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Janne Aittola
New User
Username: jannea

Post Number: 7
Registered: 7-2018
Posted on Friday, 19 April, 2019 - 00:02:   Edit PostDelete PostView Post/Check IP

Having continuous problems with SU HD8 carburettors fuel overflow to overflow tubes.

I have changed the float levers, float needles and float seats and also adjusted the levers according to the workshop manual.

I wonder if anyone has tried the new generation GROSE JET needles and seats and what type/model of grose jet needle/seat is the right one for SU HD8 carburettor?

-janneA / Silver Shadow 1968

Grose Jet
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 195
Registered: 4-2019
Posted on Friday, 19 April, 2019 - 00:42:   Edit PostDelete PostView Post/Check IP

That is one reason I got rid of my SU Carb. I was told that, that is an issue with the SU Carbs. I replaced it with an Edelbrock 1405.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 196
Registered: 4-2019
Posted on Friday, 19 April, 2019 - 04:30:   Edit PostDelete PostView Post/Check IP

I have this running joke that the SU carb is actually designed as scuba gear. (Someone will be serious and answer your question though.)

scuba Regan
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Mark Luft
Prolific User
Username: bentleyman1993

Post Number: 249
Registered: 10-2016
Posted on Friday, 19 April, 2019 - 06:42:   Edit PostDelete PostView Post/Check IP

Janne,
I have used the Grose Jets on MG's and MKII Jags in years past with wonderful success and no issues. I would contact them or maybe Moss Motors and ask them which jet you need.

Good Luck!!
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Mark Luft
Prolific User
Username: bentleyman1993

Post Number: 250
Registered: 10-2016
Posted on Friday, 19 April, 2019 - 06:44:   Edit PostDelete PostView Post/Check IP

Mike,

Your depiction of the SU Scuba rig lends a whole new meaning to "going down".
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Janne Aittola
New User
Username: jannea

Post Number: 8
Registered: 7-2018
Posted on Friday, 19 April, 2019 - 07:00:   Edit PostDelete PostView Post/Check IP

Thank you Mark!

That would be great and I can ofcourse ask myself Moss Motors about the right jets.

And to be sure I suppose I will need the forks (float levers) also in future to work with the new Grose Jets?

BR/-janneA
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Larry Kavanagh
Grand Master
Username: shadow_11

Post Number: 405
Registered: 5-2016
Posted on Friday, 19 April, 2019 - 07:48:   Edit PostDelete PostView Post/Check IP

You can log onto the SU Carburettor Company web site, there's a mine of information on your HD8 carbs in their technical section. You can buy direct online from them at a cheaper price. The float needles do occasionally stick mainly as a result of lack of use but sometimes the overflow problem is caused by fuel getting into a perforated float and weighing it down. The SU Carb Co. may sell the newer stay-up floats for your carb too. The first time one of my float needles stuck I replaced the needle and all was good but then the car was laid up for a winter and the new needle also became stuck so I simply opened the fuel pipe union at the float chamber and sprayed some carb cleaner in there and it did the trick. That was a couple of years ago and all has been fine since but the car is more regularly driven nowadays.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 198
Registered: 4-2019
Posted on Friday, 19 April, 2019 - 08:53:   Edit PostDelete PostView Post/Check IP

Here is a question partially related. I am cleaning out the engine bay now that only one vacuum hose is needed, after doing away with scuba carb. I wanted to make that massive PVC hose into a flexible rubber hose and only needed the end to fab. something up. I started cutting into the black plastic rubber cover and inside is fiber stuff. Is it asbestos, or did they ban it by 1975. Also it looks to be on the pipes from the exhaust manifold (probably to the choke(s) ) as well.
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Larry Kavanagh
Grand Master
Username: shadow_11

Post Number: 407
Registered: 5-2016
Posted on Friday, 19 April, 2019 - 11:59:   Edit PostDelete PostView Post/Check IP

That sounds like the choke stove pipe, it's function was to bring heat from the exhaust manifold which would expand the choke spring which would cause the choke butterfly to open as the engine warmed. You could unscrew it at the manifold but beware that the fitting at the manifold could disintegrate due to corrosion and heat damage so use plenty of easing oil and proceed with caution. It's a metal pipe and I'm not sure if the insulation covering is asbestos but it probably is, someone appears to have added another covering over the original stove pipe insulation on your car, probably because the original insulation was deteriorating. Inside the manifold there is the lower portion of that stove pipe, it's a bit like a coil in an old electric kettle in appearance but you can probably leave that in place because removing it entails separating the exhaust downpipe from the manifold I think but I've never had to do it. You'll need to find a female screw-on plug to seal the manifold once you've removed the choke stove pipe.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 200
Registered: 4-2019
Posted on Friday, 19 April, 2019 - 12:20:   Edit PostDelete PostView Post/Check IP

On my car the carburetor I put on is a manual choke. That saved me about $80 USD, but I have plans of putting an electric or used old spring type, and I will need a stove pipe. There is a very big one on the other side that looks like where a dip stick goes, but it goes to the exhaust manifold. Good thing I used a paint mask and cleaned up all the fiber after cutting, I was afraid it was asbestos. Probably is.
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Steve Emmott
Prolific User
Username: steve_e

Post Number: 263
Registered: 11-2018
Posted on Friday, 19 April, 2019 - 15:14:   Edit PostDelete PostView Post/Check IP

Technically there should be no need to remove the LHS manifold to remove the stove pipe loop that just sits inside the manifold.

It is just two nuts holding it in place on stud inserts fitted in the manifold.

However that said the nuts are usually that corroded and tight that it is possible to shear the studs which would mean drilling and tapping to fit new ones and then that is a pain and as Larry said the manifold would have to come off.

Just leave it in place but again the internal tube does rot through and a common problem which ends up the original choke system is not effective.





I do believe the stove pipe insulation back then was made from an asbestos cord material and right to take precautions.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 202
Registered: 4-2019
Posted on Friday, 19 April, 2019 - 15:47:   Edit PostDelete PostView Post/Check IP

First off I hope you did not take that off just for the picture. But this is the first time I have seen the business end of a stove pipe. I thought they were just holes in the manifold. Thanks
But as I said there is a big pipe from the manifold I have not a clue what it is for. (I have so many what is it questions.) What is it?

pipe
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Steve Emmott
Prolific User
Username: steve_e

Post Number: 264
Registered: 11-2018
Posted on Friday, 19 April, 2019 - 16:15:   Edit PostDelete PostView Post/Check IP

Of course Mike for you I would have taken it off

Seriously though I carry a lot of spares as when I had the car in France it was not so easy to get bits.

My biggest effort is finding them most of the time.

Not sure what that other pipe is. At first I thought it was the auto transmission fill but I can just see that in the top corner of your picture......I don't have that on my car or seen it before so possibly something to do with the US emissions junk that was fitted.

I like the way you come up with the simplest of DIY solutions. That roll pin on the steering boss in the other post is just 'factory' as we say 10/10
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Steve Emmott
Prolific User
Username: steve_e

Post Number: 266
Registered: 11-2018
Posted on Friday, 19 April, 2019 - 19:09:   Edit PostDelete PostView Post/Check IP

Mike just thought that pipe maybe just part of the US emissions requirement as we put EGR (exhaust gas recirculation) systems on the Jaguars again necessary to conform to the EPA/ Californian Emissions standards.

Probably will not be seen that much on Aussy cars or UK cars but hopefully Robert S or more members in US will know more about this system.

I read a lot of US RR/B owners just get rid of all the add ons.

You could possibly use it with the scuba-carb as a snorkel
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 970
Registered: 11-2015
Posted on Friday, 19 April, 2019 - 21:49:   Edit PostDelete PostView Post/Check IP

Janne,

If your fuel pressure is correct, the HD8's shouldn't leak.

One of the time honored methods of righting this is to tap on the float bowls.

Never had to do this on an HD8 but it happens a lot when working on equipment that has sit.

I think sometimes it is the float "glues" itself to the bottom on carbs with a lot of sediment.

Also, I had an austin healy sprite with a pinhole in the casting before the needle.

Only found out by blowing through it while looking at it and the cap covered on soapy water.

Good luck.
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Steve Emmott
Prolific User
Username: steve_e

Post Number: 267
Registered: 11-2018
Posted on Friday, 19 April, 2019 - 22:13:   Edit PostDelete PostView Post/Check IP

Yes I second the above, you should also not just assume the needle is the issue as the fault could be several reasons.

Most are well covered in this old thread.

http://au.rrforums.net/forum/messages/17001/28667.html?1524850685

Janne I have PM'd you for your address to ship out the boot seal.......just check as this is the second one I have sent now.
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Janne Aittola
New User
Username: jannea

Post Number: 9
Registered: 7-2018
Posted on Saturday, 20 April, 2019 - 05:51:   Edit PostDelete PostView Post/Check IP

Thank you Ross and Steve, I have to check more carefully also the other parts you mentioned!

And I got your PM Steve and answered it.
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Kelly Opfar
Prolific User
Username: kelly_opfar

Post Number: 231
Registered: 7-2004
Posted on Saturday, 20 April, 2019 - 05:59:   Edit PostDelete PostView Post/Check IP

As Steve mentioned, that pipe does go to the EGR valves:
EGR pipe

http://BritishToolWorks.com
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 214
Registered: 4-2019
Posted on Saturday, 20 April, 2019 - 08:13:   Edit PostDelete PostView Post/Check IP

Kelly: So that's what happened to the Snorkel to the Scuba Carb. I wondered where it had gotten to. I went through the boxes (this is the first time) and found it. Ronny will be so happy.

Thanks Kelly

snokel
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 215
Registered: 4-2019
Posted on Saturday, 20 April, 2019 - 08:33:   Edit PostDelete PostView Post/Check IP

Kelly: I hate to ask this, but can you take a picture of the whole engine with all that original California crud on there? Thanks in advance.
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Kelly Opfar
Prolific User
Username: kelly_opfar

Post Number: 232
Registered: 7-2004
Posted on Saturday, 20 April, 2019 - 10:37:   Edit PostDelete PostView Post/Check IP

Mike, all of the pictures of my car are on my computer at home and I'm not there right now but I have all of these pics on OneDrive of a parts car that I dismantled a couple of years ago. My car and this parts car are both '76's. They are only 30 cars apart - SRE24700 and LRE24730.
There are quite a few engine pics in there but there is probably not a nice, wide shot.
https://1drv.ms/f/s!AoM9aFcTDNqOwTncwI3YG7XONIy8
If there is an angle specifically that you are looking for, let me know and I'll find pics.

BritishToolWorks.com
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 223
Registered: 4-2019
Posted on Saturday, 20 April, 2019 - 14:36:   Edit PostDelete PostView Post/Check IP

What an absolute mess the engine used to be. I can see pulling in to any normal gas station repair shop and saying can you fix it and open the hood. You would get: Bubba come look at this, what the hill is it. Now look at the picture I took today.

engine
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 990
Registered: 11-2015
Posted on Saturday, 20 April, 2019 - 22:57:   Edit PostDelete PostView Post/Check IP

Mike,

The little cylinder shaped solenoid above the E in royce in your picture I believe is from the weakener system. As the system is probably in a cardboard box in the boot you can safely lose that as well.

Also, real safety. Don't forget a second throttle return spring.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 234
Registered: 4-2019
Posted on Sunday, 21 April, 2019 - 06:20:   Edit PostDelete PostView Post/Check IP

I was going to ask about that. Just one of a million "What Is It", questions I have. An easy one, how many gallons does the gas tank hold?
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 1012
Registered: 11-2015
Posted on Sunday, 21 April, 2019 - 09:48:   Edit PostDelete PostView Post/Check IP

Mike,
I think it is 28 US gallons if you have the kind that is in the floor of the boot under the disused weakner system.
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 1013
Registered: 11-2015
Posted on Sunday, 21 April, 2019 - 09:50:   Edit PostDelete PostView Post/Check IP

Mike,

The tank has drain at the bottom when it gets to that point.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 243
Registered: 4-2019
Posted on Sunday, 21 April, 2019 - 10:47:   Edit PostDelete PostView Post/Check IP

OK so what is a weakner system?
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 1018
Registered: 11-2015
Posted on Sunday, 21 April, 2019 - 11:04:   Edit PostDelete PostView Post/Check IP

Mike,

That is a good question. I think it is a bowl vent system.

It wasn't used on other applications with HD8's so I removed mine and added a conventional bowl venting schema.

You certainly won't need anything related to it.
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Robert J. Sprauer
Grand Master
Username: wraithman

Post Number: 306
Registered: 11-2017
Posted on Sunday, 21 April, 2019 - 12:42:   Edit PostDelete PostView Post/Check IP

Weakener systems achieve a change in mixture by adjusting the air or gas, but usually air.
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Mike Thompson
Prolific User
Username: vroomrr

Post Number: 250
Registered: 4-2019
Posted on Sunday, 21 April, 2019 - 13:39:   Edit PostDelete PostView Post/Check IP

So there's something scary crawling round on my gas tank? Can I kill it?
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Janne Aittola
New User
Username: jannea

Post Number: 10
Registered: 7-2018
Posted on Saturday, 27 April, 2019 - 16:57:   Edit PostDelete PostView Post/Check IP

Thank you Mark, I contacted Moss Motors and now two GAC9201X Grose Jets are on their way.

Link: https://www.moss-europe.co.uk/grose-jet-gac9201x.html

-janneA - RR Silver Shadow 1968
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Mark Luft
Prolific User
Username: bentleyman1993

Post Number: 253
Registered: 10-2016
Posted on Wednesday, 01 May, 2019 - 00:49:   Edit PostDelete PostView Post/Check IP

Fantastic, Janne. Glad to hear that.
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Janne Aittola
Experienced User
Username: jannea

Post Number: 21
Registered: 07-2018
Posted on Monday, 03 June, 2019 - 04:20:   Edit PostDelete PostView Post/Check IP

Hello again!
Chanced the grose jets and still intermittent fuel overflow to overflow tubes.

Has anyone had a problem with loose horizontal moving old style float levers that stucks to the float lid bolt thread when coming up and in that way prevents the grose jet to close?

-janneA - RR Silver Shadow 1968

RR-1RR-2
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Mike Thompson
Frequent User
Username: vroomrr

Post Number: 565
Registered: 04-2019
Posted on Monday, 03 June, 2019 - 05:41:   Edit PostDelete PostView Post/Check IP

I'll sell you my carburetor for $500 (plus shipping outside of the USA). You can then take any or all parts off it. :-)

If you go by ebay prices it's a good deal.
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 243
Registered: 01-2014
Posted on Monday, 03 June, 2019 - 05:42:   Edit PostDelete PostView Post/Check IP

Only if your float lever and pin are extremely worn and even then I don't think that could happen. Tighten up the legs of the lever that wrap around the pin for a temporary fix if there is excessive sideways slop. Also the usual problem is the float lever drop stop tab not correctly adjusted allowing the float to drop too far so that the needle jams on the lever due to the extreme angle of the two intersecting each other when the float has dropped lower than normal running condition. Arrow on pic points to drop stop tab. Adjust it so the float lever can only drop a very short distance.



SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 2109
Registered: 05-2012
Posted on Monday, 03 June, 2019 - 06:05:   Edit PostDelete PostView Post/Check IP

Janne

Has your car got the standard SU fuel pump fitted? Fuel pressure gauges are cheap to buy - may be worth checking the fuel pressure which should be 2 to 4 psi. Anything over 5 psi will cause fuel overflow.

Also, does the fuel overflow occur on a cold engine. If you turn the ignition on but do not start the engine, does the pump keep clicking, and the fuel overflowing?
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 245
Registered: 01-2014
Posted on Monday, 03 June, 2019 - 06:43:   Edit PostDelete PostView Post/Check IP

If the overflow occurs when starting a cold engine as Geoff asks that points to the needle jamming on the float lever. When the engine has sat for a while the fuel evaporates or leaks slowly out allowing the float and lever to drop lower than during normal operating conditions. This is usually when the needle will jam on the float lever.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Janne Aittola
Experienced User
Username: jannea

Post Number: 22
Registered: 07-2018
Posted on Tuesday, 04 June, 2019 - 05:54:   Edit PostDelete PostView Post/Check IP

Thank you Geoff and Jim, I will test the fuel pressure although the fuel pump is standard SU.

And the overflow occurs only with warm engine and in idle speed when the engine is shaking a bit.
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 248
Registered: 01-2014
Posted on Tuesday, 04 June, 2019 - 06:13:   Edit PostDelete PostView Post/Check IP

No need to test fuel pressure if it is the standard SU pump.
Adjust the float drop tabs so the float lever will only drop about 1/8th of an inch. Have you checked floats for leaks?

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Janne Aittola
Experienced User
Username: jannea

Post Number: 23
Registered: 07-2018
Posted on Saturday, 08 June, 2019 - 01:51:   Edit PostDelete PostView Post/Check IP

Thank you Jeff, my friend adjusted the levers and now I will have to do some test driving.
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 1153
Registered: 11-2015
Posted on Sunday, 16 June, 2019 - 21:59:   Edit PostDelete PostView Post/Check IP

Janne,

What finally happened?
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Janne Aittola
Experienced User
Username: jannea

Post Number: 25
Registered: 07-2018
Posted on Thursday, 20 June, 2019 - 06:07:   Edit PostDelete PostView Post/Check IP

Thanks for asking, so now the car is running quite well after readjustment of the levers, needles and the ingition, but still I am having irritating random fuel overflows and I am quite sure that they are caused when the levers stuck because when the fuel is overflowing and I carefully tap the float lid cover the overflow stops. So maybe I find more suitable levers that don't have that excessive horizontal movement. Also new floats are in shopping list just to be sure.

...
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 1157
Registered: 11-2015
Posted on Thursday, 20 June, 2019 - 06:24:   Edit PostDelete PostView Post/Check IP

Janne,

At least you can drive it and have a fix.

Also, knowing the nature of the problem is usually key to fixing it. I'm sure you will get it now.
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Janne Aittola
Experienced User
Username: jannea

Post Number: 26
Registered: 07-2018
Posted on Friday, 21 June, 2019 - 05:33:   Edit PostDelete PostView Post/Check IP

Ross,
you are just right!

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