1966 Corvette Big Block 427/425

[Robert W.]

I have a 1966 Big Block 427/425. When I fill it with 5 quarts of oil ( the correct amount without a filter change) the dip stick shows it being a quart over filled. The engine is a correct 427 corvette motor however, it is a re-stamp. The 425 hp takes 5 quarts of oil without a filter change whereas the 390 hp takes 4 quarts without a filter change. Since I don't have the history on the car I don't know if the re-stamped motor was a 425 hp or 390 hp. Nor do I know if the dip stick is incorrect. The dip stick is not numbered, therefore I assume its a reproduction. There were also two dip sticks for 1966 big blocks, 17 13/32" and 18 1/8". Looking for some help here. Can someone tell me the length of their dipstick for a 427/425 hp? The shorter dipstick would read correctly. Or, give me the measurement of the deepest part of their oil pan. I am assuming the 390 hp oil pan is smaller since it takes one quart less oil. Thanks in advance. Sorry for the long message.

[Wayne L.]

Re: 1966 Corvette Big Block 427/425

Also check the dimensions of your oil pan with the dimensions in the TIM & JG. Many replacement pans are shallower (less deep) the the original big block pan, which gives the "over-full" reading on the dip stick.

[Joe L.]

Re: 1966 Corvette Big Block 427/425

I have a 1966 Big Block 427/425. When I fill it with 5 quarts of oil ( the correct amount without a filter change) the dip stick shows it being a quart over filled. The engine is a correct 427 corvette motor however, it is a re-stamp. The 425 hp takes 5 quarts of oil without a filter change whereas the 390 hp takes 4 quarts without a filter change. Since I don't have the history on the car I don't know if the re-stamped motor was a 425 hp or 390 hp. Nor do I know if the dip stick is incorrect. The dip stick is not numbered, therefore I assume its a reproduction. There were also two dip sticks for 1966 big blocks, 17 13/32" and 18 1/8". Looking for some help here. Can someone tell me the length of their dipstick for a 427/425 hp? The shorter dipstick would read correctly. Or, give me the measurement of the deepest part of their oil pan. I am assuming the 390 hp oil pan is smaller since it takes one quart less oil. Thanks in advance. Sorry for the long message.

Robert------


There are several things that could affect your situation. These are whether the oil pan, oil dipstick tube, and oil dipstick are the correct ones for your application.

First of all, all 1965-74 Corvette big blocks used oil pans of the same configuration and capacity. It did not matter if the engine was a 1974 LS-4 or a 1969 ZL-1 or a 1966 L-72. However, other incorrect oil pans have found their way onto Corvettes over the years. You may or may not have one of these.

There were differences in dipsticks and dipstick tubes over the years, though. The 1966 Corvette big block dipstick was GM #3860316. This dipstick was 17-13/32" from the seat to the "full" mark and 18-1/8" from the seat to the "add" mark. The tube was GM #3870324 but I don't have dimensions on it.

[Robert W.]

Re: 1966 Corvette Big Block 427/425

Thank you Joe.

Robert------


There are several things that could affect your situation. These are whether the oil pan, oil dipstick tube, and oil dipstick are the correct ones for your application.

First of all, all 1965-74 Corvette big blocks used oil pans of the same configuration and capacity. It did not matter if the engine was a 1974 LS-4 or a 1969 ZL-1 or a 1966 L-72. However, other incorrect oil pans have found their way onto Corvettes over the years. You may or may not have one of these.

There were differences in dipsticks and dipstick tubes over the years, though. The 1966 Corvette big block dipstick was GM #3860316. This dipstick was 17-13/32" from the seat to the "full" mark and 18-1/8" from the seat to the "add" mark. The tube was GM #3870324 but I don't have dimensions on it.

[Robert W.]

Re: 1966 Corvette Big Block 427/425

Thank you Joe.

[Donald A.]

Re: 1966 Corvette Big Block 427/425

Interesting. My 70 LS-5 takes 5 qt without filter and 6 with filter change. I do use the larger capacity oil filter.

[Edward B.]

Re: 1966 Corvette Big Block 427/425

Robert, I posted a few pictures of the most common big block oil pans on the Corvette Forum site. You might be able to figure out what you have comparing your pan to the pictures.

HERE'S THE LINK (Scroll down to the number 5 post)

Ed