| Author | Message | ||
     Jeff Young Experienced User Username: jeyjey Post Number: 21 Registered: 10-2010 |
The piston doesn't appear to be able to drop low enough that it would hang on the damper rod. Is it just to keep you from losing the damper rod? There must be more to it than that. At any rate, mine are both loose on the damper rod. What detrimental effects might I notice from that? Thanks, Jeff. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 699 Registered: 6-2006 |
Nothing & None  | ||
| Jeff Young Experienced User Username: jeyjey Post Number: 22 Registered: 10-2010 |
Thanks Paul. So I've got an issue where my idle drops so low right after warmup that it sometimes stalls. It'll be after I've driven about 1/2 mile; if I go the direction when there's a very tight bend that I have to slow down for the car stalls if it's cold out. (I've also noticed that even when it's not cold out very slow turns drop the idle enough that the alternator output drops and the turn signals get very slow.) Sticky SU piston? I checked the idle, and it's usually between 650 and 800 (it'll settle down to the higher number if I let the throttle off gently, and the lower number if I let if off sharply). Is that enough info to suggest anything? Jeff. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2264 Registered: 4-2003 |
Jeff, Your idle stop is probably right out of range. The motor is probably never running with the idle on its main stop. It's probably only idling at all when warm due to friction in the linkages. Snap the throttle shut or flex the linkages on a curve, and the throttle is probably finding a lower end position. Cold idle will be supported by the fast idle cam regardless of the tuning of the main stop. Better adjust it anyhow. With the engine warm, push the choke to the fully open position and check that the fast idle cam is out of the way once you have flicked the throttle open and shut once. Then, by hand, push the throttle lever fully home at the carburettors and wind up the end stop to achieve the desired idling speed. Finally, make sure that the dashpots are filled with Dexron. The pistons are loose on the shafts to act as one-way valves: they only damp fully in one direction. Their main function is as a substitute for a separate accelleration pump as fitted to most downdraught carburettors. If the dasshpots are out of oil, then the motor will often display a flat spot when opening the throttle to accelerate. | ||
| Chris Browne Experienced User Username: chrisb Post Number: 36 Registered: 2-2010 |
Hello all, Richard - your comment about filling the dashpots with Dexron was interesting. Do you consider engine oil, which the handbooks recommend, too thick for the job? Although I have never had a problem on my car, 20W50 does seem a little viscous, especially now we are into sub-zero temperatures in the UK. I would be interested to hear your thoughts. Kind regards, Chris | ||
| Jeff Young Experienced User Username: jeyjey Post Number: 23 Registered: 10-2010 |
Richard, Interestingly, the idle adjustment screw is contacting the stop both when it's idling around 650 and when it's idling around 800. I think you're suggesting that the body (and/or engine) rolling on the subframe when going around the tight corner might be contributing. I wonder if flexure on the linkage is pushing the butterfly shafts one way or the other in worn bores and changing the idle? I'll try wiggling the butterfly shafts (and the piston lift pin) and see if either changes the idle speed. Jeff. |
