Adam, I was VERY concerned to see your drop test with the piston pointing down, and you having to stop it with your finger. Dropping it onto the floor can have disastrous effects. I would refer you to the SU Reference Catalogue 1930-1980, which details this procedure. For the HS8 carburetter, p170 of the catalogue, it refers you to the procedure for the HS2, HS4, and HS6, on p 168. I quote the relevant paragraphs (31 - 37). NOTE : The following timing check applies only to standard Suction Chambers, and need only be carried out if the cause of the carburetter malfunction which necessitated the dismantling has not been located. 31. Temporarily plug the piston transfer holes. (I actually use plugs of wet tissue paper) 32. Fit the piston into the chamber, without its spring. 33. Fit a nut and screw, with a large flat washer under the nut, into one of the suction chamber fixing holes, positioning the washer so that it overlaps the chamber bore. 34. Fit the damper and washer, if fitted. (I note that you did NOT fit the damper in your test). 35. Check that the piston is fully home in the chamber, INVERT (my exclamation) the assembly, to allow the chamber to fall away until the piston contacts the washer. 36. Check the time taken for the chamber to fall the full extent of the piston travel. For carburetters 38mm (1.5in) to 47.6mm (1 7/8in) bore, the time taken should be 5 to 7 seconds. 37 If the times are exceeded check the piston and chamber for the presence of oil, foreign matter and damage. If after rechecking, the time is still not within these limits, renew the suction chamber assembly. (I usually clean the inside of the chamber with a paper towel moistened with Isopropanol Alcohol). I have an HD6 on my car, and the procedure is the same apart from the use of the bolt, washer and nut, (which limits the travel of the piston). I usually count, 1000, 2000, 3000, etc., upto 8000, (it really takes a second to say thousand), before catching the suction cover in my hand, but that actually allows an ''extra'' thickness of the piston to exit the chamber, thus increasing the time taken. I also mark the 'keyway slot' on the suction cover so that I 'know' that this is the exact same location as in the operating position. I hope that this was not too long winded, if you want a copy of page 168, or any other page, then let me know ! Please comment !

Great video, found it just in time to see that the pistons had been switched on my SU hs6 pair. Thanks!

Thank you Adam. I have never seen this test. 🙏

Thanks for your video's they are not to long each and clearly to the point.

@LivingWithAClassic

2 жыл бұрын

Glad you enjoyed it!

Never come across that test before, I'll have to try that on mine. Many thanks for the info.

@LivingWithAClassic

4 жыл бұрын

Glad you found the test useful. Thank you for watching!

Very nice test and thank you. I will try this on a pair l recently purchased for a future project.

@LivingWithAClassic

3 жыл бұрын

So far they have been mismatched on all my carbureted cars. They run a lot better when they are correct

Very good information! Thank you from Argentina!

@LivingWithAClassic

4 жыл бұрын

Thanks for watching 😊

Great video. thanks for posting...

Thanks great easy test I’ll try it on my MGA

Fascinating, great tip, thank you

@LivingWithAClassic

4 жыл бұрын

Thanks for watching!

Hey just found you channel awsome. Thank you all this great info to get me old girl running better. 75 s1 xj6 4.2

Great tip thanks

"Swap the pistons over".... I had 2 moving at very different speeds. So I saw this video and swapped them over. Jesus it fixed everything. I rarely comment on videos but this one was 100% bang on accurate. Thank you. Liked and Subscribed.

@LivingWithAClassic

2 жыл бұрын

I'm really glad I could help Trevor! Hope your car is running well now

Going one step further, what do you do if you can't resolve a big difference in the drop rate?

Good info and good way of explanation... please do the tuning video on car as well. Good work.

@LivingWithAClassic

4 жыл бұрын

I will 😊 Thank you for watching!

A great tip 👍 Thanks.

@LivingWithAClassic

4 жыл бұрын

Thank you for watching!

Great tip.

@LivingWithAClassic

4 жыл бұрын

Glad you enjoyed it!

Tested on my son´s -71 and found it mixed, switched and now they fall at same speed. Super tip.

@LivingWithAClassic

4 жыл бұрын

Great that you found that! Hope it runs even better now 😊

Thank you good information.

@LivingWithAClassic

2 жыл бұрын

You’re welcome

Awesome info! Thanks so much!

Thanks! Pretty sure the ones on my 72 MG Midget were swapped. They fall at the same speed now.

Good video, I have a massive difference with mine, whether I swap them around either way???

And what to do if they're still not synchronised after interchanging the pistons?

Yes, to get the best sync of multiple SU carbs, you'll want to match piston drop rate as much as possible. John Twist showed this to us in 2007. Look up his MANY vids on MG's and other British cars. Drop test is nothing new - SU documentation has described it for many decades.

@LivingWithAClassic

4 жыл бұрын

John Twist has som great videos! Thank you for watching 😊

I have a 1952 mg TD carbs didn't have tag # the kit that came had slightly thicker metering rods. I don't think I tightened all the way seats car only runs with choke on

Thanks Adam. I've never seen that test before. I will try it on mine. When I saw the title I assumed you would be doing the "drop" test with the carbs together which checks that the needle is not catching on the jet (as detailed in my Mark 2 service manual). Wouldn't you need to also perform that test if, as with your result, you ended up switching the pistons over?

@LivingWithAClassic

4 жыл бұрын

On these "later" carbs the needles are spring loaded and self center. On earlier carbs like on the MK2 or my 3.8S one would need to check if the needles are centered. Thanks for watching!

@tonycollingridge4347

4 жыл бұрын

@@LivingWithAClassic oh I didn't know that either! Thanks for the response.

What oil must be used in the carbs

If you swap them over, you need to reposition the jets?

@LivingWithAClassic

4 жыл бұрын

On the older style carbs yes but the HS and newer have self centering jets

Can You explain strongberg carb ? I have a Range Rover 1973, 3.9 engine and i want make a tune the carbs

@LivingWithAClassic

6 ай бұрын

I have a rebuild and rune series on Strombergs. I think you’ll find them if you search for Stromberg and my channel name

Wait a minute here! How did you keep the piston from falling to the floor? What stops the piston at the edge of the suction chamber (dashpot), plugging the holes with tape only? If suction fails would the piston fall to the floor damaging your jet needle?

@LivingWithAClassic

4 жыл бұрын

I have 2 fingers under that keep the piston from falling out

@mikedeskins3305

4 жыл бұрын

@@LivingWithAClassic Oh I see them now. I need to be more observant. Maybe I'll try that test on my HS6 S.U's on my '67 1800S Volvo. Thanks for the video and response.

@Dievas99

4 жыл бұрын

@@LivingWithAClassic I agree with Stuart. I would at least do it over the bench with a big pillow (my wife's) to catch a mishap.

@Paintppa1

4 жыл бұрын

You can use a small screw and nut to hold a washer on the bottom of the pot that will keep the piston from dropping out. I've seen a diagram for that, but I don't have a copy I can post. If I can find it I'll add it.

What if the third carbie is out ?

@gunnarMyTube

Жыл бұрын

You then have three carbs to swap between, and find out which of the combinations show the least difference in drop speed. With some luck one of the combinations will stand out as clearly the best. But one cannot know for certain the history of part swaps some earlier owner might have undertaken. And regardless of number of carbs..that taping up the holes... make sure holes are really covered off so no leaks there will spoil test results. And as cautioned; take care to not drop parts to the floor to avoid damage.

tried this today and neither piston wants to drop. I have lightly oiled the inside of the dash pots and outside of each piston where applicable but they are sticking. They don't seem (too) dirty although they seem to be rubbing inside the dashpots.. This may be a stupid question but could they be tightening up due to the colder weather (snowing today) and should I perhaps bring them inside to bring then at least to room temperature? Thanks for any comments or email.

@LivingWithAClassic

3 жыл бұрын

I would try it at room temperature and also it should not be liked. Clean with break clean and let it dry. Make sure all surfaces are nice, clean and free from grease

@brianlake47

3 жыл бұрын

@@LivingWithAClassic "not be liked"? not sure what this means, or did you mean "should not be lightly oiled" ??

@LivingWithAClassic

3 жыл бұрын

Sorry I was typing fast. It should be that it’s not suppose to be oiled

What's with the weird hand gestures?

@LivingWithAClassic

Жыл бұрын

A secret code