Heads

I have some replacement heads out of a junkyard. I am wanting to repair this vehicle as cheaply as possible. The heads are rough looking, rust inside the valve and everything. I will say that I filled up the intake ports with cleaner and it held overnight. (Paint thinner).

Someone told me if I take the valves out to clean everything, It might not seal right when I put it back togther, and I could have a miss or check engine light.

My origional intention was to take it apart to clean it and to lap the valves. (And install new valve guides that came with my kit).

The guy at the salvage yard said they came off a motor with a lower end knock. The heads were checked for flatness and are within .001. They were taken off the motor a day or so before we got them.

I need to get this thign going cheaply. I am going to get rid of it. SHould I leave the heads alone and just mount on the truck or take apart, lap the valves, etc?

I know the "ideal" thing to do would be a valve job, tanked, etc, but around her eit is alot of money and I plan to get rid of it.

Thanks for any advice!

Reply to
stryped
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Remind me not to buy a truck from you! ;p

Reply to
Hachiroku $B%O%A%m%/(B

People will tell you anything in the world. Especially people who dont know too much but have "always heard" to do this or that.

If you want to do this, take the valves out one set at the time, wire brush them if necessary, lap them, and reinstall with new seals. Keep everything as clean as you possibly can.

If you just lap them, you should not even have to ship the springs back to specificied height.

If you did not have the heads checked for cracks, look closely by eye using a good light. Look for discolorations at odd places.

Work slowly and deliberately. Do try to "get finished".. Try to do the best job you can.

Then slap them back on and start putting this puppy back together.

Reply to
HLS

What do you mean by "ship the springs back to specified height?"

Reply to
stryped

What do you mean by "ship the springs back to specified height?"

Should have been "shim", not "ship".

Between the spring seat and the spring retainer, there is a specified distance. If you cut the valve seats very much, or the valve faces, this distance can increase. So, you just use a selection of shims to return each spring to its specified height. Thereby you assume that each spring has more or less the same compression before you start.

If you are building a better engine, you will have a valve spring tester, which will test the spring force at a certain height...a specified height.. You may select ideally matched springs from a drawerfull. Even then, you will shim the spring to the exact height that is specified for the engine with the spring installed.

If this sounds confusing, sorry. It really isnt. You just want to match the spring forces as much as possible, and installed spring height is one of the ways to approach this.

Reply to
HLS

But this is never an issue when just cleaning the head/valves and lapping them?

Or can lapping and wire wheeling the valves take off enough material to need to shim? My Hayes manual has a specification to measure spring height but says noting about shims. It said to use a machinist ruler that measures in 32nds.

Reply to
stryped

Have you checked the local shops to see what they want to recondition the heads? Last time I had heads done it was pretty cheap. You should at least check it out before you invest too much time. Though I ground the valves once myself of a bug engine using a reversible drill, and it worked well, valves are really supposed to be cut with a couple angles. Shops have the machinery to do this quickly, besides all the guide and spring work. I know you just want to dump this, but it just might not be worth the headaches doing it yourself.

--Vic

Reply to
Vic Smith

The best thing for you to do if the only problem is a lot of oily gunk may be to clean them the best you can with some sort of solvent. A few cans of brake cleaner may do the trick if they are not corroded on gasket surfaces. The gasket surfaces must be clean bare metal. This is also true of the block surface.

If may be worth the effort to replace the valve seals. You can do this one valve at a time to avoid getting them mixed up.

Unless you intend to "rebuild" the heads, do not replace the guides. That will almost guarantee that all of the valves and seats will require cutting and refacing to seal. If you want to just clean them up and then check for sealing, remove the valves and springs. Place each valve, spring and hardware on a board of some type with holes drilled to stick the valve into so you won't get them mixed up. Clean them one at a time being careful to put them back exactly where they came from. Unless you find a broken spring, don't worry about spring heights. After everything is cleaned up, put the valves back exactly where they were using exactly the same springs and hardware including collets. Recheck for sealing and keep your fingers crossed. If a valve leaks with a liquid, it is guaranteed to leak cylinder gases. A light lapping with a fine compound may do the trick. It sounds as if you may not be extensively experienced with this type thing. Make sure you get all the collets in securely and, if possible, get a friend or someone who knows a bit more than you can get on usenet to give your work a lookover. Lastly, make sure you stand behind your truck - not in front of it!

Lugnut

Reply to
lugnut

My Hayes manual has a specification to measure spring height but says noting about shims. It said to use a machinist ruler that measures in 32nds.

Would be foolish to measure something if there were no use for the measurement.

Lapping usually does not take off enough metal to make a real difference...But measuring and adjusting is easy enough to do.

Also, in the real world OEM springs can vary, regardless of their installed height. To build a stage higher engine, you would probably buy a matched set of high performance aftermarket valve springs, or you would test every one of them, and at least set the installed height to a figure which would give you equivalent valve spring compression on each cylinder.

In the real world, for your kind of engine, measure them just to be sure nothing is crazy, and re-assemble if the assembled heights are in line.

Reply to
HLS

In all my years of fiddling with race cars and family cars, I have never seen the need to replace a valve guide.

I would venture to say that most guides are not replaceable at all. If the guides (integral with the head) are worn, you ream them out to size and fit valves with oversize stems....OR you knurl, in some cases.

You can drill out the guides, tap, and screw in bronze guides if you are a glutton for punishment.

Maybe I have led a sheltered life, but unless the valve stem bores are worn rather severely, nobody takes the time and money to recondition them.

Reply to
HLS

No aluminum head has integral guides and there are quite a few iron heads that use press in guides.

Reply to
Steve W.

I had some Fiat aluminum heads with press in guides.. One of them was cracked, but the machine shop said it was not even necessary to replace it..

Most of the iron heads I have seen do not have press in guides. But, that is just my experience.

Reply to
HLS

I've seen a bunch of worn ones. If you can move the valve stem in any direction other than up/down in the guide it's worn. How you repair it depends on how long you want it to last and what you want to spend. Knurling is OK if it's something like a claimer engine or if you don't want to spend a bunch of money.

The big thing is that any guide work should be followed by cutting the seats to match the centerline of the guides.

Reply to
Steve W.

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