Barclay

First timer wants to adjust valves on 1981SC I been reading the Bentley it does not look that difficult. My question to everyone how much unbolting do I have to do to get to the crank pulley so I can turn it? Thank you

John D.

Hey Barclay,

Welcome to Rennlist..!!!!

Remove the spark plugs - and the engine will turn off the fan/alt pulley If it "slips", just compress the alt. belt with your fingers - and it will turn the crank just fine....

Also - then - all the "unbolting" will be from the valve covers....

It's easy - just take your time - and post back with any questions you have, OK????

geo.aigel

Don't remove the spark plugs. Carbon buildup can come loose from the plugs, fall off and get wedged between the valve and the head leading to false readings. As unlikey as it seems, if this happens, you will have adjusted your valves wide open, risking burning them up!

Cheers, George

Alan Herod

George -- I've heard that too, and devised a way to brace one rear wheel and turn the other wheel with the car in fourth to rotate the engine. But, I gave up on that technique since I do leakdown when I do valve adjustment. If a piece of carbon is wedged between the valve and the seat -- I will know it right away.

Barclay

Thanks John, sound easier.

Barclay

George, I have heard of carbon falling down into the valves too, so how much unbolting is involved?

quicksilver

Just use a breaker bar on the crank pulley bolt. It isn't a race so you don't have to spin the engine quickly. The pressure will leak past the rings so it is no big deal. (don't remove the plugs)

When I am lazy I turn the engine by wrenching the fan nut while squeezing the fan belt so it won't slip. If using this method, go slow so you don't have to use much torque, otherwise it will tighten the fan pulley nut.


One detail!!! Don't turn the engine backwards!


Wayne

mschafer71

Be patient and take your time. Start with the exhaust valves as they are very accessible on the passenger side but somewhat blocked by exhaust system on the driver's side. I would recommend removing the components of the exhaust system that are blocking but this alone could take considerable time depending on the condition of the hardware holding everything together. I took out my cat to replace with a by-pass pipe so now my bolts and nuts are new and the next valve adjustment will be very quick. Some of the exhaust nuts were so horribly corroded that the dremel tool was the only way to get them off (they were round and "welded" to the bolts!) . After the prep work for the exhaust valves it is pretty straight forward, turn the 24mm bolt on the fan pulley to spin the engine thru its firing order and check each valve several times. Make sure you understand that two revolutions of the crank are required to put each of the six cylinders in TDC position. The ideal gap of .004" is adjusted by fairly small turns of the adjusting screw. If you were to turn the adjusting screw a 1/4 turn it would effectively close the gap by .004". I found that just a turn of the adjuster bolt from say 3 o'clock position to 4 o'clock position would be too tight and a corresponding 2 o'clock position would be too sloppy. It is a narrow range that the adjuster screw goes thru to be properly gapped. Basically "one hour" of turn on the adjuster screw will change the gap by about .0013". Now the hard part for me was the tight area you have to work with when you go up top to attack the intake valves. It is very tight and you will have to work by touch/feel sometimes. The #2 and #5 intake valves were the tightest areas for just maneuvering the adjuster tool into position. I spent probably three times as long doing the intakes as the exhaust. I checked each valve four times and still had to go back after I ran the car to redo one that was too loose/noisy (it was # 1 intake, .0053" just "one hour" of a turn off on the adjuster screw but it was evident to my ears that it was wrong). I would leave the plugs in while doing the valves but after you are done with the gaps remove and check the plugs since they are more accessible now with some of the blocking components moved. I cleaned up the valve covers very carefully and they looked brand new before they went back on. Just don't rush it! Be meticulous and precise because its .004" you're after.

Barclay

mshafer71, if I don't turn the engine over by the fan belt pulley and turn it over with the 24mm fan nut ( isn't there markings on the pulley?) how do I know I am at TDC with each cylinder?

mschafer71

The crankshaft pulley should have four marks on it; the Z1 and two other marks spaced at 120 degrees points on the crankshaft pulley, and the fourth mark is just to the right of Z1 and represents a timing mark usually 3 or 5 degrees before TDC, depending on the year or size of engine. Z1 shows you where the #1 or #4 cylinder is at TDC, the next mark at 120 degrees around shows you when #3 or #6 is at TDC and the third mark past Z1 at 240 degrees would show when #2 or #5 would be at TDC. The distributor also turns at 1/2 the speed of the crankshaft.

Barclay

mshafer71, your a great help, you make it sound easy, appreciate your insight I have a few tools to buy, but I'm sure it will be cheaper than having a shop do it. thanks again. Barclay