Custom parts for your EFI installation. 

Here is a project we are doing for our Company car, a 1962 Corvair convertible. 

We are keeping this project on the mild side, with only updating the EFI and adding sheet metal manifolds to stock heads with a good porting job.  I am still using the small valve heads for this motor.  Below are some photos of the almost ready head and manifold.

All we did here is bore into the ports to place 1.5" tubes that are blended into the port walls.  We then made a .250" floor for the manifold so that a nice radius could be made for entry into the ports.  Then a 2.5" tube had a slot cut into it for the manifold floor, and was then welded onto the floor.  The inside of the manifold is made deliberately rough so that any fuel that drops out of the air stream will evaporate back into the air stream rather than pour into the cylinders. 

I know that a lot of guys like to use a single plenum with 6 runners.  The real problem I see with that is the length of the runners.  They get LONG on a boxer motor.  I guess that is fine if you want peak torque somewhere around idle, but even with an almost stock cam, I am looking for peak torque a little higher than that, around 3000 to 3500 rpm.  The only advantage I can see to the single plenum is that you only need one throttle body.  Hardly worth the trade off of less power to me. 

The throttle bodies I chose are from a mid 90's SFI 3100 Pontiac.  They are a little larger than I really need, but will work out just fine.  I may need to add a little extra acceleration enrichment at the first hit of the throttle due to their larger size.  Still this is nothing that a little tuning can't take care of.  The throttle bodies in stock form were a little large, and had to be machined down to prevent them from getting in the way of the fuel injectors.  Machining off one side was not a problem, as it was just a casting boss.  The other side was the IAC motor housing.  So when I machined that off, it left an enormous vacuum leak. 

Above you can see the IAC housing being milled off, then to the right you can see an un-machined throttle body next to one that has been milled down.  You can see the enormous vacuum leak at 9 o'clock on the machined body.  To fix this, I simply bored the throttle body, and then machined a ring to press into the throttle body.  Below left you can see the throttle body bored out, and below right you can see the insert being machined.

After that, a little Locktite, a little press and a finish cut, and the throttle body is that much closer to being installed on our 62 Corvair.

There is more to come on this story, so check back!