# Runs rich when cruising.



## Fathead Racing (May 28, 2014)

Timing is good as is dwell, carbs rebuilt. Idle is rock solid. Even sitting in the shop when I crack the throttle to 2000 rpm the engine runs rough. Soot in tail pipe. Jets .062 center, .066 front and rear. Here's the kicker! When I remove the center air cleaner (clean white paper element) the engine straightens out? Could it be that someone drilled the center jets and didn't grind the numbers off or are those paper filters that restrictive? Hood is ram air.


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## Roger that (Feb 6, 2010)

What brand of paper filter do you have? Yes the original AC foam filters were special to the GTO's and 2+2's in being low restricted filters. I would swap out one of the end carb filters with the center and see if that makes a change. Also did you also verify your advanced timing is working?

How does it run with accelerating hard on just the center carb and/or all carbs?

Edit: Also have you tried running it without the ram air stuff?


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## Roger that (Feb 6, 2010)

I know you have a 65 GTO but are you running 65 carbs as well? Those jet sizes are not stock for the 1965 year. It sounds like you did not alter the jets sizes during the rebuild.


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## Fathead Racing (May 28, 2014)

Paper filter I have not identified. My research shows .062 center and .066 front and rear for 65. Yes I ran it in the shop at 2000 rpm and was running rough just like on the road, removed filter and the engine smoothed out. Timing is good. End filters are the same. Looks like carbs are original 65 units. Pulls very good on center carb as well as all three. Only issue is cruise. Power valve seemed alright. I have plenty of jets all sizes. I am going to use pin gauges and see where that goes. I have heard some filters are very restrictive but Don't want K&N's unless I have too.


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## geeteeohguy (Feb 2, 2008)

No matter what jet you have, if the engine cleans up with the air filter off, you have a bad air filter, period. I've run into this in the past with the paper elements. Have been using K&N for the past 30 years due to this. Get rid of those filters and get something else. No amount of playing around with jetting will balance out a restricted air intake!


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## Fathead Racing (May 28, 2014)

I can purchase the K&N's at Auto Zone. I was leaning in that direction. Jets didn't look like they had been tampered with. I ran a hopped up 348 Chevy with three two's and ran 14's with the air cleaners on,(K&N's) and 13.55 with them removed. I agree with you, I think some of the Tri Power filters are crap!


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## Roger that (Feb 6, 2010)

Just for your info on 1965 389 jets:

Center AT: 60s
Center MT: 63s
Ends, Both front and rear AT or MT: 68s


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## Roger that (Feb 6, 2010)

Geeteeohguy might be able help me. The A193C's foam filters change the complete sound of the tri-pwr over the paper filters. It sounds like a monster of sucking going on with the A193C's. I have never tried the K&N on the tri-pwr so I just wondered if anyone has compared the A193C's to the K&N in the sound on all the carbs going?


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## Fathead Racing (May 28, 2014)

Roger that said:


> Just for your info on 1965 389 jets:
> 
> Center AT: 60s
> Center MT: 63s
> Ends, Both front and rear AT or MT: 68s


I made a misquote, the center is .063 in my center carb, the ends are incorrect at .066. Thank you.


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## geeteeohguy (Feb 2, 2008)

Roger, a friend of mine is running the AC foam filters with the arrestor screens, etc, and his sounds very similar to mine at WOT, on the intake. A hair quieter, but his has stock HO exhaust and cam. Mine has Hedman headers and a big cam. But the intake noise is intoxicating. I have driven his car, and it sounds great with the foam AC's.


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## Fathead Racing (May 28, 2014)

Update, switched middle air cleaner to one of the ends, (looked cleaner) engine ran smoother. Took the Goat out and at 3000 rpm cruise it still had a chuggle. Removed the middle air cleaner and the engine cruised smooth at 3000 rpm. I am researching air cleaners and pricing. Makes me wonder though, is the center carb over jetted? Center carb is .063 now. Wonder how engine would like say, .061 jet? I'm at 600' above sea level. What is the price difference between the K&N's and the foam Delco's? What # are the AC's?


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## Roger that (Feb 6, 2010)

I would leave your jetting alone for now. See what happens after you buy better filters. If you use the AC 193C's you will also have to get the screens that go with them.

Now I have heard from the grapevine that recently the company that makes these foam filters manufactured them wrong and was not allowing enough air flow. That might be what is happening to your paper filters as well (maybe the same company). Everyone that sells the A193Cs are backordered because of the manufacture mess up of these filters. The only one I know that has some older (pre bad batch) filters is www.pontiactripower.com

Anyway the foam and screens with run you around $70 I am not sure the cost of K&N.


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## Fathead Racing (May 28, 2014)

Roger that said:


> I would leave your jetting alone for now. See what happens after you buy better filters. If you use the AC 193C's you will also have to get the screens that go with them.
> 
> Now I have heard from the grapevine that recently the company that makes these foam filters manufactured them wrong and was not allowing enough air flow. That might be what is happening to your paper filters as well (maybe the same company). Everyone that sells the A193Cs are backordered because of the manufacture mess up of these filters. The only one I know that has some older (pre bad batch) filters is Welcome to Pontiac Tripower | Pontiac Tripower
> 
> Anyway the foam and screens with run you around $70 I am not sure the cost of K&N.


Already ordered the K&N's. Less than 100.00. Thanks for input. I'll keep you informed of my progress.


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## Fathead Racing (May 28, 2014)

*K&N's*



Roger that said:


> I would leave your jetting alone for now. See what happens after you buy better filters. If you use the AC 193C's you will also have to get the screens that go with them.
> 
> Now I have heard from the grapevine that recently the company that makes these foam filters manufactured them wrong and was not allowing enough air flow. That might be what is happening to your paper filters as well (maybe the same company). Everyone that sells the A193Cs are backordered because of the manufacture mess up of these filters. The only one I know that has some older (pre bad batch) filters is Welcome to Pontiac Tripower | Pontiac Tripower
> 
> Anyway the foam and screens with run you around $70 I am not sure the cost of K&N.


K&N's ordered, $98' and change. Auto Zone. Can't thank you enough. Us Chevy guy's (and Pontiac) think we know everything.:STFU:


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## Richard Boneske (Jul 29, 2008)

If you still have "too rich" symptoms with the new air filters, try .061" jets in the center carb. That's what I run in my GTO. Note that stock jets in the automatic '65 GTO are .060". 

I would definitely put .070" jets in the end carbs. They have no effect on drivability or fuel economy, but you will feel an improvement at WOT.


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