BillS Posted May 31, 2007 Report Share Posted May 31, 2007 About 300 miles ago I fitted new valves and guides to my TR2. Quite soon after fitting the car suffered an exasperating fault - everything would be fine and then bad missfire and mechanical noise. But before I could get home to investigate all returned to normal so firm diagnosis was difficult. Finally I decided to let the car tick over in the garage for a time and finally it repeated the fault. Quickly lifted the rocker cover to find no. one cylinder inlet stuck open (causing the pushrod to become dislodged and now banana shaped), and number two inlet also looking suspect. When I removed the rocker shaft I found the locating screw had also come out and the shaft was therefore able to move. I had noticed that oil pressure on tickover when hot was down to around 10lbs psi. The new guides are now US and I am fitting replacements. Question is how much oil normally passes down the guides and does this oil find its was through the rocker to valve and down? Or is there some other fault I have yet to discover which has caused the rapid wear of the guides? Any thoughts appreciated. Quote Link to post Share on other sites
Don Elliott Posted May 31, 2007 Report Share Posted May 31, 2007 Maybe the valve guides are not worn but too small. If they were not reamed to the correct inside diameter, valves will stick when the engine gets hot and the valve stem expands till it jams in the tight guide. Quote Link to post Share on other sites
marvmul Posted May 31, 2007 Report Share Posted May 31, 2007 Maybe the valve guides are not worn but too small. If they were not reamed to the correct inside diameter, valves will stick when the engine gets hot and the valve stem expands till it jams in the tight guide. That's right. Maybe steel guides don't need reaming always, but bronze guides are squeezed in the cylinderhead : checking the clearance by rocking the valve is mesleading : it is only at the middle part that the guide get's narrower after fitting and the valve can still be rocked even when the clearance is almost zero halfway up the guidewhere it passes the combustion chamber deck. Quote Link to post Share on other sites
ncoll Posted June 1, 2007 Report Share Posted June 1, 2007 This is the procedure i use for all race or road modified heads for triumphs, 1.check the guide bore hole in the head with 1/2 inch reamer.2. put a light counter sink on top of the hole. 3.Check outside diameter of all guides.4. Lubricate hole in head and outside diameter of guide with copper grease.5. Press guide into head. Do not hammer in. If the valve stem is tight in the guide, i use a flexi hone. If you use a reamer this can cause problems. Hope this information is useful Neil Collingwood Quote Link to post Share on other sites
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