fabrication question

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Belgian1979
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fabrication question

Post by Belgian1979 » Sat Mar 10, 2018 2:11 pm

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.

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Re: fabrication question

Post by ProPower engines » Sat Mar 10, 2018 2:14 pm

What is the purpose of this bypass??
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MadBill
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Re: fabrication question

Post by MadBill » Sat Mar 10, 2018 4:12 pm

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.
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Re: fabrication question

Post by Belgian1979 » Sun Mar 11, 2018 3:53 am

ProPower engines wrote:
Sat Mar 10, 2018 2:14 pm
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....
Last edited by Belgian1979 on Sun Mar 11, 2018 3:55 am, edited 2 times in total.

Belgian1979
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Re: fabrication question

Post by Belgian1979 » Sun Mar 11, 2018 3:54 am

MadBill wrote:
Sat Mar 10, 2018 4:12 pm
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.

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Re: fabrication question

Post by grandsport51 » Sun Mar 11, 2018 4:55 am

How about needle valve manifold for aquarium co2 systems

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

Post by user-23911 » Sun Mar 11, 2018 6:35 am

Belgian1979 wrote:
Sat Mar 10, 2018 2:11 pm
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.

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Re: fabrication question

Post by mk e » Sun Mar 11, 2018 8:26 am

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.
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Re: fabrication question

Post by bill jones » Sun Mar 11, 2018 10:12 am

---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
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Re: fabrication question

Post by englertracing » Sun Mar 11, 2018 11:27 am

Belgian1979 wrote:
Sat Mar 10, 2018 2:11 pm
PS : I don't have a mill nor a lathe.
So step 1 is to get a mill and a lathe.

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Re: fabrication question

Post by Leftcoaster » Sun Mar 11, 2018 12:44 pm

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

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Re: fabrication question

Post by peejay » Sun Mar 11, 2018 12:44 pm

Belgian1979 wrote:
Sun Mar 11, 2018 3:53 am
ProPower engines wrote:
Sat Mar 10, 2018 2:14 pm
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.

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Re: fabrication question

Post by peejay » Sun Mar 11, 2018 12:46 pm

joe 90 wrote:
Sun Mar 11, 2018 6:35 am
Belgian1979 wrote:
Sat Mar 10, 2018 2:11 pm
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.

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Re: fabrication question

Post by Belgian1979 » Sun Mar 11, 2018 2:27 pm

peejay wrote:
Sun Mar 11, 2018 12:44 pm
Belgian1979 wrote:
Sun Mar 11, 2018 3:53 am
ProPower engines wrote:
Sat Mar 10, 2018 2:14 pm
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
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Re: fabrication question

Post by Belgian1979 » Sun Mar 11, 2018 2:28 pm

bill jones wrote:
Sun Mar 11, 2018 10:12 am
---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.

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