327 oil pan bolt size

[Richard S.]

I am trying to find out the bolt size/length of the 18 pcs that hold the oil pan to the engine block.

[Michael G.]

Re: 327 oil pan bolt size

14 of them are 1/4-20 x .50" long, the 4 on the ends are 5/16-18 x .56" long.

IMG_0218.jpg

[Richard S.]

Re: 327 oil pan bolt size

Thank you for the detail. I snapped one off and looking for one without buying a set.

Thanks again.

Rich

[John D.]

Re: 327 oil pan bolt size

I always remember that the oil pan corner bolts are
5/16-18 x 9/16. Some of them are recessed hex bolt with a free spinning split lick washer. Some have aB&H logo with a circle around them and are quite similiar to the big buck '57-58 B&H bolts that hold the fuel filter bracket to the cannister. Except the thread on the original cannisters is fine thread. So bubbas like me will run a 5/16-24 die over the course thread and use them as real deal for the fuel filter. If you really know what you are looking at the circle around the B&H is not as it should be. Trivia for the day. JD

[David L.]

Re: 327 oil pan bolt size

I would say that the 1/4"-20 oil pan bolts are the same as those on the timing cover.

[Michael G.]

Re: 327 oil pan bolt size

Rich, I'd send you the one in the pic, but the shipping would cost more than a set of bolts

[Richard S.]

Re: 327 oil pan bolt size

Thank you for the information

[Richard S.]

Re: 327 oil pan bolt size

You are correct I may need to buy a set. But the good side of this is I was able to get the old broken screw out thanks to the locator punch set I just purchased from McMaster Carr.
Rich

[Joe L.]

Re: 327 oil pan bolt size

You are correct I may need to buy a set. But the good side of this is I was able to get the old broken screw out thanks to the locator punch set I just purchased from McMaster Carr.
Rich

Rich-------


The thing that causes these bolts to break is the application of too much torque. The GM spec for the torque is 80 lb/inches for the 1/4" bolts and 65 lb/inches for the 5/16" bolts. (I don't know why the torque is less for the larger bolts but that's the spec). The bolts will actually take somewhat higher torque than this without a problem and you may find that you need to use a bit higher torque to prevent/cure any leaks. However, they won't take "gorilla" torque.

[Richard S.]

Re: 327 oil pan bolt size

Rich-------


The thing that causes these bolts to break is the application of too much torque. The GM spec for the torque is 80 lb/inches for the 1/4" bolts and 65 lb/inches for the 5/16" bolts. (I don't know why the torque is less for the larger bolts but that's the spec). The bolts will actually take somewhat higher torque than this without a problem and you may find that you need to use a bit higher torque to prevent/cure any leaks. However, they won't take "gorilla" torque.

I agree with the torque issue

[Bruce B.]

Re: 327 oil pan bolt size

I just installed a very nice Fel Pro one piece pan gasket. The instructions say torque the 1/4" bolts to 8 ft/lb and the larger ones to 20 ft/lb.
Much to high in my opinion, so I did not use the specs.
Bruce B

[Gary B.]

Re: 327 oil pan bolt size

Bruce,

All I can say is wow about the Fel Pro torque specs. For the 5/16 bolts the Fel Pro value of 20 ft-lbs = 240 in-lbs. Not close to Joe's value of 65 in-lbs. Who can you trust these days???

Gary

[Jimmy P.]

Re: 327 oil pan bolt size

I just installed a very nice Fel Pro one piece pan gasket. The instructions say torque the 1/4" bolts to 8 ft/lb and the larger ones to 20 ft/lb.
Much to high in my opinion, so I did not use the specs.
Bruce B

Bruce,
Did you use your original bolts with the Fel Pro or the bolts that came with the gasket? The bolts that come with the gasket are a little longer. Maybe that's why the torque spec is different? I just installed one on my 73 SB but I didn't try my original bolts because I was worried I'd have a leak. I didn't follow that torque spec either.That gasket sure is nice to work with isn't it? Let me know if you used your OEM bolts and I'll put mine back on. I have no leaks so far
Thanks,
Jimmy

[Bruce B.]

Re: 327 oil pan bolt size

Gary,
I agree with you.
I will email Fel Pro when I get time and question their numbers.
BTY I got a in/lb ancient Kent Moore torque wrench from a friend who never used it, so I will see how it works
Bruce B