440 cuts out at 4600 rmp help please

[moper]

It's not ignition if it did it with the MSD and the replacement.
Does it rev higher in neutral or lower gears, or does it stop at 4600 even with no load on it?

 

[Dabobo1955]

I am going to take off the 6 pack and put a demon on it to see what happens

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1st gear 4th gear don't matter. I don't like to just rev the motor that high with no load on it .

 

[440beep]

Kiwi, is that Tongariro?

In the days of points in my '70 Roadrunner with a 440, the condenser just burnt out after a 2-mile run at around 150mph. Ignition just died....coasted about another 2 miles though.
View attachment 304459

 

[kiwigtx]

Kiwi, is that Tongariro?

Yes - Tongariro is the flat mountain to the right, however the cone shaped volcano is actually Ngauruhoe. :hello2:

Here's a shot I took on the way home in December;

 

[Shorthorse]

OK,
Two different ignition boxes with the same result - As Moper pointed out, that should rule out the boxes.
Same distributor and car breaks up around 4600 in any gear. Do you have anyone that can swap their distributor into your car as a quick test? Like others, it still seems like ignition to me. Try to stay focused on one area like the ignition until you're sure it's not that.

 

[lewtot184]

throw a point distributor in it for a test. this will eliminate all the electronic stuff.

 

[AR67GTX]

throw a point distributor in it for a test. this will eliminate all the electronic stuff.

And while you are at it check for worn distributor shaft bushings.