Idle too Fast

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sat Sep 17, 2011 10:54 am

I have tried most things the engine is a standard 1969 V8 37k from new!

The tick over is too fast removed the tie bar between the 2 carbs both adjust to higher revs but will not drop below 1500 most of the time!
If I blank off the breather input on the RH carb the revs drop to 400! LH makes very little difference! Pearls of wisdom required

I don't often get stuck!

DaveEFI · Post by **DaveEFI** » Sat Sep 17, 2011 11:25 am

Are there poppet valves on the butterflies? If so, either solder them up or fit new plain butterflies.

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sat Sep 17, 2011 12:12 pm

Hi thanks for the reply DaveEFI.

The butterflies are the original ones plain.

DaveEFI · Post by **DaveEFI** » Sat Sep 17, 2011 1:00 pm

johnwp5bcoupe wrote:Hi thanks for the reply DaveEFI.

The butterflies are the original ones plain.

Being a '69. it's not got the separate starting carb?

If not, other thing would be worn butterfly spindles - or muck stopping them closing, or the alignment wrong.

DEVONMAN · Post by **DEVONMAN** » Sat Sep 17, 2011 1:11 pm

My guess would be an air leak on one side of the inlet manifold. Have you checked the vacuum pipe leading to the brake servo?

Cheers Denis

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sat Sep 17, 2011 1:45 pm

Thanks both yes it still has the AED which is fed to the centre of the manifold, I tried the vacuum blocked it off at the manifold no different and the butterfly spindles are as good as new, so other than an air leak on the inlet??
Thanks,
John.

DaveEFI · Post by **DaveEFI** » Sat Sep 17, 2011 4:32 pm

Chances are it's the AED. Very difficult to stop it effecting things (if faulty) without removal and blanking off properly. But they can be overhauled.

An air leak on the vacuum side of the carbs would weaken the mixture and tend to make it stall - unlike injection engines.

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sat Sep 17, 2011 5:26 pm

Hi Dave I have had a play and come to the same conclusion the car starts ok from cold but it would appear the air flap valve is the problem!
Burlen/SU are not doing repair kits or replacement AED's at the moment with no time scale because of problems with Ethanol attacking their diaphragms so it will be a waiting game or I may be lucky and find a replacement?

John.

DaveEFI · Post by **DaveEFI** » Sat Sep 17, 2011 9:23 pm

You might find one - although most are pretty knackered by now. They don't have a long life. There was a conversion kit to manual choke made for the P5B. Saw one on Ebay recently. Or the later system as fitted to the SD1 - if originality doesn't matter.

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sun Sep 18, 2011 7:41 am

Hi Dave I have cables etc to do a conversion but the car deserves to be kept original

DaveEFI · Post by **DaveEFI** » Sun Sep 18, 2011 8:38 am

johnwp5bcoupe wrote:Hi Dave I have cables etc to do a conversion but the car deserves to be kept original

Fairy nuff. The only option is to strip the thing down and see if just a good clean will sort it - if as you say spares ain't available. The AED was used by Jags too - so that may be another source of secondhand units.

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sun Sep 18, 2011 10:53 am

The Jag ones look the same a few thinks are different but interchangeable so as you say it is another source!

BanditSid · Post by **BanditSid** » Sun Sep 18, 2011 1:59 pm

John,

I sent you a PM yesterday to say I have a new unused one, it came with a pair of new carbs I bought. If you send a pic of yours to the email address I sent I'll compare it to the one I have.

As a quick reference is that the device with the blue plastic cover ?

johnwp5bcoupe · Post by **johnwp5bcoupe** » Sun Sep 18, 2011 5:51 pm

Hi Banditsid I emailed you direct yesterday with a picture and my phone number