I have two sets of heads on my bench. the first are 493s which are 1971 smog heads off a 400. They do not have valve seals, I don't know if they ever did, but I think I am the first one to be in there since 71 to look. I measured lift potential and they appear to be able to handle a .550ish lift with just a spring change. On a set of newer 193's, swirl ports, the retainer hits the stock seal at about .480 and without the seal it hits at .600. I need .520 plus clearance on the intake and .535 plus clearance on the exhaust.
What are my options.
1. shave down the stock seals to fit lower?
2. different seals, what would they be?
3. leave them off?
if they didn'e use seals in 71, maybe I don't need them now.
sorry to sound like a newby, but I am

 

Besides throw them in the trash?

Use .050" offset keepers. Add .050" of shim under the springs.

 

Have the valve guides cut down to allow more lift.

 

Sofa
Sorry I called you Soda, I can't read either. Thanks for the idea, I did not know about offset keepers. I understand what you are getting at. Sure, all my heads belong in the trash, but it's what I got. I am not expecting to spin the motor over what a stock 700R4 shifts at, 5500 more or less. Therefore, I think they will do. and if they don't, I will look for a tow truck to use them on. When I can land a set of ARF's ---I am there.
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My 193's are totally stock virgin heads, except where I have been playing in one intake port. The guides have not been touched. There is .600 clearance between the keeper and the top of the guide, so I don't know why you would cut it down. Do you mean cut the land down that the seal sits on? That might work if I knew how to do it.

 

Just call / take it to a local machine shop that does heads. They have a cutter that cuts the top off of where the seal sets. However much clearence you need is how much to cut off. In your case .05 to .075 since you should have some extra space.

 

zipfast, every time I talk to my local machine shop the estimate for all the things I need quickly make a head like a 193 into a total loss. If I payed to have this done, and a valve job and a shave and a this and that, I would just be better off with new World or Dart SR or castings. What I am trying to do is get this 400 running, with somethin better than the smog heads. for a nickel. Because I really want a new crate engine with ARF eliminators, but it ain't happinin this year. I am looking for how I can do things in my own garage that don't cost anything. I don't know what keepers and shims cost, but that sounds managable. I am going to install 7/16 threaded studs, also, because I already own the roller tip rockers for this stud. My machine shop guys are not total jerks, they answer my questions and have loaned me tools. They are not open today, however.

 

Offset locks are about $25-$35 or so. A shim pack should be about $40, which should have Q=16 of .015", .030" and .045" I think. So you'd use a .045" shim. Or shim it up even higher to get more spring pressure.

Or you can always just hold your angle grinder to the top of your valve boss. Use a ruler across all guide bosses, and take it down until you can fit a 1/16" drill bit under the ruler (above the boss). Done, cost = $0. This isn't like a bearing clearance, it's not very picky about how perfect it is. This is "cut with axe"

 

Heads from 1971 never had positive-style seals on the top of the guides like later heads. They just used a metal shedder around the top of the valve spring and an 0-ring on the valve stem, captured by the retainer. Your 193 heads have the same thing PLUS a positive seal on the guide boss.

Either one, with a positive seal installed, will be down around .470" clearance.

And you want positive seals, if at all possible. The old o-ring and shedder arrangement was not great to begin with- it's just what they used becuase positive seal technology was not ready for prime time back then and the positive seals of that era would have worn out very quickly on the street.

The right way to do it is to cut the guides down for positive seals and adequate clearance and be done with it (ditch the o-ring and shedder arrangement completely on either head and just use positive seals).

 

Thanks for the input. I found a referance also to taking .050 off the bottom of the retainers, which would let me leave the intake guides alone. The exhaust side of my cam is a little higher lift, so I will need more off the exhaust guide, at least a little to have some clearance. I am going to the head shop tomorrow to get the seals , 7/16 rocker studs, tap and tap allignment block.