37 320cui engine overhauling question

[chstickl]

Hi there,

in the course of overhauling my engine, it happened that some of the stay bolts (threaded rods that connect the engine block to the cylinder head) don´t come out of the block. They would need to in order to plane the block.

a) is there any secret or magic that helps to get the bolts out without destroying them (apart from soaking in rust dissolvent, heating and waiting)?

if not, drilling them out and cutting a new thread is not the issue (can be done in the same machine that bores the cylinders, but nobody seems to make replacement ones. Do you know anybody who has old rods that I can buy, or is there a cross reference list from other engines where the threaded rods would fit?

Thanks for helping.

Christian

[38Buick 80C]

Christian,

I would say there is not a trick or magic specific to the engine for these bolts. As I recall on my 38 320 they came out relatively easily you just need to get leverage on the stud. Have you tried locking to nuts against each other on the stud to act as a bolt head of sorts so you can apply more leverage to the stud.

I'm sure some of the other crafty veterans here have some stud removal tricks, but there is nothing special about these studs related to the engine.

As for drilling them out I am not aware of reproduction being made. You could probably source some used ones from Dave Tachney in MN however. I also suppose you could have the machine shop fabricate new ones using a long bolt and cutting off the head and threading that end. I personally would want to have replacements before I drilled (and therefore destroyed) my originals.

Good Luck and let us know how it goes.

[Guest Harry HT]

Christian,

If you mean cylinder head studs ? Change them all. 72 years old stud is very big risk in place like that.

It's for sure already stretched from that measurement what is was in 30's. You have to tighten that cylinder head nut

quite hard torque. Some 65 -70 Lbs.ft (approx. 88 - 95 NM) and if you use old studs you may cut some of those.

Also your cylinder head is quite long and if some of those studs cut when you have engine on fire it will blow up your head gasket and may pop up a couple of other studs too.

According to buick master parts list right measurements are : 7/16 - 20 x 5 5/16

Same stud were used with quite many buick engines from 1925 till 1938. You may not find original from GM part store

but maybe from ARP or some other similar one. Bolt materials today are much more better than it was in 30's so you can

also find it from local nuts & bolts shop. Just be sure that it is harder than normal bolts. Even regular bolt will fit if you just cut off the head as Brian was telling earlyer.

And then to your question :-) . No, you dont need any magic or hocus pocus. There is a tool for taking off those studs from block. They have it in your machinery shop i think. At least they should have. Change the shop if they dont.

Good luck,

-Harry-

[38Buick 80C]

Christian,

Now that Harry posted the picture, I remembered why they were so easy to remove. I forgot I have the stud remover he pictured. I bought mine from a local MAC Tools friend I know. You may be able to rent one from a local auto parts store too.

Also for bolts if you can't find the size and grade you need locally. I have had good success with Bolt Depot - Nuts and Bolts, Screws and Fasteners online, but it doesn't look like they ship internationally. Maybe there are similar websites that do or are located in Europe. Just wanted to pass on the idea.

[chstickl]

Dear Harry,

thanks for advise. Would you have more details about those head studs from your buick master parts list? I don´t have one and it would be very helpful to get all relevant details (type of thread, measures, drawings, so that I can get them manufactured over here.

Thanks,

Christian

[Guest Harry HT]

Christian,

It's all already there what you need. Master parts lists dosn't give you any technical drawings of bolts or etc. It's just a book of numbers.

Everything you need to know is 7/16 - 20 x 5'' 5/16 . Turner man in your machinery shop get every information from that.

7/16 is size of tap (~11,11mm). 20 mean How many threads in 1 inch.(Probably UNF(?) in this case...) and 5 5/16 is lenght of whole stud ( ~ 135mm). All extra what you have to tell him is how hard that material have to be. If you were in USA you should say Grade 8. But 'cause you seems to be in europe 12.9 is the right one.(dont take 8.8 !!! That's the "normal" bolt hardness nowadays in europe.)

There can be also bolts like 7/16 - 20 in your local hardware store already. Just select suitable lenght and cut off the head.

Take care,

-Harry-

[Guest Jenny B]

Please can you enlighten me as to the bore and stroke of my engine number 3186298 below casting number 1296124-1

CM 9415

Kind Regards

Jenny B