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Spitfire Spitfire carb question

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Dono

Senior Member
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Greetings Spit-heads,
I'm finishing reassembly of a 1971 MkIV 1296cc Spitfire. The carb has been prof rebuilt but runs poorly. Choke on it runs barely, idling at 2200+. Timing is correct, new electronic ignition is strong, fuel pump okay.
Question: It has a B5AV which is the correct needle for a spitfire 1300. The engine is a '69 MkIII 1296cc. Anyone know of a needle size & source for a richer needle?
Thanks! Dono
 
B5AV is pretty slender overall. I suspect there is another problem.
 
I too have a 71 MKIV.
And chased a problem like yours for a while.
Turned out I had a major vacuum leak at the intake to engine gasket.

Have you checked, listened, or sprayed carb cleaner around?

I could close off the entire carb throat with my hand and she would rev dangerously high.

I had to re-seat the manifold and it settled right in. The nuts UNDER the intake are a PITA. Be sure your manifold clasps ( can't think of what they are called right now) are seated correctly or they only hold loosely.
 
TD -
Good call. Pulled the intake manifold, found a small piece of cra- that had stuck to it when installed 18 mo ago. Re-torqued the nuts, including the PITA ones below and POOF, I'm running closer to normal. Still have to tweak it some but I found the nemesis w/in the system - a basic one......once again. Thanks for all comments! Dono in Missoula, MT
 
One more comment. The needle is is the richer needle, B5AY. The B5CH is for leaner sitchs, like I have at 3600' elev here, but I'll work w/ this for now. Don
 
B5AY, not B5AV?
Joe Curto, THE carb specialist had advised B5AV, then later B5AY; so I'll go with the corrected expert opinion. B5AY also matches the TR manual page diagrams.
Thanks, Dono
 
Dono.., I'm not disputing anyones opinion. I was just trying understand the change.
 
No worries. I didn't mean to sound too aggressive, merely that Joe is "the" expert. He senses problems others cannot. He's amazing and I was glad to share my story. Dono
 
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