360 problem- Looking to get it right.

[willysjeepseller]

Long story short. 360 cackles on startup since it was "professionally" rebuilt. Replaced the lifters and it still does it. It was running better than ever before, but the rocker arm fell off a pushrod. Re spec'd all my pushrods and found that to get a good pattern on the valve (per a muscle car magazine article) and keep the rockers tight I needed like 4 different pushrod lengths.

Well, it still cackles a little and now it idles rough. By rough I mean the engine rocks side to side, and It does not lug as well at idle and low speeds. Looks like someone has replaced some valves, maybe they are different lengths. Anyway it runs but I don't like it. If anybody has any idea of what it might be I would love to hear it. Also if anyone can recommend a good AMC shop in nor-cal (close to Ukiah is good) that would be great. Just tired of messin with it and I want EFI and i need a good motor to put it on first.

[AMX69PHATTY]

Hope it's not wiped off cam lobes :shock: How'd the bottoms of the removed lifters look ?

[willysjeepseller]

Lobes were good. Lifters looked good.

[ironman_gq]

are the valves bent? maybe you got one leaking.

[msalaba]

Ignition timimg correct?

Carb bolted to manifold and not leaking?

Vacuum leak?

These simple gremlins can make nightmares.

[Mudrat]

. . . but the rocker arm fell off a pushrod.
Sounds like a NOT professional rebuild!! You want to explain how it "fell off"?

You said the 'lobes looked good' - assume you pulled the cam. Did you mic the lobes or just do a visual?
'Lifters looked good' - and you changed them with no change in the engine - mark that one off.

What all did these "professonals" do to the engine? deck and line bore? "True" the heads? Did you get the spec sheet for any work they did? If they weren't square on the machine if they decked or trued the heads, you may be a few .001 off in cylinder height or on the head (both a bad thing), then the push rod distances will be different.

Start with the the easy stuff;
Compression on the cylinders
Cap and rotor - decent shape?
Wires in the right order? I've gone backwards on the wires and thought the engine was going to jump off the mounts :oops:

On the more invasive side; check the pushrod lengths (and straightness)

And while you have the rockers off (to check the push rods :wink: ), check the valve spring heights. Would be a clue to different length valve stems.
If it gets down to it check the spring pressures - if they mixed old and new valve springs you have different hights and pressures - not good, but not terminal. I prefer doing this with the heads off and the valves removed, but . . .

Keep us up on what you find. Your helping others by sharing your woes. And making us scratch our heads #-o