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I have run into a problem regarding head bolts for a 1960 olds dynamic with 371 cui. I have not been able to find new ones and google have not been my friend. I really hope you can help me
Are you missing some of the head bolts? I'd wager that any head bolts you find are going to have to come from a parts car. Hopefully head bolts from a 394 will fit your 371. That should widen your search some. Don't worry though, torque to yield head bolts weren't used by Oldsmobile until the very end.
As you can see, there were several different bolts used on these engines.
Most of them fit 59 thru 63.
As Jesse said, they can be re-used as long as they aren't missing or damaged.
It is the same size bolts for the 394 cui and unfortunately they are just as difficult to find. Two bolt broke when I tied them down to specs and now I don´t trust the rest of them to be okay. I would even settle for a treaded rod 7/16 unc in 8.8 quality or better. Do any of you know where I can buy that ?? Thank you for taking the time to reply
ARP is a premier bolt manufacturer in the US. They have everything you would need. Look at their bolt catalog starting on page 152. https://arpcatalog.com/152/
It would be much cheaper to find originals, but I wanted you to know that new, high-strength studs and bolts are available.
If you use ARP you would need to use a torque plate and rebore the cylinders to account for the higher clamping force of these bolts and studs.
Last edited by VC455; December 16th, 2022 at 07:13 AM.
It is the same size bolts for the 394 cui and unfortunately they are just as difficult to find. Two bolt broke when I tied them down to specs and now I don´t trust the rest of them to be okay. I would even settle for a treaded rod 7/16 unc in 8.8 quality or better. Do any of you know where I can buy that ?? Thank you for taking the time to reply
#1 If you broke two bolts, my first thought is what torque setting were you using ?
#2 Were you using a lubricant on the bolt threads ?
#3 I would ask when you had the torque wrench checked for accuracy (calibrated).
#4 The head bolts should be re-usable. New bolts are available from ARP, as noted above.
#5 8.8 is a Metric standard and I am not sure how it cross references to the inch system. What you need is Grade 5 or Grade 8.
#6 7/16"-14 threaded rod might be available where you are through an industrial supplier. But the strength certification needs to be known and attached. You need Grade 5 or Grade 8. You would also need Grade 5 or Grade 8 nuts.
#1 If you broke two bolts, my first thought is what torque setting were you using ? #2 Were you using a lubricant on the bolt threads ? #3 I would ask when you had the torque wrench checked for accuracy (calibrated). #4 The head bolts should be re-usable. New bolts are available from ARP, as noted above. #5 8.8 is a Metric standard and I am not sure how it cross references to the inch system. What you need is Grade 5 or Grade 8. #6 7/16"-14 threaded rod might be available where you are through an industrial supplier. But the strength certification needs to be known and attached. You need Grade 5 or Grade 8. You would also need Grade 5 or Grade 8 nuts.
OLDSter Ralph
1 Standard torque setting for head bolts olds 371 cui ( 60-80 ft.-lbs ) Torqued them down i 3 rounds ending with 75 ft.-lbs
2 Yes, a bit of oil
3 Yes, the week before
4 Appreciate that information. Thank you
5. My mistake not to be clear on this point. I was talking grade 8 or above. I´m not comfortable with only using grade 5, because of earlier experience on other cars
6. I have tried to find the correct treaded rod and quality for a while, still no luck
A metric grade 8.8 is approximately equivalent to a standard grade 5 in tensile strength.
A metric grade 10.9 is approximately equivalent to a standard grade 8.
The biggest problem will be finding the right length.
Too long or too short could pose a problem.
I wouldn't recommend using anything less than a grade 8 bolt as a head bolt.
Boring with a torque plate isn't necessary in a stock engine with bolts.
Using studs in a racing engine, it's a different story.
Last edited by Charlie Jones; December 16th, 2022 at 06:15 PM.
I did a re-fresh of a 324 with a friend a few years back and had broke a few bolts and was using the proper torque spec. We just got grade 8 bolts and they have been fine.
I don't think they were Ralph, They were a special specification bolt.
I'm going to guess that their tensile strength was higher than grade 5.
I'd be interested to know what their tensile strength was.
So we could compare it to grades 5 or 8.
Charlie, let me think on that a bit. I remember in my past life, that I did some tensile strength testing. I would like to find a vocational school or college with the proper equipment to do the testing.
Many, many years ago there was a flurry of clutch explosions on Top Fuel dragsters. NHRA specified Grade 5 bolts in the bell housing/scatter shield. As a solution to clutch explosions and causing damage to the car frame, NHRA required Grade 8 be used.
After a short period of time, NHRA changed their bolt requirements back to Grade 5 from Grade 8. It seems that while Grade 8 had more tensile strength, they sheared the bolts more cleanly and created greater damage to the car frame and in some cases cut the frame in half with shrapnel.
The "school of thought" was that Grade 5 would bend, twist, contort and stretch but didn't shear off completely, which helped contain some of the shrapnel. .
I am not certain, but I wonder if your "local resident" (Ocala) Don Garlits didn't lose part of his foot from this ?
Don lost part of his foot to a clutch explosion.
While he was in the hospital, he came up with the idea for a rear engine dragster.
That would separate the driver from all the mayhem of exploding clutches , engines, and blowers.
December 14th, 2022, 03:57 AM
