My 225 1 barrel has recently started during idle. Above idle it either stops
or I can't identify it. It seemed to start after I ran a full tank of high test
gas. I used the high test to see if it would get rid of valve chatter under
acceleration. The chatter stopped but now I have the miss. Also it misses
when the choke is fully engaged on cold days.

Thanks

Sounds like a vacuum leak to me.

D/W

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If it ain't broke, fix it!

"Valve chatter?"

A) I'm not sure what "valve chatter" might be, and
B) If running premium fixed it, it was actually octane knock.

Check the plugs, if its been knocking, the plugs may be too high a heat range and may be damaged, or if not too hot, they may be encrusted with deposits.

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By "Valve Chatter" I refer to the valves making a clicking noise while
under load. On V8 engines I am more familiar with it was caused by
weak lifters bad detonation from the wrong gas/timing/cam combination.

The missing that I now get only at idle has a low popping sound.

I will check for vacume leaks as this motor has 57K original and all of
the hoses are original from 1968.

Valve and lifter noises aren't usually affected by load. Sounds that ARE affected by load which might sound like lifter tick include light pinging (octane knock) or small exhaust leaks at the manifold-to-head junction.

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Welcome to my world. I've been chasing vaccum leaks on my slant for years, and can't seem to find them all. I've just learned to live with 'em...

VM

Other things that can appear like vacuum leaks and cause missing at idle:

- Misadjusted valves (tight)

- Mis-degreed camshaft (very common on rebuilt and even factory motors)

Lou

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Home of Slant6-powered fun machines since 1988

What year is your /? If you don't have hardend exhaust valve seats, it's possible you may have damaged one or burned a valve with the higher octane fuel.

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70 Valiant Super Six

Higher octane fuel, will not have any bad effect on the engine. By the same token, if your engine is not pinging, it is a waste of money to use it. High octane fuel will, generally allow you to run more ignition advance, and get better fuel milage.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The motor is a 1968 /6 w 57k original miles

Well the amazing Dart died in the grocery store lot and would not restart.
After walking the 1/2 mile home to get my 84 F 150 to get the quickly
thawing grocerys from the trunk of the Dart I was just a bit pissed. I had it
towed to my friendly nieghborhood garage.

The problem was burnt points. They rebuilt the distributor top (points,
cap, condenser, ect.) and set the timing to spec.

Got it back 4 hours later and 250 bucks poorer, runs fine.
All the guys at the garage got a kick having the chance to work on
a vintage car with such low miles. (250 bucks is cheap at this place)

What?? $250 to change the points? Hmmm..... I'll glady change your points every day for $250 a pop.

And if you can't do the job, I may travel up there al the way from argentina. Man, they changed points? sounds like a rimjob to me

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Did that include the towing?
For $250, they should have done a complete electronic ign conversion, then you wouldn't have to worry about the points again.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225