injector bosses

[Johnny]

James Weiler wrote:
> 
> On Thu, 28 Aug 1997, Paul Witek wrote:
> 
> > Hey gang-
> 
> <snip>
> 
> > Now I just need to figure
> > out how to modify the manifold for the injectors....
> >
> Hi Paul.  You and I are at the same place.  I'm trying to figure out how
> to mount injector bosses in an aluminum intake as well.  I've thought
> about threading them in but large taps and dies are expensive, but if
> this is the way to go then I'll just bite the bullet.
> 
> Welding (I've been told) will distort the manifold too much.  What
> about bolting it to a pair of heads prior to welding?  Ideas anybody?
> I've heard alot of people have epoxied them in place but I worry about
> the durability of the epoxy.  How long will it take for gas to break it
> down is one of my concerns.  I don't know but epoxy just sounds Mickey
> Mouse.  Am I way out of line here?
> 
> My bosses have an outside diameter of 0.845 inch and I've drilled a 14mm
> hole through the centre for the O-ringed part of the injector to fit into.
> I have access to a lathe so I can mill them down to 0.75 inch diameter.
> 
> What kind of angle between the boss and the runner are you going to use?
> The Corkey Bell book claims 20 degrees is maximum.  If you look at what's
> out there (i.e. Accell for example) they mount bosses straight up.  The
> intake runner is at about 45 degrees in that case so the angle is between
> the boss and the runner is also 45 degrees.  So much for the 20 degree rule.
> 
> Perhaps I'm sweating something really trivial and I should just get on
> with it.

Both Accel and MSD sell inserts made of aluminum, in both thread in and
weld/epoxy in. I think you will find that there is not enough meat to
thread them in where you want to at the angle you want. I haven't tried
to epoxy them in, but I would think that JB-Weld would do just fine
there if everything was cleaned right (read freshly glass beaded). I
have also welded them in and can clue you in on the distorsion issue.
Make a jig out of some HEAVY angle iron and bolt the intake manifold to
it like you would bolt it to a head. Find yourself somebody that does
TIG in their sleep with both hands tied behind there back. The bead
doesn't have to be big (read too much heat) if the holes were cut well
for the inserts. After the welds are done and the manifold has cooled
all the way, unbolt the manifold from the angle iron. Take a die grinder
and remove the part of the insert that protrudes into the runner. The
inserts are longer than you need, and you will have to test fit an
injector in there to see how far you need to have your insert into the
hole you cut in the manifold. When you are done the warpage should be
minimal, but take it over to the broach at your friends machine shop and
surface it anyway. If it is very minimal, you can just use a long board
and some 50 grit cloth.

-j-