Recon Carbs - won't idle

[iani]

I fitted a pair of recon carbs yesterday and today Martin Stevenson & I spent a few hours trying to get my car to run with them. Despite almost having the idle screws on the stops the car refused too idle. We got the engine warmed through but it just wouldn't idle without either the choke or throttle being used. We had the carbs off twice, checked externally for any leaks (not wanting to strip the carbs with them being "new") but no joy, in the end we stuck my old carbs back on and the car is running fine.

I'm taking them back tomorrow to swap for another pair, not very happy about it to be honest but I'll give another set a chance, we're just stumped for what could be causing this problem.

Ian

[Bob Heritage]

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iani wrote:

I fitted a pair of recon carbs yesterday and today Martin Stevenson & I spent a few hours trying to get my car to run with them. Despite almost having the idle screws on the stops the car refused too idle. We got the engine warmed through but it just wouldn't idle without either the choke or throttle being used. We had the carbs off twice, checked externally for any leaks (not wanting to strip the carbs with them being "new") but no joy, in the end we stuck my old carbs back on and the car is running fine.

I'm taking them back tomorrow to swap for another pair, not very happy about it to be honest but I'll give another set a chance, we're just stumped for what could be causing this problem.

Ian

Do you have holes in the butterflies? = American market, if so solder them up.

[iani]

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Bob Heritage wrote:

Do you have holes in the butterflies? = American market, if so solder them up.

No, they are solid, we checked for this.

Ian

[Stagdad]

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Whats wrong with the old ones if its running fine?



Cheers Steve

[iani]

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Stagdad wrote:

Whats wrong with the old ones if its running fine?



Cheers Steve

They don't stay in tune particularly well, were rather grubby and I wanted to clean them up. I could have rebuilt these ones but I don't have the luxury of time right now, I am spending over half my time outside the UK and I am under domestic pressure to not be working on the Stag, this approach was supposed to be a quick fix.

Ian

[Stagdad]

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iani wrote:

Stagdad wrote:

Whats wrong with the old ones if its running fine?



Cheers Steve

They don't stay in tune particularly well, were rather grubby and I wanted to clean them up. I could have rebuilt these ones but I don't have the luxury of time right now, I am spending over half my time outside the UK and I am under domestic pressure to not be working on the Stag, this approach was supposed to be a quick fix.

Ian

Ah I see ,bit of a pain then having to change them.BTW sorry I didn't have time to chat properly at the National day,It was a bit busy when I saw you,hope it didn't seem rude.

Cheers Steve

[iani]

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Stagdad wrote:

Ah I see ,bit of a pain then having to change them.BTW sorry I didn't have time to chat properly at the National day,It was a bit busy when I saw you,hope it didn't seem rude.

Cheers Steve

No problem Steve, I've had a hectic few months, rotating between my job here and working in New Orleans, one more trip to go hopefully.

Ian

[Stagdad]

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I've just got a pair of reconditioned carbs done by Howard Vassey ,I'm hoping they'll not give me any trouble.

Steve

[milothedog]

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I thought you were a Weber man now Steve. Was it Alan's 157 that swayed you.

Ian.

[Stagdad]

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milothedog wrote:

I thought you were a Weber man now Steve. Was it Alan's 157 that swayed you.

Ian.

[iani]

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I picked up a replacement pair of carbs today, fitted them and now idling at 750RPM with 2.2 CO, ok for the test, there was clearly something wrong with the first pair.

Ian

[Stagdad]

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iani wrote:

Bob Heritage wrote:

Do you have holes in the butterflies? = American market, if so solder them up.

No, they are solid, we checked for this.

Ian

Just got my reconditioned carbs and they have the butterflies with a hole and a poppet valve,Are they no good then?

Cheers Steve

[iani]

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Stagdad wrote:

Just got my reconditioned carbs and they have the butterflies with a hole and a poppet valve,Are they no good then?

Cheers Steve

From honestjohn.co.uk:

"The stalling problem is due to the fact that your carbs are probably fitted with 'poppet' valves in the butterflies. These are little spring loaded valves which were 'designed' to pop open when the throttle was shut and progressively shut controlling the revs down to idle over a few seconds to reduce exhaust emissions. Over the years the springs get weak and the valves stay open for far too long as in your case giving a fast idle. The idle stops are wound fully off to try and compensate so when the valves eventually shut the engine stalls. Quick fix is to solder the valves shut or replace with plain butterflies. SU's from the same era have the same problem."

I knew the poppets weren't recommended, had to search to remember why!

Ian

[Stagdad]

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Thanks Ian ,makes sense.

Steve

[V Mad]

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The SU carbs on the RV* have those too.I had to solder them up on Trevor's stag for the same reason. Surprised to see American strommies over here though.