I tried using this cam type spring compressor. Two large handles and you'd swing the other one down and it would compress the spring real "easy" and you'd be done. Well, the first one broke on the 2nd spring, and the second one never worked at all.

I decided to suck it up and buy this bad boy. Not very comfortable to use... but it worked and didnt feel like it was about to snap.


But anyway, back to what I was really wanting to know... Are these back cut valves? I wouldnt know if they were or not and was wondering if I could get some verification on that. If they are then I'll try to reuse them instead of buying a new set of assembled heads.

I dont know if all valves look like that, or whether that's a clue that they are backcut or not.

I'd ask the guy I bought the (broken) heads from, but he's hard to get in touch with.

Secondly, what do you guys know about these valve seals? Are they worth using? Are they worth reusing? I dont know what they are exactly. Are these "nylon seals"?


Just trying to figure out if I should buy bare heads or assembled ones... but since the valves appear to have a little work into them, I'm going to have to see what size they are (I dont have a caliper to measure), but if they're 2.02/1.60, I may as well buy some bare heads to fit 'em and save the moeny on all the hardware.

Only problem I've got now is that I have no idea how to lap valves... where do you get valve lapping compound?

 

It's tough to tell from the photos, but the valves don't appear to have
any work to the seat area, or a back-cut.

Could you take a photo of the valve close up, as well as the valve seats?

Don't reuse valve seals. They are inexpensive and you would be better off
with having a positive oil seal.

One thing to note if you're going to re-use the valves. Don't mix up their
position in the casting. The guide to valve clearance is very important!

 

Well they're going to a whole new set of cylinder heads... Does it still matter?

 

No, sorry. I was under the impression you might use the current castings
again.

You'll have to check the valve to guide clearance in the new heads however.

 

What exactly is valve to guide clearance, and how is it checked? I was hoping to learn to do as much of this as I could myself.

Here are some better shots of the valves. Even if they're plain jane valves, I'm not sure I wouldnt' be better off financially to reuse them anyway. But if I've got to pay a machine shop to put it together then the price difference between buying bare heads and assembled heads starts to disappear.







Sorry tehy're so big, I didnt want to shrink them and lose some detail.

The only reason I was asking about reusing any of these parts is because they were only ran for about 30 seconds or so. For all intents and purposes, they're all brand new. The heads had some serious water leaks (porting mishaps passed on to me from the seller.) in the exhaust ports that we found pretty quickly after initial start up, which was the extent of their use.

 

Valve to guide clearance is the required amount of distance between the
valve stem and the valve guide.

The average depending on the valve material and guide material is 0.0012-0.0015". It's not easy to check without precision tools. The tool would
need to be capable of a 10th of a thousandth of an inch.

If they are brand new, I wouldn't worry too much. I didn't realize they had
only 30 seconds of run time. You might want to have a shop measure a couple
just for peace of mind. They wouldn't charge you if you happened to buy seals,
or other parts from them (at least they shouldn't charge you!).

The valves are not backcut. I don't see any angles to suggest valve work.

 

I agree; no back cut; which would look like another angle behind the seat, toward the stem. Those look like straight out of the box, lapped, and that's it. They look kind of like Eaton to me. Decent street performance valves, not really "racing", probably OK for the application at hand.

They are however, "undercut" slightly, which is sort of "necked down" where the stem meets the head. Helps improve flow both by just being smaller, and by aiding the flow in the right direction down the stem and outwards toward the seat (or upwards and inwards, in the case of the exhausts).

As said, don't even think about re-using valve guide seals.

The ones you have there are the best you can get, they're Teflon. They get scratched, distorted, and otherwise damaged too easily. They're cheap, regardless; maybe $20-25 a set. http://store.summitracing.com/partde...CCA%2D503%2D16 Other mfrs also supply them. They come in a couple of sizes, for different valve guide OD and valve stem diameter; measure your guides, they should be either .500" or .530" OD, and just buy the right ones to fit. When you go to put them on, make sure to take a piece of about 400 grit sandpaper with a drop of ATF or something, and very lightly bust off any kind of a burr that might have got thrown up around the keeper groove on the valves. Just a minor scratch from that during installation ruins them. Which is also why they're not good to re-use.

 

So is putting all these parts into a new set of heads something I'll be completely unable to do with my lack of "valve-guide clearance measurement" tools?

It'll be a brand new set of RHS vortecs... Shouldnt it be fine out of the box?

Also, I forgot to add a picture of the valve seats. Not sure whether you need em anymore, but I was taking pictures of the cause of my cylinder head woes... these welds. Buying used, sometimes you get burned I guess.

 

The heads "Should be fine", but even the castings are suspect to core shift,
variances, etc. There's probably not much need to worry about the heads,
although even a good name brand will need minor dressing (like taking off
any sharp edges from the combustion chamber, casting flash, etc.).

It's the valves that I'd be concerned about. Sure they've only been used
for 30 seconds, however you've revealed issues with the heads in which
they were sold with.

I'd rather take a couple of valves (at least one exhaust and one intake)
to a head shop and have them measure the stems, than throw them all
in a new set of heads and end up with valves binding, or flopping around.

 

Oh... well that's not a big deal then. I was thinking they'd need to assemble the heads to check that.

Is this clearance basically the thickness of the valve stem, basically how much the stem has worn out through normal use? Sorta like the valve guides and stems wear into each other kind of like cams and lifters?

 

It's the difference in size between the valve stem, and the guide or liner...

IIRC those heads have bronze guides, so probably no liners.

The sizes are "standardized", so to speak; in theory, you should be able to take any new set of heads that the guides were either made the right size or reamed to the right size after installation, and any new set of vlaves, and get the right clearance. Theory and fact, though, have ways of not matching.

You can put a valve in the guide and just rock it from side to side yourself, and get a pretty good idea of what the clearance is. Put a drop of 2-stroke oil on it for lube. Obviously it should slide through easily. You want it to just barely detectably be able to rock from side to side; if you have a dial indicator, you'd want to see maybe .002-.004" or so of motion at the head of the intake valve (.001" - .002" of clearance more or less), and a little more that that at the exhaust. If the valve binds, or if an intake can move more than .006" or so or an exhaust more than about .010", then it's a no-go. Keep in mind that exhaust valves especially get HOT, much hotter than the castings, and so, "grow" in there; so ideally you'd want to see the intakes toward the low end of the acceptable clearance range, and the exhausts towrad the high side. In fact I wouldn't hesitate to run exhausts at near .004", if the valves and guides are new.

What you're doing here, is taking the valves out of those Vortec heads you had that were ported to the point of scrap, and buying a set of bare castings and moving all the hardware over, right?

Do you know the correct installed height spec for the springs you're using?

I would strongly suggest getting a spring mic like this and a set of shims like this in the correct diameter for your springs; and makign sure you leave no opportunity for disaster lurking there.

 

I know what the pressures of the springs were at the installed height they were at before. It came out to be the same as the 981 springs at the taller installed height they were at. Not sure if the taller height was due to the machinework on the heads or something to do with the retainers or even if the valves were taller than normal. I just dont know yet.

The RHS heads aren't machined for guideplates anyway, so I figure when I bring those in I'll bring one of my old junk heads up there for them to compare and get them machined for guideplates and get the same installed spring height as before.

 

Don't bet on it....

You're going from stock heads with known high spring pockets, to aftermarket heads. Don't be the LEAST BIT surprised to find that the spring pocket is as much as .100" LOWER on these heads, than on the stockers. IOW, EXPECT the installed height to be different, because it almost certainly will be; particularly, it is likely to be higher.

There is NO SUBSTITUTE for measuring!!!! Any form of "guessing", "estimating", "assuming", "figuring", etc. is flirting with disaster. There's only a limited amount of tolerance there; too much installed height and you'll be shy of seat pressure (valve float is the inevitable result), too little and you risk having things crash into each other (parts breakage).

When you saywhat do you mean? Do they have pull-out studs, or what?

 

I do know that the springs I have installed now are installed at a taller installed height than what Comp recommended for their 981 springs that are matched to my cam. Can't remember exactly what that height was, though, might have been 1.8?


As far as being machined for guideplates, this is what RHS' spec sheet on these heads says:

And from a customer service guy at the website where I was going to buy the RHS heads:

Im guessing something to do with the stud perches?

 

It really doesn't matter so much what relationship the springs you have, have to 981s.

What matters, is the distance between the keeper groove on the valve, and the bottom of the spring pocket on the head casting.

A VERY long list of things affects that. Most of all, most aftermarket heads are designed right off the bat, with more space there than stock ones, to accomodate taller springs (taller = more lift).

There is absolutely no guarantee whatsoever that the bottom of the spring pocket is at the same place in these heads, with respect to the keeper grooves, that it was in on your other ones. In fact it is NEAR CERTAIN that it will be different. That distance IS your installed height. If it's different, then installed height will be different. If installed height is different, then you'll need to measure it and find out what it is, and add or remove shims (most likely, add) to bring it back to where it needs to be.

You'll need to either remember what the IH was before or ask whoever set the heads up so you can duplicate that IH on your new heads, or get the specs for whatever springs they are so you can figure out what it needs to be, or measure the spring pressures and just set them up for a reasonable value of seat pressure and open pressure for whatever type of cam you have.

Sounds like the heads are machined for screw-in studs, but have the narrow slots to act as the push rod guides. There's no reason you just have to enlarge those slots out to holes (so they no longer act as guides) and add guide plates, unless you just want to for some reason. If your cam is less than .550" lift or so, and your spring pressures don't exceed 400 lbs or so, then the forces on the push rod will probably not be so great that the upgrade is really necessary.