67 Running Issues

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Author Topic: 67 Running Issues  (Read 948 times)

Offline Azz67

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67 Running Issues
« on: August 02, 2021, 10:45:34 am »
Hey all,
I'm needing some advice on an issue that cropped up several weeks ago.
Car starting running weird with occasional stutters and hesitation and poor low speed acceleration, which worsened to backfiring. 
I checked the carb over the weekend (Holley 600) and it appeared to be jetting fuel ok from the front 2 nosels. The idle seems to be ok with no noticeable rpm drops or hesitancy that I can detect.
I pulled 6 spark plugs to check for condition and gapping - photos attached. They all appeared generally like this and uniformly gapped at 0.040".

They look fairly carbon fouled which is a sign of running rich am I right?
Am I also right in saying these carbs are sensitive to drops in air temps, I live in Qld but it has been cold so I'm wondering if some adjustment of air/fuel is required?

Motor is late model 5.0.
Would appreciate any assistance to try and fix the issue.

Cheers
Aaron.
« Last Edit: August 02, 2021, 10:49:53 am by Azz67 »

Offline unilec5544

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  • Name: Neil.
Re: 67 Running Issues
« Reply #1 on: August 02, 2021, 09:07:21 pm »
It looks like your Holly needs a rebuild and also an engine timing check.You can buy rebuild kits for the holly, where by you can rebuild it yourself, or take it to a carb shop and have it rebuild.

Offline Bucks

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  • Name: Dave
  • Car: 66 Fastback 289 4 speed
Re: 67 Running Issues
« Reply #2 on: August 03, 2021, 08:04:34 am »
Could be as simple as bad fuel, blocked filters/jets/stuck float valve or timing.
« Last Edit: August 03, 2021, 08:08:08 am by Bucks »

Offline GLENN 70

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Re: 67 Running Issues
« Reply #3 on: August 03, 2021, 09:42:54 am »
Just put a new set in . NGK only and a 5 heat range . Might need a good hwy run to clean it out .

Offline minipete

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Re: 67 Running Issues
« Reply #4 on: August 04, 2021, 12:35:58 am »
What fuel do you use?

I took my car to a carburettor specialist when I first got it because it would blow black smoke on acceleration and was fouling plugs.

Problem was mostly oversized jets but he suggested I not run 98 in my 289.  He said the 98 was too dense and old cars struggle to burn it properly.

I thought I was doing the right thing.  He suggested 95 octane and now the car runs much better with no black smoke on acceleration.

Offline Azz67

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Re: 67 Running Issues
« Reply #5 on: August 04, 2021, 07:56:30 am »
Thanks for replies guys.
I'll pick up some heat range 5 plugs and put those in - is the standard 0.040 gapping good for these ?

Mini- I've pretty much run 98 always - might give the 95 a go because occasionally I get the black smoke on startup...

Cheers
Aaron


Offline GLENN 70

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Re: 67 Running Issues
« Reply #6 on: August 04, 2021, 08:22:47 am »
As I said NGK plugs and the 5 heat range . 40 is good as long as it has electronic ign / dizzy otherwise 35 tho . Still needs a good run on the hwy . What was the heat range on the old plugs ?

Offline Azz67

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Re: 67 Running Issues
« Reply #7 on: August 04, 2021, 09:08:45 am »
The weird thing is Glenn was the issue was there even after a run down the hwy and up to Mount Tambo.

I'm pretty sure they're 6's in there at the moment.


Offline GLENN 70

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Re: 67 Running Issues
« Reply #8 on: August 04, 2021, 10:26:43 am »
Once the plugs go black they are hard to clean up on just a hwy run .  What dizzy ,points or electronic ? 5 heat range in NGK is a hotter plug which will help . I’m not worried about the carb to much but am interested in where the mixture screws are set at ? . Maybe 1 1/4 turns would be good from In To out,  and check the timing and 10 deg on idle would be were I start .