Gonna do some research on the Web and look for info, but thought I'd check here:  that's how you check cracks in the head, right?

I wish I had just bought a reconditioned head, but I bought a used one thinking I could scavange parts off of it and my current one to resolve my #4 cylinder low compression problem.  Stoopid idea now that I think about it  :-/  Definitely not saving enough money to make it worth while  

Anyway, I don't want to wait for a new head (wanna get this thing back on the road) so I'm gonna proceed as planned.  I guess when I pull the head I may see some clear sign of what's wrong (bad valve, bad valve seat, bad cam lobe, or bad head gasket), but if I don't, I guess I should check the head for cracks.

Thanks for any info.

One problem Jerry,  the head has to be magnetic.  You can't magnaflux an aluminum head.

They use a powerful magnet and iron fileings.  They are attracted to the crack, somehow.

Cwkick

If the replacement head got hot,
you might want to have it checked,
remember if you have a high milage
engine, new valves will kill off the rings
in about 30,000 miles, so if the used
head is OK and didn't smell burnt or
of hot oil, a simple hand lapping of
the valves would be good.

One problem Jerry,  the head has to be magnetic.  You can't magnaflux an aluminum head.

They use a powerful magnet and iron fileings.  They are attracted to the crack, somehow.

Cwkick

Cwkick,

Yup, just read that.  They apply a strong magnetic field to a cast iron head and sprinkle the magnaflux powder on it.  Cracks in the iron head disrupt the magnetic field and will show the pattern in the magnaflux.

As you said, Al ain't magnetic (OK, I paraphrased there).

Apparently, you have to pressure test aluminum heads.  Guess that's out as far as a home job (I guess magnafluxing would have been too)  :-/

I may take the head(s) to a shop and have them check for cracks, warpage (apparently a bigger problem with Al) and any other problems.  Not sure what that'd cost; Darn, I wish I had sprung for the reconditioned head  

If the replacement head got hot,
you might want to have it checked

Actually, the head that's in there now looks a little burnt to me.  It's got that dark color to it.  The new one is pretty clean looking (and I don't think it had been cleaned).

remember if you have a high milage
engine, new valves will kill off the rings
in about 30,000 miles

I remember you saying somthing about that in a post a while ago.  That happened to your engine I believe, yes?  Have you heard or read of it happening to others?  Is it a given?  The engine has 160k miles as far as I know and I have no idea how long the compression has been low (very low) in #4.  But, 30k would be pretty good for me (about 5 years   ).

I did a head at 200K miles, had a burnt
valve, it ran great after that, then by
240K it was getting tired and using oil
I got almost another 45K miles out of it,
but the last 10K were hard slow miles

Actually, the head that's in there now looks a little burnt to me.  It's got that dark color to it.  The new one is pretty clean looking (and I don't think it had been cleaned).


I remember you saying somthing about that in a post a while ago.  That happened to your engine I believe, yes?  Have you heard or read of it happening to others?  Is it a given?  The engine has 160k miles as far as I know and I have no idea how long the compression has been low (very low) in #4.  But, 30k would be pretty good for me (about 5 years   ).

Hapens in all engines. Imagine perfectly sealing valves and worn rings now all that new found preasure is forced down on rings that are already loose and rounding a bit on the sealing edge.

you got it increased wear on old parts. by the 60s the engineers had figured out the wear together for longer life formula.

now on to the valves. Zuks burn valves, 8v usually on #2&3 exhaust but it is comon in all Cylinders. 16v heads are better but still eat one now and then. I have a freind who is a tech and he warned me when I started buying Zuks. Of the first 4 I owned 3 had to have head work done. exhaust valves every time

Thanks
Wayne

Well, I pulled the head and the #4 intake was toast.  Two spots were melted away (I'de guess one 10-15 degrees and the other about 5 degrees).  It's a mess.  I'll have to post a pic when I get my camera back.  The seat looked pretty good.  I replaced the exhaust valve too because it looked a little rough.  #3 intake looks like it may need replacing too.  I'll probably do that tomorrow.  I guess I should replace the valve stem seals, but I couldn't get those stupid rocker bar screws out   I got them off of the spare head by drilling about 5 of the screws out, but I don't want to take any chances on this head.  I can remove the springs and the valves without removing the rocker, so maybe I'll see if I can replace the seals too.  I don't think there' s any great seal leaks, but it seems silly not to replace them while the head is on the bench.

I picked up a new water pump and some gaskets I was missing.  I still haven't taken the front crank seal off, but as soon as I get that off and get the #3 intake valve replaced, and maybe the valve stem seals replaced, I'll start putting it all back together.  I'll be impressed if this thing runs when I'm finished with it  

Oh, no holes in the pistons, so that was good news.

The rocker arm caps don't normally
need to come off, to get the stem
seals out you need to remove the cam,
loosten the rocker arm adjuster screws
first, pull the cam out from the distributor
drive side, now flip the rocker arms up
and out of the  way, compress the valve
springs (can be a PITA) and get the keepers
out and get the valve spring and retainer
off and pull the seals, install carefully so
you don't damage the new ones, replace
the burned valves and reinstall the springs,
retainers and keepers.

Good Luck,
Wild