Hey there.

So I posted prior about an issue with my spark plug on Cylinder 2 being too deep and not removable. I've tried everything at this point and it's leaving me with one final option: New Cylinder head.

My question is, since the 4.3L was used in a veritable fleet of GM cars and trucks, is there any particular limitations I should know about if I go the cheapest option of grabbing a Junkyard head?

For reference, this would be the passenger side of the engine. Vehicle is a 1997 Model Year Blazer.

Thanks.

 

I think the '97 year still had the EGR valve; but I do not know if later year 4.3L heads still had this passage in them or they were blocked-off. Do not know of any other differences.

I remember reading about the problem you had with #2 plug...what I do not remember is if the plug was broken-off...almost has to be. I remember someone asking if the heat shield was in the way....was it? I know when I did the plugs on my '02 a month ago, I had a problem with the heat shield on #2....and I had the inner fender liner removed....completely open....but still had some problem getting the socket onto #2.

 

They did change in later years, but I'm unsure of what year.

Later ones adapted roller rockers instead of the pivot ***** that the earlier ones used.

Top photo is from a google search from a 97 4.3, bottom picture is of my 04 when I did the valve cover gaskets.

 

I think I've determined the ultimate issue with the spark plug. That particular plug had to be re-threaded, as the Previous Owner had crossthreaded the old plug that was originally there. I performed this operation myself using a kit from Advance Auto, but I went in at a bad angle. All the other spark plugs in the engine are angled down slightly to account for the counterboring on the head. when I was re-threading this, I must have gone in at a bad angle, as this plug sticks out straight from the engine, rather than angled downward.

As for if the plug is broken, the ceramic part has seperated from the metal cradle, but remains in the engine. It spins freely and wiggles about, which I think is what causes the misfire. But I can't get a socket in due to the lack of enough gap between the counterbore lip and the hex nut.

I see. So my best bet is to stay like and make sure it's a ball pivot instead of rollers.

Now stupid question, but I recall seeing videos of engine rebuilds and teardowns where they mention the pushrods for the valves and needing to make sure they remain matched with the cylinder in question. If I were to get a junkyard head that was in serviceable condition, would I want to reuse the pushrods from the engine in the blazer, or grab the ones from the engine the head comes from?

 

Honestly I don't think it should matter... I would say just go with the cleaner ones lol. You're not trying to build a high horse power finely tuned engine, so it shouldn't be an issue.

Keeping them in order and reinstalling them the way they came out is "ideal" sure, but it's not going to make or break things.

But if you are concerned about it though, it's easy enough to just remove and reuse your original rocker arms as well as your original push rods, keeping them in order during the process. If you're installing a new head you should readjust the valve lash anyhow, so you'd have to do that either way.

 

Just a word of caution:

I would definitively try to source the exact same heads. At least from the same year and engine type.
Putting a different cylinder head on an engine is a trial and error experiment lest putting on just one.
Can cause all sorts of problems when using a different head and then only one.

Apart from mounting holes and threads you could run into detonation problems or valvetrain trouble by using "any" head.

Finally I would always change both heads.

 

This is a very good point after I looked up stuff on Valve lash. However, I'm not finding consistent info on what the stock valve lash for the 4.3L in these is. Any ideas?

 

Valve lash setting will be different between the 'ole stamped steel pivot ball rockers and the fulcrum rockers. What are you finding to be inconsistent?

blazen: are you sure those rockers are factory?

 

I'm not finding specific numbers when I search. Instead I'm finding claims that the lash is auto set, which I find... Hard to believe. I know mine are pivot ball from having done the valve cover gasket before.

 

Yes sir. GM part number 12555580