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TR2/3/3A Rebuilding a cylinder head

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sp53

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Rebuilding a cylinder head. I am working on a head that I bought off Craigslist many years ago and have had it under my work bench since. The guy was cool, and said he had the head checked for cracks at a shop and I think he said new valve guides. He only charged me 50.00 bucks.

I took some pictures to see if people thought the valve guides look new. Can I get some opinions of the conditions of the guides by these pictures or would a different angle of picture be better? I have never rebuilt a head before so any ideas are very welcome

Thanks steve
 

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+1...you can't tell anything by just looking at the guides. Place a new valve in a clean guide and check for rock in the same plane as the rocker arm. Iron guides can be as little as .0025 rock...bronze guides (which yours are not), have to be closer to .005" rock. Of course, repeat with every guide to be sure. Also, I would emphasize "clean" guide, as it looks like the head was sand blasted, and every last spec of sand must be removed from the guides!
 
When I have a head to put together, it always goes to a machine shop for crack check, flatness check, guide assessment and valve grind.
Bob
 
My favorite trick is to install new guides then have them knurled to make up for stem wear.
It acts like an oil seal and greatly reduces oil consumption .Assuming the old valves are
in good kit of course.
Mad dog
 
I tried a couple of my old valves from different heads. The valves are a looser than .0025 which is 1/400 of an inch. My measuring skills stop at about 1/64 because I am old carpenter. I could probably deal with .025 which is a 1/40 of an inch. I wanted to do this work at home and thought perhaps if I get some new intake valves and guides I can feel the amount of play and then get a feel for it.

Looking at prices I should get some new 5/16 intake valves and see how the fit in the head. The exhaust valve guides in the head are the larger 3/8 and more money.

The last time I had a head rebuilt it was $$$$. The shop used 5/16 guides and valves for intake and exhaust. They also did away with the 3rd spring on the exhaust-- plus-- put in some seats which I still cannot still wrap my mind around. How can you put a new steal ring into cast iron?

Anyways, whoever cleaned the head from carbon did a poor job there are little piles of carbon everywhere. Can I take a ½ drill and wirer wheel and clean the area in the combustion chamber where the valves sit down in that bevel seat? I do not want to damage anything and do not know how aggressive I can be cleaning. Any ideas welcome and thanks guys.

Steve
 
.0025 is about enough that you can feel there is looseness, but you cannot hear any clicking as you wiggle. At .005" you start to hear the valve click as you wiggle it back and forth...not a scientific check, but a quick one to use at a swap meet for head condition. Installing seats amazes me too. In cast iron it is an easy machine shop job that rarely goes wrong. Because aluminum expands more than steel, installing steel seats in an aluminum head can cause serious trouble if the machine shop screws it up!
 
I know it is that knurling the new guides to account for the .0025 is not completely
Kosher , but when the engine burns less than a Qt every 1500miles because of this
acting as a seal, I am all in. Try it!
Seats only on the exhausts, as the run hotter. intakes dont need it.
Mad dog
 
It seems to me the difficult part with rebuilding a head is getting the valve guides in place. How would a DYI person do something like that? The rest of the rebuilding looks like work with grit gridding compounds on the edge of the seat and valve. I do not how long something like that should take, but the area looks small. They used to charge 35.00 bucks when I was a kid and it did not look like rocket science at least now it does not.

I do not know anything about valve knurling MD. I always like to hear about a plan MD. I can always pay to have it done by an expert, well if I have resources and can find an expert. Anyways I enjoy leaning about different ways to do stuff.

Steve
 
Knurling was a way to displace the metal inside the guide to extend the life of a worn valve guide. You insert a tool that rolls around the inside of the guide, making metal burr edges that stick up. Then, you come back with a hone and bring the edges back down to the desired clearance. Since there is less material actually touching the valve stem, a knurled guide will wear faster than a new guide.

The guides are actually pretty easy to change. I made a tool from an old valve stem, and welded a steel sleeve to it. I then knock out the old guides using a BFH. I then use the same sleeve to drive in the new guides. The valve seats take more expensive tooling. They place a mandrel in the new guide and either cut or grind the new 3 angle seat, so it is perfectly concentric with the guide centerline.

Lapping with compound is used after a new valve job to ensure the valve makes an air-tight seal when closed. It should not take much on a new valve job. Lapping can also be used on a valve that has some miles on it, but is a little rough at the seat...a "poor man's" valve job.
 
Think of knurling like rifling the barrel of a gun. Tiny ridges of metal in a spiral , tighten the clearances
and capture oil in the guide instead of letting it slip past to be burned. Motors I have built this way burn a lot
less oil than new valves & guides.The plus is saving slightly worn valves that have lots of life left in them.
New guides are dirt cheap.
Mad dog
 
We have been on a Cruise and I lost my mind. I am trying to get back into my project car for therapy. I started taking the valve guides out with a small slug hammer. I was able to get the intake valve guides out pretty easily, but the exhaust valves are a different story. I think they are moving a little, so I wd40 them for the night. In addition, the guides seem to be breaking into pieces at the top. Should I be concerned about taking them out in pieces, so not to damage the casing? Moreover, I need to make a different removal tool because the diameter of the hole in the exhaust guide is bigger and my homemade tool does not fit. Anyone have a suggestion on what homemade tool works well for this application.

Thanks Steve
 

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I used old valve stems and I welded tubing...or even old guides onto the stem and turned slightly smaller than the hole it is going into. They take a lot of beating, as you have seen, so it may take a couple to do the hole job.
 
Wd40 is NOT a lubricant, stands for" water displacement 40"
Warm up the head and freeze the new guides. Dont burn your hands! It is critical that the guides are
all set at the correct height. You can save a lot of trouble by having the machine shop do it
when the do the rest of the job, the proper tools make the job easy/not expensive.
Mad dog
 
Thanks guys, yesterday I found a brass 4 inch bolt that slides in the hole just right; today I plan on hitting into the guide and then get back. MD I love WD40 I would put in on my cereal. This probably only happens when I use WD40, but I find it dissolves tar and grime, melts glue of the back of tape fast, removes tree pitch off paint without harming the paint quickly and comes off metal easily with Lacquer thinner oh, and it repels water.

I like to do what I can on these cars and consider it therapy and a gym work out. Right now, I am resting my back from mowing the lawn and pounding the crap out of the cylinder head.

MD why is it critical to install the valve guides’ the same height? What do you think would be a could a proper place for them in the head? I mean I do not know, and it sounds right to have the guides the same and I would have probably done it that way, but I would not have known where to stop with the installation. Now I am thinking the exhaust valves seem to need more care than the intake. What do you think?

John thanks for chiming in--- I am over my head again with this cylinder head rebuilding, but I figure between you guys and others I should be able to pull it together after I get it apart.

Steve
 
To borrow one of Randall Young's observations, heated metal expands equally in all directions. Thus heat will make a hole in a mass of metal smaller unless the volume of the hole is greater than the volume of surrounding metal which is being heated.
Bob
 
I think a hole in metal will get larger when heated as will every other dimension.
But I have been wrong before.
Tom
 
Do cylinder bores expand with heat?
I think every dimension,even holes get bigger.But again I have been wrong before and am willing to learn.
Tom
 
I would think some metals expand easier depending on type, size, and thickness at least. Seems to me heating the exhaust valve and then let the valve cool would separate the guide from the casting. I will try that later when I go to pound on the bolt.

steve
 
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