76dat280z Posted February 15, 2014 Report Share Posted February 15, 2014 I am doing a frame off restoration to a 1976 Datsun 620 and during the process of renewing everything, the counter weight off the exhaust manifold has been misplaced. I am hoping someone here has one that is not needed. Quote Link to comment
metalmonkey47 Posted February 15, 2014 Report Share Posted February 15, 2014 Counter weight on the exhaust mani? Quote Link to comment
TENDRIL Posted February 15, 2014 Report Share Posted February 15, 2014 muffler bearing ? Quote Link to comment
datzenmike Posted February 15, 2014 Report Share Posted February 15, 2014 It's part of the heat riser valve, I know exactly what you mean. The '75-'77 L20Bs had the intake and exhaust bolted together and used exhaust heat to warm the underside of the intake to help evaporate the gas on cold start ups. There is a shaft with a flap gate and a coil spring on it, that turns the shaft and flap gate to restrict the exhaust flow and force it up onto the intake. There is a weight on the shaft to help keep it closed at idle. When revved up, the exhaust pressure will force the valve open against the spring and weight. . 1 Quote Link to comment
datzenmike Posted February 15, 2014 Report Share Posted February 15, 2014 My old 340 had that. You couldn't miss the distinctive clatter when idling. Quote Link to comment
76dat280z Posted February 15, 2014 Author Report Share Posted February 15, 2014 Yes, that is it! Quote Link to comment
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