Changing 67 oil pan. Must I change oil pump too?

[Louie M.]

I autocross my 67 327/350 roadster a lot, so when I redo the engine this fall/winter I'll swap the stock oil pan to a 63-65 FI pan with an extra quart of capacity (up to 5 quarts in the pan) and a cool little trap door. As far as I know, the depths of the two pans are the same, and they differ only in length.

My car has its stock oil pump, which is a different item than listed for a 63-65 FI car. Since the two pans mentioned above differ only in length (presumably), what is different between the stock 67 and 63-65 FI pumps? Is it really necessary to swap oil pumps when I swap pans?

[William C.]

Re: Changing 67 oil pan. Must I change oil pump too?

Same length, just a different spring on the pressure relief.

[Joe L.]

Re: Changing 67 oil pan. Must I change oil pump too?

I autocross my 67 327/350 roadster a lot, so when I redo the engine this fall/winter I'll swap the stock oil pan to a 63-65 FI pan with an extra quart of capacity (up to 5 quarts in the pan) and a cool little trap door. As far as I know, the depths of the two pans are the same, and they differ only in length.

My car has its stock oil pump, which is a different item than listed for a 63-65 FI car. Since the two pans mentioned above differ only in length (presumably), what is different between the stock 67 and 63-65 FI pumps? Is it really necessary to swap oil pumps when I swap pans?

Louie-----

Depending upon what oil pan is on the car now, you may have to change the oil pump pick-up screen, though. If you have a stock 1963-74 "5 quart" oil pan, then you do not need to change the pick-up screen when you change to the "6 quart" pan.. If you currently have just about any other Chevrolet small block oil pan, then you will need to change the pick-up screen.

[Louie M.]

Re: Changing 67 oil pan. Must I change oil pump too?

Joe,
I won't know until the pan comes off which pan is on the engine. The past owner(s) messed up quite a few details, so maybe the swapped the pan along the way.

Currently the oil gauge is always at max pressure at normal cruising speeds, so the spring in the relief valve may be shimmed too much. The instrument cluster was rebuilt by Corv. Spec. of MD, so presumably the gauge is OK. Is it advisable to put in a new oil pump when I redo the engine?

Louie-----

Depending upon what oil pan is on the car now, you may have to change the oil pump pick-up screen, though. If you have a stock 1963-74 "5 quart" oil pan, then you do not need to change the pick-up screen when you change to the "6 quart" pan.. If you currently have just about any other Chevrolet small block oil pan, then you will need to change the pick-up screen.

[Duke W.]

Re: Changing 67 oil pan. Must I change oil pump too?

Like Bill said all C2 SBs use the same basic pump/pickup, but the pressure relief spring was changed to yield 55-60 psi on mechanical lifter engines beginning in late '63 and this carried through on C2 mechanical lifter SBs to '65.

It's never been clear to me why this change was made as earlier mechanical lifter engines, including my '63 L-76 came to no harm with the "standard" 40-45 psi relief spring including a few hundred miles of race track hot lapping, but it may have come from the experience of SCCA racers.

It's tough to watch the gages during autocross, but you should try to establish a current baseline before you go through the engine. Try to watch the gage in corners and on braking. Any "dithering" of the needle could indicate air pickup due to the pump inlet being uncovered.

The big pan/windage tray certainly will provide better pickup coverage under high dynamic chassis loading, and back before SCCA allowed dry sumps it was a common "racer trick" to run the system a quart over - 7 quarts total.

Up to the point of the pressure relief valve opening, pump delivery volume is a function of the pump's constant volume characterisitics. As pump delivery increases with increasing pump speed, pressure builds up due to the restriction of the various clearances like bearings. Once pressure reaches the relief value, excess volume is shorted back into the pump inlet, and at that point oil delivery to the main gallery is essentially constant and determined by pressure.

So the higher the pressure, the higher the oil delivery rate to the main gallery and the rate of drain back to the pan determines remaining pan volume.

Data I've seen indicates that a SB has two to three quarts of oil up in the engine at high revs, so if static pan capacity is 5 quarts only two to three quarts remain in the pan and dynamic forces can slosh this around, potentially uncovering the pickup.

Adding an extra quart to the nominal pan capacity can make a big difference in whether or not the oil pickup uncovers and draws air during spirited driving.

Duke

[Michael H.]

Re: Changing 67 oil pan. Must I change oil pump too?

Joe,
I won't know until the pan comes off which pan is on the engine. The past owner(s) messed up quite a few details, so maybe the swapped the pan along the way.

Currently the oil gauge is always at max pressure at normal cruising speeds, so the spring in the relief valve may be shimmed too much. The instrument cluster was rebuilt by Corv. Spec. of MD, so presumably the gauge is OK. Is it advisable to put in a new oil pump when I redo the engine?

Louie,

One more item besides what others have mentioned is, if you are switching to the 5 quart pan from a four quart pan, you should also purchase and install the matching baffle/windage tray designed to be used with that application.
The 4 quart pan has a small baffle built in but the 5 quart pan is different and requires a separate baffle. Without it, it's worse than the 4 quart pan for racing, especially under hard braking.
Installation of the baffle will also require special main cap studs for mounting.
I don't have the part numbers of these items handy and I don't know of their availability but I'm sure Joe can help you on that part.

[Louie M.]

Re: Changing 67 oil pan. Must I change oil pump too?

Michael,
Thanks for the reminder. I had the chance to buy a pan yesterday and also ordered the matching baffle/windage tray. I realize that special studs will be needed to mount the baffle, but don't know which ones at the moment. That purchase will be next.

Louie,

One more item besides what others have mentioned is, if you are switching to the 5 quart pan from a four quart pan, you should also purchase and install the matching baffle/windage tray designed to be used with that application.
The 4 quart pan has a small baffle built in but the 5 quart pan is different and requires a separate baffle. Without it, it's worse than the 4 quart pan for racing, especially under hard braking.
Installation of the baffle will also require special main cap studs for mounting.
I don't have the part numbers of these items handy and I don't know of their availability but I'm sure Joe can help you on that part.

[Joe L.]

Re: Changing 67 oil pan. Must I change oil pump too?

Joe,
I won't know until the pan comes off which pan is on the engine. The past owner(s) messed up quite a few details, so maybe the swapped the pan along the way.

Currently the oil gauge is always at max pressure at normal cruising speeds, so the spring in the relief valve may be shimmed too much. The instrument cluster was rebuilt by Corv. Spec. of MD, so presumably the gauge is OK. Is it advisable to put in a new oil pump when I redo the engine?

Louie-----


If it was me, I'd replace the oil pump. They are not that expensive and they are a CRITICAL component. If the existing pump happens to be a high volume pump (i.e. gears are 1.5" long rather than 1.2" long for standard volume), then I'd DEFINITELY replace it.

As Duke mentions, I don't really know that the high pressure pump is absolutely necessary. However, GM did use them for virtually all solid lifter small blocks, so I'd go with the high pressure pump.

As I recall, you were able to find an NOS external baffle, GM #3769768, or a reproduction thereof for the "6 quart" oil pan you got?

[Louie M.]

Re: Changing 67 oil pan. Must I change oil pump too?

Duke,
As far as watching the oil gauge while autocrossing, I have enough trouble finding apexes as it is!! I might have someone else drive while I watch the gauge .... someone who already autocrosses a 66 and will be familiar with the vintage handling.

Adding a quart seems like a good idea on race days. Is it OK to leave that much oil in the pan all the time? Seems like it would be OK on the street if it's OK on the course.

What do you think of replacing (or not) the oil pump at rebuild time? It seems like a basically OK idea, since I would for sure know what kind of pump I had down there.

Like Bill said all C2 SBs use the same basic pump/pickup, but the pressure relief spring was changed to yield 55-60 psi on mechanical lifter engines beginning in late '63 and this carried through on C2 mechanical lifter SBs to '65.

It's never been clear to me why this change was made as earlier mechanical lifter engines, including my '63 L-76 came to no harm with the "standard" 40-45 psi relief spring including a few hundred miles of race track hot lapping, but it may have come from the experience of SCCA racers.

It's tough to watch the gages during autocross, but you should try to establish a current baseline before you go through the engine. Try to watch the gage in corners and on braking. Any "dithering" of the needle could indicate air pickup due to the pump inlet being uncovered.

The big pan/windage tray certainly will provide better pickup coverage under high dynamic chassis loading, and back before SCCA allowed dry sumps it was a common "racer trick" to run the system a quart over - 7 quarts total.

Up to the point of the pressure relief valve opening, pump delivery volume is a function of the pump's constant volume characterisitics. As pump delivery increases with increasing pump speed, pressure builds up due to the restriction of the various clearances like bearings. Once pressure reaches the relief value, excess volume is shorted back into the pump inlet, and at that point oil delivery to the main gallery is essentially constant and determined by pressure.

So the higher the pressure, the higher the oil delivery rate to the main gallery and the rate of drain back to the pan determines remaining pan volume.

Data I've seen indicates that a SB has two to three quarts of oil up in the engine at high revs, so if static pan capacity is 5 quarts only two to three quarts remain in the pan and dynamic forces can slosh this around, potentially uncovering the pickup.

Adding an extra quart to the nominal pan capacity can make a big difference in whether or not the oil pickup uncovers and draws air during spirited driving.

Duke

[Louie M.]

Re: Changing 67 oil pan. Must I change oil pump too?

Joe,
OK I'll replace the pump ... for $100 why not? I was only concerned about new pumps if they came from overseas and were known to be poor quality.

I got both an NOS "service replacement" pan and matching NOS baffle, so mark me down as a happy camper.

Louie-----


If it was me, I'd replace the oil pump. They are not that expensive and they are a CRITICAL component. If the existing pump happens to be a high volume pump (i.e. gears are 1.5" long rather than 1.2" long for standard volume), then I'd DEFINITELY replace it.

As Duke mentions, I don't really know that the high pressure pump is absolutely necessary. However, GM did use them for virtually all solid lifter small blocks, so I'd go with the high pressure pump.

As I recall, you were able to find an NOS external baffle, GM #3769768, or a reproduction thereof for the "6 quart" oil pan you got?

[Joe L.]

Re: Changing 67 oil pan. Must I change oil pump too?

Michael,
Thanks for the reminder. I had the chance to buy a pan yesterday and also ordered the matching baffle/windage tray. I realize that special studs will be needed to mount the baffle, but don't know which ones at the moment. That purchase will be next.

Louie-----


It's not too difficult to determine which studs you need. If you have a 1963-67 block, then you need studs GM #3872718. If you have a 1968 or later block, then you need studs GM #14087508.

So, how do you tell which block you have? Well, if it has a SEVEN DIGIT casting number beginning with "37" or "38", then it's a 1967 or earlier block. Such a block will also have a canister style oil filter.

If it has a SEVEN DIGIT block casting number beginning with "39" or ANY SIX or EIGHT DIGIT casting number, then it's a 1968 or later block. Such a block will also have a spin-on style oil filter. There are a few minor exceptions to the 68 and later "rule", but they're not worth getting into since they're extremely unlikely.

[Duke W.]

Re: Changing 67 oil pan. Must I change oil pump too?

Oil pumps are easy to inspect, and I see no need to replace an OE pump if it passes inspection as mine did. The inspection process is in the "Special 300 HP" technical support paper.

"Blueprinting" the pump, an easy job, is discussed in that same paper and in How to Hot Rod SB Chevys".

At 115K miles my OE oil pump passed inspection with flying colors, so I blueprinted it, brazed the pickup to the pump body, and reinstalled it.

Most "engine builders" don't want to take the time to inspect anything. They just replace stuff apriori and charge you for the parts.

The hundreds of dollars you save by not replacing serviceable parts can be put into head massaging, which is where virtually all of the power gain come from.

At 115K miles literally everthing inside my engine was fully serviceable and could have been reused. There was no measureable bearing or cam/valvetrain wear, but I went ahead and replaced the bearings, cam and lifters, and had the valve guides rebuilt.

The ONLY real wear inside my engine (nothwithstandign the badly cracked #7 conrod) was in the cylinder bores - a couple had .005" taper at the top and the rest had .003" so rebore and new pistons were required.

I attribute most the this wear to the sh...ty OE foam air filter that was on the engine for the first 60K miles, and this is why I now only recommend a modern cellulose replacement filter - only use the OE foam POS for judging and never, ever use any kind of non-cellulose aftermarket filter.

These polyurethane foam and cotton filters pass literally pounds of tiny particles over the life of the engine, which is guaranteed to wear out the cylinders long before anything else in the engine is even near the wear limit - as long as you have bulletproof conrods.

Duke

[Louie M.]

Re: Changing 67 oil pan. Must I change oil pump too?

I just went out and looked and the block casing number and it begins with "38" so I'm good. Too much grunge back there to read all of the number. My car was built in early Dec. 1966. I'll call Dr Rebuild early Monday and maybe he can throw the studs in with the rest of my order.

Thanks once again.

Louie-----


It's not too difficult to determine which studs you need. If you have a 1963-67 block, then you need studs GM #3872718. If you have a 1968 or later block, then you need studs GM #14087508.

So, how do you tell which block you have? Well, if it has a SEVEN DIGIT casting number beginning with "37" or "38", then it's a 1967 or earlier block. Such a block will also have a canister style oil filter.

If it has a SEVEN DIGIT block casting number beginning with "39" or ANY SIX or EIGHT DIGIT casting number, then it's a 1968 or later block. Such a block will also have a spin-on style oil filter. There are a few minor exceptions to the 68 and later "rule", but they're not worth getting into since they're extremely unlikely.

[Louie M.]

Re: Changing 67 oil pan. Must I change oil pump too?

Duke,
Interesting that internal engine parts last so long. When I bought my car in late 2002 the odometer showed 49,XXX miles. Once I drove it home (MI to CA) and could take things apart, I believe that is the correct number of miles. Among other things, all the brake rotors were still riveted on, and the car is quite clean overall. For whatever reason the engine got rebuilt along the way, around a year or two before I got the car. As you've seen from its dyno sheet, it did not rebuild in any primo way.

I do avoid foam air filters too; there's just no way to wash all that crud out when the time comes, seems to me; I'd rather just toss it away. Rod-wise, I have the Crower Sportsmans just begging to be installed.

Oil pumps are easy to inspect, and I see no need to replace an OE pump if it passes inspection as mine did. The inspection process is in the "Special 300 HP" technical support paper.

"Blueprinting" the pump, an easy job, is discussed in that same paper and in How to Hot Rod SB Chevys".

At 115K miles my OE oil pump passed inspection with flying colors, so I blueprinted it, brazed the pickup to the pump body, and reinstalled it.

Most "engine builders" don't want to take the time to inspect anything. They just replace stuff apriori and charge you for the parts.

The hundreds of dollars you save by not replacing serviceable parts can be put into head massaging, which is where virtually all of the power gain come from.

At 115K miles literally everthing inside my engine was fully serviceable and could have been reused. There was no measureable bearing or cam/valvetrain wear, but I went ahead and replaced the bearings, cam and lifters, and had the valve guides rebuilt.

The ONLY real wear inside my engine (nothwithstandign the badly cracked #7 conrod) was in the cylinder bores - a couple had .005" taper at the top and the rest had .003" so rebore and new pistons were required.

I attribute most the this wear to the sh...ty OE foam air filter that was on the engine for the first 60K miles, and this is why I now only recommend a modern cellulose replacement filter - only use the OE foam POS for judging and never, ever use any kind of non-cellulose aftermarket filter.

These polyurethane foam and cotton filters pass literally pounds of tiny particles over the life of the engine, which is guaranteed to wear out the cylinders long before anything else in the engine is even near the wear limit - as long as you have bulletproof conrods.

Duke