[Fot] Stutter at 4K rpm

[Duncan Charlton]

Derek,
I’m not sure the fuel in that location tells you much.  With some carbs you can see a fuel/air fog standing in the trumpets and this can condense and be visible as droplets when you have the engine stopped.

Duncan Charlton
Elgin, Texas USA



> On Oct 15, 2016, at 10:51 PM, D V <explore8 at outlook.com> wrote:
> 
> Thanks everyone for the replies. I will inspect the pipe to manifold and manifold to head to see if anything is loose or any leaks apparent in the morning.
> 
> I actually went down a main jet 145 to 140 and that seemed like it helped some but didn't clear up the issue (which is going leaner; opposite of what Greg said). 
> 
> It is missing and backfiring when I am full on the gas. I can prevent it by easing into the gas.
> 
> I did notice some gas at my air cleaner to velocity stack connection. I wonder if it is a float issue?
> 
> 
> Sent from my iPhone
> 
> On Oct 15, 2016, at 7:35 PM, Greg Blake <gblake58tr3 at icloud.com <mailto:gblake58tr3 at icloud.com>> wrote:
> 
>> Don't know if my other email made it to you. Backfires on deceleration can be a lean condition. Have you checked your plugs?  Maybe something got "adjusted" with the bump. 
>> 
>> Sent from my iPhone
>> 
>> On Oct 15, 2016, at 12:27 PM, D V <explore8 at outlook.com <mailto:explore8 at outlook.com>> wrote:
>> 
>>> 
>>> 
>>> Sent from my iPhone
>>> 
>>> Begin forwarded message:
>>> 
>>>> From: <explore8 at outlook.com <mailto:explore8 at outlook.com>>
>>>> Date: October 15, 2016 at 10:30:51 AM CDT
>>>> To: <fot at autox.team.net <mailto:fot at autox.team.net>>
>>>> Subject: Stutter at 4K rpm
>>>> 
>>>> Two races ago I went off track and bent my exhaust pipe enough to break the welded joint near the muffler. In the interest of time, I cut the exhaust at the muffler and secured the pipe to the frame.
>>>> 
>>>> At the last race, I noticed the car would backfire at deceleration which I am not surprised but I also noticed a stutter around 4-5k rpm. 
>>>> 
>>>> At NOLA this weekend it is more pronounced and comes in when shifting hard from 3rd to 4th. After 5k, it clears up and pulls normally.
>>>> 
>>>> It doesn't seem to be affected by turns and more related to full throttle vs easing into the gas.
>>>> 
>>>> Backpressure from the loss of muffler or unrelated issues?
>>>> 
>>>> 1300 spitfire with single Weber 40.
>>>> 
>>>> Sent from my iPhone
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