[racerboy]

Here’s the little clip attached to the coil-to-points wire:



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[racerboy]

I just looked at another distributor and I think that little clip is just there to prevent pulling the wire through the rubber grommet.

[tekuhn]

Originally Posted by racerboy

I just looked at another distributor and I think that little clip is just there to prevent pulling the wire through the rubber grommet.

Yep, it's wire strain relief. Is it still running poorly? BTW - check brake booster and PCV by pulling the line and plugging briefly. The booster could have a hole in it and the PCV internal valve could stick in the open position. Use a vacuum gauge if available. See if carb cleaner sprayed in carb causes RPM increase and/or smooths it out. If it does, it's lean. If the AFR is good, move to ignition. Substitute distributor cap, rotor, points, condenser, coil, coil wire. If spark is good, move to valves. Does it have poly-locks that might have loosened? Check lifter preload, valve springs. Do a compression check to see if one or more cylinders are lower than the others.

I guess now I'm the one taking the shotgun approach, but for the engine to suddenly go from running great to bad, it can't be that hard to find.

[Jay S]

I am glad you got it going again. FWIW, If I were there helping you, I would be insisting to change out those old points. It could be just the photo, but they look very burnt to me. The contacts look like they are burnt black, then appear to have a small raised area that is burnt worse but has a natural color from the contacts trying to fuse together. The black area isn’t making much of any contact, and the small that is lighter colored is the only place the point are contacting. It will run like that, and may run fine if you of the lucky sort , but they look like they need to be replaced.

[tekuhn]

Originally Posted by Jay S

I am glad you got it going again. FWIW, If I were there helping you, I would be insisting to change out those old points. It could be just the photo, but they look very burnt to me. The contacts look like they are burnt black, then appear to have a small raised area that is burnt worse but has a natural color from the contacts trying to fuse together. The black area isn’t making much of any contact, and the small that is lighter colored is the only place the point are contacting. It will run like that, and may run fine if you of the lucky sort , but they look like they need to be replaced.

The points do look pretty pitted for such low miles which is why I mentioned the resistance wire. If the wiring harness was replaced with aftermarket and the resistance wire eliminated, it needs a ballast resistor to make the points last.

[racerboy]

I will try the new points but now I have a different problem. Remember that crazy loud backfire that happened last night? It blew out the plug on the driver-side head. As the car was idling, I noticed it was so much louder than yesterday. At first I thought it blew out a muffler but when I put my hand behind the head, I could feel exhaust pumping out.



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[racerboy]

The wiring harness is a new M&H reproduction and has the resistor wire built in.


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[tekuhn]

I started to wonder how it could blow out a freeze plug, but the picture reminded me that 670 heads have the passage for the A.I.R. nozzles. That must have been quite a backfire!

[1965gp]

Did you get a chance to pull the valve covers and see if anything is out of the ordinary? I have been surprised by bent pushrods, broken pushrods abs broken valve springs.

All of them were immediate changes in running condition.

[1969400HO]

Hard to troubleshoot long distance like this.
If no fuel dribbling out as Should, when taking inlet apart, I suspect several things.
Fuel pump possible failing for whatever reason, NEW does not mean good or durable here.

Or the eccentric pump-arm function, this piece inside on TC , may have come loose or for some reason has issues making pump look like it's failing.
If fuel bowl is low or empty then investigate those items, filling station possibly gave you debris in its fuel.

Is there a fuel filter in the rear by the gas tank?
Or is there a sharp pinch in the rubber line somewhere? Take a quick look-see on it.
Or is the gas cap vented? That may cause a vacuum in the system and starve the fuel pump.

Some day I will invent a bolt on type setup with gauge, , to check the line pressure , that mounts to the inlet bowl.
Some day...

[racerboy]

Originally Posted by 1965gp

Did you get a chance to pull the valve covers and see if anything is out of the ordinary? I have been surprised by bent pushrods, broken pushrods abs broken valve springs.

All of them were immediate changes in running condition.

I did pull the valve covers and nothing seemed out of the ordinary.

[racerboy]

Originally Posted by tekuhn

I started to wonder how it could blow out a freeze plug, but the picture reminded me that 670 heads have the passage for the A.I.R. nozzles. That must have been quite a backfire!

Indeed! I can't even find the missing plug on my garage floor! How strange is that? Any idea what size plug this is? It's bigger than 1/2 in.

[racerboy]

Originally Posted by 1969400HO

Hard to troubleshoot long distance like this.
If no fuel dribbling out as Should, when taking inlet apart, I suspect several things.
Fuel pump possible failing for whatever reason, NEW does not mean good or durable here.

Or the eccentric pump-arm function, this piece inside on TC , may have come loose or for some reason has issues making pump look like it's failing.
If fuel bowl is low or empty then investigate those items, filling station possibly gave you debris in its fuel.

Is there a fuel filter in the rear by the gas tank?
Or is there a sharp pinch in the rubber line somewhere? Take a quick look-see on it.
Or is the gas cap vented? That may cause a vacuum in the system and starve the fuel pump.

Some day I will invent a bolt on type setup with gauge, , to check the line pressure , that mounts to the inlet bowl.
Some day...

I will check to see if there is a pinch on the line. I do have another fuel pump (from my 428) that I can throw on there.

I don't think it's the fuel cap only because the car was running great and then it felt like someone threw a switch.

[steve25]

That AIR hole stock is threaded.

[racerboy]

Originally Posted by steve25

That AIR hole stock is threaded.

Yeah. I think it takes a threaded plug. I just wasn’t sure what size to get.


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[Joe's Garage]

But we don't play with many engines that are earlier than 1969.

IF it's pipe threads and around 1/2" diameter, it will probably be 1/4 NPT threads. But that's just a guess - I'm sure someone on here knows what size they are.

Good luck!

[1969400HO]

After reading it so far I would say YES, get the fuel inlet redone, these Rochesters are typical - poor material, so welcome to the club.

I am in Portland Oregon and have a regional Q-jet guy here who does this refits them, if u want his contact info let me know.

Or buy the drill & Tap and YouTube learn and do it yourself.

Anyway, Looks like a multi path hunt for the issue.

So you were Fine after about 50 mies run,
was this the NEW engine maiden voyage?

All new everything etc?

Plugs I would just clean them or maybe go down One level colder plug.

Your coil primary wire OHM should read low of 0.6 to max of 2.0. OHMS.
Primary wire is the (-) side to the (+) side reading on the coil.
Secondary is either one of those to the Center wire reading.

Secondary should be near 6 OHMS to maybe 15-ish OHMS.

Voltage to the coil is only 9.5V usually, due to built-in Resistance wire in the harness, it divides the 12V down.

Did the points friction/lobe tab have enough lubrication on it?

What was the gap when you examined the points?
Should be 0.017" +/= 001.

Lack of lube on contact tab/lobes will shortly kill any set of points, no matter what brand.

The stutter-jerking worsening as you went, sorta sounds like points got ate up from lack of lube.

When you took off the carb, did you notice if it seemed like it had a
"normal amount" full of fuel in it?

As if it was low or almost dry then look at there options on fuel supply like Pump, the centric possibly bad or failing, of crapped up lines.

Did you Replace the fuel lines and DID you put a NEW tank in car?

99% chance if you used orig tank, without an inside proper descale-cleaning, it has LOTSA debris in it and first time driving stirred it and contaminated system lines etc.

NONE of these tanks are "good' being this old.

Guarantee you put a BORO-Scope in ANY older tank to view it, and it will shock you to see 3.8" thick scale rusting inside the tank on its walls crusted up.

From pix , the inlet filter looks reasonably OK good.

Can always put a rubber hose on the output of the line there,
and run it into a container.

Put Dist., back in before turning eng over.

Turning engine over (leave plugs OUT so turns over easier). to see what fuel looks like and if pressure seems adequate and how clean fuel is.

I would try to start it before lifting the RR lids off unless you believe there was noises or mechanical issues inducing this problem.

Yes One bad spring can occur early on easily and yet shouldn't make it act like it was fuel starved or Electrical shorting symptoms though.

Let us now what you found.

[steve25]

What mean is that from your picture I don't see any threads left in that AIR hole!

[racerboy]

Originally Posted by steve25

What mean is that from your picture I don't see any threads left in that AIR hole!

There are threads deeper in. You can’t see it from the picture. I have another set of 670 heads and tried removing that plug. Would not budge.


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[steve25]

You need to get a big ass punch with a tip just small enough to fit in the square hole and beat on it with a ball peen hammer.

That will jar the threads up enough to let you remove it.

This assumes you do not have a Oxy torch to heat up a good amount wil first.