rothlane'68

As per the title, it won't start...

71 455, C heads, olds J intake, points distributor, holley 650 carb w/vacuum secondaries. I know nothing about the build/cam/etc., but I assume its fairly mild. Always been a powerful/reliable motor until now.

I am hoping its just fouled plugs (the one i pulled was pretty sooty) from all the idling I've been doing as I've tested out repairs/upgrades, also I'm not sure, but I may have changed the vacuum advance from manifold to ported vacuum when I rebuilt the carb (mixture might need to get leaned out too), so the timing might be off.

I am getting fuel, choke is operating, not sure about the pull off, haven't tested for good spark yet. Motor turns over and catches now and then but won't fire up.

Anyway, the car hasn't had a full tuneup in 10 years/10,000 miles so i guess its about time. I'm going to take advantage of the snow day, get educated, and start working on it.

Questions to Start:
What kind of advance should I be setting when I get to doing the timing?
What plug gap should I be setting for this motor with points?
Any brand I would stay away from as far as ignition parts (rotor/cap/points)?
I know there are lots of variables, but any rough idea what kind of compression I am looking at with C heads on a 71 455 block?

Gary M

Your definitely going to need to know if you're getting spark. The trying to start it without spark will foul the plugs so don't start changing timing etc until you get it running.

Check for spark first
if no spark concentrate on that.
Set the points if you can get the settings from others on here.
Age of plug wires?
Cap, rotor, coil etc.

rothlane'68

Thanks Gary, I wont have a helper until the evening so I can't do the old hold a plug against the block while someone cranks trick, can you recommend a good way to check for spark by myself?

plug wires were replaced in '09, everything else is at least 10 years old.

boese1978

If you have a timing light hook it up and watch for it to flash, ie: have spark.

Gary M

no one gets shocked that way either.

Goldenhand

I cranked it myself by taking no:1 sparkwire off and put a sparkplug in and held it against metal near front window and turn the key.
I do have long arms.

m371961

Remove cap. Place high voltage coil wire close to ground. Turn ignition on, push points open with wooden stick. Coil wire should jump fire when opening points.

m371961

https://classicoldsmobile.com/forums...-ignition.html
Good info here on points ignition.
Echlin, Napa or Standard premium Blue streak ignition parts are preferred.

tru-blue 442

+1.

joe_padavano

Clever, but there is one failure mode this won't check for - if the point gap/dwell is incorrect, this test will still show a good spark, however there won't be spark with the engine cranking.

oldcutlass

Have you performed any work on your car prior to this no start issue happening? Have you checked for spark?

Spark plugs should be gapped at .040, dwell set to 30*, timing to 8* BTDC at 1100 rpm with vacuum advance disconnected and plugged, idle speed should be 600 RPM in drive.

m371961

Good catch Joe. If they are staying closed it won't fire when cranked.

rothlane'68

Good to know thats a legitimate possibility! I'll be careful, I love not getting shocked, its one of my favorite things!

Thanks for the link, I'll read up before I start working.

Very last thing I did before this was take out a gauge pod to check something with the temp gauge. Grounds for the gauge are still not connected and I didn't want to reconnect them as they're hard to reach and I need to send the pod out for repairs. I looked over the wiring diagrams though and it doesn't seem like those grounds not being connected would interfere with spark, but tell me if I'm wrong. However, I do acknowledge that an intelligent person would have reconnected these as soon as the car would not start...

When I saw the fouled plug, and thought about the amount of time since its had a proper tune up I just assumed that must be it.

Had intended to check for spark tonight, but got home and the furnace wouldn't start so had to sort that out.

Thanks for the numbers, I'll put them to good use.

I've got a dwell meter and timing light in the mail, I'll pick up a set of points and a condenser from Napa on Friday.

Gary M

Only get shocked if wire is bad if I remember correctly.

Gary M

Furnace, top priority. Yes sir!

shiftbyear

if you have a test light or a volt meter you can check voltage to the + side of the coil with the key turned on. also is fuel spraying from the accelerator pump squirters when you move the throttle. starting fluid might help, but be safe. good luck.

rothlane'68

So Napa had to order the condenser and points I needed, won't be in until Tuesday, distributor lead wire is frayed by the connector so ordered one of those too. In any case, I couldn't do everything I wanted to but I did run some tests.

Started at the coil, with the ignition on, could only get 6.8 volts at the positive terminal, I think I saw somewhere that 12 is correct? With coil removed, the lead to the positive side reads 12+.

Took the coil out of the car and ran a test measuring resistance across the positive and negative post (primary), and then from the positive to the center contact (secondary) on 200 and 20k ohms respectively. I read that a GM coil should give readings of between 1.5 and 1.7 on the primary and better than 11 on the secondary. I get 1.8 and 9.6.

So... I'm looking at a bad coil, correct?

shiftbyear

I think the voltage to the coil with key in the "on" position is correct. when you turn the key to "start" position the voltage should jump to 12v. I believe Joe mentioned this in another post. the reason is to increase point life, a constant 12v to the coil with points causes rapid wear. good luck

rothlane'68

Checked the CSM: says the voltage I got would be correct with points closed. You get the full battery with points open. I did have spark, but it seemed fairly weak.

So I picked up my points on Wednesday and took the distributor apart and pulled the rest of the plugs yesterday.

Old plugs were all very sooty, old points were very worn as well. Centrifugal advance weights were all gummed up with rust and grease and the vacuum advance was totally frozen. All that and a bunch of dead bugs in the bottom of the distributor. Not a lot of play in the shaft though, and cap and rotor look good, so theres a silver lining I guess. I'm surprised it ran at all... oh wait...

Not one parts store in town had a vacuum advance can in stock, so I'm be waiting for a new one in the mail. I figure I'll go ahead and change the coil and plug wires while I'm at it and see if that improves the spark.

Any advice on what to use to clean out/re-lube the distributor?
anything wrong with break cleaner and a very light coat of WD-40?

joe_padavano

Considering that the last time a production vehicle came with a vacuum advance distributor from the factory was over four decades ago, this is not surprising...

It won't. The vac advance only alters timing of the spark. It has no effect on the spark itself.

rothlane'68

Thanks Joe, I get how the advance works and that it won't improve the spark, I was referring to the coil/wires.

Any input on how to clean up the guts of the distributor without making another project for myself?

rothlane'68

Meant to update this a while back.

Blew the distributor out with compressed air, replaced points/condenser, vacuum can and wires and the car fired right up. Carb floats were a bit high (probably played a role in the plug fouling).

Set everything to the specs Eric suggested:
It runs like different car. Even seems to have cured a rattle in the valvetrain. Had a hard time getting a smooth idle at 600 rpms, so upped it to 650. Its not exactly a huge deal, but any tips on how to smooth out the idle at the lower speed?

Anyway, thanks for all the support and info!

Fun71

On my car I increased the initial advance.

I have an HEI distributor that I installed a Moroso HEI recurve kit some years back and it gave 24º mechanical advance, which let me set the initial to the factory points setting of 10º. All was well until I put in a slightly more aggressive cam and read a lot of posts about increased initial giving more vacuum, smoother idle, and more off-idle torque. So, I put the factory HEI weights and center bar back in and that increased the initial to 18º, which in turn gave higher and smoother idle vacuum.

You may be able to increase the idle timing by connecting the vacuum advance to manifold vacuum instead of ported vacuum.

oldcutlass

Glad you got it running and all is well. Remember all these settings are a conservative recommendation that are not etched in stone. The engine will let you know what it likes.