E-Bodies.org Cuda Challenger Forum

Technical Shop => Engine, Transmission & Rear End => Topic started by: Fern on December 13, 2018, 03:19:55 PM

Title: How to make the exhaust smell less??
Post by: Fern on December 13, 2018, 03:19:55 PM
So I have researched this for a long time now. I can't find any good answers.  Is there a way to lessen the gas smell so you don't stink after driving these cars. I have a 440 (low comp motor) with a Hughes cam (whiplash ) it has a good loppy idel  and it tuned for best vacuum (per holley avenger carb specs).
I looked into efi but don't know if that will help.
Any one know any better ideas??
Thanks
Title: Re: How to make the exhaust smell less??
Post by: Cuda Cody on December 13, 2018, 03:31:44 PM
Yup, it comes down to carb and tuning.  Compression, cam, timing and jet size all play a factor.  You might have a dyno shop try tuning it so they can adjust things as they read the exhaust while under load on a dyno.
Title: Re: How to make the exhaust smell less??
Post by: shawge on December 13, 2018, 03:39:22 PM
Here is where I think a wide band O2 sensor would come in handy.
Title: Re: How to make the exhaust smell less??
Post by: GoodysGotaCuda on December 13, 2018, 03:46:18 PM
Quote from: shawge on December 13, 2018, 03:39:22 PM
Here is where I think a wide band O2 sensor would come in handy.

Yep, the best $150 you can spend as a carb owner.
Title: Re: How to make the exhaust smell less??
Post by: 7212Mopar on December 13, 2018, 04:03:47 PM
Fuel injection and catalytic converters.
Title: Re: How to make the exhaust smell less??
Post by: Cudajason on December 13, 2018, 05:28:41 PM
Quote from: GoodysGotaCuda on December 13, 2018, 03:46:18 PM
Quote from: shawge on December 13, 2018, 03:39:22 PM
Here is where I think a wide band O2 sensor would come in handy.

Yep, the best $150 you can spend as a carb owner.

:iagree: :iagree: :iagree:

Its amazing what that will reveal!!!

Jason
Title: Re: How to make the exhaust smell less??
Post by: bennydodge on December 13, 2018, 06:27:55 PM
If the cam has a lot of overlap it will stink even with fuel injection. If your clothes stink, a sharper carb tune will probably help. My 870 avenger (4 corner idle) took a lot of fiddling and it still smells a little. My 750 street demon also smells some too. More timing may also help.
Title: Re: How to make the exhaust smell less??
Post by: 71-440 on December 13, 2018, 07:55:19 PM
I never noticed my clothes smelling and I thought my car stunk...... lol.
My buddy had that problem with his 65 tempest. Big block,cam etc. He had to dial in the carb and timing so it wasn't running so rich. He went back and forth several times till he got it right.
When he was done it smelled better and ran better.




Title: Re: How to make the exhaust smell less??
Post by: jimynick on December 13, 2018, 07:55:28 PM
The smart ass in me wants to say "then just don't drive it so much" Sorry  :crazytalk:
Title: Re: How to make the exhaust smell less??
Post by: BIGSHCLUNK on December 13, 2018, 09:23:19 PM
I had "gas" smell issue for awhile. As I recall, my secondary throttle plates (750 HOLLEY DP) were not properly adjusted. Once that was done properly the smell was gone..
Title: Re: How to make the exhaust smell less??
Post by: Cudakiller70 on December 13, 2018, 09:39:08 PM
I have wanted to try one, would MSD multi spark help?
Title: Re: How to make the exhaust smell less??
Post by: 303 Mopar on December 14, 2018, 06:42:00 AM
Cheapest route would be a good carb tune and/or O2 sensor.  More expensive route is Sniper EFI which would also increase throttle response and quick starts.
Title: Re: How to make the exhaust smell less??
Post by: RUNCHARGER on December 14, 2018, 07:01:45 AM
Yup: O2 and a nice tune or EFI. I find most people tend to run carbs too rich on choke and warm driving/idle.
Title: Re: How to make the exhaust smell less??
Post by: Cudajason on December 14, 2018, 07:04:19 AM
Do you have your vacuum advance hooked up???
Title: Re: How to make the exhaust smell less??
Post by: Cuda_mark on December 14, 2018, 07:32:25 AM
I kind of like smelling like big block exhaust fumes. The chicks dig it too....I think.
Title: Re: How to make the exhaust smell less??
Post by: js27 on December 14, 2018, 08:53:42 AM
I have the same problem. Doesn't smell rich or smoke but go for a cruise top up or top down it doesn't matter my clothes stink. I never had that problem with any other Mopar I had. It is a 440 with a Lunati 507 cam -Holly 750 DP-MSD Pro Billet Dist with coil and 6A Box. I am not a great tuner but will look into some the suggestion here. Please let me know if you fix the problem-in the mean time my wife will keep busy washing my clothes-LOL.
JS27
Title: Re: How to make the exhaust smell less??
Post by: Fern on December 14, 2018, 01:59:15 PM
Quote from: Cudajason on December 14, 2018, 07:04:19 AM
Do you have your vacuum advance hooked up???

I do have the vacuum advance hooked up.
Unfortunately there's not a dyno shop near by to tune it properly.
The holley 770 avenger only gives instructions to tune by best vacuum at idel. There's only 2 adjustmet screws.
O2 sensor sounds like a good idea, was trying to keep costs down since I would like to do a modern hemi swap some day.
Title: Re: How to make the exhaust smell less??
Post by: Cudakiller70 on December 14, 2018, 03:51:04 PM
What do your spark plugs look like? Both a lean and rich condition can have a gas smell.
Try setting your timing by the vacuum method? I haven't done this yet, but sounds like it's worth a try.
Title: Re: How to make the exhaust smell less??
Post by: Topcat on December 14, 2018, 07:42:20 PM
Quote from: jimynick on December 13, 2018, 07:55:28 PM
The smart ass in me wants to say "then just don't drive it so much" Sorry  :crazytalk:

Or just drive faster, all windows down.   :haha:
Title: Re: How to make the exhaust smell less??
Post by: HP_Cuda on December 14, 2018, 10:05:53 PM

JS

If that is an MSD Blaster 2 coil you don't want to mount it horizontally on the intake. They are meant to be mounted vertically and eventually fail on you that way.

Anyway, I have an LM-2 AFR o2 setup on my christmas wish list  - cannot wait!!  :banana:
Title: Re: How to make the exhaust smell less??
Post by: Cudakiller70 on December 14, 2018, 10:24:12 PM
Good catch on the coil, maybe spark has been degraded?
Title: Re: How to make the exhaust smell less??
Post by: HP_Cuda on December 14, 2018, 10:32:38 PM

Possible. Easy to change out and see but pulling the plugs will also tell you how rich its running.
Title: Re: How to make the exhaust smell less??
Post by: Fern on December 15, 2018, 09:17:47 AM
Quote from: HP_Cuda on December 14, 2018, 10:05:53 PM

JS

If that is an MSD Blaster 2 coil you don't want to mount it horizontally on the intake. They are meant to be mounted vertically and eventually fail on you that way.

Anyway, I have an LM-2 AFR o2 setup on my christmas wish list  - cannot wait!!  :banana:

I have a flame thrower coil with 4 seconds flat hrr688 ignition.
Will pull plugs next.
Thanks