Hi, what thread is used on the cylinder head studs,Metric or AF or something else. I want to get a tap and run it down to clean up the thread holes. Thanks.

The tool you want is a chaser, it looks like a tap, but doesn't cut. Instead it stands the threads up straight & cleans them.

I've never seen anything older than a B18, but it has to be UNC with an outside chance of whitworth, which stands out because it has a 55° angle, not 60° as with SAE & Metric. From what I've seen from other Volvo equipment they adheared to SAE standards early on and somethings stayed SAE i.e., truck bellhousing patterns.

Also with studs, make sure you don't bottom out the top thread when you put it back together. Screw it in finger tight & back it out a little, anti-sieze on the inside threads & oil as specified by the torque method.

An often overlooked tool set and not that outrageous in price.

But you should make sure to get a combined metric and standard thread chasing kit and even then you might not have everything you might need.

For instance, I have a thread chaser for the 7/8" x 14 tpi rear axle threads as all of the kits I've seen stop at 12mm and 9/16".

But even I don't have everything I need. I have never found the correct thread chaser for the very early driveshaft bolts and nuts which have Wentworth threads and I don't have a thread chaser for the few cars that have left hand thread wheel nuts.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Make your own by grinding 3 or 4 slots in a relevant size bolt.

The only problem with this technique is you need to have a sacrificial spare bolt/stud.

Have you ever tried to find a B16 head stud?

I have, and they appear to be made of unobtainium.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Hold the tap that you want to evaluate against one of the studs - the threads should mesh perfectly.

Try doing the same with 2 studs and you will see what I mean.

The threads for the head studs in a B16 block are not a standard thread and I can't tell you what they are.

For the very few B16s I have rebuilt, I just used a stiff wire brush to clean the threads in the block and a wire wheel to clean the threads on the studs.



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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com