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Discussion Starter #1 (Edited)
I just picked up a 1982 amc spirit with a 4.2L (258cu) straight six, and its pretty slow (slower than my 1.6L sentra!!) I'm going over everything bit by bit to get it into top shape, and I'm going to do my timing this weekend. I'm wondering what is a good starting point for my total mechanical advance, I'm guessing around 38 degrees is close but I want to here what you guys have to say before I start..

the engine/car is completely stock (tiny cam)
compression ratio should be 8.6:1
The distributor is a regular FORD duraspark type.
Bore x Stroke 3.75" x 3.90"
114hp @ 3600rpm
196 ft-lbs torque @ 2000rpm

here's a pic I stole off ebay of what the combustion chambers should look like:


:D
 

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38 total sounds about right. Trial and error would be a good idea.

Max hp at 3600! Wow that cam is small. I would try installing a cam with 202-205 degrees at 0.050" on the intake and 205-210 on the exhaust. This should to get that hp up to 0.75 hp per cid with max hp at 4500 pms and maintain a stock idle and increase mpg. A single 2.5 inch exhaust system with a Dynomax Super Turbo muffler would help too. Then maybe a better intake (clifford) and carb or convert to megasquirt efi.
 

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Discussion Starter #3
I played with the timing today, and I found my mechanical advance is giving only 14 degrees!! Is this normal or do I have something sticking in my distributor? So for now I put it at 20 degrees inital, giving 34 total, I didn't really experiment with putting it higher. Also I found the stock vacuum advance can is pulling in 20 degrees advance, so hooked to manifold vacuum its idling at 40 degrees, and it seems to like it.

soo do you think my distributor is meant to only give 14 degrees mechanical advance or should I get my hands dirty and poke around inside of there?
 

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14 mechanical advance doesn't seem like enough but it could be correct for that distributor.

I wouldn't go any higher with the timing because 34 total mechanical and 20 added for vacuum advance is 54. And 54 is the amount of timing you will get on a highway drive (light load with rpms). 54 is the right amount of timing for good mpg with a light load. However, 34 seems to be a little low for WOT.

It all depends on that cylinder head. 34 maybe is ideal???? Newer style heads typically do better with less timing (32 to 34 degrees). However, not sure if that would include your cylinder head design. I don't see much quenching area in that head. It is spinning slow, so maybe it doesn't need that much timing.

Did you try ported vacuum versus non-ported vacuum for the mechanical advance?

You could try more initial timing to get more total timing a WOT, but you would need to reduce the amount of timing from the vacuum advance. Accel makes an adjustable vacuum advance canister for this purpose.
 
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