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Great video! If I’m understanding well, the momentary enrichment of fuel when opening the throttle happens because the RPMs go up faster than the piston goes up (because of the delay effect caused by the damper), thus the air velocity momentarily increases because the open cross section in the carb body is still small (piston still down) causing a higher Venturi effect in the jet-needle?

You do do some pretty units. Is that some satin clean on the body?

I do like your clearly explained videos. I've been in this game for a long time,but it does no harm to listen to the whys and wherefores . By the whey, I've throne away more than enough perfectly good wax jets in the past!

Excellent, thanks

Does the float chamber need to be mounted with a rubber mount between it and the carb body ? I was always under the impression that if they were mounted solidly then vibration could cause problems with the fuel supply.

Great video, one of the most confusing things learning when a piston flys up (thin oil etc) it leans, which I'll admit was not what I used to think due to thinking the needle was pulling out and therefore must be enriching. As a side request you once did a videos with a weight (lay shaft I think) to show approximately the drop speed on a carb, would you be able to show that test on this hs4 please?

Im enjoying my home tutoring 😁 So interesting. Thanks AC

Clear and concise quality information.....👍

Extremely interesting video, AC. The SU is an ingenious contraption and a beautiful piece of engineering. Thanks for a great video👍

Nice one Constant depression carburettors are beautiful things And you mentioned the importance of the crankcase ventilation👍 it is positively dangerous to disconnect it Carbon monoxide isn't friendly

Awesome video

Despite a wide-band gauge, and heaps of needles... I've measured them! Now I grasp why my needles don't give the result as per. spec. No two needles are the same! Thank you AC!

Just rebuilt my HS4 carbs on my Spitfire 1500. This was the exact video I was looking for. You’re a true professional in every sense of the word. I like the break down of why we make adjustments or what the function is. Too many channels throw information at you with little to no explanation of why we’re doing it.

Awesome vid, thanks for sharing.

Few months ago i left a message asking for advice on tuning up an old escort with an over-rich cruise jetting using it's original carburettor, which didn't make sense to me as the pilot jet is non-removeable, and set into the casting at a mystery angle, basically impossible to plug up and re-drill accurately for leaning out. I managed to solve the problem myself. All the workshop manuals I had contained no information on how to get into one whole area of the carburettor which could only be accessed by punching out a tiny pin, which was quite difficult but I did it. Basically the carb has a secondary, non adjustable main jet. There is a spring loaded, vacuum actuated plunger which closes a tiny valve which feeds this secondary main jet. Hard to describe but I found out holley carbs have a similar system called the power-jet. Probably something you've come across before but anyway, my "powerjet" mechanism was seized in the open position and the vacuum channel which actuated it was dirty because I didn't know I could access it seeing as there was no information on disassembling it that far in the manuals. Anyway cleaned it out and freed up this system and now my AFR's are exactly like you described in the chart you drew in your last "deep dive" video. I had a spare one of these carburetors so i pulled it apart out of interest and that system was clogged up in that one also. Surprised how bad they got despite that system is never actually submerged in fuel. It's only ever exposed to vacuum below the throttle plate. Immediately noticeable difference in fuel economy and a bit nicer to drive, pretty chuffed with myself to say the least.

AC Dodd, is that radiator fan on backwards, on the last car??

Can’t thank this man enough, he’s the sorcerer of knowledge when it comes to these little A series engine, he supplied me with top quality parts that he altered to suit my engine specifications and the amount of extra advise, knowledge and teachings he has given me not just through his videos but in his personal time through private messages which he didn’t have to do is just priceless, wouldn’t have my car on the road or running as well as it is without the help of this man, will definitely be using him again in the future before I go to anyone else.

Lobe grease. Things kids today will never understand.

Hi M8 how can one book you in too get my 1988 mini looked at thanks

Hoping to get you to sort my out AC one day but as you say you are always busy

Love watching your videos AA++

😊When are you coming to the Midlands just started watching your videos and would very much like you to come and do mine

😊Would love you to come and do my 1340

2:05, modern engines look absolutely horrible don't they ?, i have a 2010 Alfa Romeo 159 Ti with the 1750 Tbi petrol engine, goes well and has decent power (been re-mapped to 240) it's an ugly mess under the huge plastic cover, give me a 7 port A series, a Cosworth YB or a Chevy V8 any day lol.

Cracking video and channel, have a question about a Weber 40 DCOE on a Mini, is it true you cant run a Vacuum advance with the Weber as there is no facility for the Vacuum line ?

You mentioned not enough oil in the damper dashpot. As an estimate what is the consumption rate of dashpot damper oil? Or should there be no consumption of the dashpot oil at all?

Keep them going AC, your vids have been a revelation! How do we book you to work your magic?

vacuum unit? reminds me of mine.. nice work AC

Thanks for the tune up on the RSP at MLM this year AC, I thought it was going Ok but it’s got a lovely pop to it now. Good to see the guvnor chugging away on a ciggie in the background 👍🏼

Thank you for your efforts putting out all the useful information and the on the road tuning posts. Looking forward to some more deep dives...

I really enjoy your videos and am interested in getting some training with you next year.

Thanks for that, looking forward to more next year 👍.

Roll on next season. Thanks for all the effort you go to getting these vids out to the mini community. Priceless

AC can I ask why you went with BP6 plugs today .. Please

I WILL get my car in your capable hands by this time next year. Thanks again for sharing your wisdom with the community.

Another cracking episode, AC, and brilliant to see another Metro responding so well to your attentions. I'm still buzzing regarding the tune you did on mine!😁 Question for you - how often should the dashpot need topping up? Many thanks, Steve

Hi AC I have a question about my 1974 MGB. Would there be any advantage in my replacing the hif44 throttle plates with non overrun type? Please.

I am so glad that I didn't replace my fantastic old 2001 Mondeo with another Ford. With the exception of the hybrid Mondeo, the Renault 1.5 diesel engine, and the 2.0 Ecoboost with a manual (only available in the Focus ST), they've been pretty crap. The Powershift transmissions (among others, mated to the 2.0 Ecoboost Mondeo) and most of the Ecoboost engines have a shocking reputation. For now, I'm sticking with Japanese brands that don't have Jatco transmissions. To be fair, my old Mondeo had a Mazda engine.

To which SU carburetors do you offer your zero-tolerance version?

So satisfying to watch 👍

Hello, i have an Vw Golf mk4 1.6 FSI BAD, compression on cylinder 1 is 12.5 bars , on the others is 16~ bars, because of that the engine have some shakes, the difference is kind of big, i have new pistons, what do you thing is the problem ? springs, or one of the valves on cylinder 1 might not close properly ?

Sorry I missed you live, but excellent content as always. Ross built my 1220 with your Dizzy, 1.28 rockers, RT Cam and your recon Hiff44 Carb Its superb and going strong !!

Good show 👏

Hi

Watched your cideo and was really looking forward g forward to servicing my maglite. I got as far as removing the rubber on/off switch and inserting the T8 into the screw in the middle of the button. The screw turned and turned, and never backed out and the switch never came loose to remove it. End of story………….

Just up my alley, this 👍

Out of interest (as a non SU carb owner), typically what mileage should a decently tuned A series engine do before the engine needs a rebuild and the carbs become worn? I guess this is a 'how long is a piece of string' question - but given that most A series owners now are enthusiasts, how often will a car with a properly built road tune need checking. As a Ford bloke from the 80's we were always tinkering, but what are the signs that stuff has worn. Big question i know because we have to include the dizzy wear! My MIL has a mini 1000 auto... Also - in your honest opinion and given your knowledge, were many main dealer garages were equipped with the deep knowledge and training to get the best out of these lovely cars even when new? Most modern engines will smash past 150K miles but my 10 year old Escort Mk1 1300 was very tired at 70K miles. Do modem machining methods give old engines a longer life? What's Changed? Most of my early cars went to the scrappy because of rust - everything else was easy to get to on a weekend. Given that you can beat the tin worm these days, is a classic mini an viable daily drive without a garage? Asking for a wife with a love of minis (and no garage because that is where my motorcycles live)... Could be an episode there to detail what has changed in the last 30 years.

Great video! So the needle fitted was too thick right across the rev range? Making it lean? I’ve a tahini too, mines a 1275 hif38 and has an AEM needle fitted which I believe is what was fitted when new…not that that means anything 30 years later. What do you mean when you say the carb is worn? play in the spindles? Worn throttle disc? Thanks 👍

Another great video. I will definitely be giving you a call when I get my Magnette back up and running.

Perfect video, very informative. Thank you! One question, that misfire limit for high power ignition, could you share around what lambda value it is?