Oil Pan Bolts

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dibbons

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Removed all the oil pan bolts. In the process, I found one loose which was located in the center of the oil pan area. When I got ready to clean them up, I also found one was longer than the all the others (photo #1). I don't know if the longer one was the loose one or not. I do know, the longer one was NOT used in the front (timing cover-photo #2) or the rear (where the bolts can go all the way through the block without bottoming out-photo #3). Machine shop responsible for assembly sold out some years ago so I cannot go back to question anyone there.

My question is: did the factory install two different length bolts in the early LA motors, or if all the oil pan bolts were the same length? Thank you.

oilpan bolt 1.JPG


oil pan bolt 3.JPG


oil pan bolt 2.JPG
 
If I recall correctly, the two mating with the timing cover are longer. Makes sense as it is a through hole instead of blind, and more importantly it is to the softer aluminum cover.
 
I see three OEM pan bolts in your picture. The other bolts throw away. There is two longer bolts that go into the aluminum timing cover. But none of them that you have pictured.

Do yourself a favor and run a tap in the holes. Also clean the bolts. run a die on them soak them in pure Super clean overnight and rinse.
 
Yep, bolts 1,2 & 4 are correct, put the others in your spare bolt can. As OMM said, run a tap in the holes & a die on bolts, soak the to get rid of all the junk & then reinstall.
 
Just noticed my valve covers have 5 long and 5 shorter fasteners. Either size seems to work, just can't find any consistency with this rebuilt motor.

valve cover bolts.JPG
 
Just noticed my valve covers have 5 long and 5 shorter fasteners. Either size seems to work, just can't find any consistency with this rebuilt motor.

View attachment 1715592074
I think the short ones are correct for the valve covers. I was just working on the intake over the weekend so they were out. (Pretty original car with the motor never out or apart except under my ownership.)
They could have mixed them up.
 
If the short ones are correct, the long ones have no application being the fact the oil pan bolts are a larger diameter (or vise versa). Just thinking aloud.
 
Some rebuilders are famous for using whatever bolts they have if they fit. LOL
 
Larger Diameter? What are the threads then?

They also look like they were blue at some point. Not sure if your entire motor was blue like a 318 or something...?
 
Mopar small block bolt Diameter Chart (use at your own risk). For example, I have seen 340 head bolt torque listings as 95 ft-lb. And as for tightening oil pan bolts to 15 ft-lb, I have my doubts after having seen the gasket just want to squeeze itself out of place the tighter one goes.

bolt sizes.jpg
 
Mopar small block bolt Diameter Chart (use at your own risk). For example, I have seen 340 head bolt torque listings as 95. And as for tightening oil pan bolts to 15, I have my doubts having seen the gasket just want to squeeze itself out of place the tighter one goes.

View attachment 1715592097
Not to be a captain obvious but just check the diameter then. I think my valve cover bolts are 5/16-18. Granted that is a wacky '65. On the other hand the factory service manual as a typo to crank the intake manifold bolts to 270 ft lbs in the assembly section. I am not sure they proofed it carefully before published.
 
It's obvious to the naked eye the tiny valve cover bolts (cylinder head cover bolts) don't compare with the oil pan bolts.
 
It's obvious to the naked eye the tiny valve cover bolts (cylinder head cover bolts) don't compare with the oil pan bolts.
Your right. My bad.
Then I guess put the 1/4-20 bolts in the cylinder head cover and the 5/16-18 in the the oil pan. They should not be able to be used in either location unless they re drilled and tapped some of the holes. Which at this point seems possible if they did't know what was what to begin with.
 
You can also check the threads minor diameter of the hole with some dial calipers. For the 1/4-20 you should be between 0.1960 and 0.2070 (on the inside of the threads). 5/16-18 you should be between .2520 and 0.2650
 
I was just commenting on the lack of conformity with respect to the valve cover bolt "length" I found, not trying to relate them to other applications. Par for the course anytime a factory vehicle/motor has been torn down even once before.
 
oilpan-bolt-1-jpg.jpg

Oil-pan and valve cover bolts have the first couple of threads missing, making them easier to start, so the first 4 are good candidates.
All the non-corner, 1/4-20 bolts retaining your oilpan should be identical;and they all go into blind holes. I have never seen it otherwise.
The corner bolts, as mentioned, are different.
 
Just to finalize this and prevent any misunderstandings for future readers of this post; the 18 oil pan fasteners (photo left) are 5/16" and the 10 valve cover fasteners (photo right) are 1/4" diameters. The length may vary (ha-ha) depending on what clown(s) has worked on the engine previously.

bolt 5:16 vs 1:4.JPG
 
Last edited:
Alex; I'd like to call a friend
It's been 15 years since I last screwed my 360 together..... but I wouldda thought that I wouldna not forgot that. Maybe that's why my wife sleeps in her own bed.
 
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