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Post Info TOPIC: Slight Stutter every 5 seconds at idle, can't figure it out.


Addicted!

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Slight Stutter every 5 seconds at idle, can't figure it out.


A couple of things I use when diagnosing engine related issues. If you think there may be a vacuum leak take an unlit propane torch, acetylene would also work. With gas on for the torch hold it close to areas where you suspect a vacuum leak. Pay particular attention around the carb, carb base gasket, around the intake where it bolts to the heads and any vacuum lines. If the idle increases or smooths out you found a problem; fix that problem and continue testing to make sure there isn't more than one cause.

As a check on the timing you can use a vacuum gauge in conjunction with your timing light. If the vacuum is out of wack, i.e., low, it may be that your timing chain needs to be replaced. Before you rush to replace the timing chain and gears you should check for vacuum leaks and that the issue isn't carb related. If all else checks out then I would physically check the timing chain and consider replacement.

To help diagnosis and setup the carb use a tach and vacuum gauge, you may have an air screw that needs tweaking. If your car is stock, especially the cam, you should be able to adjust the air screws and get 20" of vacuum.

A vacuum gauge is a very useful tool, can also indicate if you have a sticky value etc. I use one with every tuneup.

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Canadian Poncho Superstar!

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As SD 396 stated, you never had anything major apart. 

It ran 100% fine before the body job. So don't focus on anything internal. 

You changed the wires and plugs I assume, added a pertronix and rebuilt the carb.

It's ignition related I bet. It's not intermittent, you report it as a timed miss. Can't see the carb or a external vacuum line leak causing this.

 

Start with a new quality set of plugs and a Cap. After that, if no change, find another long ignition wire and start pulling wires one at a time and putting the temporary one in.

 

 



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Poncho Master!

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I ran a 12 gauge wire from the battery to the coil,

What a difference !

Overkill but now it's sawdered to the ignition wire at the steering Colum.

However, I had the carb apart with that dirt in the needle.

That float may be not set properly.

Now that its running better, it bogs down on a 0-80 stop sign run.

Let off the gas an it recovers.

mild acceleration, no problems.

The cap is the only thing I have not changed.

I'll get one today.



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Randy(Muttwood)



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change cap fill tank with premium THROW IN A CAN OF SEAFOAM

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Poncho Master!

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I called Barry at Performance Unlimited in London where I bought the Pertronix system.

I know he wasn't there the day I bought the system.

He always recommends a cap with copper connections.

Of course I have an cheap aluminum style cap.

He said that oxidization can cause problems.

Picked up an MSD cap off him.

He also insisted that I call him, when I have the cap on, to let him know what happens.

Love these small shops !

I'll pick up some Seafoam, couldn't hurt !

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Randy(Muttwood)



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That MSD Street Fire cap & rotor made a huge difference.

This car has never been this powerful !

The old cap was definitely a week link in the chain.

But,

That stutter was still there.

Found a YouTube video about the float.

He basically stated if you turn the top of the carb upside down, the float should be parallel to it.

This is my original carb.

006a.jpg

 

Sure enough the other float wasn't set like this and not allowing the bowl to fill.

When I had it apart to get the dirt out of the needle, I must of did something wrong.

Got it back together and,

yep,

The stutter is gone.

Thanks for putting up with this novice biggrin

I think I will still take it in to get it checked over by one of the best.

 



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Randy(Muttwood)



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Good to hear!



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A Poncho Legend!

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wink
Canadian Poncho wrote:

As mentioned full 12V is important for the Pertronix to work properly. Any slop in the distributor shaft? Is your float level set correctly in the carb?


 



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Addicted!

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It's always nice to get the opinion of a pro but nothing feels as good a solving the issue yourself, CONGRATS!!!!

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