Jump to content

Olds Accessory Head Bolt Question for Techies


Guest rsd9699
 Share

Recommended Posts

Guest rsd9699

Hi to all,

In my never ending quest to a/c my various Olds - I keep getting stuck on the accessory head bolt issue.

An accessory head bolt is a "regular" looking head bolt with a threaded stub on top of the hex head of the head bolt.

I have never found a source for them - they were discontinued making several years ago and none seem to left on shelves at the places I have checked with.

So my question is can I use a stud and a cap nut to simulate a head bolt and what grades should I look for and avoid.

Thanks

Ron

Link to comment
Share on other sites

Over the years, there have been OEM applications for such bolts in some GM vehicles. Some might be in GM's "Standard Parts" catalog . . . BUT the stud on top is usuallly of a smaller diameter than the basic bolt's thread is, which might be a sticking point of sorts.

Seems like there were some on the Olds 5.7L diesels?

One "trick" part on the old 5.7L GM diesels was the radiator hose clamp on the thermostat housing. In addition to the basic clamp, it had a curved shield attached to keep the a/c belts from touching the upper radiator hose, as they flexed with the a/c compressor running. Not sure if they are still around, but they were really neat for other applications which had flexing a/c belts!

Just some thoughts . . .

NTX5467

Link to comment
Share on other sites

Guest rsd9699

Yes Mr. FITZ those are the types of creatures I am seeking.

Did you machine them? I have a old/little 6 inch Atlas that I pondered doing it on but I am a novice in machining.

The tops of the head bolts are 3/8 inch SAE and the bottoms are course threads.

I will take some pictures tomorrow and post the pictures and lengths.

Mr. NTX5467, the bolts used on the 330 thru 455 are 7/16 if I recall correctly and the 303 thru 394 are 3/8. The 303 and 324 are a little shorter than the 371 and 394 and they will work I think (never tried one). We need to meet sometime - I live on the east side of Lewisville.

Just think if Olds had used 1/2 head bolts on the Diesels, the history may different for Olds?

Mr. 1937-44, I thought of the welding as well but I was afraid that the tensile strength of the bolts would be altered and the last thing I need is a snapped head bolt when I flip the a/c switch at 100 MPH.

Link to comment
Share on other sites

Guest rsd9699

Mr. 1937-44,

I was thinking of putting a cap nut on the stud and putting an allen screw thru the nut to lock it to the stud - we think along the same lines.

Ron

Link to comment
Share on other sites

Mr. 1937-44,

I was thinking of putting a cap nut on the stud and putting an allen screw thru the nut to lock it to the stud - we think along the same lines.

Ron

You didn't specify if you were working on a first gen or second gen Olds V8, but the accessory head bolts for the second gen (1964-1990) motors are quite common. Note that the 1964-76 motors used 7/16" head bolts and the 1977-90 motors used 1/2" head bolts. The bolts show up on ebay frequently.

Link to comment
Share on other sites

Mr. 1937-44, I thought of the welding as well but I was afraid that the tensile strength of the bolts would be altered and the last thing I need is a snapped head bolt when I flip the a/c switch at 100 MPH.

No flow-thru ventilation at that speed? Worried about a bolt? What about the a/c drive belt???

Enjoy!

NTX5467

Link to comment
Share on other sites

Guest rsd9699

In this case - the 303 thru 324 engine group.

40+ years ago - I did that quite often - that is - flip the a/c on and rolled up the windows as there was a "sand belt" just west of where I was raised - someone sneezed and you had a dust storm that lasted one or more miles. Got to love power windows and a/c. I was running a single belt on the S/F and wondered why they wanted two on it? At that time I could not afford a matched set of belts....

Hey - I was younger and dumber.....

Ron

Link to comment
Share on other sites

Yes Mr. FITZ those are the types of creatures I am seeking.

Did you machine them? I have a old/little 6 inch Atlas that I pondered doing it on but I am a novice in machining.

The tops of the head bolts are 3/8 inch SAE and the bottoms are course threads.

I will take some pictures tomorrow and post the pictures and lengths.

Yes I made it for my Pontiac L6 1953 engine. The old one did not hold the spec. bolt torque. I don't remember the steel code quality, but I can get back for you I have the info somewhere, or make a set at your specific need if you want.

Fitz.

Link to comment
Share on other sites

Guest rsd9699

Well - I put the bolts right where I could put my hands on them but my hands seems to have forgotten where they put them.

Rain forcast Monday so I will force the hands to find them.

Ron

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...