Flathead head bolts

Are stainless steel head bolts OK into flathead water jackets???

Anybody done this before with any bad issues.

What precautions should I be taking???

 

Flathead head bolts are 7/16-14 threads per inch and are generally torqued to 65-70 foot pounds. Stainless bolts tend to gall which is detremental to the threads plus they cannot withstand the torque of a "same size" steel head bolt and may stretch. The chart below was taken from the Fastenal website and shows that the maximum torque allowed for a 7/16-14 stainless bolt is 376 or 393 inch pounds. Divide that by 12 and you obtain 31 and 32 foot pounds of torque. Use the recommended steel bolts which will withstand the torque. Also, if you are worried about corrosion, the thread sealant you use will protect the bolt from corrosion. ( If I am misinterpreting the chart, please let me know.)

 

The bolts I have been offered are supposed to be APR for this purpose.
Be nice to know if anybody has used stainless and whether they turned out to be OK.

 

What is APR?

 

Approved.

 

Mike, Just curious. Why do you want to use stainless for head bolts?

 

I never torque more that 50 ft lb.

 

Maybe he means ARP?

Bob

 

Use anti=sieze with stainless, but I wouldnt use them at all

 

Sorry, I think it should be ARP they are a bolt manufacturer.

 

A buddy of mine has suggested I use the water sealer on the tips and anti seize on the shafts.
It seems nobody has actually used stainless head bolts then.
It is not a good sign...

 

Just following up and my install.
It seems that the head bolt supplier short changed me 2 bolts in my set.
I contacted him and he sent me the extra bolts without a problem, but also sent me what he should have also included in the 1st package, which was a simple conversion chart for the stainless steel head bolt torque setting.

Yes stock bolts were 65-70lbs and for these bolts ARP recommends 57lbs maximum.

I thought this was worth posting as it may help somebody else in the future.

 

Ford service manual. 40 aluminum, 50 cast iron.

 

Stainless only Galls to other stainless i.e. stainless bolt and stainless nut.
This can be reduced by using Different series SS for the bolt and nut. Like 304 bolt and 316 nut. Stainless does not GALL to cast iron.

 

8BA/CM will be 67-70 FT/LBS on iron heads and most after market Aluminum manufacturers recommend 50-55.

 

ARP is one of the few American manufactures of high quality hardware.
The bolts they provide for flat head head bolts or studs are NOT made from stainless.

Here is their site ...

http://www.arp-bolts.com/

 

Ah. Should have realized this is a 8ba from the post on bolts over studs. My bad. Still think we have a tendency to over torque everything.

Also to disagree with the ford specs. Dont torque with hot heads.

 

From the VanPelt site:

 

Unless it's a "Dearborn" grade restoration, I'd go with studs,...ARP has kits available. As suggested above, use sealant on the block ends,......I have good luck using the "hardening" type "Permatex" brand. With aluminum heads, I use a little "anti sieze" along the part that goes thru the heads.

4TTRUK

 

Head bolts are listed on page 44 of the catalogue and yes you are correct as it does not describe stainless steel head bolts.
However on page 79 stainless steel bolts are described with basically the same spec's.
These are the ones I am using.

I am installing these bolts on my Cadillac flathead engine.
I am taking a risk but believe it is a calculated one.

 

Sorry but I prefer studs to bolts on almost any cylinder head install. Also other than being shiny I'm not sure of any advantage for using stainless.

 

Can you torque a stud as high as a bolt in the same application?

 

Good question. Head bolts been installed for several years now and seem to be holding during warm up and regular running. Project is not finished yet so road trail etc has not been done.
Yep , they look pretty and seem to seal OK.

You can see and hear it here.