Sputtering

bugedd

Jedi Knight

Offline

• Jun 28, 2017

• #1

Hey all, hoping I could get some advice on the car sputtering. Last winter I took the HS4's off the car to replace the header, pretty remedial. I put it all back together and I seem to get some sputtering where I never had it before. The car did sit for some time, we had a wet winter, then it went from rain to 112 degrees. So the car had only been driven half a dozen times this year. Anyhow, it did it very lightly, more like just cutting out at higher revs with my foot in it. Yesterday I took it out and under moderate acceleration it hacked pretty bad, then it would clear up and drive fine, then accelerate and it would hack. Guessing carbs as its not consistent, and the idle, start up, and steady throttle are smoooooth. The gas is new....thoughts of what to check?

 

Bayless

Yoda

Silver

Offline

• Jun 28, 2017

• #2

Have you checked the oil in the carb dashpots?

 

OP

bugedd

Jedi Knight

Offline

• Jun 28, 2017

• #3

I have not, not really familiar with that. Can you tell me what to look for? Sorry for my ignorance, had a Weber DCOE on my last car, not too familiar with SU's.

 

AN6-TX

Jedi Hopeful

Offline

• Jun 28, 2017

• #4

Reference found about halfway down the page - https://britishclassicmotors.com/3301.html

Video reference here - https://www.youtube.com/watch?v=ATLri-V0Dpw

 

OP

bugedd

Jedi Knight

Offline

• Jun 28, 2017

• #5

K, checked that out, topped them off but they needed very little. Took it out for another drive to be more precise on the issue. At WOT the car pulls fine to 5k no worries. Put it in 5th at 30mph and load it up and the issue comes up from lets just say idle to about 2200 revs. Beyond that it clears up. So loaded up at low revs. Maybe ignition after all? Car has Pertronix just to add that in.

 

histerical

Jedi Hopeful

Offline

• Jun 28, 2017

• #6

Take a look at all ignition parts. Dist. cap, center contact, plug wire connections ( both ends). Electrical can act that way under load and seem fine otherwise.

 

Joe Schlosser

Jedi Warrior

Silver

Offline

• Jun 29, 2017

• #7

double checking, car was running fine. The only thing you did was to remove carbs, replace header, reinstall carbs? Nothing else was touched. Did you separate the carbs during the work?
Now Car "loads up" in 5th at 30mph. engine clears up after hitting about 2200 revs.

 

Bayless

Yoda

Silver

Offline

• Jun 29, 2017

• #8

While I agree that weak ignition components can cause a similar symptom, yours still sounds like a lean mixture to me. Check that oil again. If it is something thin like sewing machine oil then it isn't doing anything. You have to hold those pistons down a bit under acceleration in order to richen the mixture. Otherwise you get the exact stumbling you described. Another thought. If you had the carbs off then you may have introduced a vacuum leak that could produce a similar problem.

 

OP

bugedd

Jedi Knight

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• Jun 29, 2017

• #9

Thats right Joe, and no the carbs were not separated, but they were pulled from the manifold of course. I did hit all the gasket areas with carb cleaner to see if I could find a vacuum leak, no change in idle, so nothing big at least.

 

JPSmit

Moderator

Staff member

Silver

Offline

• Jun 29, 2017

• #10

the other thought I have is ethanol - what gas do you use? the car sitting with ethanol in the floats can gum things up very quickly.

 

Joe Schlosser

Jedi Warrior

Silver

Offline

• Jun 29, 2017

• #11

My rule is that it is the last thing you touched.
Agree with Bayless that it sounds like lean mix. it runs OK at 5000 in lower gears buts misses under heavy load.
Are you getting full throttle?
Make sure the pistons are moving down freely. The piston should drop pretty hard to the bottom of the carb with a lout click
If you laid the carbs on their side you could have spilled some of the dashpot oil into the chamber. That can sometimes cause the needle assembly to act sluggish and lean.
If you took off the air cleaners make sure that the small hole on the side of the carb is not covered by a gasket or anything.

 

SD Bugeye

Jedi Warrior

Offline

• Jun 29, 2017

• #12

Leaking gasket on the intake between head and intake Or carb and intake
probly runnig a little lean.
try spraying some starter fluid or carb cleaner around the gaskets to check
you would get a change in rpm or exhaust note.

 

OP

bugedd

Jedi Knight

Offline

• Jul 2, 2017

• #13

Looks like I found it, hit the outer ends of the throttle body shafts with carb cleaner and its enough of a leak on either end that it killed the car. Time to look into having the HS4's rebuilt. Suggestions?

 

Joe Schlosser

Jedi Warrior

Silver

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• Jul 3, 2017

• #14

The last thing you touched rule

 

D

dcarlg

Jedi Trainee

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• Jul 5, 2017

• #15

Replace the worn shaft?

 

OP

bugedd

Jedi Knight

Offline

• Jul 5, 2017

• #16

there was some hack work done to make HS4's work on the car, including linkage. Thinking I'll have a pro sort it out, just need to find the right one. In the mean time, cover the car and don't worry about it.