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"I blew the head gasket a few weeks ago. Had the head gone through by a reputable shop. Received in good condition. Replaced on block. Noticed that the exhaust valve clearance was now extremely tight - the bottom of the rocker was at the top of the valve stem. Proceeded to complete reassembly. Replaced cap rotor plugs hoses belts wires filters in process."
Did you adjust the valves after you completed the assembly? That is a critical step. A miss will occur if the valves are adjusted too tight. .008 intake and .012 exhaust with the motor hot or .007 intake .011 exhaust with the motor cold (below 80 degrees).
"Motor now runs badly and does not have the same spot on the distributor to time as it used to have."
If the dist is sitting at one extreme end of the slot or the other, you may be off a tooth. Do you know if the head was shaved for flatness, and if so, how much? Milling the head on an overhead cam motor changes the cam timing (retards).You can purchase an adjustable cam gear to correct it. Rule of thumb is 1-degree advance for every .010 of material removed from the head on the adjustable cam gear.
"Exact nature of motor malfunction:
Starts easily.
Idles a little rough, but not to bad.
Powers up hills better than before.
when I lift off the accelerator at the crest of a hill, or on a long flat stretch, the motor misses- it feels just like when your car is about to run out of gas. It will normalize after a few seconds, but the cutting out is really noticeable, and makes me nervous. Sense that fuel consumption is up but not sure - speedo not working for years now."
Not sure if you have a true 84 EFI, if you do, then you have a dist with vacuum advance. Models made from about Aug of 84 and up are 85 models and the computer adjusts the timing. Make sure that the vacuum hoses are routed to the vacuum advance properly (as well as the other hoses) and they're not cracked. The inner diaphragm on the vacuum modulator is known to develop leaks. Remove each hose individually and pull a vacuum on them (either use a vacuum pump or you can just suck on the hose). I recently had this issue on my 84 EFI. Another item to check is the TPS (throttle position sensor) for proper adjustment. I'll need to know if you have a true 84 since 85+ models use a completely different method of testing and making adjustments.
"Have checked - air metering sensor, cold start injector, fuel injectors, vsv, idle sensor - all within specs.
Timing marks on crank and cam aligned according to book. Timed about 5 BTDC according to sticker on hood. In short, everything is within specification but it still cuts out."
Are you removing both vacuum hoses from the vacuum advance diaphragm and plugging them up when checking the timing?
We'll go from there. Let us know
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