Amazon: - HS6 slipping? - Page 2

Ron Kwas · Jan 30th, 2015, 14:25

Derek; "I think the vacuum that pulls the piston up sucks via the internal hole hence the need for a sealed cap. Not sure how the vacuum is applied when there is a breather in the cap. "

There is no difference in the way vacuum is applied to "Dashpot Volume" as a function of breather or no breather in cap. Dashpot Volume is evacuated by the two large holes in the bottom of Dashpot, and it occurs by venturi action...just as fuel is drawn into airstream from jet below, Dashpot volume air is drawn into airstream from above, and this evacuation lifts Dashpot against gravity and spring forces, and damper.

Venting of the "damper volume" (that's what I'll call the volume above the damper valve and fluid) is either to the outside world (by way of a hole in the cap) OR to Dashpot volume (by way of the internal hole you mention...in this case, no hole is present in cap). I don't know why this was changed (for the worse) in the later versions...it seems to me that venting to the outside (where dust/debris are pulled in every time Dashpot falls...I have verified this action...OK its just a tiny hole, but plenty big for nasties which would contaminate damping oil, accelerating wear)...this is just not as good as venting to (clean) Dashpot volume.

Damping fluid: No manual calls for ATF, agreed. They call for 20 weight oil (and so does the britishclassicmotors link, I'm happy to see)...and since that is what ATF pretty much is, and consistently over temp range (also an important factor), and I have had good results with it (I find the rate of damping, fine, with no lean stumble on hard accels...and that is my ultimate test of acceptability), and it is inexpensively available by the quart, I have made the judgement call/executive decision to use, and recommend it. BTW, I also use and recommend Marvel Mystery Oil for the same reasons!

ASt85; Certainly agreed that Ignition System advance (vacuum and/or centrifugal) must both be functioning correctly and returning repeatably before we start messing with Carbies!

Cheers from Connecticut!

volvogv · Jan 31st, 2015, 00:13

I just went out there to look at the vacuum advance tube. It looks like it's on solid. The piston caps have vent holes.

A few months ago I discovered the front jet was sticking so I pulled it out and put some light grease on there as a lubricant.

As for the dashpot oil, I could swear my owners manual said to use ATF. I'd better re-read the book!

c1800 · Jan 31st, 2015, 04:44

Go to page 2-26

specifies ATF.

http://volvo1800pictures.com/documen...ne_B18_B_D.pdf

arcturus · Jan 31st, 2015, 08:57

Quote:

Originally Posted by volvogv

I just went out there to look at the vacuum advance tube. It looks like it's on solid. The piston caps have vent holes.

A few months ago I discovered the front jet was sticking so I pulled it out and put some light grease on there as a lubricant.

As for the dashpot oil, I could swear my owners manual said to use ATF. I'd better re-read the book!

Light grease would have been washed off in minutes by the fuel. What you have just said about jet would indicate an off center needle. Check the piston for the "clunk" test
Re vacuum advance/retard. There was some discussion on this forum which recommended disconnecting vac tube and plugging hole in dizy. Others may elaborate.

Ron Kwas · Jan 31st, 2015, 11:58

C1800; I stand correct corrected (...nothing wrong with that!)...there it is on page 2-19: ATF ...I guess it's been so long that I thought using ATF had come from some great revelation of mine or development or discovery I made...when it had come from the Green manual the whole time...thanks for double-checking on us and keeping us honest.

Cheers from Connecticut!

Derek UK · Jan 31st, 2015, 12:00

Quote:

Originally Posted by c1800

Go to page 2-26

specifies ATF.

http://volvo1800pictures.com/documen...ne_B18_B_D.pdf

Interesting. I have that Green Book in my collection. I see it's dated 1969 so was probably the last printing of the B18B/D book. The 1964 P120 Lubrication book reads more or less the same as follows.
Carburettors
Every time the oil is changed on vehicles with twin carburettors, the centre spindles of the carburettors should be filled with SAE 20 oil. The nut and damping piston (Fig. 2) are removed, after which the centre spindle, but not the part above it, is filled, NB. Multigrade oil must not be used for the carburettor centre spindle.

Can only guess that in 1964 ATF wasn't used by Volvo and SAE 20 was easily available. By 1969 ATF was common and SAE 20 wasn't.
Bottom line, use either but I doubt if they mix well.
From Wiki: Type A fluid is generally difficult to obtain now. It turns out that Type A was basically a nearly 50/50 mix of Type F (Ford) and Dexron (GM).

I'm sure you won't go to that much trouble for just a pair of carbs! From various viscosity charts it does look as if ATF will thin out quite a bit if the carbs are running physically hot. This might be bad news in hot areas.

For Ron and others, the oft mentioned, in the USA, Marvel Mystery Oil, has been described as Redex in disguise. Any comments? Some people use these in the dashpots.

volvogv · Feb 1st, 2015, 01:12

This is very interesting! I have two Amazon owners manuals from different years. One says ATF and the other says oil. So none of us were crazy after all!

I worked on the carbs a little bit today and I was able to dis-prove my jet slippage theory. Instead of the nut backing itself out and enriching the mixture, it actually needed little more juice. The rear carb behaves in a textbook manner, but the front carb has something wrong with it. I lift the piston and the RPM bumps up then drops waaay off. Too lean right? NO. I give it an extra flat and then it goes up and stays up. Then I lift it again and if falls way off. I need to pull it off the engine and have a look.

While I was in there, I burped the throttle while looking at the pistons and I could see that they snapped up instantly. You know...I'm ready to give up my ATF and try oil in the dampers!

Ron Kwas · Feb 1st, 2015, 10:56

volvogv;

If you lift the piston of the same carb twice (and presumably the same amount, as the lifting pin has a stop which should assure this) and get different results, then you got what I have shown here:

I have never found that test pin method particularly consistent either...it's just too touchy...I adjust both carbs so that the react similarly when I blip throttle (next best thing to having a dynemometer with which to load engine constantly is loading the engine momentarily against its own inertia, and this is ideal for checking damping action as you monitor dashpots), and fine-adjust mixture after a road test.

Damping: If damping valve is in place (black octo-knob snugged on top of dome such that actual brass valve components on other end of rod are submerged at the bottom), and ANY kind of oil...ATF, 20W, MMO, 3-in-1, is present in damping tube, but there is no damping action and dashpots lift immediately when blipping throttle...that is not right...either something is indeed wrong with damper valve components, or the damping action is simply too fast (not enough viscosity in damping oil, or worn damping valve components), OR you are not recognizing the damping which IS indeed taking place. To check and verify damping: With engine OFF, air-filters removed, everything else normal, simply lift up on dashpots with your finger...you should feel some resistance...unscrew damping valve (black octo), and remove from carb entirely and try again...you should feel NO damping whatsoever in comparison. Replace Damper valve, try again...note the difference? Please check this and post results.

Good Hunting!

Derek UK · Feb 1st, 2015, 11:38

GV, not trying to confuse the issue, but what type of inlet/exhaust manifold are you using? Does it happen to be one of the emissions type with the extra butterflies?

volvogv · Feb 1st, 2015, 17:28

Derek: I have the old style non-emisson manifold.

Ron: I tried the lift test as you suggested. When I push up, i can feel solid resistance which goes away when the damper is removed.

I found something that might explain the randomness.....When I lift up on the pistons (engine off, damper in), the rear carb has 1/4 inch of free play with no resistance before it starts to dampen. The front carb has the same problem but with 1/8 inch of free play. In other words, the first 1/4 inch of lifting has no resistance to motion.

It seems to me that there should be no free play at all. Maybe this would explain the erratic behavior of my carbs. One of my dampers is new, the other is old. I wonder now if the piston bores are worn out from years up up and down motion against the dampers?
Oh, and there was no evidence of needles sticking.

Jan 30th, 2015, 14:25	#11
Ron Kwas Premier Member Last Online: Today 19:08 Join Date: Jul 2007 Location: Connecticut, USA	Derek; "I think the vacuum that pulls the piston up sucks via the internal hole hence the need for a sealed cap. Not sure how the vacuum is applied when there is a breather in the cap. " There is no difference in the way vacuum is applied to "Dashpot Volume" as a function of breather or no breather in cap. Dashpot Volume is evacuated by the two large holes in the bottom of Dashpot, and it occurs by venturi action...just as fuel is drawn into airstream from jet below, Dashpot volume air is drawn into airstream from above, and this evacuation lifts Dashpot against gravity and spring forces, and damper. Venting of the "damper volume" (that's what I'll call the volume above the damper valve and fluid) is either to the outside world (by way of a hole in the cap) OR to Dashpot volume (by way of the internal hole you mention...in this case, no hole is present in cap). I don't know why this was changed (for the worse) in the later versions...it seems to me that venting to the outside (where dust/debris are pulled in every time Dashpot falls...I have verified this action...OK its just a tiny hole, but plenty big for nasties which would contaminate damping oil, accelerating wear)...this is just not as good as venting to (clean) Dashpot volume. Damping fluid: No manual calls for ATF, agreed. They call for 20 weight oil (and so does the britishclassicmotors link, I'm happy to see)...and since that is what ATF pretty much is, and consistently over temp range (also an important factor), and I have had good results with it (I find the rate of damping, fine, with no lean stumble on hard accels...and that is my ultimate test of acceptability), and it is inexpensively available by the quart, I have made the judgement call/executive decision to use, and recommend it. BTW, I also use and recommend Marvel Mystery Oil for the same reasons! ASt85; Certainly agreed that Ignition System advance (vacuum and/or centrifugal) must both be functioning correctly and returning repeatably before we start messing with Carbies! Cheers from Connecticut!

Jan 31st, 2015, 00:13	#12
volvogv Master Member Last Online: Aug 29th, 2016 19:28 Join Date: Oct 2013 Location: Seattle	I just went out there to look at the vacuum advance tube. It looks like it's on solid. The piston caps have vent holes. A few months ago I discovered the front jet was sticking so I pulled it out and put some light grease on there as a lubricant. As for the dashpot oil, I could swear my owners manual said to use ATF. I'd better re-read the book!

Jan 31st, 2015, 04:44	#13
c1800 Master Member Last Online: Apr 22nd, 2024 18:48 Join Date: Oct 2013 Location: Alberta	Go to page 2-26 specifies ATF. http://volvo1800pictures.com/documen...ne_B18_B_D.pdf

Jan 31st, 2015, 11:58	#15
Ron Kwas Premier Member Last Online: Today 19:08 Join Date: Jul 2007 Location: Connecticut, USA	C1800; I stand correct corrected (...nothing wrong with that!)...there it is on page 2-19: ATF ...I guess it's been so long that I thought using ATF had come from some great revelation of mine or development or discovery I made...when it had come from the Green manual the whole time...thanks for double-checking on us and keeping us honest. Cheers from Connecticut!

Feb 1st, 2015, 01:12	#17
volvogv Master Member Last Online: Aug 29th, 2016 19:28 Join Date: Oct 2013 Location: Seattle	This is very interesting! I have two Amazon owners manuals from different years. One says ATF and the other says oil. So none of us were crazy after all! I worked on the carbs a little bit today and I was able to dis-prove my jet slippage theory. Instead of the nut backing itself out and enriching the mixture, it actually needed little more juice. The rear carb behaves in a textbook manner, but the front carb has something wrong with it. I lift the piston and the RPM bumps up then drops waaay off. Too lean right? NO. I give it an extra flat and then it goes up and stays up. Then I lift it again and if falls way off. I need to pull it off the engine and have a look. While I was in there, I burped the throttle while looking at the pistons and I could see that they snapped up instantly. You know...I'm ready to give up my ATF and try oil in the dampers!

Feb 1st, 2015, 10:56	#18
Ron Kwas Premier Member Last Online: Today 19:08 Join Date: Jul 2007 Location: Connecticut, USA	volvogv; If you lift the piston of the same carb twice (and presumably the same amount, as the lifting pin has a stop which should assure this) and get different results, then you got what I have shown here: I have never found that test pin method particularly consistent either...it's just too touchy...I adjust both carbs so that the react similarly when I blip throttle (next best thing to having a dynemometer with which to load engine constantly is loading the engine momentarily against its own inertia, and this is ideal for checking damping action as you monitor dashpots), and fine-adjust mixture after a road test. Damping: If damping valve is in place (black octo-knob snugged on top of dome such that actual brass valve components on other end of rod are submerged at the bottom), and ANY kind of oil...ATF, 20W, MMO, 3-in-1, is present in damping tube, but there is no damping action and dashpots lift immediately when blipping throttle...that is not right...either something is indeed wrong with damper valve components, or the damping action is simply too fast (not enough viscosity in damping oil, or worn damping valve components), OR you are not recognizing the damping which IS indeed taking place. To check and verify damping: With engine OFF, air-filters removed, everything else normal, simply lift up on dashpots with your finger...you should feel some resistance...unscrew damping valve (black octo), and remove from carb entirely and try again...you should feel NO damping whatsoever in comparison. Replace Damper valve, try again...note the difference? Please check this and post results. Good Hunting!

Feb 1st, 2015, 11:38	#19
Derek UK VOC Member Last Online: Today 20:59 Join Date: Jul 2006 Location: Chatham	GV, not trying to confuse the issue, but what type of inlet/exhaust manifold are you using? Does it happen to be one of the emissions type with the extra butterflies?

Feb 1st, 2015, 17:28	#20
volvogv Master Member Last Online: Aug 29th, 2016 19:28 Join Date: Oct 2013 Location: Seattle	Derek: I have the old style non-emisson manifold. Ron: I tried the lift test as you suggested. When I push up, i can feel solid resistance which goes away when the damper is removed. I found something that might explain the randomness.....When I lift up on the pistons (engine off, damper in), the rear carb has 1/4 inch of free play with no resistance before it starts to dampen. The front carb has the same problem but with 1/8 inch of free play. In other words, the first 1/4 inch of lifting has no resistance to motion. It seems to me that there should be no free play at all. Maybe this would explain the erratic behavior of my carbs. One of my dampers is new, the other is old. I wonder now if the piston bores are worn out from years up up and down motion against the dampers? Oh, and there was no evidence of needles sticking.

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