Hi Steve,
I know this is a bit late, since I did this way back around October of
1999, But better late than never.
If you remember I bought a used Edelbrock F4B intake manifold that
turned out to have some stripped threads where the stud mounts to the intake
manifold to bolt the carburetor down. The stripped threads kept the
carburetor from being torqued to the recommended 10 ft-lbs. This in turn
caused a vacuum leak that kept the engine from running correctly. I solved
the problem by using a thread repair system.
The size I used was a UNC 5/16"-18. You will need a 21/64" drill bit.
Before drilling make sure all openings on the intake manifold are covered to
keep all metal fragments from entering the engine and damaging the engine
internally. You must drill perpendicular to the mounting surface. I used a
small carpenters angle to check myself before drilling and had another
person watching to make sure I did not move and change the angle. If you do
not drill the hole so it is perpendicular to the mounting surface, your
carburetor will not be able to clear the studs as it is lowered onto the
manifold. (If you are off just a little you can always use your drill to
enlarge the mounting holes on the carburetor base plate. The gasket will
also have to have the mounting holes changed to adapt. Do not force the
carburetor over the studs or you may damage the threads on the studs and I
do not recommend forcing the gasket or you might damage the gasket.) I used
my vernier to check web thickness and found that the least I had at the top
was 3/16". Since the web gets thicker as the stud goes deeper I thought I'd
try to measure the thickness as the stud went deeper. Again the smallest
measurement I could find was 1/8". These measurements vary so each manifold
will be different just as with mine, each hole has different measurements.
Make sure you clean the holes of all metal shavings so the inserts will go
deep enough for the studs to mount properly. This needs to be done after
drilling and before mounting the inserts. Once everything has been finished
and checked to see if it all works, you may want to remove all the inserts
and apply some locktite to the inserts then re-install them. I let
everything set up for 24 hours after applying locktite. Since completion
I've had the carburetor off and on several times without any problems. Just
remember to torque the carburetor to 10 ft-lbs. Hope this helps someone
else. I know there was concern over the web thickness, but I have had no
problems so far. Crossing my fingers it stays that way.
Dan Eiland
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