1/2" studs.

Geoff

Asking for clarification please. If considering converting a 308 motor to 1/2" studs, this would involve re-tapping the block. As there is a t.p.i. difference on the 1/2" threads (13 against 14 for the original 7/16" bolts) I presume there is enough metal around the hole to allow this tapping? I have to rebuild the motor in my Hornet sometime, so just considering if it is worth the extra effort to go to studs.

Ol racer

Its the way to go... Be sure to use a Tap 'guide' to ensure tapped straight. Some have block tapped in a Machine Shop.
Another alternative (if not racing) is just buy Dorman 7/16" Studs with large washers & use 7/16 wheel lug nuts. Studs enable 'True Torque' without defection when twisting Bolts as torqued.
The Best Brand Permbond gasket is best to use....

[Deleted User]

Geoff: a valuable tip, Marvel Mystery Oil (MMO); I use it even in my lawn mowers (add one ounce at each oil change and keep oil clean --> if you can smell bad exhaust fumes it's past time to change it, even if it looks clean).

I use it in my cars and truck (Nissan Frontier w/162,000 and still no oil useage and tight timing chain) I always change the filter and use Valvoline synthetic blend, plus add 2-3 ounces of MMO.

On that Hudson 308, once the rings fully seat and not before, start using this MMO and you'll never have to rebuild it again.

It will help revive the older engines too !! Try this in your 308 and you might not need to rebuild it. Add some to the fuel tank and you'll see a smoother-running engine. It's marvelous !!

barrysweet52

Can anyone find MMO outside the USA?

[Deleted User]

this may help:

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bob ward

Geoff, tapping drill for 1/2" UNC is 27/64", it won't quite clean up the old 7/16" threads, it misses by 8 thou per side. Not strictly kosher, but the 1/2" studs will hold in the block just fine.

FWIW the 7/16" head bolts in my 53 Hornet have been increased at some time in the past to 1/2" bolts (bolts rather than studs) and the head holds on just fine. If/when I ever need to do anything major to the engine I'll change the bolts to studs.

http://www.carbidedepot.com/formulas-tap-standard.htm

Geoff

Thanks for the info Bob. I presume you also had to enlarge the holes in the head as well? May catch up with in Dec., coming to Brisbane for Christmas.
Geoff

bob ward

Geoff, its a long time since I looked at this but IIRC there are 3 different size bolt holes from the factory in a stepdown head. Out of the 7 sets of 3 holes in the head, the centre set are pretty tight on 7/16" and locate the head on the block, the 2 sets each each side of centre are 15/32", ie 1/32"slop, and the 2 sets at each end are 1/2". Something to bear in mind when locating each head hole before enlarging it.

Sent a PM.