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#31 80sMiniCity

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Posted 30 December 2012 - 11:46 PM

Okay, I worked on the Mini for 6+ hours today, with a lot of results.

The advance is dead on. Set the idle to 1500 rpm and if I turn the dizzy clockwise or counter=clockwise the rpms drop.

I put a “Grose-Jet” needle & seat in and gas (a lot) started coming out of the overflow above 2500 rpm. I used the included washer and it didn’t solve the problem. The two floats I have are plastic non-adjustable floats. I put the original needle and seat back in. that seemed to solve the problem.

Here’s what is going on with a variety of different setups. All have a spring aaa needle in common.
  • Fixed jet installed one spring and 20 weight oil in dashpot. I need 24 flats to get it started and both slow and fast revs cause massive drop in revs. Not drivable.
  • Waxstat jet installed, one spring and 20 weight oil in dashpot. 12 flats to get it started and a slow rev will work but a fast rev causes it to stall. The engine needs to be over 3000 rpm to get it moving.
  • Waxstat jet installed, two springs and 20w50 oil in the dashpot. 12 flats to get it started and bot slow and fast revs will work and I can drive the car.

There are no intake leaks and the advance is around 26 degrees for all of the above. If I retard it or advance it past 26 degrees the revs will drop.

I have a aac needle maybe I’ll try that one tomorrow.

All I can say is what the hell

#32 jaydee

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Posted 30 December 2012 - 11:52 PM

You need to 'lap' the grose jet with thootpaste before assembly. I'm not kidding. Adjusting the damn thing is some sort of art..

26 deg advance is what you get at 1500 fast idle with vacuum connected? You need to get the reading at full advance, 30° between 3500/4500 rpm with vac disconnected.

I need to read the whole thread about your carb setup question so hold on a minute..

#33 jaydee

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Posted 31 December 2012 - 12:08 AM

Ok, its not the first i've seen it happening on the bloody HS4, it just requires the correct tuning and some attention at float chamber settings (set float to lid clearance as per AVON's post, and check that the chamber is sitting dead vertical). Double check for air leaks at the manifold, the big servo take off can be troublesome, and the manifold flanges aswell, they need to be the same thickness as the exhaust manifold flanges, you can file some washers to make sure the nuts will clamp down the manifold evenly.
Two dashpot springs is a no no because they will bind each other. One red spring is fine for your application.
Swap the 20w50 oil for a lighter 10w40 and keep the AAA needle, fit the air filter for setting up (i see you've removed it in the video).

If using a colourtune, look for a turquoise blue colour at 1k rpm idle.
If you open the throttle colour should be orange/yellowish then blue again
At steady rpms correct colour is a deep blue, lighter blue above 3k rpm.

To adjust it properly, you definately need a CO reader and tweak the needle. An AAU needle is a great starting point for fine tuning.

Edited by jaydee, 31 December 2012 - 12:16 AM.


#34 dklawson

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Posted 31 December 2012 - 12:50 AM

Lot's of misinformation in this thread, for a start. The starting adjustment of the jet holder is, screw it lightly up against it's seat and then back it out 22 flats. Not 12..........


Brooklands Book: SU Carburetors Tuning Tips & Techniques, Chapter 3, page 13 & 14, paragraphs 2 & 3
Paragraph 2© (partial text): "Screw the jet adjusting nut up until the jet is flush with the bridge..."
Paragraph 3 (partial text): "Then turn down the adjusting nut by 2 complete turns."

This information is also found on the Burlen web site
http://www.sucarb.co...tail.aspx?id=80
Step 2(d).

The adjusting nuts on my SUs have 6 flats, therefore 2 complete turns is 12 flats.

Please show where you have seen the adjustment listed as 22 flats. Is there a later type of HS4 whose adjusting nuts are threaded differently? If there is, shouldn't this be listed somewhere on the Burlen web site?

Jaydee, Grose Jets are the ones with the ball bearing sealing bits. You cannot lap them like you can traditional needle and seat float valves. There are lots of reports that Grose Jets are shipped with a Cosmoline like coating on the steel balls to prevent them from corroding in storage. I have seen several people post that they should be cleaned before use by soaking them in carb cleaner followed by being blown out with spray carb cleaner and compressed air. I gave up on Grose Jets and use float valves with Viton tipped needles.

#35 ANON

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Posted 31 December 2012 - 12:55 AM

have you centred the jet when you've changed it?

Edited by ANON, 31 December 2012 - 07:09 PM.


#36 dklawson

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Posted 31 December 2012 - 02:01 PM

LMAO and they've been messing with su's for how long..............Funny how the op got it started after 24 flats but still not right........
Don't try and teach your granny to suck eggs doug...........


If I understand your reply, you cannot provide a source for your "22 flats" statement and you contend that SU themselves don't know what they are doing.

Also see...
The Haynes Mini Manual (purple cover) 1959-1969
Chapter 3, page 93, section 12.19 "... jet is flush wit the bridge in the carburetor body. Now screw the nut down two full turns"
and
The Haynes Weber/SU/Stromberg Manual
Section 4, page 19-9, Steps 2-3: "...until the jet is flush with the bridge... " & "... screw down the jet adjusting nut/screw two turns...."

If you have seen "22 flats" listed in a text somewhere please cite the source. Otherwise... the absolute closest thing I have found to your 22 Flats is a statement in the Haynes Weber/SU/Stromberg manual that on "tamper proofed carbs" you adjust the nut down (3) full turns (18 flats). I have never seen a "tamperproofed carb" but even if that's what the OP has, (3) turns is 18 flats, not 22.

Anon, that's a good point about centering the jets. If this carb has a fixed (not spring-loaded) needle then the jet does need to be centered prior to making any running adjustments. Also any "open ports" on the carb need to be capped prior to making adjustments to eliminate any possibility of air leaks.

#37 dklawson

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Posted 31 December 2012 - 06:03 PM

So you cannot or will not cite a source for 22 flats and you don't want any more text references. You are also discounting the information on the SU/Burlen web site that contradicts you.

Re-read my post and Anon's regarding jet centering. I did not suggest centering a spring-loaded needle. Not all HS4 carbs were made with spring-loaded needles. If the HS4 has a fixed needle you have to center the jet as part of a rebuild.

Apologies to the OP. None of this is really helping you solve your problem. It should not take 24+ flats to get your engine started and running, something is clearly not right. I am sorry I cannot tell you exactly what it is. Out of curiosity were you making your jet adjustments with the choke completely disconnected?

#38 dklawson

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Posted 31 December 2012 - 07:45 PM

The S does designate a change from the H series with its fixed float bowls but it clearly does not mean Swinging needles. There are too many examples without swinging needles. The first HS4 carbs I saw were on a 1964 MGB. They were clearly fixed needles. Swinging needles came about as a later phase in HS production. Saying that all HS4s had swinging needles is like saying they all had Waxstat jets. It simply isn't true.

Dilligaf, I am through discussing this with you. You will not cite your sources and yet you are accusing this thread of being full of misinformation. At the moment neither of us is helping the OP so this is my last post to this thread. I hope you will also bow out or contribute to solving the OP's issue.

#39 ANON

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Posted 31 December 2012 - 09:27 PM

All HS4's fitted to that left the factory had swing needles, have a guess what the 'S in HS stands for...........


the S stands for short as in "horizontal short"

#40 80sMiniCity

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Posted 31 December 2012 - 11:58 PM

For clarity sake, It’s the stock HS4 with a “swing” needle from the factory. Originally it had a AAC swing needle and I replaced it with an aaa swing needle when I put on the stage 1 kit. It had a waxstat jet from the factory too. I replaced the waxstat jet with a fixed jet this summer. That’s when I needed 22-24 flats to get it started. I put back the waxstat jet a few days ago with the same aaa swing needle and only needed 12 flats to get it to idle.

I started playing with the advance and long story short, nothing worked. As a last resort I removed the piston damper and stuck a wooden dowel and pressed the piston down. The revs jumped from a lumpy 800 rpm to over 2000 rpm. While holding the piston down with the dowel I dropped the rpm back to 800 and the engine ran smooth, Also, while putting pressure on the dowel I was able to rev the engine with no issue, it sounded great. Please tell me the carb is not bad. No clue what to do next. I have a HIF44 from a Metro but I’m assuming that’s way too big for the 998.

#41 ANON

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Posted 01 January 2013 - 12:50 AM

again...have you centred the main jet?

and ignore any idiots who say you don't need to as i will be glad to show where su say to do this.

#42 80sMiniCity

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Posted 01 January 2013 - 01:08 AM

again...have you centred the main jet?

and ignore any idiots who say you don't need to as i will be glad to show where su say to do this.


Not sure what you mean. I know you need to center a fixed jet/ in the jet bearing (carrier) when using a fixed needle. The jet moves freely in the jet bearing. The choke works fine. The piston moves up and down freely with no binding. I always assumed a spring needle did away with having to center the jet.

#43 80sMiniCity

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Posted 01 January 2013 - 03:31 AM

Okay, I did a little research on the “centering the jet issue.” For those of you who care, I found the following. Have a look at the attachments and decide yourself. Happy New Year all, now I’m resorting to a few drinks.

I got this excerpt Attached File  SU 001.jpg   178.86K   18 downloads from the book I have. Attached File  SU 002.jpg   53.09K   6 downloads I always wondered why there was a fixed needle jet bearing and a spring needle jet bearing. This answers that.

#44 ANON

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Posted 01 January 2013 - 11:06 AM


again...have you centred the main jet?

and ignore any idiots who say you don't need to as i will be glad to show where su say to do this.


LOL shows what you know, as much as the others in this post..........


yeah..like what the s stands for, you decided not to reply to that one i see ;-)


Okay, I did a little research on the “centering the jet issue.” For those of you who care, I found the following. Have a look at the attachments and decide yourself. Happy New Year all, now I’m resorting to a few drinks.

I got this excerpt Attached File  SU 001.jpg   178.86K   18 downloads from the book I have. Attached File  SU 002.jpg   53.09K   6 downloads I always wondered why there was a fixed needle jet bearing and a spring needle jet bearing. This answers that.


section 1, last paragraph...http://www.sucarb.co...tail.aspx?id=93...so it doesn't really answer that does it, but forgive me for trying to help and good luck with sorting it out.


i'd best go now, as i obviously haven't got a clue about rebuilding carbs i'm going to have to deal with all the complains from people i've sold carbs to, bit odd though that on one has decided to complain yet???

ah well, as neil said boom shanka :-)

#45 Shifty

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Posted 01 January 2013 - 01:04 PM

Ok, I think that's enough of the arguing, its not helping the OP get to the bottom of his problem.




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