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Try a leak down test, its possible head gasket between cylinders has failed.
he has compression.

loosen the rockers on the cylinders and close the valves. apply air to the cylinder. listen for a massive leak out of the intake or exhaust pipe. orange spark is a weak spark. should be bright blue

take the plug out and verify the spark is actually happening.
 

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I think the orange spark is due to the type of bulb in the tool shown above. When I pull a wire off of the cap; the spark is blue and jumps quite a gap.
Can't I rotate the engine by hand to close the valves?
as long as you can verify the rockers are loose meaning there is no pressure in the spring and that means the valve is completely closed. verify the plug is actually firing. ive seen too much anti seize cause plugs not to fire.
 

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after that check noid.

if noid is good, do a fuel pressure drop on the affected cylinders. you need a fuel injector tester and a pressure gauge.for this. they are inexpensive.

one thing at a time though.
 

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What you call easy is not so for me. To pop the vc's; I have to undo hoses (boost), throttle cable, upper intake, alternator and wires, remove fuel lines, undo cold side piping, and on and on. I'd rather do a proper leak down test to identify any issues before I start pulling everything back apart. Thanks for the advice though.
it aint going to fix itself. you verified you have spark, fuel, injector, noid etc and your problem is lack of compression. vcs are coming off whether you like it or not.
 

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I knew I'd be hearing from you and you're right. I wish you weren't.
to be honest, with all the crap in the way, Im sorry that I was. I really hate taking off valve covers now.

invest in trick flows valve cover studs. worth there weight in gold.

I hope you found the problem. if it is a loose rocker arm, after you bring it on the base circle and take the lash out of the pushrod, then give it your required preload, back it off 1 or 2 flat sides, run the set screw down until it makes contact, then re tighten the nut. this locks down the rocker and i can guarantee it will never come loose again. gl
 
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