924Board.org

[smoked_g60]

Hello everyone, I am new to this list nad I hope I can get clarifaction about adjusting the valves. From reading the manual, and other topics I take it that the cam must come out when replacing the adjustment screws. is this true for the 924 head?
When we got this free 924, the head was missing 2 of the screws, is this head toast?
I also wanted some clarifaction on adjusting the screws. Say the proper measurement came between two of the "clicks" in the adjustment screw. Should I try a larger one and screw it in less? Also, is it possible to screw it too far in and dislodge the screw from the threads, and lose the screw in the head?

[Lizard]

Well let me be the first to say congrats on getting a great car for a great price.

second let the nightmare begin

with the adjusting screws being missing I doubt any damage has been done to the head.

and yes to get the screws in you should take the cam out, and while at it put in a new timing belt, if alot of money replace tappets and all screws. I doubt that the correct adjustment would be inbetween a turn of the screw, I don't know if the screw can go in too far but I think it would just but up against the wall on the other side of the tappet.


Oh and read the FAQ and the tech section

[Joes924]

Last question 1st,Yes itis possable to screw in the adjuster to far and it will scrape on the wall of the cyl. ruining it. 2nd question adjust the screw to where the feeler guage just till it wont fit know more then back it off.you want it as close as you can get it having it fit.Thats the way I did it. 3rd question yes the cam must come out,no big deal though tkae out the plugs and put the cam on its mark looking at the back of the cam pully and the pointer on the valve cover on the then take off the belt. Pull the valve cover and pull the distibutor noting that its on #1 then loosen the bearing caps starting with 2 bolts from the rear of #5and then cam oil tube.Then loosen #3 bearing cap bolts 2 turns at a time working out to the other bearing caps in a crosspattern. Install the cam with #2 and #4 cap nuts snugged then the others and torque them down starting with #3 working out to the ends .Torque should be 11 to 15 ft lbs
the 2 end bolts on #5 should be7 ft lbs. make sure you notice how the bearings caps are place there numbered put them back the same way .Theres a O-ring on the end of the oil tube make sure you use it and that its not cracked.

[Joes924]

See the way I used my signature here, It shows my motor enforcing that I am
..maybe..knowledgeable of the workings of
the 924 motor. And I wont use again on this post. Ill use a smilie

[Lizard]

good note joe replace the plastic elbow to for the oiler tube

[gohim]

Yes, you can have the adjustment screw too far in or too far out. I think that the adjustment screw will fall out of the threaded hole if it is too far either way, or it will run too close to the bore walls, and that is why the adjustment screw might need replacement.

What no one has mentioned is that there are four different length adjustment screws available. The different length screws are marked with a line, or a paint dot, or you can measure them to ifgure out what the next length up or down would be.

There is an acceptable range of adjustment, with a minimum amount engaged (screwed out), and a maximum amount engaged (screwed in). What you have to do is start with an adjustment screw in the middle range, then adjust the valve clearance for that valve, and checked the "engagement" (the depth that the head of the adjustment bolt is screwed in, or out of the lifter body when you are done). If the screw is too far in of out, you need to pull the cam, and lifter, and replace the adjustment screw with the next longer (or shorter) screw, and check the engagement again.

To do the valve clearance adjustment, you only need a hex head wrench. BUt then you have to go back when you are done and measure the "engagement" of the adjustment screw when you are done.

I use a specially made tool that has the acceptable "engagement" range marked on the tool itself. To use the tool, all I do is adjust the valve clearance, and then look at the tool. If the engagement is within the acceptable range, I can see a green painted mark on the tool. The tool cost less than $10 back when I bought it.

Make sure that you replace the plastic elbow (they cost less than $2) in the oil supply line when you pull it to remove the camshaft. Check the tube for cracks (engine vibration can cause the tube to crack near the support brackets).

[smoked_g60]

Thanks everyone. So if it won't advance another click, due to the gap closing between the cam and lifter, I should just go with the wider gap?

[924RACR]

Excellent post, gohim. That tool is still available from the usual mail-order places, and I believe it is still around $10-15USD.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jpab924]

[Paul]

I bought mine from Performance Products.

[dpw928]

Just one suggestion and one correction. The adjuster screws are marked base on the thickness, not the lenght. The newer/replacement versions have 1 to four lines on the ends. One line is the thinnest and four lines are the thickest.

When installing the screws, center them in the bucket. Once the cam is installed, check the actual clearance. Since each 360 degree rotation on the screw adjusts the clearance by .002", a little addition of subtraction will tell you how many turns are required to get it into spec. Clockwise reduces the clearance and counterclockwise increases the clearance. The adjustment may be accomplished with a cold engine but the readjustment should made after 1000 miles to the warm spec.

Dennis
_________________
81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

[jpab924]

ok, so what is the original size that came in 924s? Thick ? Basically what I`m thinking is, do I need to go to a thinner size or thicker after getting my valve seats reworked?

Dpw, how many revolutions in or out from center position do you think would be too many? I`d rather have the correct tool to do this job, but I can`t seem to find one....I`ve looked through Perf. Parts. and an ofset wrench keeps popping up.

[dpw928]

The adjusters from the factory on my 80 NA were varied based upon clearance during assembly. Most were two or three notch but there was one or two four notches. When you screw the adjuster into the bucket, run it to center then count the full turns (.002" each) until it runs out of thread in the center or protrudes too far out to clear the wall. This should tell you how much adjustment can be made without going to the next size.

As mentioned earlier make a note of how the journals come off. If you put them on backward and torque them, they WILL break. Also, don't over torque them as this will lock the cam and tear up the timing belt. don't ask me how I know.

Dennis
_________________
81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

[jpab924]

Ok dpw, I think I`ve got it figured out. I`ll just look at the adjusters in the buckets before installing them and make sure they are at center and then count the number of turns out and in I can make before install.

So hopefully with 2 spare heads, I can come up with the right size adjusters I will need......hopefully.

[dpw928]

I may have a few adjusters in some old/bad buckets if you need them. Not sure what size/notch they are but if you come up short let me know.

Dennis
_________________
81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black