It was running fine before I started messing with it!!

Fritz Maurer · Oct 5, 2018

'71 350 CI Chevy. Had a dead miss when cold,that went away when hot. Plugs were filthy so I put in a new set of R44s.
It ran much better then and I wish I had stopped there. Since the points were from the previous century,I thought it be nice to do a full tune-up. All the rest of the parts fit ok, but the points are giving me trouble. The original points and condenser were separate pieces, and the new ones are the points/condenser unit assembly. The guy at the auto parts store assured me they would interchange. Is he correct? With the new points, I can only get 44* of dwell because the tension spring on the adjustment screw is stacked up solid, and the dead cylinder is back. As removed from the distributor, the old points have plenty of adjustment in either direction. What gives? Should I go order the same points that came out of it? Thanks, Fritz

Bob · Oct 5, 2018

No reason a "uniset" shouldn't work, but the quality of today's points isn't typically very good, and you aren't the first to find a set that couldn't be adjusted properly.

Or, it's possible that the shaft and bushings in the distributor are badly worn.

NOT really worth messing with either, unless originality is important when there's "drop in" aftermarket HEI distributors available on ebay and elsewhere for $45 and up.

As to the miss, have you done a compression check?

Also, it's not uncommon for an intake gasket to leak causing a misfire and oil consumption/plug fowling if it leaks on the lower/internal side.

ramblineagle · Oct 5, 2018

Go back to the original style of points, never did have any good luck using those one piece point assembles.

Bruce(OR) · Oct 5, 2018

Uni-points drop right in and will work. Spark Plug gap is at .035, timing at 6 degees BTDC and dwell is set to 30 degrees with that friendly dwell meter. Dwell effects timing. Basic static point gap should be around .018 to .019. Setting static timing with uni-points is a pita.
You need to get the points gap to .019 to start with. Grab the ignition rotor on top of the dist and give it a twist. Does it snap back or slowly return or not at all?
Is that a 2 bbl or 4 bbl carb? Rotenchester?
Once you get the timing set, Make an index mark from the dist base housing to the intake manifold. Next time you think the timing is off, check the mark and reset the dwell instead. Your timing will come right back in line.
Let me know about the rotor twist. if it's buggerd up, I can walk you through fixing it.
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grizz02 · Oct 5, 2018

is the choke opening up ?

rustred · Oct 5, 2018

first things first... check the compression, that will eliminate guessing and headache. standard procedure when doing a tune up. those chev. v8's use the one piece assembly as thats why the distributor cap has the window there for point adjustment. funny thing today i had happen... i put in a new set of plugs in grain truck 366 engine last fall. went to start it no way running on 2 cyl's litterly.unburned gas leaking out from exhuast manifolds , holt christ im gonna start a fire! what going on here? went and got an old set of R44TS PLUGS i had , put them in and bingo! fired right up , WTH im thinking brand new plugs not firing. and yes i checked the compression last fall when i installed the new plugs. compression was right up to snuff. some thing about those plugs as it started missing right after i put those new ones in. good thing i keep old parts of all kind that i think i may need. have all kinds of old plugs i keep.

MarkB_MI · Oct 6, 2018

It seems impossible to get good-quality points and condensors these days. I gave up on the points in my Ford tractor and did the Pertronix conversion. HEI conversion kits for small-block Chevys seem to be pretty cheap; I'd sure consider making the switch.

Steve@Advance · Oct 6, 2018

The uni-points are the standard replacement points now. If they won't adjust, either they are manufactured wrong, improperly installed (an easy mistake), or the distributor shaft bushing is worn.

How are the plug wires? Sometimes disturbing them can finish off a borderline bad set. Those are a real pain to replace if it has ram horn manifolds, but best do it right to get the best fit.

Also look for vacuum leaks. The PCV hose will collapse inward on the bottom side, hard to see. Also check the brake booster as a source of a leak.

If it's a 4 barrel, make sure the secondary throttle plates are fully closed.

IanC · Oct 6, 2018

I'm not normally a fan of electronic conversions, but in this case, if I was you I'd go to my local older salvage yard and get an HEI distributor from a '75-79 Chevy. Those had all the electronics in the distributor, not needing an ECM.

timcasbolt · Oct 6, 2018

(quoted from post at 02:01:06 10/06/18) '71 350 CI Chevy. Had a dead miss when cold,that went away when hot. Plugs were filthy so I put in a new set of R44s.
It ran much better then and I wish I had stopped there. Since the points were from the previous century,I thought it be nice to do a full tune-up. All the rest of the parts fit ok, but the points are giving me trouble. The original points and condenser were separate pieces, and the new ones are the points/condenser unit assembly. The guy at the auto parts store assured me they would interchange. Is he correct? With the new points, I can only get 44* of dwell because the tension spring on the adjustment screw is stacked up solid, and the dead cylinder is back. As removed from the distributor, the old points have plenty of adjustment in either direction. What gives? Should I go order the same points that came out of it? Thanks, Fritz

I'm one of the few people left in my friend circle that still owns a dwellmeter and knows how to use it. I don't like unisets because the spring is so weak the engine won't rev up like it should. But they do work. Nowadays, the first thing I like to do is install a conversion kit such as the ones offered by Mallory, Pertronix, and others. I think the price is around $80, and you never have to touch it again.

When you wiggle the rotor like the other poster said, pay attention to the amount of up and down movement. Sometimes it's necessary to pull the distributor out, remove the drive gear and add a shim to take up some of the slack. If the shaft wobbles in the housing, throw it away and get another one. The factory ones are riding in aluminum, the aftermarket ones ride on bearings.

jimg.allentown · Oct 6, 2018

So far, everybody has mostly missed the point.
If you have a MISS, it would be affecting ONE cylinder.
Everything mentioned here affects ALL cylinders.
Bad or misadjusted points will not give you a miss. They will affect all cylinders.
First thing you need to do is track down the missing cylinder. There is a whole list of things that can cause a miss:
Bad wire.
Cracked or carbon tracked cap.
Bad plug.
Burned valve.
Intake manifold gasket.
Vacuum leak.
Camshaft lobe worn down.
Broken rings.
Hole burned in piston.

And the list goes on. Time to do some diagnostics. Bear in mind that a miss affects ONE cylinder. Every other thing that the others have mentioned affects MORE THAN ONE cylinder.

OregonAaron · Oct 6, 2018

I will give a second vote for a compression check. It's one of those basic steps many times you regret not taking. I had a issue with my old ford truck missing and I did not do a compression check... I chased a zillion potential problems before i discovered a had a broken valve spring. A simple compression check would have had me zero in on this quickly.

Bob · Oct 6, 2018

(quoted from post at 06:33:20 10/06/18) It seems impossible to get good-quality points and condensors these days. I gave up on the points in my Ford tractor and did the Pertronix conversion. HEI conversion kits for small-block Chevys seem to be pretty cheap; I'd sure consider making the switch.

WHY would you use a pertronix conversion when you can by a whole "HEI style" distributor with a MUCH hotter spark, with a new cap, rotor, coil, and advance mechanism for 1/2 the $$$$?

Determined · Oct 6, 2018

Sounds like either your initial gap of the points was off by too much or the adjusting screw on the point set was near maxed out on it's travel before you installed them.

Find the middle of the travel for the hex screw then re-gap your initial point setting, you should then have plenty of travel to adjust the dwell.

JMOR · Oct 6, 2018

Bruce (OR) pointed out that 44 is not correct dwell and JIM****pointed out that your problem is on one cylinder, not all cylinders. All good points. Bob, good on HEI!

used red MN · Oct 6, 2018

As others have said a 1 cylinder miss does not come from points, so you have other issues. As far as the dwell not adjusting I would add the possibility of the point set not being seated right before the attachment screws were tightened. There s a locating pin on the bottom of the points that must seat in the mount plate when set in place. Not saying there is no possibility that the points are not manufactured incorrectly just throwing out another possibility. And it is another one of those don?t ask me how I know deals.

Fritz Maurer · Oct 6, 2018

Thanks guys I will get that compression check done and see where we're at.

Tony S. · Oct 6, 2018

Replace the cap and rotor and wires while you're at it

It was running fine before I started messing with it!!

Fritz Maurer

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Bob

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ramblineagle

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Bruce(OR)

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grizz02

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rustred

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MarkB_MI

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Steve@Advance

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IanC

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timcasbolt

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jimg.allentown

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OregonAaron

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Bob

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Determined

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JMOR

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used red MN

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Fritz Maurer

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Tony S.

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