8n running poorly

cory52

New User
1952 8n started losing power and backfiring under load got worse and now starts ok but runs rough and backfires with no load newbie at the 8n game so need lots of help not afraid to get my hands dirty but has been a while since i have worked on a project like this
 
Not that it matters but side mount or front mount dizzy? Either way I would be a looking at the cap of my dizzy and also the points first.

Make sure you don't have any condensation inside the cap and there is no arcing going on inside the cap. Also make sure nothing weird is going on with the rotor

Also make sure the points are gapped properly.

Make sure all your plug wires are in good shape and that nothing got inadvertently crossed up. Things getting crossed up will definitely cause some misbehaving.

Those are things I would look at to determine a root cause before I would spend any money on parts.
 
Good move to not guess or buy parts before you diagnose the problem.

When is the last time you replaced the points, plugs, condenser, cap and rotor and set the timing?

A 1952 has a side distributor, so get out your feeler gauge and screw driver. And multimeter.


Check the firing order, 1-2-4-3, CCW. If the wires/boots are cracked or brittle, replace them.


Look at the cap. Are the contacts grooved? Brass dust anywhere? Is the rotor tip or contact burned? ( CAUTION: be careful when you remove the rotor; there is a
little clip under it. Order a spare when you order new points).

Next, do a quick continuity check. Do you have battery voltage across the points when they are open? (with the points open, put one probe on one side of the
points & the other probe on the opposite side of the points) Verify the gap on the points at .025. Make sure you have voltage across the points, as in past the
insulator on the side of the distributor. That is a very common failure point on sidemounts, along w/ the attached copper strip. It's hard to find a short
there because it is usually an intermittent . So 'wiggle' the insulator & the copper strip a bit when you are doing your checking. If you find the short there,
the Master Parts catalog lists everything you need on page 154. You can make the strip and you could also make the insulators as well. But, somethings are just
easier & in the long run cheaper to buy. Get the strip, 12209, screw 350032-S, 12233 bushing & 12234 insulator & just replace it all.


Look at the points; are they burned, pitted or misaligned? Check the point gap, .025 on all four lobes. Make sure the blade is at a perfect right angle to the
points. You want to feel just the slightest bit of drag when you pull the blade through the points. Set the points on the high side of the cam and ensure they
align correctly. Make sure you have the star washers under the screws on the points. If you need to replace the 8-32 X.19 fillister head screws, ensure that the
new screws do not interfere with the advance weights. Dress the points by running a piece of card stock or a brown paper bag through them. New points sometimes
have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. And, don?t
forget to lube the rubbing block w/ cam lube; not Vaseline, not bearing grease, but cam lube .

Of course, if the points are burned, replace them. See tips 66, 67 & 68. Get quality parts. This sit has them, as does nnalert's, Dennis Carpenter or NAPA.

Got a timing light?
75 Tips
 

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