How to balance (tune) twin SU carburettors on a 1500 Triumph Spitfire
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- เผยแพร่เมื่อ 30 ก.ย. 2024
- How to tune/balance SU carbs for smooth running, efficient running and maximum mpg. Also helps to keep the car running cool and start better.
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I enjoyed you video 😀 by the way the nuts are BA not metric or whitworth 😀😀👍
The balance process doesn't look terrible with the appropriate tools. I am considering getting a pair of SU H4 carburettors for my Volvo Amazon since SU seem to be a lot more popular than the downdraft Zenith. Difficult to find someone to refurbish a Zenith, but plentiful of people do SUs.
As Paul said, once SU's setup, lasts for years. Strombergs are ok but there is a diaphragm inside which does perish over time.
Sus are great, they have very few parts, so simple to work on and vert efficient. Used to run the original rover v8 ones on mybtuned rover, ported the bodies, wedged the pistons, even knife edged the butterflies, my rolling Road man made custom needles and it made really strong power. I love them
@@YorkshireClassicCarsltd I had a Grinnall conversion done in the 80's, the V8 had the SU's but each SU is shared between the banks, and the outer 4 pistons get a lower mix, I think there should have been 4 SU's on it, but the Holley with offenhauser manifold was a great update but a pain to set up!
@ChrisFEJackson I did it differently, used the stock manifold sawed off the pent roof (by hand!) Tapped and sealed the water bleed, removed the divider in the mouth and had an adapter for a twin choke weber welded on I fabricated. Used a 32/36 dgav many years then swapped for a 38dgas with the choke mech removed etc, drove very well right through the rev range, made 240@wheels at 5000 rpm
@@YorkshireClassicCarsltd You are the man!! That sounds bleddy brilliant!!
Question. I have a Austin Healey that coughs when the it's not up to operating temperature while giving it some gas. Once it's up to temp, it might cough but normally does not. It's not a backfire. Any suggestions what to look for?
The other two holes on the carb allow air in and out of the dash pot chamber. If the holes wernt there the dash pot would be operating with a presure differential and wouldnt want to move as freely. As you rev the engine and the piston in the dash pot moves up it needs to allow the air out of the dash pot.
So as the piston lifts the air is expelled out and as the piston drops the air is drawn back in. It just keeps internal and external presures equal so that the desighned damping afect is achieved from the dash pot oil and spring.
It still looked a smoother idle than my mgb , even when out of sync !
If you have lift on the butterfly spindles you will always have a lumpy idle, so it might be that?
@@YorkshireClassicCarsltd No, they are in good shape... they ran fine on a 1500 engine.
You need a timing light to check the ing timing an many timing lights have a rpm counter
Yes it's an easy job when you have done it a few times. I have done my own car by ear I was out the first time when then using a sync, but after got used to the ear method. It can affect the temperature, once mine was set correctly it did drop about an eighth of a segment lower (TR7). Cheers. This is a good example for anyone to embark initially setting their dual carbs.
I hoped it would be of use, I usually do it by ear but check with the synchroniser just to be sure, but of course you can't really teach that, especially in a video it just comes from experience really
Thank you for this vid! Going to buy my Synchrometer today and have a go when the parts turn up, really informative and exactly what I was looking for
Thank you, glad to help. Check the timing first, sometimes takes a couple of goes to get it spot on
@@YorkshireClassicCarsltd have fitted all parts over the weekend sounds fine on idle but doesn;t go past 3500rpm when driving loses power? I've fitted new plugs, new battery and cleaned fuel filter and run it without fuel ca to try and get air through but feels like a compression issue to me now.
Thats identical to mine right down to the carbs needing doing 😂😂😂
Is yours topaz too?
@YorkshireClassicCarsltd yeah it is. The one you were working on was in great condition there. If you could do a video on the mixture, that would be very interesting, esp for me. Thank you for the effort put into the video. Put very straightforward
@fazorboy thank you, I can do a mixture setting video, I've done that car now mixture wise, but I could do it again to show the procedure, it's pretty easy , but I have a wide band o2 sensor so I'm a but spoilt!
Great video very helpful is there any chance you could show setting the mixture screws on the 1500 spitfire.
They don't have screws it's the nut under the carb that the jet slides through that adjusts thr mixture
Metric spanners on a 70's British car?
Yup, like I say in the vid, no idea what thread the crews are, but the metrics do the job admirably! Think they are bsf or Whitworth, but af doesn't fit as well as the metric!
I never found anything other than a 9mm fits! What size imperial do you use, or you don’t?
Excellent explanation but even as a newbie I've never understood why it is suggested to unclamp the linkage. Certainly using the SU balancing tool you don't do this. I then double checked using a flow meter (still with the linkage connected) and it was spot on. Very much enjoying all the videos on your channel.
It's to make sure that you adjust each carb individually, sometimes as you adjust one that's a long way out, it will start to open the other carb slightly, if that makes sense?!
@@YorkshireClassicCarsltd Also, from my experience, with engine running, once the adjustment is made, you need to 'blip' the adjusted carb & allow to settle, recheck and once happy move to 2nd carb. With the linkage loose it allows you to blip each carb in turn, after making any adjustment.
Great explanation of running you own business
I'm run my own Carpentry business in Queensland Australia, doing small renovations. I can identify with what you have spoken about.
I use a hose the my ear and go from carb to carb with my grip on the base to get the same depth in the air intake and set the same sucking noise in my ear
Yes please do a video on fuel mixture adjustment. Thanks
I always adjust the fuel mixture when I balance the carbs.
Est video I’ve see on how to set up the carbs. Thank you
very useful , used info to do my TR7
Glad it helped
Great video thanks 👍
Thank you
Good video, thanks
I'm struggling to set up the carb on my spitfire would love to see a video on how to adjust the mixtures.
My engine idles around 1k, anything below that is rough. As I rev the engine it becomes smooth after 2.5k. However when I open the the throttle fully and close it the idle rpm keeps dropping until engine stalls.