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Discussion Starter #1
I picked up an old comp car with a stock GM block & caps, short filled 355 sbc,....forged crank, engle roller, aluminum rods, ross pistons 13-1, old casting brodix heads. Because the car had sat in a trailer for the last twelve years I decided to pull the pan and poke around the bottom end a bit.

Look what happened when I reinstalled the oil pump last night.....I didn't even have the torque wrench on it yet. This happened with the pump fully seated in the dowles with a 3/8 ratchet just snug....

The funny part of it is...I fired it up two days before with almost 80 lbs of oil pressure.

Im glad this happened in the trailer....Imagine this motor bouncing up and down in a circle flat bottom!

Im officially over stock junk...
 

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I picked up an old comp car with a stock GM block & caps, short filled 355 sbc,....forged crank, engle roller, aluminum rods, ross pistons 13-1, old casting brodix heads. Because the car had sat in a trailer for the last twelve years I decided to pull the pan and poke around the bottom end a bit.

Look what happened when I reinstalled the oil pump last night.....I didn't even have the torque wrench on it yet. This happened with the pump fully seated in the dowles with a 3/8 ratchet just snug....

The funny part of it is...I fired it up two days before with almost 80 lbs of oil pressure.

Im glad this happened in the trailer....Imagine this motor bouncing up and down in a circle flat bottom!

Im officially over stock junk...
The stock bolts in a sbc are stronger than many think. The main cap bolts are some of the best stock bolts in the industry.
I venture to bet that bolt wasn't the stock bolt, AND It would be to your benefit to pull that cap and see if the bolt is bottomed out on the bearing.

Not saying it can't happen



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The stock bolts in a sbc are stronger than many think. The main cap bolts are some of the best stock bolts in the industry.
I venture to bet that bolt wasn't the stock bolt, AND It would be to your benefit to pull that cap and see if the bolt is bottomed out on the bearing.
Bingo Bob! Look at the bottom and see the seat for the bolt kinda freshly rubbed. Bolt bottomed out and cracked the main saddle.
 

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Is the bolt broken off in the hole? I don't see that. I see the casting broken. That doesn't "just happen". I know once in a while someone will mistake a short head bolt for an oil pump bolt and they're too short, not enough engagement. This is what typically happens...they either just strip out the threads of the cap, or break the casting.
 

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Is the bolt broken off in the hole? I don't see that. I see the casting broken. That doesn't "just happen". I know once in a while someone will mistake a short head bolt for an oil pump bolt and they're too short, not enough engagement. This is what typically happens...they either just strip out the threads of the cap, or break the casting.
No. I thought it did and then I edited it out. At first thats what I thought he was refering to, then I saw the broken piece from the cap. I agree, a short bolt will do that. Even if the bolt is the correct length now, doesn't mean it always was. Hard to imagine exactly what caused it to bust that piece out of there. But its NOT common.

Hard to say in the pic, but I think I would dress that with a stone and toss a stud in it.
Its what I like about studs for oil pumps. You can thread them in and check for max thread ingagement, make sure it isn't into the bearing, lock tite and forget em.



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It looks like there's two more cracks at 7:00 and 9:00. I'd address that before proceeding with a stud. With any luck they can be ground out and not lose the main cap.
 

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Discussion Starter #8 (Edited)
That doesn't "just happen". I know once in a while someone will mistake a short head bolt for an oil pump bolt and they're too short, not enough engagement. This is what typically happens...they either just strip out the threads of the cap, or break the casting.
Yup I've seen that too... but this motor has studs.

I agree that doesn't "just happen"......nothing ever does
 

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Sorry to put you thru that Whiskeybent. What I meant was to look at the back side of the bearing and see if the bolt had bottom out on it. But I see that the problem is different than I originally saw it. I have to go with Steel on this. My hunch is that the pump was bolted down at some point with too short of a bolt and fratured the cap. Its still a guess, but that is not a usual problem.

What do you if thaty happened in a boat. I have had 2 iron pumps break in 2 in the oast. I gave up on iron pumps years ago.



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Its Home Depot grade 5 bolt. It has no business holding on an oil pump in anything. A hardware store socket head allen would be better suited, although I am not recommending that.

Is the "shiney" area on the end of the threads the ONLY pplace the bolt was ingaged into the cap threads? If so, you just found your problem.
Any bolt you replace it with, run it in byu hand with the oil pump in place with the capn off and the bearing out, and verify that the bolt has max thread purchase but does not protrude into the bearing saddle.

better double check that cap for any additional cracks first. In the pic it looks like there are others, but it just a pic.



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Discussion Starter #15
I can't seem to take a decent picture of the bottom of the hole because of the flash, but this bolt did not bottom out. Mabey I can try tommorow in daylight. I think GN is right... maybe its to short?

Like steel said this dosen't "just happen." My conclusion is that I didn't realize the main was messed up when the bolt originaly came out.

Either way lesson learned on my part. Don't check the threads upside down in so so lighting when doing a bottom end. (this isn't top alcohol)

OH well....this is just God's way of telling me it should be a BBC and blown. ;)
 

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Discussion Starter #18
Ok...read in another forum the answer is 2' 3/8 bolts in some and 2 inch bolts in others.

There's the answer folks. Burned by the guy before me and not enough attention to detail on my part.

Lessoned learned. I won't be doing that again.
 

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Lil E, Go ahead and throw the big block in.....sell the sbc...part it out..I'll take the heads for the sbc we'll, oops I mean that Steelcomp will be putting together...
 

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Yup, seen it before.. if memory serves (20 years ago) there are 2 different length oil pump bolts. One was about 1/4 to 3/8" longer than the other. The short one will yank those threads right out when trying to torque.
Your pic looks like only 3 threads were pulled out. Not very good.
Wags
 
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