Oil Pump Mounting Bolts?

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694spd

694spd

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I finally putting my 340 back together. I went to install the oil pump, but I'm unable to locate the bolts that originally removed. Does anyone know how long they are and if they are both the same length? Are they Grade 5 or Grade 8 bolts?
 
Well I did some measuring on the depth of the hole and they appear to be the same length and can't be more than 1-3/4" long.
 
Grade 5 is plenty but like I always say grade 8 wont hurt a thing.
 
HaHaHa, Well then don't cross thread it !!

I stopped cross threading bolts when I was 12 years old.
 
I would put in grade 8 here simply because the threads are machined better than on a grade 5.
 
it's no "biggie"...the rub is a grade 5 if stressed will bend or deform but hold together.A grade 8 being harder is more brittle and if pushed beyond it's limit will snap and fail.That is why suspension fasteners are built bigger for strength but remain grade 5.You always want to replace the fastener not the part.
unless you really know your stuff i'd stick with what the factory used.
 
ir3333 said:
it's no "biggie"...the rub is a grade 5 if stressed will bend or deform but hold together.A grade 8 being harder is more brittle and if pushed beyond it's limit will snap and fail.That is why suspension components are built bigger for strength but remain grade 5.You always want to replace the fastener not the part.
unless you really know your stuff i'd stick with what the factory used.
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IIRC, the oil pump bolts have the same head stamping as the main cap bolts, they're just a smaller size. I wouldn't even think of using hdwe store bolts as a substitute for main cap bolts.
 
They're 3/8-16 x 1-1/4" These I got from Hughes, grade 5 on the label, but the bolts have the six lines so they are grade 8​

IMG_20170616_212319.jpg
 
Thanks for all of the replies. I'm sure that I still have them somewhere.
This just the start for finding all of the hardware need to put the motor and tranny back together and into the car. I did label a lot of the fasteners, but there was a percentage that just got tossed around during the disassembly process.
 
Can always buy a pack of 4 of arp bolts in that size, believe its like $11.05 from summit, part number 642-1250
 
rustycowll69 said:
IIRC, the oil pump bolts have the same head stamping as the main cap bolts, they're just a smaller size. I wouldn't even think of using hdwe store bolts as a substitute for main cap bolts.
Click to expand...

If the factory used grade 8 then i know what i would use.
 
Thanks for pics/dimensions. Hard to tell but doesnt appear to be any shoulder? I would think OEM would have a shoulder to "locate/mate" the pump better to the bearing cap?
12many said:
They're 3/8-16 x 1-1/4" These I got from Hughes, grade 5 on the label, but the bolts have the six lines so they are grade 8​

View attachment 1715057949
Click to expand...
 
4spdragtop said:
Thanks for pics/dimensions. Hard to tell but doesnt appear to be any shoulder? I would think OEM would have a shoulder to "locate/mate" the pump better to the bearing cap?
Click to expand...
I can’t recall whether there should be shoulders on them or not as I built my engine from scratch. Ordered those oil pump bolts and whatever I got is what went in. Motor still running and pump is still pumping.
 
Grade 5 is 120,000 lbs./sq.in
Grade 8 is 180,000 lbs./sq.in.
Sheesh...how tight are you 'gonna torque those little buggers?
I'd still use factory pieces if possible.
 
Thanks, I'm just sifting thru buckets, lots of 3/8 just wasnt sure if there was a shoulder or not.
12many said:
I can’t recall whether there should be shoulders on them or not as I built my engine from scratch. Ordered those oil pump bolts and whatever I got is what went in. Motor still running and pump is still pumping.
Click to expand...
 
4spdragtop said:
I would think OEM would have a shoulder to "locate/mate" the pump better to the bearing cap?
Click to expand...
My stock bolts had the shoulder on them, but the melling HV pump I put in had larger diameter mounting holes than the stock pump which made the shoulder kinda redundant. I added some arp washers when it went back together as the larger holes didn't leave much contact for the bolt head.
Don't forget to drop the oil pump drive in to align the pump before you torque it down.
 
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