I would appreciate some advice on how to adjust the Chevy valves. My engine was rebuilt in 2010 and the valves were set up properly then. I was hearing a "thunk,thunk, thunk" at a low idle, so after consulting some friends, I pulled the valve cover and sure enough, the nuts on six of the valves were loose. I was told, via telephone conversation, that the top nut adjusts the clearance and the bottom nut tightens/sets things. I was also told that I can do this without pulling the head.
I have done a lot of mechanical work to this car, but I have never touched the valves, so this is new territory for me. I do have the MTFCA engine manual as a reference, but from what I have read thus far, it discusses clearance using the KW tool with the head off. The book states that there should be .010 for the intake valve and .012 for the exhaust, but there isn't a photo or drawing to show, so I am a bit confused. Any help would be appreciated.
Before the new Stipe 250 cam, I adjusted the valves according to piston position. After the new cam installation, I adjusted to .010 both inlet and exhaust.
If you think it is difficult with the carburettor in place, try doing it on a Right Hand Drive with the steering column as well!
Difficult, knuckle barking and time consuming, but now I have a very quiet engine with little, if any loss of performance.
I hope I will never have to do it again with the engine in place.
Try this procedure by Glen Chaffin. Worked for me.
Mark. Here is a simple method for setting valves with the head on. Works very well. You will be happy with the results.
SETTING VALVE CLEARANCE
A SIMPLE PROCEDURE
BY GLEN CHAFFIN
AN ORIGINAL USED MODEL T FORD CAMSHAFT WILL HAVE REDUCED LIFT AND A CHANGE IN VALVE TIMING CHARACTERISTICS DUE TO NORMAL WEAR ON THE LOBES. THE ENGINE WILL STILL RUN GOOD BUT MAY HAVE A REDUCTION IN LOW END TORQUE AND HORSE POWER. EVERY LOBE OF THE CAM WILL HAVE A DIFFERENT WEAR CHARACTERISTIC.
BACK IN THE EARLY 1920’S, K.R. WILSON SUGGESTED THAT MODEL T VALVES BE SET USING THE PISTON TRAVEL METHOD. HE EVEN OFFERED A SPECIAL TOOL TO DO THE JOB. THE IDEA WAS TO ADJUST THE OPENING AND CLOSING OF THE VALVES TO CORRESPOND WITH A CERTAIN POSITION OF THE PISTON. IN THEORY THIS WAS GOOD AS IT COMPENSATED FOR THE WEAR ON THE CAM LOBES AND RESTORED VALVE TIMING TO THE ORIGINAL FORD SPECIFICATIONS. IN PRACTICE IT CAUSED OTHER PROBLEMS.
MANY ARTICLES HAVE BEEN PUBLISHED IN THE VINTAGE FORD ON HOW TO ADJUST VALVES BY PISTON TRAVEL. HOWEVER, YOU SHOULD KNOW THAT THIS METHOD IS ONLY USEFUL FOR SOMEONE USEING THE ORIGINAL CAST IRON HEAD VALVES AND TRYING TO RESTORE OPTIMUM PERFORMANCE BY ADJUSTING VALVE TIMING TO COMPENSATE FOR A WORN CAMSHAFT. EVERY CAM LOBE HAS A DIFFERENT WEAR PATTERN AND WILL REQUIRE A DIFFERENT ADJUSTMENT TO RESTORE THE ORIGINAL VALVE TIMING. USING THIS METHOD WILL RESULT IN THE VALVE LASH OF EACH VALVE BEING DIFFERENT FROM THE NEXT ONE. WHEN THE PROCEDURE IS COMPLETED TYPICAL VALVE LASH WILL VARY BETWEEN 0.010 IN. AND 0.030 IN. THE NET RESULT WILL BE A MODERATE IMPROVEMENT IN ENGINE PERFORMANCE AT THE EXPENSE OF A NOISY ENGINE.
FORD SET MODEL T VALVE CLEARANCE TO A “THIN DIME”. TYPICALLY, 0.022 TO 0.028 IN. THIS WAS NECESSARY DUE TO THE USE OF CAST IRON HEAD VALVES WHICH HAD A LARGE THERMAL EXPANSION COEFFICIENT. IN TODAYS WORLD ANYONE REBUILDING A MODEL T ENGINE WOULD NOT EVEN THINK OF USING THESE CLEARANCES AND THE POROCEDURE OF SETTING VALVE CLEARANCE BY PISTON TRAVEL IS OBSOLETE. WITH MODERN STAINLESS STEEL VALVES THE CLEARANCE IS TYPICALLY SET BETWEEN 0.010 IN. AND 0.015 IN. THIS WILL INCREASE VALVE LIFT ABOUT 0.010 IN. AND SLIGHTLY INCREASE VALVE DURATION.
DURATION IS THE TIME DURING WHICH A VALVE IS OPEN MEASURED IN DEGREES OF CAMSHAFT ROTATION. DECREASING VALVE CLEARANCE INCREASES VALVE DURATION. WITH A TYPICAL CAM GRIND, THE VALVE DURATION WILL INCREASE APPROXIMATELY 1 DEGREE FOR EACH 0.001 IN. IN REDUCED CLEARANCE. USING THE NEW RECOMMENDED VALVE CLEARANCE WITH A “STOCK” CAM THE DURATION SHOULD BE INCREASED ABOUT 10 DEGREES TO 228 DEGREES. THIS IS NOT BAD AND COMBINED WITH THE ADDITIONAL VALVE LIFT SHOULD ACTUALLY IMPROVE LOW END TORQUE AND OVERALL HORSE POWER.
MY ORIGINAL 1913 ROADSTER WAS REBUILT USING THE ORIGINAL CAM. THE VALVE LASH WAS SET TO 0.015 IN. FOR EACH VALVE. THE CAM VALVE TIMING WAS THEN MEASURED AND HAD TYPICAL WEAR CHARACTERISTICS. INTAKE VALVE DURATION VARIED BETWEEN 229 AND 243 DEGREES. EXHAUST VALVE DURATION VARIED BETWEEN 222 AND 235 DEGREES. THIS SOUNDS TERRIBLE, BUT IN PRACTICE, THE ENGINE RAN BEAUTIFULLY WITH VERY GOOD LOW END TORQUE AND HORSEPOWER. I HAD NO PROBLEM DRIVING 50 MILES PER HOUR OR PULLING STEEP HILLS IN HIGH GEAR WITHOUT A RUCKSTELL.
THE MODEL T FORD ENGINE IS A MARVELOUS MACHINE AND WILL PERFORM WELL EVEN WITH A WORN CAMSHAFT. HOWEVER, IT IS NOT A MODERN PRECISION RACING MACHINE. THE ENGINE WAS DESIGNED AND PERFORMED WELL FOR IT’S ORIGINAL APPLICATION. THE ENGINE PERFORMANCE CAN BE IMPROVED TODAY BUT STILL HAS IT’S LIMITATIONS.
SETTING VALVE CLEARANCE
A NEW CAMSHAFT IS GROUND TO GIVE THE BEST PERFORMANCE AT A SPECIFIED VALVE CLEARANCE. A USED CAM WILL HAVE SOME ERROR IN IT’S GRIND DUE TO WEAR BUT WILL STILL PERFORM WELL WITH ALL OF THE VALVES SET TO THE SAME CLEARANCE. I KNOW THAT MANY OLD TIMERS WILL DISAGREE, BUT IN PRACTICE THIS IS TRUE, AS DEMONSTRATED BY MY 1913 ROADSTER.
WE THEREFORE RECOMMEND THAT VALVE CLEARANCE BE SET THE SAME FOR EACH VALVE WHETHER THE CAM IS A NEW CAM OR AN ORIGINAL WITH MODERATE WEAR. THE AVERAGE MODEL T DRIVER WILL NOT BE ABLE TO TELL THE DIFFERENCE IN PERFORMANCE AND THE ENGINE WILL RUN QUIET. HOWEVER, THERE ARE ALWAYS EXCEPTIONS TO EVERY RULE!
SETTING VALVE CLEARANCE NEED NOT BE A DIFFICULT CHORE IF YOU KNOW WHAT TO DO. FIRST, BASED ON WHAT YOU KNOW ABOUT THE CAM, CHOOSE A CLEARANCE BEST SUITED FOR THAT CAM. ANYTHING BETWEEN 0.010 IN AND 0.015 IN. SHOULD WORK.
THE CAM GEAR HAS 48 TEETH. THE CRANK GEAR HAS 24 TEETH. THIS MEANS THAT THE CAM GEAR TURNS AT ONE HALF THE SPEED OF THE CRANK GEAR. IF THE CRANK GEAR IS TURNED ONE COMPLETE REVOLUTION (360 DEGREES), THE CAM GEAR WILL TURN ONE HALF REVOLUTION (180 DEGREES). THE TOE OF EACH CAMSHAFT LOBE IS 180 DEGREES FROM THE HEEL. VALVE CLEARANCE IS ADJUSTED AT THE HEEL OF THE CAMSHAFT LOBE. THIS INFORMATION CAN BE USED TO EASILY SET THE VALVE CLEARANCE ACCURATELY.
IF THE CRANK IS TURNED SO THAT THE VALVE TO BE ADJUSTED IS SET AT MAXIMUM LIFT. ALL THAT NEED BE DONE IS TURN THE CRANK ONE FULL TURN (360 DEGREES) AND THE VALVE LIFTER WILL BE SETTING ON THE EXACT CENTER OF THE CAM LOBE HEEL. THIS IS THE POINT WHERE YOU SHOULD ADJUST THE VALVE TO THE DESIRED CLEARANCE.
THE PROCEDURE IS AS FOLLOWS:
NOTE: THIS PROCEDURE DOES NOT REQUIRE REMOVAL OF THE OIL PAN INSPECTION COVER.
1. REMOVE THE FAN, FAN BELT, VALVE COVER (S) AND HEAD FROM THE ENGINE. YOU MAY ALSO WANT TO REMOVE THE RADIATOR TO MAKE THE JOB EASIER.
2. MARK THE VALVES NUMBER 1 THRU 8 WITH NUMBER 1 AT THE FRONT OF THE ENGINE AND NUMBER 8 AT THE REAR. VALVES NUMBER 1, 4, 5 AND 8 ARE THE EXHAUST VALVES. VALVES NUMBER 2, 3, 6 AND 7 ARE THE INTAKE VALVES.
3. TURN THE CRANK HANDLE UNTILL NUMBER 1 EXHAUST VALVE IS AT TOP DEAD CENTER (MAXIMUM LIFT). YOU MAY WANT TO USE A DIAL INDICATOR TO DETERMINE THE MAXIMUM LIFT POINT. THE END OF THE CRANK PULLEY PIN SHOULD NOW BE NEAR TOP DEAD CENTER (APPROXIMATELY 11:58 O’CLOCK). PLACE A MARK ON THE CRANKSHAFT PULLEY TO IDENTIFY THIS POINT AS YOUR REFERENCE POINT.
4. NOW. USING THE CRANK HANDLE, TURN THE CRANKSHAFT EXACTLY 360 DEGREES. THE VALVE SHOULD NOW BE SEATED AND THE END OF THE CRANKSHAFT PULLEY PIN SHOULD BE BACK AT 11:58 O’CLOCK.
5. CHECK THE VALVE CLEARANCE OF NUMBER 1 VALVE AT THIS POINT. IF NECESSARY, MAKE ADJUSTMENTS TO THE VALVE CLEARANCE TO OBTAIN THE PROPER CLEARANCE. AFTER ADJUSTMENT RECHECK THE CLEARANCE.
6. REPEAT THIS PROCEDURE FOR ALL FOUR OF THE EXHAUST VALVES,
(NUMBERS 1, 4, 5 AND 8).
7. NOW, TURN THE CRANK HANDLE UNTIL NUMBER 2 INTAKE VALVE IS AT TOP DEAD CENTER (MAXIMUM LIFT). NOTE: IN THIS PROCEDURE THE END OF THE CRANKSHAFT PULLEY PIN SHOULD BE NEAR 1:00 O’CLOCK. MAKE NOTE OF THIS POINT AS YOUR REFERENCE POINT.
8. REPEAT THE PROCEDURE ABOVE FOR ALL FOUR OF THE INTAKE VALVES,
(NUMBERS 2, 3, 6 AND 7), USING THE 1:00 O’CLOCK REFERENCE POINT.
9. THIS COMPLETES THE VALVE ADJUSTMENTS.
10. CHECK YOU’RE WORK CAREFULLY AND YOU WILL BE PLEASED WITH THE RESULTS.
I HOPE THAT THIS INFORMATION IS USEFUL AND WORKS WELL FOR YOU AS IT HAS FOR ME. PLEASE LET ME KNOW IF YOU HAVE ANY COMMENTS OR SUGGESTIONS.
It sounds like you have the adjusters that require three wrenches to set the clearance and lock the holding jam nut. You will need to grind a 3/8 inch wrench fairly thin to be able to lock the jam nut. One wrench holds the bottom part of the adjuster, the upper wrench turns the "bolt" the third wrench locks the jam nut. The problem is with the adjuster down, not enough of the lower piece is exposed to get a wrench on it to prevent it from turning. I find it easier to remover the head and manifolds. Take out the valve springs a well. Then you can press the valve down to check the clearance, if adjustment is necessary, you can lift up the valve and adjuster so there is room to use all three wrenches. Then recheck the clearance. Repeat as needed to obtain the clearance you want. Not ideal, but you can get the job done with the least amount of contortions.
Jim, you will certainly need the ground thin wrench. I use two.
If you hand crank the motor over until you can see valve number 8 fully open, then number one will be fully closed. The gap needs to be set at .012 - .015" Measure what gap you have. To be able to adjust the gap, the motor will have to be cranked again to lift the tappet up to access the nuts. You may have to repeat this process a couple of times to get the adjustment just right.
Each valve can be done in turn. When number 7 is open, number 2 is closed etc, just keep the number 9 in mind, 1+8 = 9, 2+7 = 9.
Hope this helps.
Allan from down under.
Thanks for the advice and here is the update. I hate to admit it, but as it turns out nothing was wrong. Having never been into the valves before, I didn't realize that what I thought was the "top" nut was actually the top of the bolt going into the tappet. Thankfully, with the help of a friend stepping me through the parts over the phone and my Dykes manual, I was able to note that all of the nuts were tight and that the clearances between the valve and the tappet were no less than .016 and no greater than .018. I didn't have uneven feeler gauges - the .016 fit and the .018 didn't. It is just barely over, so, unless this is something that is really bad, I think I will leave it.
Ruling out the valves as the cause for the "tap-tap-tap," I called Dave Johnson up again. He had just put a reground crank in it this past March, along with new rings. I questioned him whether or not it was a loose wrist pin bolt or even a loose main. He said that it was most likely the new AL timing gear; the first rebuild had a nylon timing gear. I am not sure which one is better as far as performance goes, but the AL gear is definitely noisier, especially at a low idle.
It sounds like the timing gear is not meshing properly. Perhaps the crank gear is worn too much, yielding excessive clearance?
I hope while he was at it he put in a new crankshaft gear to mesh w/the new camshaft gear.
It's not a good plan to mix old and new gears. Especially in this application.