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H6 carb jet bearing assembly

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NutmegCT

NutmegCT

Great Pumpkin
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Jet assembly in both carbs seems "tight". You've seen my earlier questions about this. Choke is *very* tough to operate. Takes two people tugging on the choke knob to get it to pull the lever arms back. No way that could be right.

I removed the linkage and jet bearing assembly (Moss catalog, p. 24, #89, part #370-395) from the rear carb. I wanted to clean the assembly as well as grease the cork seals. In my carb the seals are cork, not rubber o-rings.

I soaked the metal parts in gasoline, and brushed off the dissolved carbon. Also scraped off the carbon deposits from the two upper cork seals and the bottom seal (inside the aluminum ring).

The two upper cork seals were very dry, so as advised, I rubbed bearing grease into them.

Carefully re-assembled all parts and began to replace in the carb. As a test I tried manually sliding the jet assembly (part #102) up through the seals. Seemed just as tight as before cleaning, but I continued with the re-assembly.

As I tightened the sealing nut (part #99) I discovered the jet assembly got even tighter, harder to slide up and down. Loosen the nut just a single flat, assembly got a bit easier to move. Tighten the nut to "stop", assembly got much harder to move up and down.

I finished assembly, re-attached the linkage, and found there was absolutely no change in the choke difficulty. Still way too hard to move that lever.

With lots of hand pressure, jet lever "snaps" back to fully toward firewall. Spring can't return it without some hand coaxing.

I'm about to try cleaning the assembly in the front carb, greasing the two cork seals as I did the rear. But as doing this to the rear changed nothing, I'm asking for advice here.

Thanks all.
Tom
 
Tom, I'm one who advised the bearing grease. I had the same problem as you described and the bearing grease resolved it. If the jets don't move somewhat freely after adding the grease and reinserting them in the carbs, I wouldn't even think of attaching the linkage till you can get them to move freely. There are 2 different nuts that have to be tightened, one that holds the assemble in the carb and one at the bottom of the assemble that adjusts the jet height. From my experience, After adding the grease to the cork seals and reinserting the assembles, I tightened the top mounting nut till snug and sealed. I didn't force it tight. Then, I made sure the jet moved freely up and down. Then,I hand tightened the lower nut to loose stop(meaning I didn't force it), seated the needle into the jet. Making sure the piston moved up and down smoothly and then backed the jet nut down 2 complete turns (about 8 flats) to start the tuning process. If at this point the choke jet doesn't move up and down freely, I am out of suggestions. Is it possible that you got the 2 jet rods switched and they are in different carbs and could that cause them to bind up. At this point I can only tell you what worked for me. Good Luck.
 
Thanks for the quick reply!

What I find mysterious is that the jet does move smoothly when the whole assembly is held in my hand. It gets really tight (almost stuck) when back in the carb and those nuts are tightened.

The upper nut ("sealing" nut) is the one that seems to get things bound up. I can loosen it a full turn and the jet moves relatively easily.

But the nut is supposed to be completely turned in, right? I can find no reference that the nut is to be "adjusted".

The lower nut (adjusting nut) when fully turned in raises the jet head even with the top of the assembly - no more. Loosening that nut drops the jet down. But that doesn't affect the tightness of the jet sliding up and down.

A thought: when I fully tighten that upper sealing nut, am I squeezing the cork seals so they expand? Altho' those seals seem whole and are now greased, do they "swell" over the years and thus become "too big" compared to their original size when installed?

Darn - I just sent an order for parts. Maybe I should have added new cork seals. Or can I just substitute a generic Sears Hardware o-ring?

Edit: I only worked on the rear carb, so I couldn't have got front/rear parts switched.

Argh.
Tom
 
Tom,


Stop!


You need to center the jet to the needle properly. This process may take a few attempts.


Do one carb at a time so you do not mix up parts. From the beginning,


1. remove the air filters and remove the dampners (those brass caps the oil goes in).


2. remove all linkages and pull the jet assy out.


3. unscrew the jet adjusting nut.


4. <span style="color: #FF0000">remove the spring above the nut.</span>


5. replace the jet adjusting nut and the jet head <span style="color: #FF0000">only</span> and screw the nut up on the thread as far as it will go. then push the jet all the way up to the bottom of the adjusting nut. <span style="color: #FF0000">do not overtighten</span>.


6. slacken that upper lock nut about a half turn. (this is that upper nut that holds the seals in place and acts the same as a faucet valve stem seal gland nut.


7. raise the piston with a small screw driver through the air intake to it's highest point and then let it drop freely under it's own weight. Insert a #2 pencil down from the dampner and gently press the piston down to the bottom of it's travel, if the piston does not move freely repeat the lifting and pressing down operation. if the piston still is not free remove the top cover and piston and clean them. Don't forget to clean the jet. Be very careful with the needle that protrudes from the piston and check that the shoulder of the needle is flush with the underface of the piston.


8. <span style="color: #FF0000">with the piston pressed down to the bottom tighten the lock nut.</span> lift the piston and let drop under it's own weight noting the noise it makes when it hits the bridge (bottom). Then pull the jet down as far as it will go without removing it and repeat the lifting and dropping process. If after lowering the jet down and raising and dropping the piston results in a louder click. the jet to needle will have to be centered again by the above process. If after several failed attempts the click is not satisfactory suspect a bent needle. If the process yields good results, remove the jet head and adjusting nut. replace the spring, adjusting nut and jet head. screw the nut fully home and then slacken it two and a half turns for initial mixture setting. this is usually a rich setting and will have to be adjusted for the proper mixture setting once all is back together.

the truth of the matter is you may never get that piston to drop with the same clicking noise with the jet fully out or in. the trick is to get it as smooth as possible and get some kind of noise out of it. mine makes a nice click fully out but with the jet up it achieves what i would call a dull thud!

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Tom,
Harry's advise is absolutely right. I was wondering if the needle was rubbing against the jet, although I am not sure that it can be that far out. From what I remember from when I rebuilt my carburettors, I left the cork washers soaking in grease for several days before I fitted them. They already seemed to have graphite on them. The seals were triangular in cross-section and when I assembled the carbs I put the jet in and during the centering process I tightened the big nut up fully against the carburettor body. There is certainly some resistance when trying to slide the jet up and down, but I have no problems pulling out the choke.
 
Harry and Nick - this is excellent! Thank you!

Harry - where did you find those instructions? Is that from your as yet unpublished book? My manual doesn't give nearly the detail you give.

Glad I did some shopping (cotter pins, o-rings, bearing grease) before starting this again. I'm about to head out to do the deed.

Details will follow. Thanks!

Tom
 
Done. Thank you Harry! No way I could have figured that out from my manuals alone. Pistons go up and drop smoothly, with a reassuring "thunk" when they return to the base. The jets slide easily up and down.

However, there's no change whatsoever. Choke cable is still way too tough to pull.

Note: the jets slide very easily up and down until the linkage is re-attached.

As I watched all the action, I noticed that as the choke cable is pulled back, there's a *lot* of lost movement in the jet levers (Moss part #33 pp. 24-25). As if the hole for the clevis pin for the jet lever links (parts #21 & 60) is about twice the diameter of the clevis pin.

I'd think that a lot of the effort needed to pull the choke is lost in that looseness. As the cable is pulled, the jet lever actually moves *up* about 1/4 inch before the jet assembly actually begins to be pulled down.

Do you folks know if the clevis pin hole on the jet levers is supposed to be much bigger than the pin itself? That's a lot of lost movement. Does anyone have a jet lever out, and could measure the diameter of that clevis pin hole? (the hole in the "middle" of the lever, not the one at the bottom for the connecting rod)

At least now I know the jet assemblies are now clean and the o-rings greased.

Tom
 
NutmegCT said:
Harry and Nick - this is excellent! Thank you!
Harry - where did you find those instructions? Is that from your as yet unpublished book? My manual doesn't give nearly the detail you give.
Tom
Click to expand...

Tom,

Sorry to dis-appoint! The instructions as I learned them were originally written and published by Mr. Kenneth Ball thirty-five years ago. Wish I didn't look that up!

What you got was the American translation by Harry. Who BTW is too cheap to buy new parts so he's had to do this a few times as well. The pins fit rather loose but mine are probably worn as well. You do not want any of it tight to where it will cause binding. That's where we are now. If it's not the cable, or the jet to needle alignment, then it's the linkage and how it travels. The important thing is that the jet is pulling out to enrich the mixture and then returning tight against the adjustment nut bottom. Don't forget you are pulling a lot of mechanicals with a small cable so it will be somewhat of a stiff pull.

Then there is always my TR mechanicals code, If somethings not working right or partially working it will surely break quickly and completely at the worst possible moment. Then and only then will you know what the problem is for sure. Did I forget to mention that the part will also be N/A?

I'm also running out of thought on your sticky choke cable though if it's still tight.
 
Harry - I was sure you had a $1 million advance on the way for that book!

You're right - I'm running out of ideas.

Unless someone can tell me the size of that clevis pin hole, I'll have to give up on the choke. I'm pleased with how much smoother the jet levers move now that the corks are greased. But alas the tough - nearly impossible - cable pull remains.

By the way, as previously noted, the choke pulls very easily and smoothly when disconnected from the linkage. I had thought it might be the slight kink (very slight) in the cable where it comes out of the sheath at the linkage, but can't imagine all that resistance from such a small kink. The kink easily slides into the sheath by the way.

Just out of curiosity - is that inner cable a stranded cable? Mine is stranded. Is it possible I've got an incorrect choke cable in there?

Tom
 
Tom,

Like yours, my choke cable only comes out about 1-1/2". I fretted over that for a while but ended up concentrating on getting the timing and mixture set correctly - and that made my starting a snap. I never use the choke anyway. Granted I live in CA where the temps are usually no lower than 60's. So for fair weather driving, if everything is in tune, i believe you can live without the choke.

BTW, when I first got my car, the carb seals were shot and they leaked gas. The mechanic who replaced my cylinder head gasket replaced the jet seals with the o-rings from Moss, so far no problems.

Tim
 
Tim - thanks for the info. When the temp is 60+ here I don't need choke either. But of course it's not always over 60!

I'm just one of those weird guys who wants the car to run like it was designed. You mention your cable only comes out 1 and 1/2 inch. Is it really tough to pull out? When it's out is the choke fully engaged (jet lever back parallel to the stationary arm)?

Thanks.
Tom
 
Tom,

It is easy to pull to 1-1/2" then it stops. And the lever is nowhere near parallel to the stationary arm. Probably about 1/3 of the way.

I thought I could fix this too but I am afraid of doing something that would cause a recurrence of my gas leak. Since the car runs so well I just left the choke actuation like this. But I definitely understand the feeling of wanting everything to work as designed...


Tim
 
Did you try to work the cable while disconnected from the carb lever mechanism? Being a stranded cable, it may be frayed inside the sheath, which would make it very difficult to pull. Or, maybe there is a bad kink in the sheath.

I would disconnect the the cable where it hooks onto the jet lever. Leave the sheath attached to the arm, and then try to work the choke. If you still have problems, then it's time for a new cable.
 
Thanks for the ideas.

Yes, the cable works perfectly smooth and easy when disconnected from the carb lever. Pulls with hardly any resistance at all.

The problem (choke knob nearly impossible to pull) occurs when the cable is attached to the linkage.

If I disconnect the connecting rod and choke cable, the jet levers both move easily in their full range. You feel a slight resistance just as you begin to pull back the lever. The resistance "releases" as the lever begins to move. The jet slides down, the lever pulls back, and then there's a slight "click" when the lever is fully back (parallel to the stationary arm on the front carb).

It is *much* easier to manually pull back those jet levers now that I've cleaned up the jets and replaced/greased the seals.

In my next post I'll add photos of the entire cable and linkage setup.

And as Don says - the choke cable is stranded.

Tom
 
Just a thought, as I have had the same problem. Did you try and have someone pull the choke out while you watch the jets come down. They only have to travel about 1/4 of on inch to enrich the carbs and they have to travel evenly.

Is is possible that they are coming down the correct amount and your trying to pull them even down more. Is it possible that one jet is coming down completely and the other is not, causing it to bind. Is it possible that the connecting rod between the 2 jets is incorrect.

I do remember having to adjusting the connecting rod between my 2 carbs, to get both jets to travel down (choke) at the same time and evenly. These are just suggestions, cause without physically being there, I can only give you my experience with this problem. Good luck
 
Good suggestion. Yep - when I pull the knob, it goes about 3/4 inch quite easily before the jets begin to move down. That 3/4 inch is the knob travel as the looseness in the linkage is used up. Once the looseness (as described earlier) is used up, the knob is nearly impossible to move. Even happens when I've got the connecting rod disconnected.

As the jets are relatively easy to slide up and down, I'm really thinking the problem is in that linkage "play".

Maybe if someone could let me know the diameter of the hole in the jet lever, where the clevis pin connects to the jet lever links (Moss parts #21 and 60)? Then I could figure if I've got a very worn link hole? I know the clevis pin does move about 1/4 inch up and down in that hole. Or maybe the clevis pin is the wrong size?

Onward!

Tom
 
Tom, I believe that is normal. When I was trying to fix mine, I bought 2 new jet levers thinking the holes in the old ones had worn. The new ones were the same as the old ones. The linkage seems to normally have a fair amount of play in it.
 
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