It pains me that so many idiots gets so many views, yet these gem of video series on building classis Porsche 911 doesn't get as many, well Tom your videos are hidden gems.
Thank you Tom for making the black magic of carb tuning a scientific procedure. Just got done rebuilding and tuning a set of Webber 40IDF. I have a set of triple throats on a 914-6 I will have to fine tune soon
Maybe I take my background for granted at times? I've always been curious how stuff works even as a kid. I also learned as a kid that it's harder to put something back together than take it apart. This is still true, ha ha.
Lots of people say that webers are no good for a 912/356 engine but once you have them dialled in correctly I think they are great. Adjusting things is all part of the fun of tuning. Well done!!
I ran Webers but I'd tune and sync them up perfectly then a week later they were out. I swapped to PMO's and never looked back. Great carb explanation. For carb settings I just throw some chicken bones on the hood and read the wisdom of the gods.
Awesome video, I'm just starting out with my webers. But my car is a 63 bug with a 1915cc engine and dual 40mm webers. At the moment she barely runs. So the fun begins.
Great video, as always. Weber’s are awesome, but dang, a potential rabbit hole of adjustments for transitions, etc. Hats off to you for understanding and digging in with your own tools and homemade devices. Had a good friend with a 914/6 back in the 70’s. He was constantly fiddling with his Webber’s. My garage built 63 1/2 Falcon with a real crate Shelby 289, w/Paxton blower, ran great through the double pumper Holly. It made for never ending debate on which carbs were better, which I look back on with a smile. BTW, long live nerdy engineers/mechanics. 👍👍
My hope is to leave it alone now. Set it once and done😄. This isn't a performance engine that I'm trying to get the last 2HP. I just want it to drive and I'm thrilled so far. The Wideband guage removes years of tinkering and guesswork. Too bad they didn't have them in the 60's
Wow! Makes me feel fortunate that my Weber equipped S90 ran so well with just minor adjustments to synchronize. I hope it still does when I get everything back together after long term storage. If not I’ll be back to this video for guidance. Awesome job...thank you for sharing!
Once carbs are setup they run great unless they get clogged with something. Make sure get any old fuel out of the carbs while they are stored. Spray carb cleaner through all the passages or they will turn to goo
Great video and explanation of how the jets and progression ports work in relation to each other. I'm running IDFs on a VW 1776 Bus with crank fired ignition (Ford Edis and Megajolt) drawing a vac signal from each barrel combined, to present a MAP reference for the Load bins on the megajolt timing map ( which uses RPM and load). When setting the Idle mixture, one barrel/cylinder doesn't seem to respond to adjustment half as much as the other three. Leakdown test confirms everything's in order, so I'm guessing either the throttle spindle is slightly bent (and the plate is starting to uncover a progression port or there's an air leak... I used the airbypass screws to bench match the flow through each pair, but it was a very minor adjustment, and I'm not convinced it makes a great deal of difference when other discrepancies stack up....still, it's nice to have something else to play with. Will share your video with a friend of mine who's just about to start setting his twins up. Another useful DIY gadget for making sure each idle speed screw is just touching the actuating plate, is a 12v test light, grounded on the carb body....
Best of luck trouble shooting your engine. Sounds like a good one with great parts. Here are a couple ideas to try. 1) when you pull each plug wire does the RPM drop the same amount? 2). Have you tried a IR temp gun at each exhaust header? Might tell you if you have a plugged jet or something strange? 3). Maybe try color tune? It's a window into the combustion chamber so you can see how it's running. Rich or lean? 4). Run the engine in complete darkness and look for ignition leaks. Just thinking out loud here. My hunch is that you know this stuff already
Hello! Really really good video! If i can make a sugestion, get an mallory distributor. You can advance the idle timing without advancing top rpm timing... Im using obe with 15 degree idle and 28 degree top speed and my idle is very crispy. Great work!
Ideally shoot for 14:0 at LBI and at part throttle condition 15-16 AFR (if you run vac advance). If not then set timing at 28 full and no lean tune jetting at cruise. Always keep the air bleed screws closed. You may see as much as (1) point difference on the snail between (1) barrel and another but that is nothing out of the norm. The difference is generally due to either one barrel being eager than another and/or a slightly twisted throttle shaft or differences in throttle plate alignment. Your mixture screws will only affect the mixture at idle speed only. So get the idle speed to 14:0 LBI. 12.5 at idle is too rich. You'll also do better to get an SVDA or a 123 distributor in the car then lean tune it for part throttle (cruise) condition. No lean tune jetting with centrifugal only distributor.
Thanks, good info here. I'm set a bit richer from your recommendations, but will try on my 356 engine. I have a programmable 123 distributor for that and I'm excited to try it out. Sometimes after idling for a while the advance weights are reluctant to move and the engine falls flat. What WOT AFR do you target and does it differ with RPM range?
@@GarageTimeAutoResto At WOT shoot for 12:5. At cruise (part throttle) shoot for 15-16. Remember....Load = Throttle position. This is with an SVDA or programmable distributor (Black box) only, not centrifugal (mechanical). If the 123 distributor is sticking I'd be inclined to take it apart and clean the lower advance and re-lube it. I do this with any new/used distributor prior to install. The following is the Type-4 engine I set up for my 72 Westy still runs like a dream....th-cam.com/video/0EoAeY8dG0o/w-d-xo.html
Gotcha, I targeted 12.5 also. My 022 distributor was sticking, not the 123. Sorry about that. The engine in this video isn't in this car anymore, so I'm done playing with it for now. My 123 distributor doesn't have any mechanical advance weights.
Thank you for that Vid. Very informative, details are important 👌. I have the same exact carburetors that I’m glad I inspected ... one of the idle jets was drilled only on one side 😄 I’m going to try your jet setup,and I switched from f-11 to the f-7 e.t. I jyst wsnt to thank you , because now I have help(through your many vids) in completeing my long overdue 356 project🤙🏽
Some interesting points I've had to use the air bypass screws to sync my carbs front/rear. I have a colour tune but I find it ready different to see the spark. After getting mine nicely tuned I went to a rolling road and he moved me lower in the air correction jet to sort out a lean condition after 3.8/4k
The air fuel ratio guage is so good that it feels like cheating. I'm able to see exactly where the lean or rich spots are and fix them. I overkilled my sychronization, but man it does run smooth! Colortune is tricky to see on an aircooled car, but if you dim the lights and use a large inspection mirror, its not too bad. The mirrors in the kit didn't work for me.
Really helpful video... thanks. When dipping for the fuel well height your paper flags were all in 28mm - 36mm range... yet in your voice over you said you measured 48mm. Is that really what it was... or was it 38mm perhaps?
Thanks Daniel. Sorry for the confusion. I'm talking as I'm filming and sometimes don't catch my mistake while editing. The goal is to have the float level a few millimeters below the port where fuel dumps into the engine. I think I meant to say 38mm. This method is a bit tricky because the fuel sometimes climbs up the walls.
Ya... Feel your pain have webers on a 2.4 t motor originally set up with mfi... The webers don't like the cam and even though the Bosch diz is recurved.. It isn't the marelli.... Switching to an ms system. Still have the mfi but it's WAY to expensive to put back on..
Hey Tom, how does your car idle while it is still cold? That is what I'm having trouble with, or is it just something I'm going to have to live with? You're explanation of the system is by far the best I have found. Thanks.
It idles low at about 700 RPM. Many times I back out of the garage, run inside to close the big garage door and come back and the car is still idling. It's normal for it to cough a little through the air cleaners, but it warms up pretty fast. Keep in mind though that I live in warm climate. If its cold outside, I think its normal to baby sit it for a few minutes before it will idle on its own.
Thanks for video I wonder if you fold the bottom of flag Like a z so creases go vertical it will keep the gas on side of jet well off the center of flag paper
Not a bad idea at all. How about wax paper with a thin band of regular paper down the middle? There must be a paper that changes color when it touches fuel? Thanks for sharing your ideas👍
I would recommend better air filter housing. The ones from CB performance are a lot better at keeping the idle jets clean. Also I would recommend a cdi style ignition system for that engine. Just my opinion. Great info on the Weber's 40 IDF'S. 👍
It's a precision test instrument from degree C. Not cheap if I remember right. This was left over from an engineering project and probably overkill for an engine. I do wonder if a used mass airflow sensor could be adapted to a portable synchronizer.
Fantastic video, thanks so much for share. Really good to hear the car is running good now. Can you go into more details on the hot wire anemometer? When you plugged it into your laptop, what program/app was reading the results? Did you find it useful and reliable? Would you use it for more high speed/load tuning?
Thanks! I'm so happy that the car runs great and the tuning is behind me. Maintenance will be much easier and once carbs are set they don't need much. The anemometers are very good. The are from degree C or cambridge accusense. I think one company bought the other one, but the probes come with a tracking software. I should have shown the graph of the readings. They are very stable. Now I'm wondering if one could get a MAF from a junkyard and adapt it for synchronization? Hmm.
Wow, a ton a great information. I may not have IDF carbs, but the basic process is helpful, even in tuning my Zenith-Stromberg carbs. It's been a real long time since I've had a car with carbs. LOL. One question...so you get yours dialed in at sea level there, but then you drive to Lake Tahoe, would the Porsche still be running great or would the altitude throw everything off? The tinkerer in me loves the idea of carbs, but the driver in me might just prefer some throttle bodies that look like Webers running fuel injection. Cheers!!
I'm at sea level so I'm also curious to know how it will run at altitude too. Less air means a more rich mixture so the car probably will feel more lazy. For a day trip, I don't think any changes would be needed, but if I did lots of mountain driving then I'd probably go down one jet size.
What? You don't have one lying around? Ha ha, kidding of course. I have these from my days testing laboratory equipment airflows. They are from Cambridge accusense and they are pricey. I'd love to convert a GM MAF for this purpose. Maybe will do for my flat 6 engine with ITBs?
I was hoping to find a mass airflow sensor at a junk yard and then press it into service. Precision isn't important, because we're only comparing the flow in two carbs -- but it has to cover a broad range, from idle to pretty much full throttle. Would be nice to find two matching sensors so that they could be attached to the two carbs to compare flow rates without having to move single flow sensor from one carb to another. I have a Uni-Syn. I think it restricts the flow on the carb being measured. A hot wire doesn't.
Thank for sharing that great video. However is there a reason, why you tuned your idle mixture that way instead of using the LBI + half a turn method? 12.5:1 AFR seems to be very rich.
Thanks. I have no problem with the LBI method and I know it's common. I will say that a 1/2 turn is a LOT will result in 12.5 or less. I was tuning in 1/8 turn increments and saw significant changes in AFR. What AFR do you like to see on an air cooled engine?
@@GarageTimeAutoResto Okay got it :) I usually end up with high 13s-low 14s at idle.. But then again, idle afr doesn't really matter, I was just wondering if you chose that value for a reason. For the progression circuit I try to stay lean of peak and around 12.5 to 12.75 on the main circuit. Which values are you targeting there?
It depends! part throttle or light throttle gets into the 14's some times. WOT dips into the 11's. I'm not tuning for max HP on this engine. This engine doesn't cough, backfire, hesitate or bog at all. It also runs cool which is important to me. My 911 engine will get a much more aggressive tune.👍 Idle AFR is a bit rich because these carbs don't have chokes for cold start, so it's all a bit of a compromise. I do love the AFR Guage as it takes so much of the guesswork out of it. I still have it connected. A few weeks ago I got a plugged idle jet and it showed up on the Guage immediately.
Hey Tom.... I was woundering if you set your float levels (in addition to your float level ck.)by measuring the float travel in relation to the float pin. Weber says 14mm open (without pressure on the ball) and 22mm closed. Many 356,sndVWGuyes set the floats at 10.5 and 32.5 mm respectively. By carefully bending the float tabs (top and rear) you can ajust to get it exact,... what are your thoughts on this? And where did you get the nylon spacer on the top of carb. Setup that you made? Thanks again Tom🤙🏽
Hi Bill, as always there are many ways to skin a cat. Physical measurements are good, but its an indirect measurement in my opinion. How does the fuel pressure affect the float level? What about seat or pin wear? The thing that actually matters is what the actual fuel level is when you are driving. That is why I like measuring the fuel level with it running. Solex 40P11 has a screw on guage that lets you sight the fuel level when running. This is my favorite method. Weber does not allow this, which is why I made those little paper sticks to check. Fuel level can also be a tuning parameter to tune when the main circuit kicks in. I think the best performance is when the actual fuel level is a few millimeters below the main circuit port. Too high and unwanted fuel will spill in. Too low and the main circuit kicks in too late. We all want a set it and forget it number. The ENGINE may want something else. That's the rub! The nylon spacer was homemade by me on a CNC machine. Best of luck on your carb journey.
@@GarageTimeAutoResto The Weber manual is wrong with respect to 'initial' float settings. The rule of thumb is check fuel pressure first...max 3.5lb (critical). Once fuel pressure is confirmed adjust float height to 10-11.5mm with gasket in place and ball NOT depressed. The float drop is not as critical 28-32mm will suffice.
I have these same carbs on a 2110cc VW type 1 engine that I'm trying to get dialed in. So far it idles perfect and WOT seems pretty good but off idle transition to mains stumbles a little, almost an on-off feel. I'm starting with 55 idle, 200 air, and 125 main jets with I believe the f-11 emulsion tubes. I'm at 6000 feet elevation. I also have a vacuum/centrifugal combination distributor that I can't seem to get any vacuum advance? I have vacuum tubes from both carbs into a T and then to distributor. Can you tell me if I need some sort of check valve in those vacuum lines? I'm wishing I would have gone with centrifugal advance only and may end up switching. I really liked your video and I learned a lot watching it. I'm definitely going to check the float levels running as well as run the idle circuit without the main jet stacks in to isolate the idle circuit.
I'm not super familiar with VW engines, but they are very similar to Porsche obviously. Are you running a cam with large duration? Is that why the vacuum is low? Here's what I recommend: Start with the distributor and set the total advance with the vacuum disconnected. Porsche engines like 35 degrees, but I think VW engines like less. It depends on your compression ratio, cam and head geometry ultimately. I don't think you need a check valve for the vacuum lines. The vacuum advance comes in handy under part throttle. Research the max advance for engine and set it at that. If not try 28 degrees? Hopefully it will still idle ok. Back off the accelerator pump screws out several turns so they don't interfere with jetting. My guess is you are way too rich- I'd go with leaner mains and idle jets. Are you using 28mm venturis? An engine that size might do better with 30 or 32mm vents.
Yes, the carbs came with 32. It didn't drive well at low speed. I also have 30mm which might work, but I'm not after high RPM performance with this engine
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Thank for watching! I'm thrilled this thing is running great considering it began with a box of parts. www.patreon.com/ahhgaragetime
Car sounds great! Good job.
It pains me that so many idiots gets so many views, yet these gem of video series on building classis Porsche 911 doesn't get as many, well Tom your videos are hidden gems.
Its okay, as long a few true car guys get what I'm saying it's worth it. Not many people are even interested in the why or how things work.
I wish I had run into you 25 years ago when I still had my 66 912. And I wish I still had that car. So fun to drive around in.
So fun to drive! If you are ever in socal, I'll take you for a ride.
Thank you Tom for making the black magic of carb tuning a scientific procedure. Just got done rebuilding and tuning a set of Webber 40IDF. I have a set of triple throats on a 914-6 I will have to fine tune soon
Your welcome. The wideband AFR guage is your friend.
Another master class, Tom. I think your engineering background is really beneficial on elements of the project like this one.
Maybe I take my background for granted at times? I've always been curious how stuff works even as a kid. I also learned as a kid that it's harder to put something back together than take it apart. This is still true, ha ha.
Lots of people say that webers are no good for a 912/356 engine but once you have them dialled in correctly I think they are great. Adjusting things is all part of the fun of tuning. Well done!!
Fun my foot!
My 356 will have Solex, so it will be a fun comparison. Dellortos are also good! Everything is fixable😄
I think it's because people don't understand how they work and don't have knowledge to work on or adjust them.
Amen. This 912 engine with Webers runs better than I remember my 356 running with Solex. It's been 15 years though.
I ran Webers but I'd tune and sync them up perfectly then a week later they were out. I swapped to PMO's and never looked back. Great carb explanation. For carb settings I just throw some chicken bones on the hood and read the wisdom of the gods.
Something about new carbs versus old carbs without worn shafts and throttle plates I presume? PMO are great.
Awesome video,
I'm just starting out with my webers.
But my car is a 63 bug with a 1915cc engine and dual 40mm webers. At the moment she barely runs. So the fun begins.
Thanks and have fun with yours. They are very tunable! The distributor advance also plays a big role, but you can do it!
Carburetors are an enigma to be- thanks for the informative video.
People write books on two phase flow in emulsion tubes! In some ways fuel injection is much easier
Great video, as always. Weber’s are awesome, but dang, a potential rabbit hole of adjustments for transitions, etc. Hats off to you for understanding and digging in with your own tools and homemade devices. Had a good friend with a 914/6 back in the 70’s. He was constantly fiddling with his Webber’s. My garage built 63 1/2 Falcon with a real crate Shelby 289, w/Paxton blower, ran great through the double pumper Holly. It made for never ending debate on which carbs were better, which I look back on with a smile. BTW, long live nerdy engineers/mechanics. 👍👍
My hope is to leave it alone now. Set it once and done😄. This isn't a performance engine that I'm trying to get the last 2HP. I just want it to drive and I'm thrilled so far.
The Wideband guage removes years of tinkering and guesswork. Too bad they didn't have them in the 60's
Wow! Makes me feel fortunate that my Weber equipped S90 ran so well with just minor adjustments to synchronize. I hope it still does when I get everything back together after long term storage. If not I’ll be back to this video for guidance. Awesome job...thank you for sharing!
Once carbs are setup they run great unless they get clogged with something. Make sure get any old fuel out of the carbs while they are stored. Spray carb cleaner through all the passages or they will turn to goo
Yes, they were stored dry and I cleaned and serviced them while the car was in the body shop. Viva la ultrasonic cleaner!
Superb manual! I will be tuning My Weber 40ies quite soon, this is great manual. Thank you sir!
Have fun with those webies👍
Really enjoyed this video and learned so much - thank you!
You're welcome Keith. I learned a lot too😄
Great video and explanation of how the jets and progression ports work in relation to each other. I'm running IDFs on a VW 1776 Bus with crank fired ignition (Ford Edis and Megajolt) drawing a vac signal from each barrel combined, to present a MAP reference for the Load bins on the megajolt timing map ( which uses RPM and load). When setting the Idle mixture, one barrel/cylinder doesn't seem to respond to adjustment half as much as the other three. Leakdown test confirms everything's in order, so I'm guessing either the throttle spindle is slightly bent (and the plate is starting to uncover a progression port or there's an air leak...
I used the airbypass screws to bench match the flow through each pair, but it was a very minor adjustment, and I'm not convinced it makes a great deal of difference when other discrepancies stack up....still, it's nice to have something else to play with. Will share your video with a friend of mine who's just about to start setting his twins up.
Another useful DIY gadget for making sure each idle speed screw is just touching the actuating plate, is a 12v test light, grounded on the carb body....
Best of luck trouble shooting your engine. Sounds like a good one with great parts.
Here are a couple ideas to try.
1) when you pull each plug wire does the RPM drop the same amount?
2). Have you tried a IR temp gun at each exhaust header?
Might tell you if you have a plugged jet or something strange?
3). Maybe try color tune? It's a window into the combustion chamber so you can see how it's running. Rich or lean?
4). Run the engine in complete darkness and look for ignition leaks.
Just thinking out loud here. My hunch is that you know this stuff already
Tom, I thoroughly enjoyed watching this video! Content was excellent and I tried keeping up with understanding all things carburator...ha ha ha!
Thanks Shane, I'm so happy with the way it's running now.
This should help me tune my vw beetle. They sound very similar.
Hello! Really really good video! If i can make a sugestion, get an mallory distributor. You can advance the idle timing without advancing top rpm timing... Im using obe with 15 degree idle and 28 degree top speed and my idle is very crispy. Great work!
Good choice! I already have a 123 distributor for 6V.
learn something everyday. the L shape ruler. nuts
Great video. Learned a lot. I have Weber’s coming for my 356C.
Great, you will love them after initial setup
Super helpful. Imagine I can tackle similar way with my Solex carbs...
Thank you.
Cool, I'll be doing the same thing with Solex carbs on my 356 engine in a few months😄
Ideally shoot for 14:0 at LBI and at part throttle condition 15-16 AFR (if you run vac advance). If not then set timing at 28 full and no lean tune jetting at cruise. Always keep the air bleed screws closed. You may see as much as (1) point difference on the snail between (1) barrel and another but that is nothing out of the norm. The difference is generally due to either one barrel being eager than another and/or a slightly twisted throttle shaft or differences in throttle plate alignment. Your mixture screws will only affect the mixture at idle speed only. So get the idle speed to 14:0 LBI. 12.5 at idle is too rich. You'll also do better to get an SVDA or a 123 distributor in the car then lean tune it for part throttle (cruise) condition. No lean tune jetting with centrifugal only distributor.
Thanks, good info here. I'm set a bit richer from your recommendations, but will try on my 356 engine. I have a programmable 123 distributor for that and I'm excited to try it out.
Sometimes after idling for a while the advance weights are reluctant to move and the engine falls flat.
What WOT AFR do you target and does it differ with RPM range?
@@GarageTimeAutoResto At WOT shoot for 12:5. At cruise (part throttle) shoot for 15-16. Remember....Load = Throttle position. This is with an SVDA or programmable distributor (Black box) only, not centrifugal (mechanical). If the 123 distributor is sticking I'd be inclined to take it apart and clean the lower advance and re-lube it. I do this with any new/used distributor prior to install. The following is the Type-4 engine I set up for my 72 Westy still runs like a dream....th-cam.com/video/0EoAeY8dG0o/w-d-xo.html
Gotcha, I targeted 12.5 also. My 022 distributor was sticking, not the 123. Sorry about that.
The engine in this video isn't in this car anymore, so I'm done playing with it for now.
My 123 distributor doesn't have any mechanical advance weights.
thank you so much for this video ,masterclass for sure
You nailed it. This was an awesome video with great explanations. Thanks for sharing.
Glad it was helpful!
Thank you for that Vid. Very informative, details are important 👌. I have the same exact carburetors that I’m glad I inspected ... one of the idle jets was drilled only on one side 😄
I’m going to try your jet setup,and I switched from f-11 to the f-7 e.t. I jyst wsnt to thank you , because now I have help(through your many vids) in completeing my long overdue 356 project🤙🏽
Perfect. Best of luck on your carbs! I'm still messing around with the accelerator pump jets
Some interesting points I've had to use the air bypass screws to sync my carbs front/rear. I have a colour tune but I find it ready different to see the spark. After getting mine nicely tuned I went to a rolling road and he moved me lower in the air correction jet to sort out a lean condition after 3.8/4k
Ps the engine sounds very smooth as you accelerate. Still going strong after 5k
The air fuel ratio guage is so good that it feels like cheating. I'm able to see exactly where the lean or rich spots are and fix them.
I overkilled my sychronization, but man it does run smooth!
Colortune is tricky to see on an aircooled car, but if you dim the lights and use a large inspection mirror, its not too bad.
The mirrors in the kit didn't work for me.
Really helpful video... thanks. When dipping for the fuel well height your paper flags were all in 28mm - 36mm range... yet in your voice over you said you measured 48mm. Is that really what it was... or was it 38mm perhaps?
Thanks Daniel. Sorry for the confusion. I'm talking as I'm filming and sometimes don't catch my mistake while editing.
The goal is to have the float level a few millimeters below the port where fuel dumps into the engine.
I think I meant to say 38mm.
This method is a bit tricky because the fuel sometimes climbs up the walls.
Ya... Feel your pain have webers on a 2.4 t motor originally set up with mfi... The webers don't like the cam and even though the Bosch diz is recurved.. It isn't the marelli.... Switching to an ms system. Still have the mfi but it's WAY to expensive to put back on..
It's a challenge to get all these things happy. The air file ratio meter is key to understanding what the engine needs imho
Hey Tom, how does your car idle while it is still cold? That is what I'm having trouble with, or is it just something I'm going to have to live with? You're explanation of the system is by far the best I have found. Thanks.
It idles low at about 700 RPM. Many times I back out of the garage, run inside to close the big garage door and come back and the car is still idling. It's normal for it to cough a little through the air cleaners, but it warms up pretty fast. Keep in mind though that I live in warm climate. If its cold outside, I think its normal to baby sit it for a few minutes before it will idle on its own.
Thanks for video
I wonder if you fold the bottom of flag
Like a z so creases go vertical it will keep the gas on side of jet well off the center of flag paper
Not a bad idea at all. How about wax paper with a thin band of regular paper down the middle?
There must be a paper that changes color when it touches fuel?
Thanks for sharing your ideas👍
I would recommend better air filter housing. The ones from CB performance are a lot better at keeping the idle jets clean. Also I would recommend a cdi style ignition system for that engine. Just my opinion. Great info on the Weber's 40 IDF'S. 👍
Cool thx for the recommendations
Great job as usuall👍
Thx, I'm still playing with accel pumps many months after this video was made.
That little tube with the usb wire in it is intriguing. Where would one source such an item?
It's a precision test instrument from degree C. Not cheap if I remember right. This was left over from an engineering project and probably overkill for an engine. I do wonder if a used mass airflow sensor could be adapted to a portable synchronizer.
Excellent
Still running great. Actually even better after I put the 022 distributor in
Fantastic video, thanks so much for share. Really good to hear the car is running good now. Can you go into more details on the hot wire anemometer? When you plugged it into your laptop, what program/app was reading the results? Did you find it useful and reliable? Would you use it for more high speed/load tuning?
Thanks! I'm so happy that the car runs great and the tuning is behind me. Maintenance will be much easier and once carbs are set they don't need much.
The anemometers are very good. The are from degree C or cambridge accusense. I think one company bought the other one, but the probes come with a tracking software. I should have shown the graph of the readings. They are very stable.
Now I'm wondering if one could get a MAF from a junkyard and adapt it for synchronization? Hmm.
Wow, a ton a great information. I may not have IDF carbs, but the basic process is helpful, even in tuning my Zenith-Stromberg carbs. It's been a real long time since I've had a car with carbs. LOL. One question...so you get yours dialed in at sea level there, but then you drive to Lake Tahoe, would the Porsche still be running great or would the altitude throw everything off? The tinkerer in me loves the idea of carbs, but the driver in me might just prefer some throttle bodies that look like Webers running fuel injection. Cheers!!
I'm at sea level so I'm also curious to know how it will run at altitude too. Less air means a more rich mixture so the car probably will feel more lazy. For a day trip, I don't think any changes would be needed, but if I did lots of mountain driving then I'd probably go down one jet size.
Thank you 🙏
Welcome👍
A hot wire anemometer! Where did you get that? I'd like to make one for the Zenith 32NDIX carbs on my 356C.
What? You don't have one lying around? Ha ha, kidding of course. I have these from my days testing laboratory equipment airflows. They are from Cambridge accusense and they are pricey. I'd love to convert a GM MAF for this purpose. Maybe will do for my flat 6 engine with ITBs?
@@GarageTimeAutoResto I
I was hoping to find a mass airflow sensor at a junk yard and then press it into service. Precision isn't important, because we're only comparing the flow in two carbs -- but it has to cover a broad range, from idle to pretty much full throttle. Would be nice to find two matching sensors so that they could be attached to the two carbs to compare flow rates without having to move single flow sensor from one carb to another. I have a Uni-Syn. I think it restricts the flow on the carb being measured. A hot wire doesn't.
This would be awesome! Reach out if you want to collaborate on this.
Thank for sharing that great video. However is there a reason, why you tuned your idle mixture that way instead of using the LBI + half a turn method? 12.5:1 AFR seems to be very rich.
Thanks. I have no problem with the LBI method and I know it's common.
I will say that a 1/2 turn is a LOT will result in 12.5 or less.
I was tuning in 1/8 turn increments and saw significant changes in AFR.
What AFR do you like to see on an air cooled engine?
@@GarageTimeAutoResto Okay got it :) I usually end up with high 13s-low 14s at idle.. But then again, idle afr doesn't really matter, I was just wondering if you chose that value for a reason. For the progression circuit I try to stay lean of peak and around 12.5 to 12.75 on the main circuit. Which values are you targeting there?
It depends! part throttle or light throttle gets into the 14's some times. WOT dips into the 11's.
I'm not tuning for max HP on this engine. This engine doesn't cough, backfire, hesitate or bog at all. It also runs cool which is important to me.
My 911 engine will get a much more aggressive tune.👍
Idle AFR is a bit rich because these carbs don't have chokes for cold start, so it's all a bit of a compromise.
I do love the AFR Guage as it takes so much of the guesswork out of it.
I still have it connected. A few weeks ago I got a plugged idle jet and it showed up on the Guage immediately.
Cool info! 👍🏻
Hey Tom.... I was woundering if you set your float levels (in addition to your float level ck.)by measuring the float travel in relation to the float pin. Weber says 14mm open (without pressure on the ball) and 22mm closed. Many 356,sndVWGuyes set the floats at 10.5 and 32.5 mm respectively. By carefully bending the float tabs (top and rear) you can ajust to get it exact,... what are your thoughts on this? And where did you get the nylon spacer on the top of carb. Setup that you made? Thanks again Tom🤙🏽
Hi Bill, as always there are many ways to skin a cat. Physical measurements are good, but its an indirect measurement in my opinion. How does the fuel pressure affect the float level? What about seat or pin wear?
The thing that actually matters is what the actual fuel level is when you are driving. That is why I like measuring the fuel level with it running. Solex 40P11 has a screw on guage that lets you sight the fuel level when running. This is my favorite method.
Weber does not allow this, which is why I made those little paper sticks to check. Fuel level can also be a tuning parameter to tune when the main circuit kicks in.
I think the best performance is when the actual fuel level is a few millimeters below the main circuit port. Too high and unwanted fuel will spill in. Too low and the main circuit kicks in too late.
We all want a set it and forget it number. The ENGINE may want something else. That's the rub!
The nylon spacer was homemade by me on a CNC machine.
Best of luck on your carb journey.
@@GarageTimeAutoResto The Weber manual is wrong with respect to 'initial' float settings. The rule of thumb is check fuel pressure first...max 3.5lb (critical). Once fuel pressure is confirmed adjust float height to 10-11.5mm with gasket in place and ball NOT depressed. The float drop is not as critical 28-32mm will suffice.
I have these same carbs on a 2110cc VW type 1 engine that I'm trying to get dialed in. So far it idles perfect and WOT seems pretty good but off idle transition to mains stumbles a little, almost an on-off feel.
I'm starting with 55 idle, 200 air, and 125 main jets with I believe the f-11 emulsion tubes.
I'm at 6000 feet elevation.
I also have a vacuum/centrifugal combination distributor that I can't seem to get any vacuum advance? I have vacuum tubes from both carbs into a T and then to distributor. Can you tell me if I need some sort of check valve in those vacuum lines?
I'm wishing I would have gone with centrifugal advance only and may end up switching.
I really liked your video and I learned a lot watching it.
I'm definitely going to check the float levels running as well as run the idle circuit without the main jet stacks in to isolate the idle circuit.
I'm not super familiar with VW engines, but they are very similar to Porsche obviously. Are you running a cam with large duration? Is that why the vacuum is low?
Here's what I recommend:
Start with the distributor and set the total advance with the vacuum disconnected. Porsche engines like 35 degrees, but I think VW engines like less. It depends on your compression ratio, cam and head geometry ultimately.
I don't think you need a check valve for the vacuum lines. The vacuum advance comes in handy under part throttle.
Research the max advance for engine and set it at that. If not try 28 degrees?
Hopefully it will still idle ok.
Back off the accelerator pump screws out several turns so they don't interfere with jetting.
My guess is you are way too rich- I'd go with leaner mains and idle jets.
Are you using 28mm venturis? An engine that size might do better with 30 or 32mm vents.
You wont be able to get enough vacuum for that distributor. You would only get two cylinders of vacuum vs four with a single carb
Nice
What tuning software and USB attachment?
You have tried venturis 32?
Yes, the carbs came with 32. It didn't drive well at low speed. I also have 30mm which might work, but I'm not after high RPM performance with this engine
I don't have a synchrometer can I use something else instead?
You can use a piece of hose and hold it up to your ear. Be careful for backfires!
@@GarageTimeAutoRestoDidn't the response until now😬 But thanks! I bought a synchrometer😅
Keep seeing the scooter and can't help but think gta points... Haha
I know, he kept circling around me like a gnat
And you do have a look alike on You Tube. I swear you guys could be brothers. His name is Matt Risinger.
Ha ha
You dont just kick the tyre and everything magically works?
Well, this is TH-cam, ha ha
What size is your 912 engine?
1720 cc . I also forgot to say I'm at sea level
Really kinda bummed you don't have way more views... You're not even putting out a cup...
Keep commenting and sharing I guess?