Sputtering

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Sputtering

Postby Drummerskey » Wed May 11, 2016 4:01 pm

You guys helped so much with the starter and 12v plug, here again.

Carbs adjustment done about a month ago......after more driving than I have done in a short amount of time, along with some aggressive driving keeping up with my brother's AC Cobra (a lot better than I thought I would :), I am getting sputtering at low rpm and sometimes the mid range. I assume I need another adjustment, there is a timing issue or a leak somewhere. Odd I would need another carb adjustment so soon. Thoughts?
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Re: Sputtering

Postby Drummerskey » Wed May 11, 2016 8:09 pm

I did some reading here. My carb and intake stack aren't loose, I check that frequently after my last dilemma. Those gaskets were changed last fall.

The sputtering and what feels like lagging is mainly low rpm, she runs great at high.

Started while driving it on a colder day but it continued on a 65 degree day.

Going to clean the idle jets this weekend.


I don't know what the hose is feeding into the top of the drivers side carb but if I can just take off the top of the air filter, I'd like to check that too
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Re: Sputtering

Postby Larry Jowdy » Thu May 12, 2016 3:39 am

The hose going into your air cleaner just recycles fumes from your engine case.

You're on the right track, clean the idle jets. Go here for more information http://www.spyderclub.com/viewtopic.php?f=19&t=8411
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Re: Sputtering

Postby RVosari » Thu May 12, 2016 6:21 am

Keep in mind that if you bury the throttle (quickly at low RPM) you most certainly will get "sputtering"...the motor will not take full throttle at low RPM...either feed in the gas slowly or shift down to a lower gear [8D]

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Re: Sputtering

Postby Larry Jowdy » Thu May 12, 2016 7:18 am

I have to disagree with the "sputtering" statement. I've tuned Weber's to the point that you can stab the throttle from idle to maximum butterfly opening with only a microsecond of hesitation.
Rough running below 3,000 RPM's is usually dirty idle jets. Once above 3,000 RPM give or take, the main jets take over delivering fuel
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Re: Sputtering

Postby RVosari » Thu May 12, 2016 7:36 am

Larry...so you are saying that on a 2 liter Type 1 motor you can floor the throttle (in gear) at 2000 RPM in 3'd or 4th gear and it will walk-up the RPM scale like a fuel injected motor without audible distress :-k

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Re: Sputtering

Postby Larry Jowdy » Thu May 12, 2016 7:42 am

Yes. Provided the jetting is correct, the carbs are adjusted properly and the left and right carbs are sync'd. it's a matter of fine tuning the accelerator pumps.
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Re: Sputtering

Postby Drummerskey » Thu May 12, 2016 7:50 am

Larry, If I bought you a plane ticket and say.....a ham sandwich to sweeten the pot, would you like to spend a few weeks fine tuning my car :)
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Re: Sputtering

Postby Larry Jowdy » Thu May 12, 2016 9:34 am

A 12" carver turkey sandwich from Subway would probably do it.
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Re: Sputtering

Postby RBP » Thu May 12, 2016 10:53 am

Most people run too large a jet in the idle circuit. What size jet are you running right now? Have you pulled out the main stacks and drive it around on just the idle circuit? If so how did it run? At what point did the engine fall down? If you have an A/F Ratio gauge and you are running a standard distributor then ideally you want to be at mid 12 to mid 13 at idle, mid 13 at low load cruise (3rd gear 2500 RPM) and high 12's to low 13's at hard pull WOT.
Last edited by RBP on Thu May 12, 2016 2:40 pm, edited 1 time in total.
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Re: Sputtering

Postby RVosari » Thu May 12, 2016 11:30 am

If by correct jetting, you mean a 30mm choke and a .9 main jet and 110 air corrector maybe you can make the car tractable...but you will be down 25 HP from ideal !

Most of the spyders I have seen have a short 3 1/2" throttle throw vs. 6 or 7 inches on a Ferrari or Lambo. So...you get a very sensitive throttle that people may not be used to hence the problem. After all these are not constant depression (SU, Stromberg) type carbs.

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Re: Sputtering

Postby Drummerskey » Thu May 12, 2016 11:54 am

RBP wrote:Most people run too large a jet in the idle circuit. What size jet are you running right now? Have you pulled out the main stacks and drive it around on just the idle circuit? If so how did it run? At what point did the engine fall down? If you have an A/F Ratio gauge and you are running a standard distributor then ideally you want to be at mid 12 to mid 13 at idle, mid 13 at low load cruise (3rd gear 2500 RPM( and high 12's to low 13's at hard pull WOT.



uhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh. :)

She has been running really well for the past few months. I ran her for about an hour straight and the last 20 minutes was pretty aggressive with quick acceleration and 85mph top out (fastest I have gone in the car since I bought it). As stated, my older brother was running his AC Cobra and I was following, keeping up with him better than I thought I would with plenty of room left (although I know he still has more than I did). It was a mid-50's day and I chalked it up to cold weather. I took it home afterwards (2 hours with freeway and side streets) on a mid 60's day and it was still felt laggy. My brother drove it and said the same, lagging a bit on low rpm but great at high.

Just changed the oil to Brad Penn Racing (not sure what was used before) and the carbs were just adjusted in early April.

p.s. I get way better gas mileage than I thought I would. An hour of back roads with few stops and I was only down 2 gallons at refill.
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Re: Sputtering

Postby BB73 » Thu May 12, 2016 12:35 pm

Hey Drummerskey, what number Beck do you have?

I have 865
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Re: Sputtering

Postby Drummerskey » Thu May 12, 2016 1:26 pm

774.

Are you hanging out Downriver? Those are my old stomping grounds.
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Re: Sputtering

Postby RBP » Thu May 12, 2016 2:45 pm

Glad your car is running the way you like it, that's really what matters. Your car may have been sorted out for jetting by the previous owner.
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