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Discussion Starter · #1 ·
I have a 1500 engine from a Spitfire and it has twin SU HS4 carbs with the concentric float chamber underneath. Car has been standing for a while. I have no experience of these carbs. I fitted a small test tank, ie gravity fed as I didn't know how clean the fuel system was. The engine would start and run on choke but died if the choke was gradually taken off and it also tended to flood from the overflows with the engine stopped. I have removed the carbs just to clean them mainly and found a fair amount of hardened lacquer in the float chambers and one float needle was sticky in its jet housing. No sign of a blockage as far as I could see. Also, when I put some ATF in the dashpots (what should the right level be?) it leaked out into the bore of the carb especially when the piston was raised and allowed to drop. Is there a U-Tube overhaul video for this carb? I found one for the side float carbs which helped a little. I really need to know how to set the carb initially to get the engine running evenly enough to fine tune. Please help. Cheers, Dave
 

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As Weslake-Monza said, if the float chambers are underneath and they're SU carbs, they're HIFs for sure, almost certainly HIF 38s as they're the equivalent to the HS4s that the earlier 1500 Triumphs had.

You may need to block off some of the numerous emissions connections fitted on most of these carbs if you aren't using the OE fitment carbon filters etc.

The Haynes manual for SU carbs is surprisingly useful for rebuilding and setting up these carbs, be as good a place as anywhere to start if you're not too familiar now. Burlen Fuel Systems sell all the parts and complete overhaul kits too.
 

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Did they use the HIFs on Spitfires? I thought they only showed up on much later Austin Rovers like the Metro? All the Triumph engines I've ever had used the HS carbs with the float bowls slung on the side.
If you want a HS4 (single, from a Toledo), I have one free in the Freebies section!
 

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looking through rimmer bros hs2 and 4 were used through to early mk 4


is it this type?, if so if memory serves correctly, float hieght is set by removing chamber bottom put straight edge across bottom of housing so it passes the middle of float, float should be approx 1/16 off straight edge if not readjust.
mixture is set as a rough guiide by turning adjusting screw until jet rises level to insert top it travels in, then screw one and a half turns on the adjusting screw so jet drops down insert.
Oil in the dash pots had always been engine oil in them days, just top up the piston tube half way. once engine running a quick set up on gas machine would be benificial, don't forget to balance the carbs when you are done though very important if you want them to work together properly

Bill
 

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Discussion Starter · #6 ·
looking through rimmer bros hs2 and 4 were used through to early mk 4


is it this type?, if so if memory serves correctly, float hieght is set by removing chamber bottom put straight edge across bottom of housing so it passes the middle of float, float should be approx 1/16 off straight edge if not readjust.
mixture is set as a rough guiide by turning adjusting screw until jet rises level to insert top it travels in, then screw one and a half turns on the adjusting screw so jet drops down insert.
Oil in the dash pots had always been engine oil in them days, just top up the piston tube half way. once engine running a quick set up on gas machine would be benificial, don't forget to balance the carbs when you are done though very important if you want them to work together properly

Bill
Thanks for the pictures Bill. Yes its the second one which I now assume is the H1F38. I couldn't find a number on the carbs so assumed Wikopedia were right which said the 1500's had HS4's. Anyway thats that cleared up so now I will ring Burlens and get some overhaul parts. The advice on set-up is really useful. One carb has the vac take off for a gauge (distributor) so I assume I need to drill and tap for a take-off on the other for balancing. Thanks to everybody for your replies it has put me in the right track. Cheers, Dave
 

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Discussion Starter · #9 ·
We are in Essex and have many years experiance on the SU carbs. Perhaps pop down??
Yes I just looked up your website. I have ordered a service kit for the carbs and I would give up now if I didn't think I could set the carbs to their basic settings given the sort of help you are all providing and the technical department at Burlen. When I have the car running I am sure I will need your expertise in tuning the carbs. When the engine is running smoothly it is coming out of the Spitfire and into a Prefect. Do you do any motorcycle work? Regards, Dave
 
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