[Spoileddaddy]

Okay, folks. I rebuilt the engine(SBC 400), got it started, Holley 750 DP was puking fuel into the block, smoked like a chimney(possible messed up Power Valve, carb does not have PV Blowout Protection-built in '87)installed new Edelbrock 750. Fired up the first time I tried. Still smokes out of the passenger side exhaust(blue/gray color)at least no more puking fuel. I read on this site that it could be Valve guide seals. Is there any way aside from tearing the Heads apart to troubleshoot them to know for sure? I did not re-build the heads(Pro Heads) when I did the engine, I just cleaned the mating surfaces. I got a feeling that may be coming back to haunt me........As usual, I appreciate any help.


Spoileddaddy

 

[Pete 67]

You can replace the seals with the heads still on the engine, it's just a little trickier this way.

You'll need a little ingenuity, a valve spring compressor, a magnet, & some rope to fill the cylinder (about 2 - 3 ft).

Start with the #1 cylinder, bring it to TDC, & remove the spark plug. Stuff the rope inside the cylinder to keep the valve from falling inside the head. They make a tool to fill the cylinder with compressed air to do the same job, but the air pressure tends to spin the engine over.

Once you are sure that the valves can't slide down, remove the rockers for the #1 cylinder & compress the springs. Remove the valve locks with the magnet to ensure they don't find their way into the lifter galley. Next, remove the spring, & inspect your seals. If they are worn or dried out, you have your answer. If you go to all that trouble, I would replace them all, even if they were a week old. :yes:

Repeat this process for all 8 cylinders, remembering to bring them all to TDC before attempting to compress the springs.

The hardest part of this job is stuffing the rope into the head. The rest is simple.

 

[Cokonuthead]

While the rope certainly sounds like a good idea, the compressed air works well, too. You don't have to use a lot of pressure, I used 20 psi...it's enough to keep the valves closed without turning the engine.

I like the rope idea, though, that's ingenious.

 

[Spoileddaddy]

I agree that the rope idea sounds good. However, should there be concern about threads from the rope getting left behind in the cylinder? Also, does anyone know the P/N or the name of the adapter for compressing air into the cylinder? Or is it just called "spark plug adapter"? I tried modifying a Compression Tester fitting with an air gun fitting on the end of it, but it kept leaking out of the cylinder(wait, don't tell me the rings are no good.......)



Spoileddaddy

 

[rustbucket79]

You will get some leakage around the rings, nothing you can do about it. (with shop air in the cylinder)

 

[Rich-L79]

Use a cotton rope only. Any threads left behind will be burned the first time the engine fires. Nylon rope remnants could leave undesireable residues when they burn.

DO NOT use a remote starter button to turn the engine over when the rope is in the cylinder. If there is enough rope in there to cause the piston to bottom out on the cylinder head you could bend a rod by using the remote starter to turn it over! Just turn it over by hand.

 

[wotr]

I use a piece of spark plug wire,, works good. LJ

 

[Mr69]

I did not re-build the heads(Pro Heads) when I did the engine, I just cleaned the mating surfaces.

I think you are answering your own question.
Any time you have the heads off you should take them apart and check everything.

 

[Dave427]

Its probalby the residue from flooding it so bad. Drive it, it will go away I bet.

Dave

 

[swcash]

Use the air pressure method. Pull the push rods so that if the air pressure pushes the piston to bdc, the valves will still be closed and it will make no difference.

If you can't find the right fitting, bust the center out of an old spark plug and either thread it to 1/4" nptf or weld a hose fitting into it. Squirt a little oil into the cylinder to help seal the rings while replacing the seals.
Squido