The Stovebolt Site Forums The Shop Area Engine Shop head bolt search

hi,

i need to replace a few of the cylinder head bolts on my 235. i thought a few grade 8 bolts would work but the guy at the counter of my flaps said that was not adiquate. he tried to find head bolts in "the book" with no luck.

my question; is a grade 8 bolt adiquate?

Good question. I don't see why not. Your head-bolts torque at 90-95 ft/lbs and a 1/2" grade 8 bolt is good for up to 119 ft/lbs. There may be other considerations like head thickness that might make them unsuitable though. Hopefully one of the resident experts will be along soon.

i can't answer your question but one thing i have noticed about head bolts- they don't have a shoulder the same size as threads on the end, it is always smaller on the ones i have seem. all standard grade 8 bolts have the larger shoulder the same od as the threaded portion. i thought the head bolts i had seen were grade 5 anyway. have you checked with arp, i think that's the name of the company? you can buy high strenth connecting rod bolts and i thought head bolts. i may be wrong.

another thing, i thought the connection was only as strong as the cast portion in the block, so i still don't know if there's need for a grade 8 bolt.

there was an arp book at my flaps. there were not head bolts listed for the 235 application. they were going to call the distributor on monday.

i also spent some time on the "intertube" looking. if there are 235 head bolts out there, they are hard to find.

Try The Filling Station, Jim Carter or Chevys of the 40s. They show head bolts in their catalogs. All 3 are online also.

i looked on the jc website and classic parts of america and came up empty handed. i'll look a bit harder.

Head bolts are designed to give a certain clamping force at a certain torque. The smaller diameter is to allow most of the stretching to occur outside of the threaded portion. I would try and get the real thing.

Have you tried the local salvage yards? A few years ago I needed a few 235 head bolts and bought a "sack of bolts" from a scrap yard. These are used. If I can find them, I will ship them for shipping cost. Send me a pm if you are interested. As truckernix says (and also explained in the ARP catalog, I think) the the body is turned down to control the stretching and, possibly, to equalize the preload in the long and short bolts.

Another source you may try is the local tractor dealers. I needed a few bolts for my 235, the owner of the machine shop i use told me to try the local Deere dealer. Lo and Behold, John Deere head bolts were an exact match. I forget which ebgine they came from, we matched it off one fo the good bolts.

thanks for all the good info. so it sounds like grade 8 bolts will work but they are not the best choice.

chevs of the 40s has the bolts on their website but they are not turned down. they look like grade 8s or 10s.

i have a few bolts for referance so i'll try the local tractor supply and if no luck i'll try an auto recycler.

i'm suprised at how difficult it is to track these bolts down.

don't be suprised, the frustrating thing is: someone is throwing some in the trash now as we speak. that's why i stick back and old parts i can, you never know when you will need them.

The old diesel Oldsmobile head bolts work. That's what I used. Bought them over the counter at a Chevy dealership.

That's just what I'm talking about. Check other engines, you might be suprised at what might match up!