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Discussion Starter · #1 ·
Hi all. I think the valve guide seals are seriously gone in my 68's big block. The engine was built in 1992, only has 10K miles, but it sat for a 2 year period. It has good compression, no intake leaks, plugs look nice, and it is extremely strong. But it belts out an embarrassing puff of smoke when I start it, and swills a quart of oil every 250 miles.

I don't want to leave it at a shop to be worked on, and I especially don't want someone else leaning over the award winning paint on the fenders. So, I am going to remove the heads so I can take them to a machine shop for seals, possible guides, and a general check out.

But first, will the heads even come off? Will the air conditioner evaporator box cause problems? Can I get the Hooker Super Comp headers out to clear some room? Will I be able to remove the distributor and get it back in the right orientation? Is this a dumb idea??? I have the tools and general mechanical aptitude, I've done the clutch in my Accord transaxle, 4x4 hubs and transfer case conversions, etc.

I would really appreciate some on-line help from you experts, even a post by post approach if anyone is willing to help and loosely follow along. I have drained 3 gallons of anti-freeze out, and I am ready to go. It looks like the carb and alternator are the next easies, but I want to know if the heads will actually come off with the engine still under the hood.

Whadda ya say, will you help?
 

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I've done this a couple times, the hardest part about doing it in the car is putting them back in. Just because it's awkward leaning over the quarters.

Just unbolt all the accessories, remove the intake and carb. Remove the rockers (make sure and label the rockers or something so you know which rocker came from which stud, and keep the pushrods and lockers together so you can put everything back the same way).

Unbolt the headers and pull them back away from the head. Unbolt the head and pull it off.

You may want to think about removing the hood, it's not necessary but will make it a lot easier and only takes a minute.

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Chris Dagenais
Saskatchewan
'71 Malibu with a home built 454!
"Hard work MAY pay of in the long run, but laziness pays off NOW"
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You sure you need to yank the heads? If it is just valve seals is possible to change those without taking off the head.
The guy I use when I am lazy or just get lost works on a lot of show and race cars. Never worry about anything getting trashed.
 

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I had a 350 engine and the oil rings had swelled up around the pistons and was consuming about 1 quart of oil every 100 miles and was fouling the plugs about ever 250 miles. Is the bottom end in good shape. Maybe your oil rings on your pistons have swell up.

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Michael Minery
Orange, California
1968 Malibu El Camino
<a href="http://www.angelfire.com/ca/mineryhomepage/1968elcamino.html">My 1968 El Camino!</a>
 

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Hey michaelem, copy this and use it in your signature:
My 1968 El Camino!

Aside from using shop air to hold the valves up while changing your valve seals.... If you don't have a compressor.....you can also use a length of cotton rope, just sfeed it into the sparkplug hole (leaving a piece hanging out) and rotate the crank until the piston contacts the rope, which contacts the valve and holds it up while you use the on-head valva spring compressor
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[This message has been edited by junglejimmie (edited 02-11-2001).]
 

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I agree with John. If you are sure it is the oil seals. There is a fitting that screws in the spark plug hole to allow an air hose to be connected. This puts pressure in the cyllinder to hold the valves closed while you remove the valve keepers and spring. That allows the new seal to go on. Of course if the guides are shot, the heads have to come off. I would try to find out what the real problem is before I did anything. Also, something to consider is pulling the engine.
It really will not take as long as you think. I have done heads both ways, and I really don't like laying over the fender for a day and a half.


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Dave
69 Chevelle
454 500+ HP
M21 4spd.

"Fire all your guns at once and
Explode into space."
Steppenwolf "Born to be Wild"
 

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Discussion Starter · #7 ·
I am making an assumption that it is the seals, hoping it's not the gudes. In 1991, did anyone make guides that would still need leaded gas? The previous owner said he never used a lead substitute, but the engine builder said he should have. When I very first got the car it had been sitting for a couple of years, and it didn't smoke. But within a couple of weeks, it started to smoking and burning oil. Any thoughts?

If the guides are shot, do the valves wobble around and wreck the seals? If so, how long does that take? We only drive it 1000 miles or so a year. Would new seals every couple of years be easier than pulling the heads off?

Will I be able to reach all the bolts to remove the heads with the AC evaporator in the way?
 

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I just took the heads of my 68 SS with A/C and it wasn't that bad. They did clear the evaporator but the head bolt in the rear corner by the evaporator wouldn't come all the way out. It did come out enough to remove the head though. Just remember to unbolt the transmission vacuum line on the back of the passenger side head if you have an automatic. I forgot about this and bent the line pretty good. I left my headers in because the only way to get them out is to take the motor out. They got in the way a little but nothing to worry about. I found it was easier to just remove the radiator and stand inside the engine compartment rather than hang over the fender and waste my back. Good luck, Jay.
 

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Puff of smoke when you start it; that's top end. This is purely a judgement call on your part. Even though this engine was rebuilt in 1992 and 10,000 ago, did the rebuilder pay close attention to the heads? A lot of people slap a set of rings and rod bearings in an engine and call it rebuilt. If the valve stem seals were even replaced, I'd see if they are still pliable, that is, not rock hard and brittle. If they're still soft, go ahead and pull the heads and have them done right.
 

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put a vacuum gage on it. if it has steady vacuum the guid's are fine, if the needle on the gave fluter's fast you have bad guid's. go from there..also since it sat for awile the seal's could have dried out and got hard a craked and have fallen off and are in the oil pan and head. if you have no seal's or they are hard and brital the vacuum gage will read like bad guids some time's.
 

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Do them in the car and be sure to use positive seals,the manufacture'er will tell you the guides need to be machined I have installed them without and no problems.Did an old 350 with 100k stopped using oil and ran another 100k...FRED

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First the leaded fuel was needed for the valve seats and not the valve guides, the recomendation to do a vacuum check is where you should start or go back and do if at all possible, ilbl8 is correct that if the valve guides are worn the needle on the gauge will fluctuate or bounce pretty erratically, this can commonly happen especially with 10,000 miles on a "cheap" head rebuild where the valve guides were "knurled" instead of being replaced, if the gauge is steady and smooth, the guides are good, and you may need to only change the valve guide seals, I'm a small block guy and have used "umbrella type" seals on many motors to help with this, maybe the right approach for you if they make em. my .02

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RicksRag
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