Questions about Intake Manifold 77 Suburban 454

You could indeed have some worn guides or seals. You could but full umbrella oil seals on the valves with out removing the heads. You need to put each piston on bottom of it's stroke with both valves shut, use an adapter in the spark plug hole to fill the cylinder with compressed air, keeping pressure in the cylinder. This will hold the valves up while the springs are removed. You can rent an over head valve spring compressor if you don't have one. To clear up the carbon in the cylinder heads and combustion chambers I would highly recommend "Top Engine Cleaner" sold at your Chevy dealer. The way I've used it in the past is with the engine running I would work the throttle by hand running the RPM's up to around 2000 to 2500 while slowly pouring the Top Engine Cleaner in the carburetor. The motor is going want to stall so you have to meter the solution by hand and work the throttle to keep the engine running. Then when there is about 1/4 of the bottle left I would pour it in the motor making sure that you get it past the carburetor throttle plates letting it stall the motor. Then after 30 minutes or so restart the motor and clean out the solution by running the RPM's up. Of course the whole time you are doing this the truck will be smoking from the cleaner out the exhaust.

nospam

If you are unable to obtain the air compressor or the adapter for the spark plug hole try this.

Draw the piston down until the valve just start to open....do not open the valve too far. Insert a lenth of nylon rope into the cylinder. Pretty much go until you can't shove in any more. Bring your pistion back up enough to compress the rope and hold the valves up. Use a rope that will not leave behind any debris (I used nylon). I bet you could use vacuum hose too if you had it available.

If you chose to pour ANYTHING into the intake while it is running, be aware that the slightest bump that causes a flood into the engine, may result in a hydaulic lock and one or more bent connecting rods. My dad used to use tranny fluid (on older carburated NON ECM cars) to perform the same procedure, and it worked great. He never bent any rods, but watched someone do it. Wouldn't pour that stuff into a newer electronically controlled motor though.

I totally agree with you about newer computer controlled cars. But they also don't get as much carbon build up as his 1977 454 Chevy will get. Most of the time if you have the fuel injectors cleaned with a pressure cleaner and commercial cleaning solvent any carbon in the cylinder will be cleaned as well.

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"NoSpam" wrote

You probably wouldn't believe how much carbon the newer vehicles get and how quickly. And the kind of chemicals that are introduced through the intake system.

Ian

Really? I haven't had a motor apart in many years and just assumed that with the leaner computer controls that the motor would stay cleaner. Does unleaded gas leave a lot of deposits in the combustion chamber?

nospam

Thanks to all of you who responded. I picked up the manifold at the shop and described what my intake valves look like and they seem to think that they are in pretty good shape considering what most valves on engines they tear down look like. Some valves they see look like "Christmas trees" there is so much buildup and they say it's mostly caused by crappy gas and too little highway/agressive driving. I'll definetely give the "Top Engine Cleaner" a try making sure that I do it slow and steady for the first 3/4's. As far as the oil goes they say some oil doesn't hurt as long as the plug electrodes and insulator look pretty clean and they would wait until I do a full engine overhaul to address it.

They also reccomend tossing the new front and rear manifold rubber seals and using high temp rtv and letting it set up for 15 minutes before assembling. Any opinions?

Thanks, Bob

"Eightupman" wrote in message news:9WJdc.12086$ snipped-for-privacy@twister.southeast.rr.com...

I like to use the neoprene gaskets that come with the intake gasket set. I usually use a little silicon on both sides but I don't like relying on the silicon for holding the engine pressures. If you sit your manifold on the engine with just the intake port gaskets you'll see a gap of around 3/32" between the block and manifold. My opinion is that is to much gap for just silicon. I know a lot of people have done this and it worked for them. But if you use the seals and silicon your going to get a good seal.

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