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1500 midget carb replacement

tweety

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dklawson said:
Out of curiosity, would a CA inspection officer know the difference between a single Stromberg and a single SU?

Well..... My first and only experience, as an MG owner, with the smog checker..... had me explaining that the air inlet on the air filter box was an INLET! The checker insisted that it was some sort of exhaust and must be hooked up to something.

After about 10 minutes of arguing, I finally got the guy to ignore it. I asked.... "Does the car pass the exhaust gas test?" His reply, "No it's a gross polluter" Then way are we arguing?
 

dklawson

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That sounds about like I expected.

My British cars have now aged out of the inspection process. Until recently, our backup car was my wife's first car, a 1981 Rabbit. The car was a true Wednesday car and always ran great until neglect slowly allowed it to fall apart. During one of its last inspections I had an argument with the inspector who accused me of removing the carbon canisters. Fortunately I had my Bentley manual with me and was able to locate them on a picture and then tell the inspector where to look. However, while he was searching for them HE bumped vacuum lines (for the climate control system) off a connection block. He then accused me of disconnecting vacuum lines associated with the emissions system. When I showed him what those were for and explained they had been connected when I drove up (since the climate controls had been working) he failed me because of a cold start air preheater corrugated cardboard tube that had collapsed. When I took the car back after repairing that I had a lengthy discussion with the guys' boss. Some inspectors appear to be a bit over zealous regardless of what coast you are on.
 

dklawson

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I took the project Spit around the block today, it's first outing with the new HS4 carb. It's not right, not right at all. It idles beautifully but stumbles badly under load, eventually backfiring through the carb. The HS4 jet is already way low so I put a ColorTune on it today. Rich, way rich at idle but as I said, stumbles and backfires through the carb under load. I'll look for vacuum leaks and double-check the points and timing, but I suspect I need to move up to that #5 or AAA needle.
 
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Dk,
I found when setting up my twins that float height had a lot to do with jet height. Also i was running 20wt motor oil and had some very similar symptoms to what you describe- switched to marvel mystery oil and that made a HUGE difference.

mark
 

dklawson

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Thanks Mark. I'll add checking the float bowl/level to my list of things to check.
 

Billm

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OK- Now I am a first time 1500 Midget owner and have virtually never worked on any Triumph products before.
Question- does the 1500 fuel pump run around 3 psi (like all other Spridgets) or is it some higher pressure? I am looking at putting an HS4 on it (along with a common "points" distributer).
BillM (blazing new frontiers!!!)
 

JPSmit

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Bill, pretty sure the pressure is the same - HS4 is a fabulous conversion - pretty much a bolt in after about 20 minutes filing open the holes.
 

dklawson

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Kellysguy, as of about three years ago NC implemented age specific rules on emissions and they apply statewide at this time. Prior to that emissions testing was location specific with regions like where I live being subject to tail-pipe sniffing. Now there is ODB emissions testing required on all late model cars. If your car is "newer" than 25 years and does not have an OBD port, the vehicle is now only subject to safety inspection. If it is older than 25 years, no inspection is required at all. Apparently they assume a car that old is a collector car, not a daily driver. All the rules changed within the past few years.

Regarding my running problems mentioned above (November 2009), the project Spitfire is still not on the road and I have not completely addressed the running issues. However, I know two things that are/were wrong on my Triumph. The needle I have is too lean. The "stock" MGB needle is a much richer ABD profile. I will be installing one soon. The main problem I was having was running 10W30 oil in the dashpot. It was way too thin. I changed to 20W50 since I had that immediately at hand and all the problems I was having during acceleration went away (once the engine was warm). It would still balk when cold but behaved much better with thicker dashpot oil. I would have thought 20W50 way too thick. However, I saw recently on one of John Twist's YouTube videos that he was actually encouraging his customers to try 90W oil in the dashpots. (I know his shop is closed but John's videos are still on YouTube).
 

DrEntropy

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Back-when, I used straight 30W ND in the SU's. In western PA winters. No issues. Now use 20~50W GTX.
 
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I was using MMO. Had troubles with twin HS4-1500. Awitched to 20-50 and what a difference! For the record the needles are ABT's.

m
 

dklawson

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Unicorn, my reference to the ABD needle was for what's typically "standard" in the mid-1970s MGB HS4 and HIF carbs. The people I know who have fit a single MGB HS4 (or HIF-4/38) to a 1500 have told me that's the needle to use. I did not mean to imply that the ABD was correct when a pair of HS4s are installed on a 1500. I'm sorry if my earlier posts suggested that.
 

Billm

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OK- so what are people running for air-cleaners on a 1500 w/ single HS4?
(I will probably just use an MGB cleaner can if it fits).
Also it really looks like that header will be cooking the HS4, has anyone had problems with vapor-lock? I think that I need to make a heat shield!
BillM
 

Gundy

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Is your header ceramic coated?
I run a single carb without a shield and have had no problems.
I use the pancake looking K&N. Sort of a flat cone.
Not a 1500 so take this for what it's worth. :wink:
 

dklawson

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For the 1300 I'm working on I made a heat shield to also serve as a spring anchor and clamp for the cables. However... I can't comment on how effective it is as a heat shield since the car remains largely driveway art. For the air cleaner, I made sandwich plates to hold a stock Spitfire ZS carb filter. I have heard others say that they opened up the holes of the stock Stromberg filter housing so they could use it on the SU. I know the spacing for the filter mounting holes is different but I don't know how much "slotting" is required to make the stock filter housing fit an SU. I also don't know how different the Midget filter housing is from the one used on the Spit.
 
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dklawson said:
Unicorn, my reference to the ABD needle was for what's typically "standard" in the mid-1970s MGB HS4 and HIF carbs. The people I know who have fit a single MGB HS4 (or HIF-4/38) to a 1500 have told me that's the needle to use. I did not mean to imply that the ABD was correct when a pair of HS4s are installed on a 1500. I'm sorry if my earlier posts suggested that.

no misunderstanding here. i certainly did not mean to correct you. I only meant that the needles i mentioned were working well for me on my car and i wanted others to know for reference..My apologies

Mark
 

dklawson

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I have a pair of HS4s to go on the Spitfire someday so I'll be sure to save your info on the ABT needles for when (and if) I get around to that conversion. Thanks.
 
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