Well, I think I got through the 3810 main body preparation this afternoon.
First thing was to check the plane of the base and metering surfaces. They looked pretty flat but you never know.
Before getting into the planing, I noticed that this 3810 main body had only 6 of the 8 screw holes attaching the throttle body to the base tapped for screws. I took out only 6 screws where there are 8 holes in the throttle body.
In researching this in old Restorer stories, I found that original 67 3810's and 66 3367's had only six screws attaching the thottle body to the base. Maybe the reasoning was, that the L79 or other manifolds with larger top openings had an opening which would allow the two screws to loosen and fall into the manifold, or reason two was that they may just wanted to save a few pennies.
Since I have a standard 4 hole manifold, for which there is no possibility of the screw going into the manifold, and since the 2 extra screws would provide a better seal between the throttle body and main body, I opted to tapped the two extra holes and add the two screws from another carburetor (which I had previously plated).
Here's the process in pictures:
The last shot is the eight screw locations. I used a #12-24 thread tap. The base plate at the screws is 3/8" thick, so you need to tap the holes deep enough for less than 3/8" between the screw head and the baseplate. It's best to check the thread depth by mounting the base plate and see if you can tighten the base plate snug to the main body.
Now on to main body planing.
First thing was to check the plane of the base and metering surfaces. They looked pretty flat but you never know.
Before getting into the planing, I noticed that this 3810 main body had only 6 of the 8 screw holes attaching the throttle body to the base tapped for screws. I took out only 6 screws where there are 8 holes in the throttle body.
In researching this in old Restorer stories, I found that original 67 3810's and 66 3367's had only six screws attaching the thottle body to the base. Maybe the reasoning was, that the L79 or other manifolds with larger top openings had an opening which would allow the two screws to loosen and fall into the manifold, or reason two was that they may just wanted to save a few pennies.
Since I have a standard 4 hole manifold, for which there is no possibility of the screw going into the manifold, and since the 2 extra screws would provide a better seal between the throttle body and main body, I opted to tapped the two extra holes and add the two screws from another carburetor (which I had previously plated).
Here's the process in pictures:
The last shot is the eight screw locations. I used a #12-24 thread tap. The base plate at the screws is 3/8" thick, so you need to tap the holes deep enough for less than 3/8" between the screw head and the baseplate. It's best to check the thread depth by mounting the base plate and see if you can tighten the base plate snug to the main body.
Now on to main body planing.