/4", it takes the "thin" front seal; if it's 2-3/8", it takes the "thick" front seal.

[David L.]

Re: 1967 L79 Oil pan

John,

I found the front radius on the 75 & newer oil pans with the "thick" gasket (0.41" as per the parts catalog) to be 2 7/16" (2.44").
2.44" - 0.41" = 2.03"

The front radius for the 74 & older oil pans with the thin gasket (0.22" as per the parts catalog) is 2 1/4" (2.25").
2.25" - 0.22" = 2.03".

Mathematically it all works out.

Dave

[David L.]

Re: 1967 L79 Oil pan

Dave,

How do you tell the difference between the two oil pans besides some kind of measurement ? The reason I'm asking is I have an oil leak between my original timing chain cover and my oil pan ( don't know if my oil pan is original or not ) so I'm trying to figure out if I should be using the thicker front seal to stop the leak, any thoughts ? I don't know what's been done to the engine over the years but I think its been rebuilt and the harmonic balancer has been replaced with a non-fin unit.

Mike

Mike,
If you were using the 75+ oil pan with the 74- "thin" gasket I think the oil would be pouring out. The leak may be caused by a worn out timing cover seal along with a wear groove on the harmonic balancer shaft. This is common on engines with a lot of mileage. This repair is quite easy. It just take a little time.
Dave

[Michael H.]

Re: 1967 L79 Oil pan

Mike,
If you were using the 75+ oil pan with the 74- "thin" gasket I think the oil would be pouring out. The leak may be caused by a worn out timing cover seal along with a wear groove on the harmonic balancer shaft. This is common on engines with a lot of mileage. This repair is quite easy. It just take a little time.
Dave

Thank you all for your inputs I'll pull the pan and do some measuring. The leak is a slight drip and I need to change the oil pump as someone installed a high pressure pump which is pegging my oil pressure gauge and maybe contrubuting to my oil leak.

Mike

[Joe L.]

Re: 1967 L79 Oil pan

Thank you all for your inputs I'll pull the pan and do some measuring. The leak is a slight drip and I need to change the oil pump as someone installed a high pressure pump which is pegging my oil pressure gauge and maybe contrubuting to my oil leak.

Mike

Mike------

Assuming the pump is just a high pressure and not also a high volume pump ( standard and high pressure pumps have 1.3" long gears and high volume/high pressure pumps have 1.5" long gears; all high volume pumps are also high pressure pumps, but all high pressure pumps are not necessarily high volume), you don't necessarily need to replace the pump. All you need to do is replace the pressure relief spring. A GM #3814903 is all you need. About 5 bucks, GM list.

[Michael H.]

Re: 1967 L79 Oil pan

Mike------

Assuming the pump is just a high pressure and not also a high volume pump ( standard and high pressure pumps have 1.3" long gears and high volume/high pressure pumps have 1.5" long gears; all high volume pumps are also high pressure pumps, but all high pressure pumps are not necessarily high volume), you don't necessarily need to replace the pump. All you need to do is replace the pressure relief spring. A GM #3814903 is all you need. About 5 bucks, GM list.

Joe,

Thank you for the information, I'll stop by GM and order one on Monday.

Mike

[Joe L.]

Re: 1967 L79 Oil pan

Joe,

Thank you for the information, I'll stop by GM and order one on Monday.

Mike

Mike------


Do confirm that it's not a high volume pump, though. If it is a high volume, I'd recommend changing the whole pump to a standard volume. Most likely, though, it will just be a standard volume, high pressure.

You can check this easily by simply measuring the length of the gears as I described. This is easy to do. First, remove the oil pump from the engine. It's easy; just one bolt retains it to the rear main cap. Then, simply remove the oil pump cover and the gears will drop out. You can inspect them at the same time to ensure that no damage or wear is evident. Check the inside surface of the cover, too, for significant wear or damage.

If all is well, then remove the pressure relieve spring. This is easy too. Just pull the small pin on the cover that retains the spring and valve assembly. Swap out the spring and re-install everything just as you otherwise found it. Then, re-install the cover and install the pump on the engine. You'll need to make sure the slot in the oil pump drive shaft aligns with the blade on the intermediate shaft in the engine. If you have the type of intermediate shaft that uses a nylon coupler, replace the coupler. It's GM #3764554. About 2 bucks.

There's another advantage if you're able to re-use the pump and simply install a new pressure relief spring: you won't have to install and adjust a new oil screen and pick-up assembly in a new pump. That's usually the most difficult part of installing an oil pump.

[Michael H.]

Re: 1967 L79 Oil pan

Mike------


Do confirm that it's not a high volume pump, though. If it is a high volume, I'd recommend changing the whole pump to a standard volume. Most likely, though, it will just be a standard volume, high pressure.

You can check this easily by simply measuring the length of the gears as I described. This is easy to do. First, remove the oil pump from the engine. It's easy; just one bolt retains it to the rear main cap. Then, simply remove the oil pump cover and the gears will drop out. You can inspect them at the same time to ensure that no damage or wear is evident. Check the inside surface of the cover, too, for significant wear or damage.

If all is well, then remove the pressure relieve spring. This is easy too. Just pull the small pin on the cover that retains the spring and valve assembly. Swap out the spring and re-install everything just as you otherwise found it. Then, re-install the cover and install the pump on the engine. You'll need to make sure the slot in the oil pump drive shaft aligns with the blade on the intermediate shaft in the engine. If you have the type of intermediate shaft that uses a nylon coupler, replace the coupler. It's GM #3764554. About 2 bucks.

There's another advantage if you're able to re-use the pump and simply install a new pressure relief spring: you won't have to install and adjust a new oil screen and pick-up assembly in a new pump. That's usually the most difficult part of installing an oil pump.

Joe.

Thank you for the great information I'll try it and see how it goes.

Mike