Rather odd this little gem, I have a pair of hiff6 carbs on a TR6, the rear carb insists on vibrating when the throttle is at constant depression, I think it may be the dash pot springs are not man enough, the ones in it are from a Rover 3.5 V8.
Why would the dash pot piston shake about and vibrate?
Alastair
Usually because of harmonics in the gas flow through the carb. It tends to happen on race engines with long duration cams which is one reason for fitting Webers in those cases. I'd be looking at something unusual in the cylinders that carb feeds. Burnt valve etc or maybe an inlet or exhaust manifold problem. A compression test would be a place to start. If not then it's just down to something in the carb itself and lack of damping in the dashpot would be favourite so check the oil level. If the spring is the same as in the front carb then I see no reason why that could be the cause.
Dave Baker - Puma Race Engines
In message , ajmac writes
Low dashpot oil level?
Sounds like a burn't valve or valve clearance too tight, do a compression check and check the tappet clearance.
Do a piston drop test. Only time I've seen this, there has been wear in the dashpot so that the piston could wobble around its axis. Whenever you get a force that varies depending on position (in this case the piston seal leaks as it moves), you get oscillation.
You could simply swap the complete piston assemblies since I doubt they'd both be worn. But I'd bet this isn't the fault.
Very much doubt it -- a diffent matter if it was using the last types of SU carb which had a ball bearing sleeve assembly between the piston rod and dashpot.
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