# new 400 pan on old 400 block



## Cudaboy_71 (Jun 10, 2017)

I'm rebuilding an original 67 GTO 335hp 400. The oil pan is kinda beat and I thought I'd replace it while the engine is out.

I ordered this part from summit:
https://www.summitracing.com/parts/sum-g3542

It says its compatible on the site page above, even though the stock pan does NOT have a baffle, and the Summit one does.
But, when I got the pan, the packing list stated '71-'82. And, looking at the pan it also has the hole and slots in the rear seal area, where the stock pan has no holes but a raised ridge that looks like it seats in the oil slinger groove.

I immediately called summit and they told me, 'no, it'll work'. Mainly I wanted on the record as having lodged an issue since I wouldn't be building for a few weeks.

Well, now that I'm building, the pan will not seat fully at the rear seal. Even with the gaskets out it feels like the pan is hitting something--though I can't see what. If I move the whole pan rearward about a 1/4" it "comes off" of whatever was holding it up and sits flush on the block. But, then of course the holes don't line up.

So, am I doing something obviously dumb? Is there some mod I can do to make this pan fit? Or is this pan simply NOT compatible and I need to send it back?

And, if that's the case--that I have to send it back--anyone have a source for a vintage 400 block pan? I can use the original, worst case. I just don't want to. It just has a giant dent in the bottom that I'm afraid to beat out as I'll distort the lip. So, I can sandblast and repaint--but it will keep the dent :frown3:


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## Goat Roper (Oct 28, 2014)

I don't see why removing a dent in the bottom would distort the lip.
I couldn't find a replacement for my '67 so I hammered it out and bead blasted it.
There was a factory recall back in the day they would install these parts at no cost.

https://secure.amesperf.com/qilan/D...25P&order_number_e=NDM4MzE3MQ==
&web_access=Y

I would buy this set if you don't have them and for sure just go with the original regardless of you removing or leaving the dent.


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## Pinion head (Jan 3, 2015)

On near stock builds I've always used nice original GM oil pans. Original oil pans are separated into:
-'64 pans
-'65-70 "front dump" pans
-'71-72 "side dump" pans with no spot welded in baffle
-'72-74 "side dump" pans with spot welded in baffle, rear seal area has one small hole & two slots
-'75-79 "side dump" pans with spot welded in baffle, & multiple slots to locate the common multi tab rubber rear seal.

For many years I kept a national Pontiac engine builder in specialty cores, 400 blocks, 6x-4 heads, timing covers, as well as tin & hardware. When I supplied him a '72-74 oilpan with the small centering hole & only two slots, he used the earlier cork type rearpan seal. On many builds I've used the later multi tab pans & rubber seals. Have not used the recently introduced one piece oil pan seal. Looking forward to trying one on next build.


'


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## Goat Roper (Oct 28, 2014)

_Have not used the recently introduced one piece oil pan seal. Looking forward to trying one on next build.
_

You won't be disappointed and go with the Viton rear main seal.
I have 4 vehicles and my goat is the only one that doesn't leak a drop of anything.


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## Cudaboy_71 (Jun 10, 2017)

Pinion head said:


> On near stock builds I've always used nice original GM oil pans. Original oil pans are separated into:
> -'64 pans
> -'65-70 "front dump" pans
> -'71-72 "side dump" pans with no spot welded in baffle
> ...


This is kinda getting to what I'm after. So, I know I have a '67 "front dump" pan. No baffle. The pan I got from Summit is a side dumper with a baffle and a single small/two slot rear main. For more than twice the price I can one without the baffle. But, it's still a single small/two slot main like I have in my hand now from Summit.

I don't want to go to the trouble of ordering the no-baffle pan though, if it's still going to hit "something?" when the holes are aligned. Currently, I can't tell if I'm hitting the baffle, or it's the lack of the lip on the rear main that's causing issues.

I do have both the rubber rear main and the straight piece of cork for the rear seal in my gasket set.

Are you saying that using the cork seal and a no-baffle pan should work?


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## dan woodland (Jul 24, 2013)

Goat Roper said:


> _Have not used the recently introduced one piece oil pan seal. Looking forward to trying one on next build.
> _
> 
> You won't be disappointed and go with the Viton rear main seal.
> I have 4 vehicles and my goat is the only one that doesn't leak a drop of anything.


Not trying to highjack the thread - just offering up some "test" results on the one piece unit.

I'm told they used one of those on my rebuild's rebuild - the multi-piece unit leaked squirting oil on the end of the crank so it looked like the rear main was leaking.. I'll let you know how it goes. Dan


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## Goat Roper (Oct 28, 2014)

I doubt it will leak Dan, it is reinforced so it can't squish out.
If you had installed it yourself you would really see how superior it is to the cork.


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## PontiacJim (Dec 29, 2012)

Your pump & pick-up should not be the problem. The baffled pan is actually a better choice than the non-baffled pan - but it should not pose any interference problems.

That said, sometimes it is a manufacturing problem with aftermarket pans. Aftermarket parts are not always 100%. Reading the reviews on this pan https://www.summitracing.com/parts/sum-g3542/reviews/?filterReviews=OneStar seems to indicate that several buyers have indeed experienced fitment problems with this pan as you are now experiencing - so it may indeed be the pan.

But, you indicate that something seems to be hitting or holding it up. You might consider removing the oil pump to eliminate it as the culprit. If the pan does seat correctly, then I would look at a few things. Do you know that the pick-up screen has been mounted correctly? If it twisted or is not positioned flat to the oil pan bottom, it could be hitting. Could be the baffle - maybe incorrectly positioned/welded and hitting the oil screen pick-up in some way.

Might it be the windage tray/bolts be hitting the baffle/pan? That would be something I would also look at. They shouldn't be a problem normally, but given it is a replacement pan, just another thing to check at this point.

If the rear main seal has been installed correctly, it should not be a problem if I am understanding you correctly. There should be no stickout of the seal as it is fully enclosed within the main cap. Here is the BOP PDF for their Viton rear main seal which shows you how the seal fits. https://www.bopengineering.com/seal_instructions.pdf

If you go to the BOP website, it provides pics and descriptions of the oil pan seals - both factory types and their 1 piece seal. You can click on the images to expand them. The cork seal should work as the rear pan seal. https://www.bopengineering.com/pontiac_replacement_parts4.shtml


An uploaded pic of the engine/problem area might be helpful for us to see. :thumbsup:


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## Cudaboy_71 (Jun 10, 2017)

PontiacJim said:


> Your pump & pick-up should not be the problem. The baffled pan is actually a better choice than the non-baffled pan - but it should not pose any interference problems.
> 
> That said, sometimes it is a manufacturing problem with aftermarket pans. Aftermarket parts are not always 100%. Reading the reviews on this pan https://www.summitracing.com/parts/sum-g3542/reviews/?filterReviews=OneStar seems to indicate that several buyers have indeed experienced fitment problems with this pan as you are now experiencing - so it may indeed be the pan.


that may very well be. It's a $60 pan. The alteranative is the Milodon one for $150. For that price, I'll just beat out the original and repaint. I was trying to go cheap/easy.



> But, you indicate that something seems to be hitting or holding it up. You might consider removing the oil pump to eliminate it as the culprit.


I knew there might be issues simply from the packing slip saying '72-82 (even though the website said '64-71). So, first thing I did was try to line up the holes before I ever put the pump and windage tray back in. This pan is hitting a main cap, or the crank. On the baffle or something else??? I can't tell because I can't see anything once the pan is on. It feels like it's toward the rear though.



> If the pan does seat correctly, then I would look at a few things. Do you know that the pick-up screen has been mounted correctly? If it twisted or is not positioned flat to the oil pan bottom, it could be hitting. Could be the baffle - maybe incorrectly positioned/welded and hitting the oil screen pick-up in some way.
> 
> Might it be the windage tray/bolts be hitting the baffle/pan? That would be something I would also look at. They shouldn't be a problem normally, but given it is a replacement pan, just another thing to check at this point.


ya..see above. none of that is even installed yet. but, thanks for the ideas.



> If the rear main seal has been installed correctly, it should not be a problem if I am understanding you correctly. There should be no stickout of the seal as it is fully enclosed within the main cap. Here is the BOP PDF for their Viton rear main seal which shows you how the seal fits. https://www.bopengineering.com/seal_instructions.pdf


My fault for bad terminology. I'm not talking about the rear main seal. I just meant the round portion of the pan that goes around the crank at the rear of the pan. *That* part of my gasket set came with a cork (original) and the rubber one with 'teeth' that go through the center hole and two slots on newer pans. I've heard of some people using the rubber seal on vintage pans by just cutting off the 'teeth'. For what it's worth, I did replace the main seal with the Graphtite 2-part seal per the instructions. So, it should be good. Nothing looks abnormal about that at all.



> If you go to the BOP website, it provides pics and descriptions of the oil pan seals - both factory types and their 1 piece seal. You can click on the images to expand them. The cork seal should work as the rear pan seal. https://www.bopengineering.com/pontiac_replacement_parts4.shtml
> 
> 
> An uploaded pic of the engine/problem area might be helpful for us to see. :thumbsup:


I took a video of the issue. Unfortunately, it's taking a while to upload to youtube. I'll post a followup when it's done. thanks.


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## Cudaboy_71 (Jun 10, 2017)

here's the aforementioned video, if anyone can tell anything from that. apologies in advance for the shoddy, one-handed camera work.


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## PontiacJim (Dec 29, 2012)

OK, good video. It appears to me like it is rocking on the half round contour where the rear pan cork seal will go. If me, to confirm this, I would make cardboard cutout that fit snuggly and tightly into the half round cut-out on your original pan and match it against the new pan to see how it fits and where the differences are.

Could you use a feeler gauge to check for the gap consistency? Put your side rail gaskets between the block and pan just like mounting it. This will raise the pan up off the block equally. Then find a feeler gauge that will slide under/around the half circle at the rear of the pan and note the differences.

If you want to check the windage tray bolts, use some good old Playdo and make a couple of large round balls and set them on top of the bolts and then set the pan down on top. This will squish the Playdo down and you should be able to get an idea of your clearances by their thickness and note any problems.


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## Pinion head (Jan 3, 2015)

Another example of a Chineseum ill fitting junk sheet metal part. Summit has a very liberal return policy, I'd return it. Your '67's stock oil pan appears to be in good shape, I'd clean it up & reuse it. The cork rear pan seal works extremely well when properly installed, if you have a Felpro gasket kit, it will have a cork one in it. 

Find it amusing, the idiots that had this pan reproduced, used the '73-74 version as a model. As mentioned earlier, that particular version only has two slots versus 4 in the rear pan seal area. Over the last twenty years, have had three SD T/A owners who've ordered a nice used '73-74 style baffled pan from me. While I'm totally in tune with originality, have also reminded each of them, what my longtime Pontiac engine builder stated, the reason Pontiac went to the 4 tab style pan was to eliminate that early style two tab neoprene seal from creeping out. Having a nice straight unrusted '73-74 style pan on hand, one could carefully add the extra outer slots with carefull use of a Dremel off wheel & thin grinding bit, then use the 4 tab '75-81 style neoprene seal, OR one could again properly install the '72 & earlier style cork gasket.


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## Cudaboy_71 (Jun 10, 2017)

ya..i think im just gonna send it back. the original pan isnt that bad. I was just going for quick/cheap/easy. This looks like 1 out of 3.

I'll beat the bottom of the pan back flat, sand blast, and paint (once i find the correct blue--see the other thread on paint)

thanks for all the replies, guys.


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