twin carb conversion

[bravekozak]

pulse air

The main reason for going with a twin carb setup was to do away with all computer and pollution controls. Unfortunately, the setup included pulse air. There was a set of two tubes to bring it from the left to the right side of the engine. I removed the aluminum reed assembly and left the four screws in their respective holes. I turned the air cleaner housing upside down and cut the two spotwelded clamps off with a super disc. Less clutter + my EFI cat has no connection tube.

http://bwbronze.com/festiva/under.jpg

The stock throttle cable will not hook up properly. It is too short to be supported with the stock valve cover cable bracket. I am currently investigating a couple of sources:

http://greenskyadventures.com/throttle_cable/custom.htm

I found a source for a twin choke grommet (#1806):

http://www.datsunparts.com/Rubber-Parts

Here are the tune up instructions for the twin carbs:

http://bwbronze.com/festiva/laser.pdf

[Festiva_tunner]

looks like its comming along - cant wait to hear it when its finished

[bravekozak]

choke hole

I drilled an oblong hole today for the twin carb choke. I used a 5/8" hole saw + a Dremel with stone and a carbide. As you can see from the picture the wide part is where it splits into two. After considering locating it in place of my cigarette lighter, I ruled it out, based on the way it attached to the carb brackets.

http://bwbronze.com/festiva/tcc_hole.jpg

As you can see, the best location is directly below the 1" round hole I dilled for my cruise control wiring. I am dismayed that I tossed out my grey 89 dash, which had provision for a manual choke. All choke knob supports have a flat spot to prevent rotation. I will not be able to simply drill a round hole to mount it. I am leaning toward a dash undermount bracket, since there is steel reinforcement behind the normal mid dash mounting position.

[FeistyFesti]

I think the second most gorgeous thing in the world next to a beautiful woman is machined aluminum or stainless steel parts.

[bravekozak]

throttle

I am having a custom cable made up from parts taken from an Acura Integra cable and the stock Festiva throttle cable. The cable would have to sit low to the cover and have a long lead.

http://bwbronze.com/festiva/cable1.jpg

http://bwbronze.com/festiva/cable.pdf

[bravekozak]

custom cable

I finally got my custom throttle cable.
Festiva blue plastic and the rest from an Integra.

http://bwbronze.com/festiva/custom_throttle.jpg

I was at Performance Improvements speed shop Midnite Madness sale last night. I got what I needed. Since I can't put on a mechanical fuel pump because of interference from the carb, I had to swap back an EFI tank and pump. These carbies run at just under 4 psi. So I bought a Holley bypass regulator to send most of the fuel back to the tank.

http://bwbronze.com/festiva/holley.jpg

[bravekozak]

wingnuts

The Ford laser came with two different air filter housing lids. One had large holes and one with regular holes. The Hitachi carbs have 6mm studs. I collected sets of everything I could find with a 6mm thread.

Here is a picture of them showing both sides:

http://bwbronze.com/festiva/wingnuts.jpg

Which pair should I install?
Can you guess which pair is the stock one?

Hint:
The Cadilllac TBI ones are round and have a threaded metal insert.
The Geo Metro ones are all metal

[bravekozak]

Pcv

To properly suck from the PCV (positive crankcase ventilation) valve, the EGR (exhaust gas recirculation) adapter had to be installed on the manifold. Since I am not using an EGR valve, I had to fabricate a simple block off plate.
I simply drilled two holes in a small piece of 1/4" thick aluminum. Then scribed an outline, cut close to the scribe line with a hacksaw, used a small end mill in a drill press to finish the profile.
I need the large port for the PCV vacuum hose.

[drddan]

^^^ ???? Huh? Please explain ....adaptor?

[bravekozak]

There aren't many places on top of the intake manifold to locate vacuum ports, because of the two carbs. I was going to leave off the cast iron EGR mount, however, the PCV valve needs a large diameter hose. I had made a block off plate for the cast iron adaptor, but I had to discard it and make a smaller block off plate for the EGR mount. I will take a picture of the stock Laser PCV hose so you can see what I mean. The hose is rather long and wraps around the entire right hand side of the manifold.

[bravekozak]

fuel pump switch

I cannot use a mechanical fuel pump because of interference (not enough room).
If I use the factory electric fuel pump and relay, I don't have a vane air flow meter. The fuel pump switch is part of the vane air flow meter.
I presume if there is no air flowing, the switch opens and the fuel pump is shut off. Should I just ground the VAF contact on the fuel pump relay so that the pump always pumps when the engine is running? Or should I put a manual kill switch in between so nobody steals the car and I can shut the pump off if I am still conscious after an accident? Or should I wire it to respond to oil pressure instead of air flow? See the two pressure switches that say "electric fuel pump" on the last page.
Most newer vehicles have the oil switch control the fuel pump power. Should the vehicle run too low on oil, the pressure will drop, the fuel pump will turn off and the engine will shut down preventing serious damage.

Even with an oil pressure switch, if I put a kill switch in the ground circuit for the fuel pump relay, just about any tiny switch will work since at most I will be switching 500mA (1/2A).

[mattman]

just wonder what kinda growl is gonna come from under the hood ..had a friend with a old z an multi carbs that sounded flat out evil ..way kool project you have going on hear i love it

[bravekozak]

Blue Christmas

It looks like I'll be having a blue Christmas this year. Another adapter for the second extra set of carbs I have.

[drddan]

Oh, yes! The blue toolmaker's ink. Invaluble.

[bravekozak]

custom throttle mount

Here is a pic of the custom throttle mount plate I cut, drilled and tapped to place the throttle cable in the proper position. The reason why it's so large at the front, is to eventually install a stud for the air cleaner snorkel hold down. The aluminum plate is 1/4" thick.