Perfect idle until throttling

Evening all,

Odd one this.
Car starts fine, I usually give it a bit of throttle (habit) but the idle is rather low and lumpy, thought this might be due to the mild cam. Sounds like it is about to stall, but it never does, I'd say its about 700 rpm. When it is warm it idles fine.
I noticed today when I started it (cold) without touching the throttle, it sat perfectly at 1000 rpm, never moved. Then when I blipped the throttle, the idle dropped down to about 700. Tried it again later in the day, same thing.
Car drives fine and like I said idles great when warm.
Any ideas what the cause could be?

Thanks,

J

Don't know what the issue is but I have something similar when I'm running mine. Seems to idle fine on start up and if I leave it it idles great. Soon as I blip the throttle it revs up then comes back down way lower than before and then stalls….. eventually. I was wondering if is something to do with the vacuum pod on the distributor? I was wondering if it was timing related or something to do with the vacuum advance or such………..I'm running down other issues but I have this issue too lol!

Oh, I forgot to mention my car is cammed too, running TT 276, think it's 114° and 110° or something. Not as lumpy as I had hoped but sounds…..ok.

Consider checking the vacuum hoses.  
Mine started mucking about, and I found all the hoses had  perished the last 5mm or so.  It's only a little leak, but lots of little leaks add up.
Might be worth letting it tick over and spraying something like wd40 at each connection / gasket area (including the inlet manifold to head).  One thing at a time.  If the idle changes, then you've found your leak.

Yeah I first started out hunting for a vacuum leak because I thought it might be that but it made no different to mine. I capped off the vacuum ports on my carbs and the problem still existed.

What I did do is pulled out my carb balancing tool. Carb tune, and found my carbs were all way out of sync. I managed to re-sync three out of the 4 barrels but cylinder 2 just won't come down for some reason. Looks like I have way more vacuum on that cylinder the other three. Not sure why. Also while I was doing this I messed around with the idle mixtures screws on my carbs. Engine sounded better after all the tweeking but still don't know why cylinder 2 won't tune up like the rest.

Anyway, long story short, after I did that tweeking the car runs better now and doesn't die after I throttle it. So i seem to have fixed one problem but found another…….