OK 2E2 folk, my 'car porn' video arrived this morning Carburation III, The 2E3 & 2E2 Carburettors. My first duty is to offer a humble apology to rubjonny for ever questioning his theory/knowledge of the warm-up idle speed situation. Though I did recently acknowledge that I was possibly misunderstanding the interaction of primary throttle angle and the rev speed of a cold engine, I shouldn't have argued with 'the great one' in the first place. Lack of documented info from Pierburg is my only excuse. It seems from a first viewing that 950 rpm is indeed the maximum that should be observed in the period during which the waxstat is governing the idle speed. This time window is said to be from about t=20s (depending on ambient) to t=6min. Interestingly, 750rpm is more-or-less confirmed as the 'correct' hot idling speed (engine at operating temp). This confirms my suspicion that Haynes 1081 has a typo here (but 4177 has it right). Edit 03/05/07: Just realised that as the video was made in 1985 some things may have changed subsequently, for new engine-codes etc. This may affect the above paragraph's validity. The vid makes frequent reference to material in the Carburation I, and II vids, as well as a 'workbook' which would all be useful to track down copies of. I'll be chatting to the (local) guy that had this vid, rest assured, though I think vids I and II are the basics of carb theory and the 'B' range of carbs respectively, so possibly inessential. Lots of little gems of info on how the 3-point, or 4-point unit works, in interaction with the TTV and over-run/idle control valve (and a second valve for the 4PU). How to adjust the secondary diaphragm action, how to adjust the warm-up cam and the waxstat itself, how to test lots of bits and bobs, fault diagnosis etc. Funnily enough, lots of the stuff that the 'team' on cgti have figured out is, of course, spot on. (Trust me that is not a pat on my own back, I feel I've only just begun to understand). Off outside to have a play now... Pete
So, all you need to do now is how to find out how to lower the idle speed. Chances are, haynes just had the initial setup info, although it's a shame this extra video info didn't make it into the carb manual. If it was all better known, maybe the weber wouldn't be so widely used. I've just had a thought!! Do you think Weber have been purging copies of this video throughout the world in order to boost their own sales? That must be the reason why this video has not appeared before now!
So, spent a lot of time this weekend doing a total refurb of the whole thing. First time I've had the 'lid' off, and pleasantly surprised how clean it was inside. A very few tiny bits of grit in the bottom of the float chamber, zero calcium deposits . Attempted the adjustments to the warm-up cam that I've been threatening for a while. One of these sets a cam position for a 'warm' waxstat, such that it disengages the cam from any influence on the primary throttle, ticked that box, no hassle. The other adjustment is for a minimum (or maybe maximum, can't remember) throttle angle with a 'cold' waxstat. I thought this would solve my over-reving problems once and for all... Totally 'show-stoppered' by Haynes carb manual saying "use a twist-drill to set this clearance, find the appropriate size from the specifications". What effing specifications? Looked through the list of numbers pertaining to my engine-code etc, couldn't find anything that looked like the right number. The only thing relating to the primary throttle angle was a 0.5mm dimension that I think actually is what it should be at the 'final' idle, not sure though. Anyway, all cleaned out inside and out, new gaskets, o-rings everywhere, thoroughly tested out all my diaphragms, cleaned out everything I could, the kitchen table's never seen anything like it . At operating temp. the car runs sweet as a nut now; for the first time I actually know what 'induction noise' is... Still had my over-revving during waxstat control situation [:^(] . Turns out (from watching the vid) that this is easily adjusted within the waxstat itself. I'd assumed that as it was new, it would be right 'straight out of the box'. Nah; just needed a bit of an 'unscrew' of the brass inner bit, relative to the plastic outer. Though I did briefly have a water leak problem after doing this, 'cos Pierburg had used a green 'paint' to fix the position to some notional 'ideal' setting, which had run down onto/around the o-ring seal that separates the 'wet' and 'dry' side of things. Easy adjustment really, shame I assumed that this was unnecessary! Things are finally better now, though a bit of fine-tuning probably reqd. Pete
the mk2 haynes recons put a 10mm nut between the 3/4 point unit & throttle stop, and the choke valve gap should be 6.3 +- 0.3mm
To clarify this a little (?); there's a lever attached to the primary throttle set-up which rests against the 'warm-up' cam (which in turn is moved by the waxstat pin). It's the angle that this lever sits at relative to the actual throttle-cable-holding bit on the extreme lower right of the carb that is adjusted by this procedure. So it's not a minmum, or maximum throttle angle, just, well, a throttle angle, that's set up here. There's an M4 caphead with a grippy washer which can move in a slot, then a stopper grubscrew against a plate to help it stay where it's put. You kinda need to look at a spare carb, off the car, to see this stuff... Rubjonny is talking about the setting procedure of the 'wide open kick' mechanism in his post above. This is an over-ride system on the choke flap to avoid problems of over-choking when driving off enthusiastically from a cold start. Edit 22:05; And I've just worked out why this (quoted) adjustment is required to be about right (where earlier I thought, hell, I can just adjust the waxstat itself to give me the cold revs I want). Trouble is, if the adjustment is not right, the waxstat cam will get to the 'drop-off' point (the adjustment I did manage) too early, or too late in the warm-up period. Both these adjustments are done with a special setting tool, which imitates a waxstat at two particular temperatures/extensions. I made one to the description in Haynes carb man. Just need to find that primary throttle angle now...
I've adjusted this by feel on the car Pete. there are two hex bolts on the cam warm up wax stat arrangement underneath the autochoke (you know the two bolts I am sure) one of these (bolt 1 call it) adjusts the wax stat position at which the waxstat no longer controls the throttle position (ie the temp at which the lever fall off the end of the cam - see the linkage and it'll make sense) and the other (bolt 2) controls the throttle plate angle relative to the waxstat linkage. first up, with the engine hot and just stopped ensure that the lever (that rests on the cam under warm up) is just clear of the waxstat cam. I think the carb manual has a sentence on this but the lever should be close to the cam but not touching it. Adjust bolt 1 if necessary and move the linkage until it is correct (ie cam relative to the lever which rests on the cam). once this is done wait a while and with the engine cold and running (and over-revving in your case?) loosen bolt 2 and adjust the throttle position until you are happy with the revs and then retighten bolt 2 job done, hopefully the revs will now be sensible under warm up (ie after the TTV has done its bit but before the throttle position is controlled by the 3/4 point unit)
Cheers Drew Thanks for this reply Drew, I had just about come to the same (approximate) conclusion, but I think it'll take a bit of to-ing and fro-ing. Now that I've worked out all the things I can adjust, and what they do, I'm sure I can get it to somewhere I'm happy with soon. Also have a spare carb I can examine for similarity/differences in the positions of everything. Trouble is, you never know which bits previous owners/garages may have 'tweaked' with less than full understanding of the situation. I'm gonna ask around at my local VAG place tomorrow, possibly armed with a beer/wine incentive, see if they'll give me access to any official info (like what the operating temp. idle really is meant to be for a 1991 EZ; what the waxstat controlled revs are really expected to vary between etc.) Got a pack of info from a Lady at GSF yesterday, but it didn't have quite the level of detail I was hoping for. Does have a good diagnostic/fault-finding table for 2E2 and 2E3 carbs though, which I'll post up at some point. Incidentally, the high rate of waxstat failures must be a consequence of the warm-up cam being slow to disengage, or never doing so, as an indirect result of the coolant-channel o-ring's demise. This would put more stress on the waxstat as it tried to hold the primary throttle open against both waxstat spring and main return spring. Another reason to get in there and replace the o-ring. Pete
once upon a time I had a whole haynes manual just for the pierburg carbs. its out there somewhere if you can find it... (dont know what I did with mine)
'kin car kept conking out every time the revs dropped on the way home today Think I may have been a bit cavalier when I guestimated the idle mixture after the rebuild... 3PU was still in the right spot, idle jet itself not blocked, don't think. Seemed to respond to setting the idle air screw half-way up the slot, then richening a bit from there. Wanted to take that out anyway to renew the o-ring, still one more (o-ring) left over from the recon kit, wonder where that one goes? Popped the idle speed back up to 950 again for good measure. Working again now, for now. Wonder WTF happened there? 'kin cars! 'Pure' Pierburg manual's out of print I think, but someone on here must have one, could be worth good money... [:^(] [:^(] [:^(]
Make sure your sitting down and well braced before you click this pete http://www.amazon.co.uk/gp/offer-listing/1850107858/ref=dp_olp_1/203-0206149-0129572?ie=UTF8&qid=1178211547&sr=8-1
Nope . Just thought I'd be nice and help. There is a much cheaper one on ebay at the mo (search for pierburg)
Wasn't serious, but it could be someone having just read the thread! Bit like when the 'recondition your tappets' thing came on here, then they started popping up for sale on the bay!
Just 'impulse bought' the one (manual) off the bay that you (maxmo) kindly pointed out. I wonder if that'll work out? Never bought anything so fast in my life, 'cept maybe drinks. Bet there's nothing in it beyond what I've already seen, but never mind. Always a chance. Reconning 2E2s for money, hmmmmmm. Time for another stick of nicotine gum to calm down. Cheers for all the support folks.
At the risk of having the Pierburg Brotherhood hit squad visit me in the wee small hours having read this thread I'm more than happy to - here comes the knob gag - pull a small knob on the dash to warm my Driver up - it's got a Weber and for this I am truely thankful. A sorted Pierburg may be a thing to behold but there are but two adjustments upon the mightly DMTL and lo they offer idle mixture and idle speed variation, and are sorted in moments with a screwdriver. You need only ask yourself did Enzo every bolt a Pierburg onto a Ferrari? M'lud the defence rests. An unrepentant unbeliever Barkstar
