I asked this question in preparation for rebuilding my B30 with a blown head gasket. I am suspecting poor gasket quality and I will be purchasing a gasket kit from Volvo for the re-do. All head bolt threads looked OK during the first rebuild, but I had to clean all of them due to surface rust. The rods and mains were fine. Should they be replaced? In questions I posted after the gasket failed, replacing the head bolts was suggested to remove them from the equation as suspect. Advice?
Thanks,
Nick

You can't buy regular bolts & use them for head, main or rod bolts as they are specially designed with necked down shanks, etc.

What I recommend is hardened grade 8 washers for the head bolts & new grade 8 nuts for the rod bolts if the the rod bolts are still good. When installing grade 8 nuts (3/8" UNF), one side is ground perpendicular to the threads & goes towards the rod, the other side with 6 lines goes out.

If you are going to boost the motor, then I would get head studs. If you are going to rebuild the rods, i.e., polish beams, shotpeen, resize & rebush, then I believe ARP Cleveland bolts are the ones to use.

Rhys is right.

Sizes are:
Head Bolt: 191523 7/16"-14 UNC
Main Cap: 942852 or 945799 ½"-13 UNC
Rod Bolt: 415223 or 463090 3/8"-24 UNF
Rod Nut: 191410 or 463643 Same as bolt

In over 40 years of playing with Volvos I have NEVER bought a head or rodcap bolt.
The ONLY reason I have bought maincap bolts is that I put 6-bolt innards into a BARE 8-bolt block I found
in Panama and had to get metric maincap bolts to fit, which turned out to be impossible in the Republic.
I found them fairly easily in Dallas. They were M12-1.75. CAUTION: this size is a TRAP for people with UNC bolts!
A 7/16"-14 UNC bolt WILL screw in the hole but it is about 0.035" smaller and the pitch differs by about
a tenth of a thread per inch so the bolted joint has very little strength and will strip easily!
8-bolt blocks seem to use this same thread on the bellhousing mount bolts also.
Otherwise the 8-bolt block (at least the one I had) had Unified threads throughout, only maincap and bellhousing were metric.
--
George Downs, Bartlesville, Heart of the USA!

Hi Nick;
The head bolts are 7/16 UNC - the others I don't know off hand. George will know.
However, in my experience it is not necessary to replace the bolts in these engines. For sure the rod bolts and nuts are very specific, and you will not find them easily. I doubt even ARP lists them. They don't fail in any event. The main cap bolts are massive and also don't fail. The only ones that need replacement are head bolts that become rusty and pitted in service, like the center bolt on the four cylinder engines. I simply install used bolts from another engine.
About twenty years ago I priced rod bolts for an engine I was building and intended to buzz to 7000 rpm. Volvo Canada had them for $14.00 each! I passed on that purchase, and the engine did buzz to 7k and never blew up.
Rhys