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Bored&Stroked · 08-23-2020, 11:15 AM

There are many ways to skin this cat - heck, I'd just pick one. You can run longer plugs with 'shims' (I'd prefer them to be made of copper), you can chamfer/change the bottom portion of the head chamber-side (chamfer/blend), you can machine steel or aluminum inserts and machine the original threaded holes to insert them - these can do TWO things:

1) Gives you a specific length and quality of thread as far as wearing out over time. Many of us have experienced that sickening feeling when you tighten a plug and the old aluminum threads give way . . . boy does that suck.

It usually happens when you are in a hurry to get someplace, are far away from home and your tools and/or have no time to now pull the heads and "fix" them . . . . that 'Murphy' is a rotten Devil!

2) You can make the threaded inserts to support 3/4" reach plugs - which are by far the most common and give you a ton of different heat ranges, suppliers, etc..

Keep in mind that folks like Edelbrock retooled most of their patterns (if not all) and machining operations to produce heads that take 3/4" reach plugs . . . a very smart thing to do! This is one reason I use Edelbrock heads on many modern builds.

08-23-2020, 11:15 AM	#27
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,062	Re: AutoLite 216's in Offy heads There are many ways to skin this cat - heck, I'd just pick one. You can run longer plugs with 'shims' (I'd prefer them to be made of copper), you can chamfer/change the bottom portion of the head chamber-side (chamfer/blend), you can machine steel or aluminum inserts and machine the original threaded holes to insert them - these can do TWO things: 1) Gives you a specific length and quality of thread as far as wearing out over time. Many of us have experienced that sickening feeling when you tighten a plug and the old aluminum threads give way . . . boy does that suck. It usually happens when you are in a hurry to get someplace, are far away from home and your tools and/or have no time to now pull the heads and "fix" them . . . . that 'Murphy' is a rotten Devil! 2) You can make the threaded inserts to support 3/4" reach plugs - which are by far the most common and give you a ton of different heat ranges, suppliers, etc.. Keep in mind that folks like Edelbrock retooled most of their patterns (if not all) and machining operations to produce heads that take 3/4" reach plugs . . . a very smart thing to do! This is one reason I use Edelbrock heads on many modern builds.