Remedial SU 101. Sputtering when accellerating

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esmeby

Remedial SU 101. Sputtering when accellerating

Post by esmeby »

Car has been sitting mostly for a year or so due to 2 kids, and I can't find all my tech files.

I have taken it out 3 times this year, and it sputters a bit when hitting the gas, but evens out when the rpms climb to around 3K.

When idling, if I lift the piston for the front carb, no change. When I lift the rear piston, it sputters and coughs.

So if I remember, one is too rich or one is too lean. I can't remember where to go from here.
esmeby

Post by esmeby »

Ah- all my tech files are at 311s.org

http://www.311s.org/tech/engine/su.html
Redtail

Post by Redtail »

maybe check and make sure the is oil in the domes. that was a problem for me once. and my timing was off.

what's the weather like in MN these days? I'm from Stillwater!

-zack
esmeby

Post by esmeby »

Domes are good, that was the first thing I checked. Fiddled a bit and found the balance was way off, then went back to the first step to adjust the mixture. Hopefully I will get an hour or two in the next few days to try again.

We have had 8 Saturdays in a row with rain at some point in the day, but generally Mondays have been quite nice.
hport

Post by hport »

Most carb problems are ignition related.......I'm an old Jaguar mechanic / restorer of light ( Lucas).

Once the carb's are setup correctly, big word correctly, they stay pretty much in tune. The ignition however, tends to foul and wear much quicker...hence a good ignition solves most carb issues.

Just something to thing about.


JC
twinight
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Re: Remedial SU 101. Sputtering when accellerating

Post by twinight »

esmeby wrote: So if I remember, one is too rich or one is too lean. I can't remember where to go from here.
Try pulling the choke while accellerating.
If it smooths out, you are too lean.
Bungle

Post by Bungle »

I'm with hport. Mine sputters on acceleration - thought it was the carbs so I rebuilt them - although the carbs really needed a rebuild, the real culprit is actually the distributor. Timing is fine at idle, but goes awol at higher revs probably due to too much play in the cam and/or tired springs. Oh that and whatever the hell the vacuum advance decides to do.... I'm bighting the bullet and am going to buy a Garry Boone EI soon. At least that'll be one less thing on the 'to do' list...
esmeby

Post by esmeby »

Roadster gremlins are in my car. I have a Gary Boone Dizzy, so that pretty much rules that out.
But,
I now have a fairly pronounced oil leak at the timing cover/head area, and as I was looking at that, coolant started dripping from the waterpump. damn damn damn. The worst part is, I know they are my fault.
So- I was toying with the idea of a KA24 swap, but money makes that an issue (as well as time). If only there was a kit available with motor/tranny mounts and some wiring diagrams. I would attempt the swap with that. I think something along those lines was available a few years back, but no more.

Instead, I think the cover goes on until this fall, then engine comes out and gets a refresher. Hone, new rings, rear main seal, new chains, gaskets etc. Head will get a once-over. Not a full on restoration build. My father in law is a mechanic so he will be helping me.
My carbs were rebuilt 2 years ago, I have the EI dizzy, and if I read my caliper correctly, my U20 head has never been shaved. So I do have all that going for me.
I will be in Vegas in October and I may need to take a ride in someone's car there to give me the proper motivation to get this done.
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