fabrication question

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peejay
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Re: fabrication question

Post by peejay » Sun Mar 11, 2018 2:49 pm

Belgian1979 wrote:
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


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 ?
Try ACDELCO 19160423 as an example.

Note that this is a stepper motor, and requires specific circuitry to control. I believe it works the same as GM's air valve type IACs.

joe 90
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Re: fabrication question

Post by joe 90 » Sun Mar 11, 2018 4:21 pm

peejay wrote:
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.
No they don't.Only when done wrong.
ITB manifold engines drive even worse when done wrong, or more realistically don't even go at all.

With ITBs, the throttles all need synchronising properly first which is difficult if you've not done it before.
Then, depending on the setup, the adjustment changes as the metal bits expand with heat.
To synchronise them, the backstops all need backing off, then readjusting by the exact same amount to open each one slightly, then all locking together so they open together, if even one shaft is worn, it's not going to perform right.

If the throttles aren't synchronised first, no amount of fiddling with pipes and fittings and vac chambers will get it right.


If you're having to ask questions all the time, the answer is going to be too hard.

stealth
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Re: fabrication question

Post by stealth » Sun Mar 11, 2018 5:28 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....
After you contemplate all the pros and cons you will see the problem has been addressed quite well a few years ago....it’s called EFI
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man.

Belgian1979
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Re: fabrication question

Post by Belgian1979 » Sun Mar 11, 2018 6:14 pm

stealth wrote:
Sun Mar 11, 2018 5:28 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....
After you contemplate all the pros and cons you will see the problem has been addressed quite well a few years ago....it’s called EFI
It's EFI. [-X

digger
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Re: fabrication question

Post by digger » Sun Mar 11, 2018 8:08 pm

So you want to sync the throttles at idle without the iac functioning and then recheck after the iac is working and you want to be able to change the distribution by being able to restricting the relevant individual bypass(s)?

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MadBill
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Re: fabrication question

Post by MadBill » Sun Mar 11, 2018 9:38 pm

I've synchronized many dozens of IR carb systems and a goodly number of EFI ones and it continues to amaze me how much better they drive (and sound!) when they're synched as perfectly as humanly possible rather than just really close. Among the several devices and listening tubes I've used, the Uni-Syn with various fabbed adapters gets my nod.
One trick that helps with some less well-designed linkages is to sync the throttles first with the idle stops, then use the linkage to just crack them open to verify or tweak the linkage as necessary to ensure synchronization is maintained in the off-idle position.
Felix, qui potuit rerum cognscere causas.

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modok
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Re: fabrication question

Post by modok » Sun Mar 11, 2018 11:28 pm

Yes indeed.
I'd say your efforts are best directed to make the linkage as precise and solid as possible, rather than spend a lot of time synchronizing the idle air flow or making bypass controls to control the idle speed.
IR setups idle very stable on their own, so you don't really need an IAC valve, OR maybe you do but it is low on the priorities.

Holding the throttle a little open with your foot should be fine for warmup. You guys that want to control everything with a computer....ok fine, but don't do a zillion bypass valves, just make a computer controlled foot. It's simpler.
Glen Urban

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Re: fabrication question

Post by joe 90 » Mon Mar 12, 2018 1:01 am

One of the old tricks for synchronising the throttles was "needle and thread".
It becomes obvious after a bit of thought.

As for using computers.......software never works properly with broken hardware.
So long as you get the hardware right, you don't need software, or not much of it.

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Re: fabrication question

Post by Belgian1979 » Mon Mar 12, 2018 5:30 am

digger wrote:
Sun Mar 11, 2018 8:08 pm
So you want to sync the throttles at idle without the iac functioning and then recheck after the iac is working and you want to be able to change the distribution by being able to restricting the relevant individual bypass(s)?
correct

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Re: fabrication question

Post by Belgian1979 » Mon Mar 12, 2018 5:33 am

MadBill wrote:
Sun Mar 11, 2018 9:38 pm
I've synchronized many dozens of IR carb systems and a goodly number of EFI ones and it continues to amaze me how much better they drive (and sound!) when they're synched as perfectly as humanly possible rather than just really close. Among the several devices and listening tubes I've used, the Uni-Syn with various fabbed adapters gets my nod.
One trick that helps with some less well-designed linkages is to sync the throttles first with the idle stops, then use the linkage to just crack them open to verify or tweak the linkage as necessary to ensure synchronization is maintained in the off-idle position.
No matter how good you synchronize them, as soon as the engine warms up the linkage changes a minute amount of length. So what is good in terms of idle rpm when warmed up, is not enough when cold, hence the need for IAC. The problem is that IAC tends to make some cyls run rich and some lean. So, although I'm convinced that the changes I intend to make will improve this, I want to be able to make minute changes to each cyls iac air. The more equal they are the better the engines runs overall.

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Re: fabrication question

Post by MadBill » Mon Mar 12, 2018 9:28 am

On my cross ram 2 x 4 set ups, I use a scrapyard* A/C solenoid like this with a simple toggle switch. Although it is not usually strong enough to force the linkage open from the warmed up curb idle position, it will easily hold it open, so the drill is to open the throttle slightly, power up the solenoid, then foot off and crank. The stroke is fully adjustable to provide the desired RPM. *Found by the thousands in Canada/US yards; likely not so much in Europe..) http://www.ebay.com/bhp/idle-solenoid
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Re: fabrication question

Post by mk e » Mon Mar 12, 2018 11:34 am

You could convert to dbw with something like this:

https://www.dtafast.co.uk/dta_products/ ... ontroller/

I use a BMW actuator from one of their ITB cars, it was like $50 used on eBay.

An option anyway.
Mark
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Re: fabrication question

Post by bill jones » Mon Mar 12, 2018 1:02 pm

-this is the valve taken apart---it has a simple .153" hole with a taper.
individual idle air valve for crower fuel injection.JPG
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Belgian1979
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Re: fabrication question

Post by Belgian1979 » Mon Mar 12, 2018 3:24 pm

bill jones wrote:
Mon Mar 12, 2018 1:02 pm
-this is the valve taken apart---it has a simple .153" hole with a taper.

individual idle air valve for crower fuel injection.JPG
Thanks. Interesting setup.

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Re: fabrication question

Post by modok » Mon Mar 12, 2018 11:31 pm

Belgian1979 wrote:
Mon Mar 12, 2018 5:33 am
MadBill wrote:
Sun Mar 11, 2018 9:38 pm
I've synchronized many dozens of IR carb systems and a goodly number of EFI ones and it continues to amaze me how much better they drive (and sound!) when they're synched as perfectly as humanly possible rather than just really close. Among the several devices and listening tubes I've used, the Uni-Syn with various fabbed adapters gets my nod.
One trick that helps with some less well-designed linkages is to sync the throttles first with the idle stops, then use the linkage to just crack them open to verify or tweak the linkage as necessary to ensure synchronization is maintained in the off-idle position.
No matter how good you synchronize them, as soon as the engine warms up the linkage changes a minute amount of length. So what is good in terms of idle rpm when warmed up, is not enough when cold, hence the need for IAC.
So, fix that. It's easy, for me, ok maybe not for you but maybe you could take a picture, we can brainstorm.

And why be so concerned with the idle? I'm more concerned with how it works cruising. You just like to idle?? hmm, I know why.

Emissions testing! right? I used to just adjust everything in the parking lot, then do the test. No more tests here tho.
Glen Urban

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