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Making my own EFI intake... The First Casting


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The best way is to let idle synch be handled by your IAC on the log.

 

After that, have a throttle stop to open you throttles slightly (1500 to 2500 rpms) and use something like the EMPI UNIVERSAL PRO-SYNC to set throttle opened synch.

 

http://www.dansperformanceparts.com/buggy/intake/intakeacc.htm

 

This does not depend on the flow restriction to get a reading like the Uni-Synch does, so you can keep the engine at a set speed and adjust each linkage to get the same off-idle flow through each barrel. Then set your limit stop on the linkage to prevent overtravel during WOT. The idle snaps shut to fully closed with idle airflow coming through the IAC and your Manifold Logs.

 

This is how we set up the TWM setup on the Bonneville Car.

 

I hate the UniSynch because of the way it works. I prefer the Weber Tool, or the equvalent sold through JC Whitney (Scheyler Carb Synchroniser).

 

http://www.jcwhitney.com/autoparts/Product/Pr-p_Product.CATENTRY_ID:2008076/c-10101/Nty-1/p-2008076/Ntx-mode+matchallpartial/N-10101/tf-Browse/s-10101/Ntk-AllTextSearchGroup?Ntt=Weber+Carb+Synchronizer

 

(For the Record, when I bought this EXACT same tool from JCW in 1985, I paid as much as they say 'you save' on their current price! And the second review of hte product is priceless---35 years of ownership!?!?!, I'm thinking I may get the same paranoia myself! I thought I had mine for a while!!! I knew they were availabe in the catalog for A WHILE before I bought mine.)

 

You 'could' do it with a Uni-Synch, Far easier at idle than off-idle. The ability to check off-idle synch and adjust linkage length to equalize flow with the Weber Style is awesome.

 

Quick, too!

 

And if you didn't notice, you could buy two or three of these for the cost of a single manometer style. Check Demon Tweeks in Wrexham Wales for a Gunson or equivalent plastic manometer carb synchroniser. I bought one there last pilgrimage to their store, ran across it in my 'track case' while cleaning last week! I don't think it was 57 Pounds Sterling!

 

The manometers are nice for idle flow, you can actually make one with six tubes as easily as you buy one that you will have to fudge. Or buy two of the four cylinder models and manifold them into one tool. That way when you make your setup for the SBC replacement after the tragic explosion following over-rev of your L-Series, you already have the tool to synch it's custom-cast ITB setup...

 

Not the one I got, but leave it to Demon Tweeks to have absolutely EVERYTHING in the store you could possibly want. Check the "options" tab, they have 'six carb' click on it! Only 123.31 pounds sterling. A mere pittance more compared to the 99 pounds asked by those other ruffians. Mere farthings, sir. Mere Farthings!

 

http://www.demon-tweeks.co.uk/products/ProductDetail.asp?cls=MCYCLE&pcode=DAV62006

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Just how in the hell am I going to synchronize these things!

I'm thinking my old Uni-Syn just ain't gonna cut it.

Motion Pro sells this:

http://www.motionpro.com/motorcycle/partno/08-0411

 

And Morgan sells this:

http://www.carbtune.co.uk/c.com/index.html

 

Obviously since they're for a four cylinder I'll have to do it in stages.

The Morgan seems to get generally better reviews.

 

Thanks

Derek

 

Hey Derek-

 

For synchronizing why don't you just use the lines that go into the log. You could put an accurate vacum gage on each line one at a time. It appears that your connectors on the log are Pneumatic quick release type with a air throttle on the top ( they look like the ones from production lines that I have seen ) which you can adust the airflow with. Is that what they are ? It would be very easy to match runners that way.

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That will only match idle synchronisation. And all the throttles need to be connected to speed up the process. When you open one cylidner, they all get a higher vacuum.

 

Having all six on a manifold 't'd' into his manifold block would be the way to set idle. With the over the horn gauge, you can quickly jump from each barrel to the next quickly checking where they all are and make the idle adjustments. You can get the off-idle done while the engine is warming up, and have it damned close by the time it's at operating temp to do the idle synch with the manifold needle valves.

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Hey Derek. Im going to jump in here on the synchronizing of these things. Ive synched many of a motorcycle carbs and ITB's. There is a reason that the industry standard for doing this job is the mercury sticks. They just plain work. And Id say buy 2 and do them all at once. It will make your life so much easier. It is possible to make your own if you have a source for mercury. Hell my dad even went on the cheap before i had a set of the mercury sticks and used engine oil instead of mercury. You wont be able to get a "true reading" but it will read the same for all cylinders and its more about that than getting a certian number. Do a google on making your own and im sure you can find some plans for it. And then with your abilities im sure you can make something work for ya.

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Ive got a Dwyer Slack Tube Manometer I can use for four cylinders---I just attach each end of the tube to the vacuum port on each carburettor---it's not like you can adjust cylinder pair balance on a Mikuini....

 

The guys that have seen me do that tell me I'm using it wrong...but hooking up each end shows you differential between the carbs---same thing as hooking up an individual stack to their own individual manometer without the hassle of having the levels and scales calibrated beforehand.

 

The manometers are fine for stationary shops, but travelling with them is a royal PITA.

 

For that matter, Omega makes a nice digital Manometer that is pretty slick! I've used one of those as well.

 

That Scheyler is handy to have laying around, especially for the cost!

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Hey Derek. Im going to jump in here on the synchronizing of these things. Ive synched many of a motorcycle carbs and ITB's. There is a reason that the industry standard for doing this job is the mercury sticks. They just plain work. And Id say buy 2 and do them all at once. It will make your life so much easier. It is possible to make your own if you have a source for mercury. Hell my dad even went on the cheap before i had a set of the mercury sticks and used engine oil instead of mercury. You wont be able to get a "true reading" but it will read the same for all cylinders and its more about that than getting a certian number. Do a google on making your own and im sure you can find some plans for it. And then with your abilities im sure you can make something work for ya.

 

Well I figured with your background I'd be hearing from you on this one!

 

 

That will only match idle synchronisation. And all the throttles need to be connected to speed up the process. When you open one cylidner, they all get a higher vacuum.

 

Having all six on a manifold 't'd' into his manifold block would be the way to set idle. With the over the horn gauge, you can quickly jump from each barrel to the next quickly checking where they all are and make the idle adjustments. You can get the off-idle done while the engine is warming up, and have it damned close by the time it's at operating temp to do the idle synch with the manifold needle valves.

 

INFORMATION OVERLOAD!!!!

 

I need to backup a bit and get a little egimikated on this hear synchronization thing.

 

So we have idle synchronization and off idle synchronization. In a perfect world the butterflies would be air tight and the idle would be handled with the base idle screw. there would be no need for idle synchronization. The off idle synchronization would be handled with the needle valves on the log.

Since I built this with a broad ax the butterflies are not perfect so I need a method of synchronizing them at idle. Or I need a way to get the butterflies as airtight as possible at idle.

 

I was running under the assumption that when the needle valves are set at idle then this would make all things equal the the off idle would follow suit.

 

 

Derek

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A common solution is to engineer a tiny bit of play ( 0.020 - 0.050 ") into the linkage between the master and each individual throttle. That way, at idle, the individual adjustment screw controls that runner, allowing very fine adjustment. As the go-pedal is pushed, the master takes up the slack, and then controls all of them. Ideally, the play is equal for all, so that off-idle synch can be performed. But at WOT, they are all open fully against the stop anyway, and so any play becomes moot.

 

Carter

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Hey Derek:

 

I've been watching your thread! Nice work Buddy! Throttle Plate seal is critical, more than .002" "Butterfly to bore" clearance and the IAC Valve is a MUTE Point, as it will not idle less than 1300-1500rpm. The smaller the Displacement of the motor and the larger the ITB's are this Tolerance goes down from there!

 

Nice IAC Unit, you been Peaking in my Computer? :)

 

Kevin

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Well this sounds like something you need to INSTALL it all for first. :D Really, You should start off w/ all your needle valves shut and see how much air leakage you have in your ITB's. the IAC should allow enough air through to get you idling. I though you were going to use that BMW/NISSAN goo stuff to seal the throttle plates

 

one thing to keep in mind is that since all your TB's are connected via the balance tube, each of your needle valves are going to have an effect on each of the other cylinders. opening one valve even a little will allow air into your balance tube rather than front to back of each TB. isn't that the function of the IAC?

 

Maybe I'm wrong, and perhaps I should have spoken up sooner, but these balancing valves aren't going to be very useful in that sure they work for carbs to balance pull from cylinder to cylinder, but for EFI, especially on a batch fired system (MS) they're just going to make it harder for the IAC to do it's job controlling idle. if you didn't have a Balancing tube between each cylinder & between the manifolds, then yes these valves would be invaluable in balancing flow at idle. Using just one valve should allow you to adjust your idle. This, and the IAC could have been built into your manifold. I had an idea for this that you could just mount to the end of the balance tube by Cyl 3 6 or better between the two manifolds. I'll draw up a pict...

 

of course, I've never built a manifold, and my EFI experience is limited to playing with GM EFI on a couple jeeps so maybe I'm wrong. if I am, please explain ... :)

 

Phar

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So we have idle synchronization and off idle synchronization. In a perfect world the butterflies would be air tight and the idle would be handled with the base idle screw. there would be no need for idle synchronization. The off idle synchronization would be handled with the needle valves on the log.

Since I built this with a broad ax the butterflies are not perfect so I need a method of synchronizing them at idle. Or I need a way to get the butterflies as airtight as possible at idle.

 

I was running under the assumption that when the needle valves are set at idle then this would make all things equal the the off idle would follow suit.

 

 

Derek

 

Off idle synchronisation is a combination of how the barrel is flowing, and mechanical synchronisation of the throttle plates.

 

As stated above a 'slight' slop in the linkage allows minute variations throttle to throttle to be accomodated so all the throttle plates seal as tightly as practical.

 

Then, once they are seated (which should starve the engine or have it operating WELL below target idle speed... some people set them arbitrarily at 0.003" open with a feeler gauge on a bench-setup before installing them---that was a Carburettor specification and can not be applied to EFI. Frank 280ZX tried that with his ITBs and got an engine that was idling at 2500rpms! Since you have a balance log, all air admitted to the engine will (MUST) come from that point, and you can meter the air to each cylinder to get it at equal vacuum and work up to your desired idle speed (say 900rpms). EFI will fire and run this engine at 400rpms, without issue, so you work up from there to first get them all flowing correctly, then equally open them all in little bitty increments to raise the idle speed. Same as setting the idle stop screw on a carburettor when doing synch.

 

If you mechanically set the closed position with the linkages and not a throttle stop on each individual barrel, then from that point mechanical and off-idle synch should take care of itself.

 

Once the throttles are cracked more than maybe 0.030", you are TOTALLY dependent on the angle of the throttle plate for airflow synchronisation. nothing you can do with a bypass will have any great effect.

 

And truthfully, it's FAR more important to have off-idle synch correct, and make sure all the throttles reach full WOT at the same time than having a slight imperfection in idle synch.

 

The power imbalance off-idle is what will cause massive vibrations and break things (or cause cylinders to run rich or lean because of cylinder to cylinder airflow disparities).

 

Really, it takes more time to type this that it does to actually DO it! And once it's set, locktite everything with Wicking Green Loctite Threadlocker for Assembled Fasteners and you're done for the next 20 years of driving.

 

Or until one of those terribly overloaded heim joints starts exhibiting wear and has to be readjusted...:P

 

Really, you want no throttle opening AT ALL. If you have it on one barrel, it's going to make it difficult to get your idle speed down. This is why I was mentioning the sealant that BMW uses to seal the throttle plates to the bore. This is a very important part of the construction.

 

The IAC, remember is for idle speed corrections. It's not designed as the base-idle maintainer. That is what your bypasses are for. You will set your idle speed to just below target (say 800-850 for a final idle speed warm of 900 rpms) with your bypasses. This will keep you from drop-throttle stalling. Use the IAC and the computer to bring the idle up the final 50 rpms so it always is in it's functional range and operating. This heightens it's response characteristics. As you drop-throttle, the idle bypass will keep enough airflow to keep your engine from stalling while the IAC target idle response works it out to open the thing and admit that last bit of air. It's true the individual bypasses will show very little difference in anything other than idle speed, but on a good gauge you will be able to read the different flows through the cylinders and adjust from there. On our external balance tube, we simply pinch off each of the cylinders from the main tube to check airflow through that runner. Once the synch is set, we re-enable the whole log.

 

On my turbo car, I could feel individual cylinders hit during hard acceleration when I didn't have a balance tube. AFter I installed one, I had some trouble checking synch unless it was disabled, but the power was MUCH smoother under acceleration than it had been with the non-balance tube setup.

 

IAC tuning is more important if you are using accessories like A/C, but I'll stop now...:-D

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A common solution is to engineer a tiny bit of play ( 0.020 - 0.050 ") into the linkage between the master and each individual throttle. That way, at idle, the individual adjustment screw controls that runner, allowing very fine adjustment. As the go-pedal is pushed, the master takes up the slack, and then controls all of them. Ideally, the play is equal for all, so that off-idle synch can be performed. But at WOT, they are all open fully against the stop anyway, and so any play becomes moot.

 

Carter

 

Hi Carter

Unfortunately that would require a redesign on the levers and linkage so that won't be happening right now. Thanks for the input though.

 

Hey Derek:

 

I've been watching your thread! Nice work Buddy! Throttle Plate seal is critical, more than .002" "Butterfly to bore" clearance and the IAC Valve is a MUTE Point, as it will not idle less than 1300-1500rpm. The smaller the Displacement of the motor and the larger the ITB's are this Tolerance goes down from there!

 

 

 

Kevin

 

Hi Kevin

Well it was your idea to use the needle valves to begin with.

 

Nice IAC Unit, you been Peaking in my Computer? :)
I have spys everywhere!

Actually I was looking at the IAC housing at DIY auto tune and the log on your site and figured that needs to be all one piece. Then the visual of the needle valves with the lines running over to the runners just sealed the deal. I had to have it!

 

Well this sounds like something you need to INSTALL it all for first. :D Really, You should start off w/ all your needle valves shut and see how much air leakage you have in your ITB's. the IAC should allow enough air through to get you idling. I though you were going to use that BMW/NISSAN goo stuff to seal the throttle plates

 

 

 

Phar

 

That's my original plan. I'll establish a base line on the butterflies and then decide if I need to make changes. Right now I'm trying to get a feel for all this so that if I have a problem I'll have plan be ready to go. I can't get started on the install yet so I might as well work this crap out in the meantime.

 

 

I though you were going to use that BMW/NISSAN goo stuff to seal the throttle plates
I couldn't come up with any unless I bought $500.00 worth. That coating is really more of an antifouling/sticking compound anyway.I'd rather have it work without anything. This is really just a problem with the prototypes. There were a couple of areas I needed to be more precise on and kind of blew it. The embedded stainless tube idea is a winner. I just need to make a couple of changes in the way I align everything prior to the pour.

 

one thing to keep in mind is that since all your TB's are connected via the balance tube, each of your needle valves are going to have an effect on each of the other cylinders. opening one valve even a little will allow air into your balance tube rather than front to back of each TB. isn't that the function of the IAC?

 

Maybe I'm wrong, and perhaps I should have spoken up sooner, but these balancing valves aren't going to be very useful in that sure they work for carbs to balance pull from cylinder to cylinder, but for EFI, especially on a batch fired system (MS) they're just going to make it harder for the IAC to do it's job controlling idle. if you didn't have a Balancing tube between each cylinder & between the manifolds, then yes these valves would be invaluable in balancing flow at idle. Using just one valve should allow you to adjust your idle. This, and the IAC could have been built into your manifold. I had an idea for this that you could just mount to the end of the balance tube by Cyl 3 6 or better between the two manifolds. I'll draw up a pict...

 

of course, I've never built a manifold, and my EFI experience is limited to playing with GM EFI on a couple jeeps so maybe I'm wrong. if I am, please explain ... :)

Well It's my understanding that the needle valves introduce a small amount of air just behind the butterfly but in front of the balance tube. This simulates cracking the throttle plate a little. The needles are just for synchronization. The base idle is set manually with the large idle screw on the log. The IAC is for controlling cold start.

 

And as far as mounting the IAC in the manifold it can't possibly look as cool as the log...I mean did you see that thing!!

Sniff...Sniff... I'm so proud....

 

Derek

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Well I got back on the old google and came up with a source for the DAG 213 that will sell me a quart. It's 95.00 plus shipping. They're going to see if they can sell me a pint but either way I'm going for it. $95.00 is very cheap insurance.

Her's a link to the data sheet if anyone is interested

http://www.laddresearch.com/SpecSheets/LaddDAG213.pdf

 

It's a baked on product. I'll have to do some trials first. Not sure how resilient it is. If it's too hard then the high area of the butterfly will just hit the DAG and continue to leave a gap. If it's flexible it will allow the butterfly to sink and create a seal.

 

Derek

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...

 

Well It's my understanding that the needle valves introduce a small amount of air just behind the butterfly but in front of the balance tube. This simulates cracking the throttle plate a little. The needles are just for synchronization. The base idle is set manually with the large idle screw on the log. The IAC is for controlling cold start.

 

And as far as mounting the IAC in the manifold it can't possibly look as cool as the log...I mean did you see that thing!!

Sniff...Sniff... I'm so proud....

 

Derek

 

Oh I wasn't at all knocking the beauty of your creation, I think your log is on the "really really" side of "look really cool" I wish I could create like you.

 

I was merely trying to say that with a balance tube, and separate log idle screw, I'm thinking you won't need much if any adjustment from your needle valves. but they will look really cool.

 

IMHO, You should try your manifolds w/o the $95 goo first and just see what happens. if they idle too high, then you can work on sealing the butterflies better. I went and looked at my 4.0 throttle body and there's about an 1/8th inch "idle" hole in the plate which I guess would tell me you can get away with a little leakage in your setup.

 

Phar

 

I need to search for your thread on the MS setup you're using.

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What's 0.125" divided by 6? Equivalent to about a 0.020" hole in each throttle plate. Assuming total circumfrential seal.

Now, take the diametrical distance to find circumfrence and divide that legnth into 0.020" and you start seeing where Accurate Injection gets his data about less than 0.002" being too much on a 45mm bore!

 

There is a BIG difference between breathing through ONE plate, and SIX!

 

I cracked my dual SU plates less than the 0.003 mentioned to get my idle speed correct. I could have drilled a hole in the throttle plates, but since I didn't have any spares and didn't want to JB Weld any mistakes I defaulted to throttle position instead of a hole. I figures something on the order of 1/16" in each of the two plates would be more than enough with throttle angle being used to 'trim up' to the final idle speed during synch.

 

But that's only two plates, not six!

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What's 0.125" divided by 6? Equivalent to about a 0.020" hole in each throttle plate. Assuming total circumfrential seal.

Now, take the diametrical distance to find circumfrence and divide that legnth into 0.020" and you start seeing where Accurate Injection gets his data about less than 0.002" being too much on a 45mm bore!

 

There is a BIG difference between breathing through ONE plate, and SIX!

 

I cracked my dual SU plates less than the 0.003 mentioned to get my idle speed correct. I could have drilled a hole in the throttle plates, but since I didn't have any spares and didn't want to JB Weld any mistakes I defaulted to throttle position instead of a hole. I figures something on the order of 1/16" in each of the two plates would be more than enough with throttle angle being used to 'trim up' to the final idle speed during synch.

 

But that's only two plates, not six!

 

The old cumulative error problem.

And that's my biggest fear. I'm going around and around on the goo. As Tony has said before there is a very real problem of build up of crud between the butterfly and bore. So much so that ford got a patent specifically for their goo. BMW uses it as well. Heck even Rochester used it on their tri-power setups. The DAG 213 is a dry lubricant that just so happens to provide a bit of sealing depending on how it's applied. Put it on a bore surface and install the butterfly and it's a lubricant. Paint it on a bore with the butterfly installed and it's a sealer and lubricant.

Here's my reasoning for buying the goo.

1) It's my daily driver and I want it to be dependable.

2) I'm hoping to sell a few of these and I want them to be the best quality.

3) In the time it will take me to pull the manifold and apply the DAG I can earn more than $95.00

4) I've spent many thousands in time (not hobby time but pattern making a living time) and materials on this rig so what's another $95.00

 

I'm ordering it today.

Derek

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The old cumulative error problem.

And that's my biggest fear. I'm going around and around on the goo. As Tony has said before there is a very real problem of build up of crud between the butterfly and bore. So much so that ford got a patent specifically for their goo. BMW uses it as well. Heck even Rochester used it on their tri-power setups. The DAG 213 is a dry lubricant that just so happens to provide a bit of sealing depending on how it's applied. Put it on a bore surface and install the butterfly and it's a lubricant. Paint it on a bore with the butterfly installed and it's a sealer and lubricant.

Here's my reasoning for buying the goo.

1) It's my daily driver and I want it to be dependable.

2) I'm hoping to sell a few of these and I want them to be the best quality.

3) In the time it will take me to pull the manifold and apply the DAG I can earn more than $95.00

4) I've spent many thousands in time (not hobby time but pattern making a living time) and materials on this rig so what's another $95.00

 

I'm ordering it today.

Derek

 

okay, Well on the time idea, then that's probably a good idea. I was thinking you might want to try it w/o any good first, just to see how your stock leakage has a cumulative effect before sealing, and with all the needles closed. that might give you an idea of what your tolerances are. my 4.0 has no goo but it precision machined. I guess it would be interresting just to figure. but it's your project, n if you want to goo it right away, then more power to ya, no pun intended...

 

Phar

 

now to find your megasquirt thread. search search, where is that damned button..

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