[Healeys] HS4 Tri-carb tuning

warthodson at aol.com warthodson at aol.com
Tue Jul 7 14:52:53 MDT 2020

I just performed the piston lift pin test on my tri-carbs. FYI, I have 3 SU HS6 carbs & an mid-aggressive cam. I cannot recall the specs. About a 9.5:1 compression & run premium pump gas. To keep my engine running (idling) at stop lights I need to set the idle at 1000rpm. It will drop to 600-800rpm when I depress the clutch.It is 93degrees here today when I performed the lift test. All three carbs performed similarly. With the piston lifted the rpm dropped & the engine ran rougher but did not die. But each time it was on the verge of dying. After releasing the lift pin the rpm did not return to 1000, until I cleared the carbs by revving the engine. My carbs have a stock balance pipe. I understand that there were 2 different original balance pipes. I believe mine is the later style.I hope this is some help.Gary

-----Original Message-----
From: John Spaur <jmsdarch at sbcglobal.net>
To: warthodson at aol.com
Sent: Tue, Jul 7, 2020 11:51 am
Subject: RE: [Healeys] HS4 Tri-carb tuning

#yiv5757757009 #yiv5757757009 -- _filtered {} _filtered {} _filtered {} _filtered {} _filtered {}#yiv5757757009 #yiv5757757009 p.yiv5757757009MsoNormal, #yiv5757757009 li.yiv5757757009MsoNormal, #yiv5757757009 div.yiv5757757009MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:12.0pt;font-family:New serif;}#yiv5757757009 a:link, #yiv5757757009 span.yiv5757757009MsoHyperlink {color:blue;text-decoration:underline;}#yiv5757757009 a:visited, #yiv5757757009 span.yiv5757757009MsoHyperlinkFollowed {color:purple;text-decoration:underline;}#yiv5757757009 pre {margin:0in;margin-bottom:.0001pt;font-size:10.0pt;}#yiv5757757009 span.yiv5757757009HTMLPreformattedChar {font-family:Consolas;}#yiv5757757009 p.yiv5757757009msonormal, #yiv5757757009 li.yiv5757757009msonormal, #yiv5757757009 div.yiv5757757009msonormal {margin-right:0in;margin-left:0in;font-size:12.0pt;font-family:New serif;}#yiv5757757009 p.yiv5757757009msochpdefault, #yiv5757757009 li.yiv5757757009msochpdefault, #yiv5757757009 div.yiv5757757009msochpdefault {margin-right:0in;margin-left:0in;font-size:12.0pt;font-family:New serif;}#yiv5757757009 span.yiv5757757009msohyperlink {}#yiv5757757009 span.yiv5757757009msohyperlinkfollowed {}#yiv5757757009 span.yiv5757757009htmlpreformattedchar {}#yiv5757757009 span.yiv5757757009emailstyle19 {}#yiv5757757009 span.yiv5757757009emailstyle20 {}#yiv5757757009 p.yiv5757757009msonormal1, #yiv5757757009 li.yiv5757757009msonormal1, #yiv5757757009 div.yiv5757757009msonormal1 {margin:0in;margin-bottom:.0001pt;font-size:11.0pt;font-family:sans-serif;}#yiv5757757009 span.yiv5757757009msohyperlink1 {color:#0563C1;text-decoration:underline;}#yiv5757757009 span.yiv5757757009msohyperlinkfollowed1 {color:#954F72;text-decoration:underline;}#yiv5757757009 span.yiv5757757009htmlpreformattedchar1 {font-family:Consolas;}#yiv5757757009 span.yiv5757757009emailstyle191 {font-family:sans-serif;color:windowtext;}#yiv5757757009 span.yiv5757757009emailstyle201 {font-family:sans-serif;color:#1F497D;}#yiv5757757009 p.yiv5757757009msochpdefault1, #yiv5757757009 li.yiv5757757009msochpdefault1, #yiv5757757009 div.yiv5757757009msochpdefault1 {margin-right:0in;margin-left:0in;font-size:10.0pt;font-family:New serif;}#yiv5757757009 span.yiv5757757009EmailStyle33 {font-family:sans-serif;color:#1F497D;}#yiv5757757009 .yiv5757757009MsoChpDefault {font-family:sans-serif;} _filtered {}#yiv5757757009 div.yiv5757757009WordSection1 {}#yiv5757757009 Gary,  You understand my question! J Yes, disconnected the linkages and tuned them by the book. They are working great although I have not taken the car on a long drive or connected the choke cables yet. With the tuning kit I can easily see that the pistons rise equally at different throttle settings. Incidentally, the jet nut settings on each carb are almost identical to what the old ones were.  Let me know what you find out when you test the pins on your carb. It would be very helpful.  TIA,John Spaur  From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of warthodson--- via Healeys
Sent: Tuesday, July 7, 2020 7:27 AM
To: healeys at autox.team.net
Subject: Re: [Healeys] HS4 Tri-carb tuning  John, Are all 3 carb interconnecting throttle linkages disconnected during all the tuning steps? I have never seen this test before in any literature, so I have never tried the test on my tri-carb setup. I will give it a try later today & let you know what I find.If your 3 carbs all perform the same on all the other tests, I think they will perform correctly together. I am assuming you have confirmed that all 3 carbs have the same needle. Also, when you say the "piston is lifted all the way up" you are referring to lifting the piston by the pin, (approximately 1/2" pin travel), not by literally lifting the piston all the way up.Gary Hodson

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