I get a puff when i start my car for about 5 seconds, but only after shes been sitting for a while. She "Roxy" now has 100k on her. I haven't done a compression test yet, but all my research has led me to believe the valve seals are causing it. Has anyone ever changed them with the heads still on, and using an air compressor to keep the valves up?? Is it as simple as screwing in the adapter piece and hooking it to the compressor, unbolting the rockers, springs, and away you go??

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I have the same problem and it is the valve seals. My mechanic said it was a waste of money to do a valve job to it. He said it won't hurt my performance as long as I run some of that fuel injection treatment to keep the carbon from building up in the walls of the combustion chamber and all over my valves.

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TPI 305,
Gutted airboxes,
gutted MAF,
K&N filters,
Corvette Servo.
14.9@93mph

"Speed kills, wanna live forever, drive a Ford."

 

Performance seems good, its just really annoying. You know goto have diner with your girl..start your shiny red car and puff
:-( I have the tools and can do this, just not sure if its going to be worth it. Theres always AFR's 190cc heads :-)

 

I changed my valve seals...very easy I used GM seal kit and just brought each clyn.to tdc that way you don't need air in the cyl. to keep the valves closed.Mine doesn't smoke at all now.

 

So if you bring each cylinder up to TDC the valves won't drop down too far to work on them???? Putting the springs back on won't be a pain in the rear will it?

 

You are gonna need a valve spring compressor,and some careful thinking about how valves work before you start.if you take the distributer cap off you can line the rotor up with each cylinder by comparing it to the cap or if you wish....use the harmonic balancer <you will need to use degree tape on it to do that,If you don't have any experience with valve seals at all i would find a friend who does ...its not a hard job....but you need some basic knowlege

 

Now i would have to start at number one cylinder and i could just follow the timing order...right??? Everyone i talk to about doing it this way keep saying the same thing.....just how far down will the valve drop...and will it be a pain to get the spring back on it??

 

well think about it ...how much clearance do you think there is with the piston at TDC between the valve and the piston????NOT TOO GOD DAMM MUCH!!

 

My mechanic said the same thing. Dont worry about it. If you want to screw the TDC stuff just put your air compreeser into a fitting whichs goes into the spark plug hole and fill the cylinder with enough air to hold the valve up.

 

Thanks for the info guys...keep up the good work

 

I've just decided to live with the puff until I can afford a set of aluminum heads, a cam and better lower intake. I am undecided on which heads. I'm waiting until the verdict is in on the SDPC TPI Vortec intake. Originally the intake was supposed to be under $300, but last I saw Jeff@SPDC was suggesting mid $400 range.

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87 Formula 350 14.61@94.07
98 Z28 1LE 13.15@107.59

 

For those still interested in doing this job without the obligatory air compressor: with the piston at TDC the valve only drops perhaps 3/4 inch or so. Easy to grab with your fingers and lift back up when re-installing the springs and keepers etc. Piece of cake, really. Given that I don't have an air compressor, and given that my Edelbrock headers make the spark plug holes a nightmare to reach on several cylinders, this procedure worked perfectly for me.

The trick is to make damn certain that the piston is at TDC when you remove the keepers, or else you have just turned a simple valve seal job into a cylinder head replacement job. You just have to keep your wits about you when rotating the harmonic balancer, and make sure you can identify TDC by watching the valve motion while you rotate the crank. Following the spark plug timing sequence is the easiest way to keep from getting confused or otherwise out of sequence.

 

for real peace of mind when trying to find TDC, pull the plug and stick something down in there, like a dowel rod or something. turn the crank over, and when it starts to dwell at its highest point, you've found TDC (more or less.. you'd need a degree wheel to find the absolute, exact TDC but for what we're doing here its accurate enough)

 

One other thing to remember... the basic problem is GM's decision to use rubber valve seals on the intake where as they use plastic on the exhaust. The plastic exhaust seals are much more durable and reliable than the rubber intake seals.

GM did this as a cost savings decision. The plastic seals cost about $.10 more than the rubber one. $.10 x 8 x 1,000,000 engines per year = lots of money. The REAL fix is to use the plastic exhaust valve seals on your intake. Don't make the mistake and cheap out on a few bucks like GM does. You'll just end up doing the job again, again and again.

 

Glen what seals do you use...i used the GM 40 dollar kit<not cheap...now after about 10 thou.miles i'm starting to see a little smoke again.....dam GM foreign parts ...probably used old rubbers from a cat house to make um!

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87GTA,MAF screens removed,K&N,modified air intake,ADSchip,3:73s,3inch cat back Flowmaster,TPS.54,Bosch Plat plugs,base timing 6BTDC,Bilstiens in the rear....,don't let yer meat loaf

 

[QUOTE]Originally posted by Glenn91L98GTA:
[B]One other thing to remember... the basic problem is GM's decision to use rubber valve seals on the intake where as they use plastic on the exhaust.[END QUOTE]

FYI, GM didn't even use the "plastic valve seals" on the exhaust valves on most of these engines. GM only supplied the intake valve with the bottom rubber seal while the exhaust valves made due with an tiny little O-ring seal attached near the top of the exhaust valve. The valve-stem seal kit "generiously" supplies the plastic exhaust valve seals which should have been installed on these engines from the factory. GM may have saved "more" money than you think. Mike.



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1989 Firebird GTA: black on black 5.7 liter (N10 dual exhaust) with T-tops and leather.