fabrication question

[Belgian1979]

I need to construct an air bypass line for intake runners. I would like to be able to restrict the airflow if needed. What would be the best way to tackle this ?
PS : I don't have a mill nor a lathe.

[ProPower engines]

What is the purpose of this bypass??

[MadBill]

You're a little short on detail but if for example you were talking say a 3/16" neoprene hose to each runner, you could press in brass Allen head set screws drilled to the desired orifice size. A box of 50 is only a few bucks from McMaster Carr or the like and would give lots of scope for going too big and starting over. If you're talking one big hose, you could just drill a metal or plastic slug of the right diameter, either pressed or threaded in.
.

carb jets 003.jpg

[Belgian1979]

What is the purpose of this bypass??

iac air to individual runners that I need to get balanced. The full details would mean a very very long explanation....

[Belgian1979]

You're a little short on detail but if for example you were talking say a 3/16" neoprene hose to each runner, you could press in brass Allen head set screws drilled to the desired orifice size. A box of 50 is only a few bucks from McMaster Carr or the like and would give lots of scope for going too big and starting over. If you're talking one big hose, you could just drill a metal or plastic slug of the right diameter, either pressed or threaded in.
.
carb jets 003.jpg

That looks like something I could work with. However I'm dealing with an alu line which is fixed into the runner. Need to give this another thought.

Thanks Bill.

[grandsport51]

How about needle valve manifold for aquarium co2 systems

http://www.aquacave.com/aquarium-co2-su ... alves.html

[user-23911]

I need to construct an air bypass line for intake runners. I would like to be able to restrict the airflow if needed. What would be the best way to tackle this ?
PS : I don't have a mill nor a lathe.

Dump the ITBs and use a proper manifold with plenum.

[mk e]

The easiest would be don't bother then adjust the throttle plates to balance it. If you set the unloaded warm idle using the throttle not the is the whole system will be much less sensitive and your off idle throttle will be easier to manage

A version Bills suggestion is the other path. The fanciest version is to use needle valves, they make pipe thread on 1 end that you could screw into the little plenum. The very cheapest version is solder the fittings you have shut and drill to size.

[bill jones]

---I did the same thing on a Crower fuel injection---
---I found 8 small needle valves with 1/4" tube spouts and 1/8NPT male fitting ends---just use some short pieces of push-on hose.

---I don't remember where the valves came from.

individual cylinder idle air control for Crower fuel injection.jpg

[englertracing]

PS : I don't have a mill nor a lathe.

So step 1 is to get a mill and a lathe.

[Leftcoaster]

Your local plumbing or hardware store should have small brass bleed screws very similar to those posted by Bill Jones

They're used to vent air bubbles out of the radiators in countless large buildings such as libraries and hotels

[peejay]

What is the purpose of this bypass??

iac air to individual runners that I need to get balanced. The full details would mean a very very long explanation....

It would be far easier to use an IAC motor that opened the throttle directly, for various reasons related to the strangeness of IR setups. 1980s Cadillacs with the 4.1/4.5/4.9l engine used a stepper motor throttle stop for idle control that would serve you well.

[peejay]

I need to construct an air bypass line for intake runners. I would like to be able to restrict the airflow if needed. What would be the best way to tackle this ?
PS : I don't have a mill nor a lathe.

Dump the ITBs and use a proper manifold with plenum.

Plenum manifold engines drive like shit. Poor throttle response and awful midrange.

[Belgian1979]

What is the purpose of this bypass??

iac air to individual runners that I need to get balanced. The full details would mean a very very long explanation....

It would be far easier to use an IAC motor that opened the throttle directly, for various reasons related to the strangeness of IR setups. 1980s Cadillacs with the 4.1/4.5/4.9l engine used a stepper motor throttle stop for idle control that would serve you well.

This certainly is a possibility, but I never found a stepper motor powerfull enough to work against the springs and such. Do you have a part number ?

[Belgian1979]

---I did the same thing on a Crower fuel injection---
---I found 8 small needle valves with 1/4" tube spouts and 1/8NPT male fitting ends---just use some short pieces of push-on hose.

---I don't remember where the valves came from.

individual cylinder idle air control for Crower fuel injection.jpg

Bill,

Interestingly enough I was thinking of doing something similar. Did the needles work in a 1/4" hole. Most needles I see are very tiny and wouldn't allow enough airflow past them.