Valve Guidance

[Tony Marc]

Ok….Looking for some ideas / suggestions on this.

I picked up a AMC 258 i6 / 4.2l that was out of an 86 CJ. When I picked it up it was already out of the vehicle so there was not chance to actually hear it run.

I got it home and cleaned up the out side a bit. It was an oily mess for sure.

One thing led to the next and I wound up taking off the intake and exhaust manifold. BTW its on a stand and not in the vehicle.

After taking a closer look at the exhaust ports of the head…. I could see all kinds of gunk on top of the exhaust valves (see pics). It actually looked like paint that burnt and flaked off.
Supposedly the motor had about 90k on it.. Allegedly that is.

So my options are…

• Forget that I even saw it and put it all back together and hope for the best?
• Dig deeper and take the head off and do some “home grown” valve clean up and lapping?
• Take the head off and bring it to a machine shop and let them have at it? New valves, springs, etc?
• Grab a 4.0l head off Ebay that is ready to go and put that on…and eat PB&J sandwiches for a month cause that all I could afford?

So I’m just looking for suggestions… ideas…. Or anything….. It all started with committing to changing the timing chain and gear set…then the oil pump sounded like a good idea too…. Might as well hit the W/P as well…. No I’m facing tearing it down to a short block.

I do have the basic know how… and a decent set of tools…..

I’m trying to keep the costs down as much as possible… and this is looking to turn into a lot more than I originally though…..

So please … any suggestions would be helpful….

Thanks,

 

[gert]

The first 2 look pretty bad looks like water got down the intake. The first thing that I would do is to make sure it spins over. It would be really nice to do a compression check on it but you need a flywheel, starter and bell housing for that. Me Im the guy that would be dropping the hed off at the machine shop and checking the bore s for wear and bearings but that will be your call, the further you dig the more you spend

 

[mtnwhlr]

I agree with gert it looks like rust but then it might just be the pic but if the head looks that bad it would make me wonder about the rest of the motor. If you put a new head on a old motor it will just start sucking oil up past the rings. I would pull the head and check how muck wear there is in the cylinder walls. You can tell by the size of the lip at the top keep in mind when it was new ther wasn't any.

 

[Torxhead]

Lots of opinions here,thanks for sending in those pics, all I see is a little carbon build up. This can be removed by adding an additive to the fuel like a can of BG44K or a lesser expensive Techron. The gas companies say that their additives keep valves clean, but it doesn't seeem so. I think the deposits are from oil coming down out of hot and tired valve stem seals. Also a quick way to do it would be to use a can of Sea Foam, just follow directions or watch it being used on YouTube. Putting that exaust manifold back on can be a real bear also since they warp, so good luck with that.

 

[tarry99]

Ok….Looking for some ideas / suggestions on this.

I picked up a AMC 258 i6 / 4.2l that was out of an 86 CJ. When I picked it up it was already out of the vehicle so there was not chance to actually hear it run.

I got it home and cleaned up the out side a bit. It was an oily mess for sure.

One thing led to the next and I wound up taking off the intake and exhaust manifold. BTW its on a stand and not in the vehicle.

After taking a closer look at the exhaust ports of the head…. I could see all kinds of gunk on top of the exhaust valves (see pics). It actually looked like paint that burnt and flaked off.
Supposedly the motor had about 90k on it.. Allegedly that is.

So my options are…

• Forget that I even saw it and put it all back together and hope for the best?
• Dig deeper and take the head off and do some “home grown” valve clean up and lapping?
• Take the head off and bring it to a machine shop and let them have at it? New valves, springs, etc?
• Grab a 4.0l head off Ebay that is ready to go and put that on…and eat PB&J sandwiches for a month cause that all I could afford?

So I’m just looking for suggestions… ideas…. Or anything….. It all started with committing to changing the timing chain and gear set…then the oil pump sounded like a good idea too…. Might as well hit the W/P as well…. No I’m facing tearing it down to a short block.

I do have the basic know how… and a decent set of tools…..

I’m trying to keep the costs down as much as possible… and this is looking to turn into a lot more than I originally though…..

So please … any suggestions would be helpful….

Thanks,

Tony,
Options & Opinions ...................You think it had 90k miles on it and it looks like it did or even more........that is just carbon on the top of the exhaust valves.
I guess my first question is what's wrong with your old motor? Using anything off that used motor is at best a short term band-aid..............

At that stage in its life it needs a valve job maybe guides & springs, and maybe Piston's and rings notwithstanding grinding the crank. .....Obviously someone took it out for a reason?

Not sure what your hoping to gain?

 

[jasonmark1993]

Im with Tarry. Unless your engine is blown up, its probably safer to run it than installing that one you have there.

Looks like normal carbon/oil build up with some rust on everything else. Might pop the valve cover and look in there.

 

[Tony Marc]

tarry99- As for the old motor... it had a distinct knock, 158k on the clock, and for the most part, it was just plain evil towards me. From manifold bolts getting stripped out from the head to the EGR tube being rusted to the exhaust manifold. I was done with that motor.

Of course... I had all the hopes and aspirations of dropping in a Ford 5.0l... well I was given a short block 5.0... I sold the original AMC 258 i6 / 4.2l to help fund my 5.0l conversion.

I picked up some heads and went off to the machine shop to have it checked and freshened up. I paid nothing for the short block so I figured I was ahead of the game. So the machine shop guy calls me to come down so we can go over everything. After a few mins of small talk he tellms me "this needs to be cut, this needs to be ground, I would do this... and I would suggest that...." I asked him ... ok what is the bottom line that this is going to cost me.... just to get it to near stock 5.0L form..... " about $2,400 and I would need half to start"... I told him I'll check back with him is a week.... Needless to say i have no intention of picking up the block.. He probably would have charged me $200 just for storage on it.

After a long mental break down... and several arguments with my insignificant other….. and the thought that I’d have to spend $200 for motor mounts… an adapter for the Dana 300 to the NP435 for $500…. I soon realized the V8 was not in the near future.

Enter the AMC 258 i6 / 4.2l that I posted the pictures of....

My thought is this…. I’m going through with the timing chain and water pump and all associated gaskets (intake / exhaust, oil pan, valve cover, etc). I’ll drop it in and see what happens…..

If it runs… it will be a celebration….

If not….. well…. I’m not sure…. Time for a fire sale on Craigslist.

Besides … I get the taste of agita every time I hear…. “You got to get that thing out of the driveway….” (meaning the CJ7 under a silver tarp).

I guess my CJ7 taking up too much room for her precious Benz…..

Go figure….

Thanks to all the comments... I'll let you know if its Miller time.... or time to bring the marshmellows to the fire!!!!!!

 

[jasonmark1993]

Trade the wife for new Jeep parts......j/k....not really

How much did you pay for the AMC 258 i6 / 4.2l ?

Seems like one thing we all do when working on our old rides is spend a bunch of money on what we arent going to be happy with anyways. Trying to save money usually backfires; unless you get a deal from someone you trust and know what youre getting. I'm afraid you'll spend a bunch of time and money and its possible that one might knock too. Or maybe not, like you said you can give it a shot.

If we were closer I've got a running AMC 304 Id give you for a couple hundred bucks.

No matter what you do its gonna cost some coin and time so prepare yourself and wife.

 

[jeepboy45]

Tony...
Normally I say, do it right the first time....

However, with wifey on your butt, I gotta ask: If you decide to spend lots of $$ on this, how long is it gonna take you to get it running? If your Jeep is just going to sit for 9 months while you save money, why not take a chance and drop the AMC 258 i6 / 4.2l in and see what happens? All you've lost is the time to install it, right?

If it runs decently, (probably better than the one you took out), you'll be content for now.

I had a AMC 304 that I swore I wouldnt throw another dollar into. I was DONE. Friends kept pushing me to rebuild (again). Instead I found a 360 with 170K miles on it and dropped it in. (At the time I thought it had 120K on it) It ran decently for about 2-3 years. Until it gave up and I took it off life-support. But at least I gained a few years of driving my Jeep. By that time, I accumulated some parts to put towards my new 360 and now I am happy.

A AMC 258 i6 / 4.2l is awesome and worth building, but I'd say take a shot and see how it runs. If it runs lousy, then decide from there. Pull it and build it, or drive it till it pukes. Who knows, in the mean time something might come along you can build up.

 

[Tony Marc]

So I did a bit more digging on this so called 90K AMC 258 i6 / 4.2l that I bought. I took some pics and i really am scratching my head…..

I took off the front cover to take a peek at the timing chain…. It was pretty darn loose to say the least. Now I did some searching…. By the way the Chilton book I have is about as useless as a toilet with no water….. It doe not tell you jack squat about reinstalling the timing set on a AMC 258 i6 / 4.2l . It give some detail about the 4cycl and the AMC 304 V8. Anyway…. Here’s my dilemma…

1st I tried to find TDC on #1 cylinder by holding my finger in the spark plug hole and turning the crank. I can hear hissing and stuff… but I never get any type of “forceful” air pushing out against my finger. Maybe I’m cranking it too slow? Kind of hard to do both by yourself. My neighbors must look at me and shake their head. So the TDC is baffling me….

My other concern is the timing chain marks and their relationship to the distributor (sorry… I just can’t bring myself to refer to a distributor as a “dizzy”… just a personal preference…). The service manual in the “docs section” says nothing about bringing #1 to TDC. If I read it correctly… it says to line up the marks…take the cam gear, crank gear, and chain off. Then put the new timing set on making sure the marks line up…. Rotate the engine I full revolution and then look at the marks and count the pins.. 15 I think is the magic number…. So do I even need to figure out where TDC for #1 is or do I just make sure the marks are lined up?

Also is it necessary to have a tool to push the timing cover seal into place? I don’t mind picking up a kit to do this… I’m just wondering if it is one of those “its nice to have… but not absolutely needed” tools. I also saw something on NAPA’”s site called a “sleeve and seal” kit. I guess this is like a cap that goes over the crank to take up the wear from the old seal??? Well .. I attached a pic of my crank…it looks like its worn pretty good….. Any thoughts? Do I just yank the head and really see the disaster... or do I bang head against a hard object?

I’m also attaching some pics of the head and the rockers………I did zero cleaning on the rockers…. What you see is how it was when I took off the valve cover.

The water pump area looks pretty gnarly too….

Well.. my big thing is the timing set….. Align the marks and go to town? Or do I need to find TDC? I whish I had one of those old school whistles that would thread into the head. When you rotate the engine… you would hear the whistle when that cylinder went into its compression stroke…..

 

[mtnwhlr]

You do need to find top dead center. With the valve cover off it is pretty easy to find top dead center both valves will be closed whan it is 180 out one will be open. So rotate it until the timming mark hits 0 and look at your valves if both are closed you are there. And the chain does have to much slack thats why it has been rubbing on the cover. To put the seal in the cover you just need a piece of wood that will cover it and tap it in. I hope this helps.