Ah, that explains it. I thought it was another "adjust until revs are 1600" type of thing. I'll keep quiet....
Don't do that.. It's an easy confusion to have! The so-called 'fast idle' speed is only about the throttle angle produced by the 3PU being at max thrust when the TTV's in charge; after that it's over to the waxstat/choke interaction, 'cos the 3PU has withdrawn away into it's 'normal idle' position.
I'm confused!! FYI, my car will rev to about 1500 for a second or so unitl the TTV drops the idle (move from piston control to waxstat control). Generally this will be about 600rpm, or higher depending on what the choke is doing (ie ambient temp). Once warm it will settle to a normal idle of about 550rpm, this is now back to control on the piston as the waxstat is fully out. I deliberately keep the revs real low, always have. I think its supposed to be 750, although 950 for some older cars. This gem of info was Golden's originally (IIRC). Shexual, I would guess something on your choke is not good, and would start by testing the pulldown unit for correct operation. Though if your car runs fine then this is no major issue. So long as your normal running is OK then warming up a bit rich is not the end of the world
Thanks Drew That's helpful information, maybe some others could add their 'warm-up-rev-situation' experiences, now that there's a Carburettor Forum! TBH I can't see it making much difference to those of us who have an interest; should just be better for those who don't! Why the super-low idle Drew? I know mine doesn't mind 750 at all, lovely and quiet. You have to listen reasonably carefully to know she's running. I might get round to looking at the adjustments to do with the warm-up cam this weekend, but I doubt it as we've got friends staying etc. I think a misunderstanding that I might be harbouring is that the waxstat will cause the idle to be higher during warm-up than at 'normal operating temp'. Sure it will make the throttle angle greater, but this might just balance the various rev-slowing forces of a cold engine. If this proves to be the case, I owe rubjonny a biggish apology for doubting his (and it seems yours Drew) version of 'the truth'. Pete
a couple of years back when I had just tuned the carb, the idle was a bit higher. Now as things are a bit out of setting then I guess the mixture is slightly out, hence a lower idle. I need to get back to it but a head rebuild on my BM is taking my car time. I think my warm up is quite "out" at the mo so my warm-up revs may not be "book". I will look at it when it causes me a problem (so this winter it is then )
Thanks again Drew, that comment makes me think maybe I'm not completely barking (though I may take some convincing of this!) after all. Trouble is, when you refer to 'book' settings, where the hell's the book!? Predictably, my e-mail to Pierburg about the warm-up rev sequence went unanswered... Wonder whether the info's out there somewhere on this web thing? Best of luck with the BM.
