Compression issue, valves, and guides

G

galaxyjb

Junior Member
I will start off by saying I'm a newbie to A's and engine work in general.

With that said I did a compression check on the A this spring, cylinder 1,3,4 had 90 psi, 2 had 60psi (adding oil brought it up to 64 psi). The I did a vacuume test and at idle the gauge would show about 20 but would bounce quickly and rapidly down 3 or 4.

I figured this was a valve issue with number 2.

Pulled the head, it looks like a brumfield head (or at least hicomp, not stock) and the previous owner said the pistons were 90 over. The number 2 exhaust seat looks pitted (will post photo). I pulled the valve cover and removed the spring and retainer for the valve, it had a lot of play in the guide as well.

So being new to this can I change the guide and valve (I have spare new ones), lap the valve in like crazy and do you think this will get my compression up? Or what should I do?

I also know number 4 plug likes to get a little oily so I figure there is something going on there as well with the guides or something.

So should can I try to change the valve and guide for #2 in hopes getting compression up and not having the valve wiggle around so much or just lap in what's is there and run the motor till it won't go anymore?

Thanks,
jb

Here is the photo I promised of the valve seat on cylinder #2 in question

http://s24.postimg.org/65jt4ri11/IMG_3681_1.jpg
 
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Do you have adjustable lifters and have you checked the clearance? What you propose is a "shade tree" fix, but they worked back in the day. In fact an interesting thread might be shade tree fixes folks have done/seen. But lets not hijack this one.
 
It appears to me that cylinders 1,2 and 4 are fine and the problem is with #3. Check the lash/clearance on that cylinder [ it would be nice to do on all cylinders actually] and try to determine if the #3 problem is valve or rings/piston. If there is no lash on either valve then that could be your problem. It seems as though you have an issue with the #3 rings/piston. It would have been nice to pump air into the cylinders to see where they were leaking before removing the cylinder head.
 
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I'm sorry, I edited my original post, I meant to state the issue was with cylinder #2, not 3, but all the rest of the info remains the same, and I have corrected the 1st post.

Here is the photo I promised of the valve seat on cylinder #2 in question
http://s24.postimg.org/65jt4ri11/IMG_3681_1.jpg

PC/SR: I do have adjustable lifters, I checked cylinder 1 for the heck of it and they look loose like 25 on the exhaust valve kinda loose.
 
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It looks like that valve may be starting to burn. You'll know better its out and can get a good look at it. You may get lucky. Normally a bad valve will show zero compression. One that is just starting to burn will show a lower compression, but, they go bad quickly.
 
Looks like the valve is recessed already and may not be possible to save the seat. The pros could better tell you if a seat insert would work with the pitting you have.
 
For a quick fix, follow your first thought and install a different valve and lap it in if the seat is not too bad. It looks pretty bad from up top but, the actualseat may be better. Adjust the valves cold to .013 intake and .15 exhaust. I suggest this lash since you have original valves. If you had modern valves, I would suggest .011 for all.
 
Well I decided to go the remove the valve and guide approach and lap in a new one. The seat looks ok, no cracks. I have the "good" guide removal tool problem now is the guide won't come out, it's a two piece. I sprayed liquid wrench down on the guide and even giving a few firm hits with a rubber mallet the guide is really stuck in. Any guidance would really help. Thanks, "the newbie"
 
Lift the valve up as high as it will go & cut the stem with a die grinder & cut-off wheel,then a simple matter to drive the guide out.When installing new guide ,put a bit of Never Seeze on the guide so that it will remove easily years down the road.The single lock lifters have a tendency to loose adjustment.The double lock type are a little harder to adjust,but will hold adjustment well.In the past,I have ground valves with the Clover grinding compound in the double lidded tin & the suction on a stick & it worked just fine.If seat is badly pitted,you couldhave the seat reground with a portable valve seat grinder or a early style hand operated valve seat reamer kit.
 
Just an update. Thanks for all the help, the guide came out with the steel hammer to the valve Tom and the new valve and guide are now in. I'm going to lap it in like crazy this evening and adjust all the valves, the seat looks in ok enough condition and I'm hoping by removing the play in the guide/valve things will seal better. Will keep you posted on how the compression looks when it's all done.
 
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