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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #1 ·
I am reassembling my '65 GTO's 389 (without internals), as I plan to paint the block heads, pan, timing cover, etc. then disassemble and discard the gaskets with painted edges to replace with new set when I do the final assembly of the engine. Anyway, there is a steel strap (1/2" wide) that "I believe" goes under the oil pan beneath the oil pan gasket piece that fits in the groove on the outside (curved) of the rear main bearing. The strap has tabs with holes for the rear-most oil pan bolts (which may also act as stiffers to keep the oil pan edges down at either end of the main cap. Anyway, I have a new oil pan and when I install the strap it doesn't hug the curved oil pan flange - it seems to float about 1/8" above it (larger radius). Is there some other gasket (or piece that I'm forgetting to mount) that goes between this strap and the pan? During disassembly (years ago) I did not take pics of this area, so maybe I'm installing something wrong. I'd appreciate any thoughts or suggestions.
 

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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #3 ·
betcha its the repop oil pan
I would find an original ,,,
It's a new Canter. Good baffling, bolts line-up, etc. Just can't figure out why the strap won't snug-down. I still have the original pan (but it's damaged beyond use), so I can compare the rear main cut-out and see if there is a dimensional difference. Thx, though, for the post - much appreciated.
 

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Later years used two reinforcement tabs at the rear corners of the pan. Bolts at the rear tabs are torqued to 20 ft-lbs rather than the normal 12.
They are available from your favorite vendor but may need slight grinding for a perfect fit.

The BOP one piece pan gasket fits great without all the hassle of lining up the different gaskets.


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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #6 ·
Later years used two reinforcement tabs at the rear corners of the pan. Bolts at the rear tabs are torqued to 20 ft-lbs rather than the normal 12.
They are available from your favorite vendor but may need slight grinding for a perfect fit.

The BOP one piece pan gasket fits great without all the hassle of lining up the different gaskets.

Thx Ed - great post. I recently found-out about the corner braces, and will look into the BOP one-piece gasket. Thx for the inputs.
View attachment 142648

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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #7 ·
Thx Ed - great post. I recently found-out about the corner braces, and will look into the BOP one-piece gasket. Thx for the inputs.
 

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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #8 ·
You may have issues with that pan and the center link.

Yikes! I still have the old pan. It has a major dent in the deep end, like someone set the car down on a jack stand. However, I can (before installing new pan) take a closer look, comparing all aspects of the two designs. I'm glad you told me. I thought Canter was a pretty good name, and the baffling/windage inserts in the pan impressed me. That said, I will now re-assess things ... side-by-side.
 

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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #9 ·
Yikes! I still have the old pan. It has a major dent in the deep end, like someone set the car down on a jack stand. However, I can (before installing new pan) take a closer look, comparing all aspects of the two designs. I'm glad you told me. I thought Canter was a pretty good name, and the baffling/windage inserts in the pan impressed me. That said, I will now re-assess things ... side-by-side.
Sorry - I typed "Canter" and meant "Canton" - regardless, I will do a closer comparison before I go further, I do NOT want to finish the engine only to find that it interfere with the chassis ... so, thanks for the insights.
 

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Sorry - I typed "Canter" and meant "Canton" - regardless, I will do a closer comparison before I go further, I do NOT want to finish the engine only to find that it interfere with the chassis ... so, thanks for the insights.
This has come up before. I am using a Canton pan on the engine that's going back in mine. To be proactive, I am going to install spacers under the chassis mounts. I'll hopefully know in a couple weeks if they work or not.

 

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Discussion Starter · #11 ·
This has come up before. I am using a Canton pan on the engine that's going back in mine. To be proactive, I am going to install spacers under the chassis mounts. I'll hopefully know in a couple weeks if they work or not.

Great reply. I'm still at the stage where I could select another pan, but the spacer option (under chassis mounts) is a good thing to know. Wow - is the potential interference only 3/16"? If so, that will make my pan-to-pan comparison more difficult to determine (if aftermarket will rub or not). Good information, though, so "thank you."
 

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From what I've gathered, the interference is very minimal, to the point where the engine will fit in the car but the pan will just make contact. So 3/16 should be plenty without causing other issues (hood clearance, geometry, etc). Others have added clearance by denting the oil pan where it's going to hit. I didn't like this idea for me so I'll try the spacers. These aftermarket pans probably fit fine when the cars were much newer but in the 50+ years since they were built, things have spread a bit. Not uncommon to find and old A body that has a slight lean. Mine does and it has never been hit. I corrected that with a very thin spacer over one of the rear springs.

You mentioned about having a sloppy gasket around the back of the pan. Was this just during test fit or after you tightened all the bolts? Mine looked like it would have way too much space when I test fit, but snugged right up once everything was torqued to spec. I'm using the BOP gasket mentioned above. I was really careful to make sure the gasket was in the grove before tightening everything because it didn't seem to want to stay in place.

One more thing that will save you headaches in the near future. Don't go with cheep motor mounts. Buy from a reputable source and not from a discount site. You really get what you pay for. I'm using the ones sold through Butler. They are expensive but come with a 3 year warranty which I never expect to use. My car had the discount ones on it and one was blown out when the engine came out.
 

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1965 GTO Hardtop 389 tri-power (WS), close ratio M21, 3.90 posi rear (ZK)
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Discussion Starter · #14 ·
From what I've gathered, the interference is very minimal, to the point where the engine will fit in the car but the pan will just make contact. So 3/16 should be plenty without causing other issues (hood clearance, geometry, etc). Others have added clearance by denting the oil pan where it's going to hit. I didn't like this idea for me so I'll try the spacers. These aftermarket pans probably fit fine when the cars were much newer but in the 50+ years since they were built, things have spread a bit. Not uncommon to find and old A body that has a slight lean. Mine does and it has never been hit. I corrected that with a very thin spacer over one of the rear springs.

You mentioned about having a sloppy gasket around the back of the pan. Was this just during test fit or after you tightened all the bolts? Mine looked like it would have way too much space when I test fit, but snugged right up once everything was torqued to spec. I'm using the BOP gasket mentioned above. I was really careful to make sure the gasket was in the grove before tightening everything because it didn't seem to want to stay in place.

One more thing that will save you headaches in the near future. Don't go with cheep motor mounts. Buy from a reputable source and not from a discount site. You really get what you pay for. I'm using the ones sold through Butler. They are expensive but come with a 3 year warranty which I never expect to use. My car had the discount ones on it and one was blown out when the engine came out.
Thx for the reply. The sloppy gasket is actually a sloppy half-round steel strap that seems to go outside of the oil pan, from side to side, fastening (via 2 bolts nearest the rear main cap, through 2 tabs (the ears of this half-round), then through the pan rim, and into the block. I have not seen any other '65 389 pics with this strap (very curious). Anyway, thx for the insights. By the way, I bought my mounts through either Year One or Performance Years, so I hope they're OK. Have a good weekend.
 

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Discussion Starter · #15 ·
Thx for the reply. The sloppy gasket is actually a sloppy half-round steel strap that seems to go outside of the oil pan, from side to side, fastening (via 2 bolts nearest the rear main cap, through 2 tabs (the ears of this half-round), then through the pan rim, and into the block. I have not seen any other '65 389 pics with this strap (very curious). Anyway, thx for the insights. By the way, I bought my mounts through either Year One or Performance Years, so I hope they're OK. Have a good weekend.
Maybe I can take and send a pic of the steel strap I'm trying to describe.
 

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Discussion Starter · #17 ·
From the four pics attached, hopefully you will see the strap (outside of the pan, outside of the cork gasket, outside of the rear main cap). Hopefully, you'll also see the gap between the strap and the pan. I don't know what originally filled this gap, or if - with the new pan - it is just not snugging-up.
 

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Does it fit your old pan? I looked through my parts manual and there's no mention of or any diagrams of a reinforcement strap. I faintly recall a strap similar to that but it wasn't on a Pontiac. Maybe it's an old Chevy piece you had laying around.
 

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Discussion Starter · #19 ·
Does it fit your old pan? I looked through my parts manual and there's no mention of or any diagrams of a reinforcement strap. I faintly recall a strap similar to that but it wasn't on a Pontiac. Maybe it's an old Chevy piece you had laying around.
Ed - the odd thing is I don't remember taking it off the engine during disassembly. I do have the old pan; it is unusable but I can at least check if it used to fit-up. I had that strap in my container with all of the oil pan bolts. Is there another spot it could have been bolted along the underside (e.g., part of lower baffle? part of dipstick arrangement? part of oil pump config?). It is honestly a mystery to me. Well, maybe I should just not use it (esp. if not parts manuals show it) and just buy the aftermarket corner braces (which were not on my original pan), to help spread the load on the rear corners of the pan rail. Head scratcher.
 

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Discussion Starter · #20 ·
The attached pic has the oil pan bolts the the "strap" - I tried to lay things out as they came off the engine.
 

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