Rough from cold - Thermostat?

#1
Hi

Well my Federal 2000TC does not get too many miles put on but lately it’s really been horribly rough. Usually I put it down to inability to tune it up at my skill level, despite all the attempts over the years but I noticed that the temp needle is struggling to get out of the blue. It’s tricky as I don’t really know my baseline but it used to do really well from cold - or at least cold for here, which is not that cold. And I was quickly at the vertical on the temp needle.

I started up from warm with the rad cap off and I soon, well almost immediately, saw swilling motion in the radiator. The inlet hose location was heated up to about 54C on the metal part of the radiator on that side so I would think the water temp was similar.

When the temp eventually gets into the normal zone the car runs fine.

Is my thermostat knackered? Would be pretty annoying that, as it is only 50 years old. My friend does not have this trouble with his old Model A. Serves me right for buying a modern.....

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#2
the thermostat certainly sound lazy,but not difficult to change- hope the new one lasts as well......!
i'd check your points are clean and correct gap/dwell is correct -if you're still on points .
a cold engine shouldn't be rough regardless of a cooler temp,the two arent really related
neil
 
#3
having noted cold engine ought not run rough .mine does! a 3500 lump and starts easily enough now iv used those metal tablets in fuel tank and added electronic ignition system.
runs as though on 4 pots when cold and if I don't keep a few revs up for around 30 seconds will shutdown on me! all fuel system checked. with new pump. filter. new leads.plugs even a new dizzy ! timing checked .gunson colour check ( when warm) new air filters etc
but when warm ( better when hot) runs like a sewing machine.
thermostat. check with no cap on cold start -get warm(ISH) flow across rad is ok. though now swapped to waterless coolant . if anybody else having same issues and has solved it ? please let us all know. ( carbs also been refurbished )
at least not only one having cold running lump engine regardless where choke is set . only lasts couple of mins though .
 
#4
on your v8 perhaps one of the carbs if full + one not so much??
when you had did test it ,did you have a couple of colourtunes in adjacent plugs so you could see both carb were feeding ALL the cylinders equally? as they cross feed of course....perhaps thats why it seems to be running on half the cylinders?
 
#6
With the choke out it runs OK but without that, there is a lack of power and hesitation. I took pics of the spark plugs after a run and comparing to pics on the internet still left me wondering about the mixture!

But if the thermostat is RIP then the last thing I want to do is start farting around with the carbs. F64D3001-F495-4560-BB12-55AF535C782C.jpeg
 

Demetris

Well-Known Member
#7
You should certainly change the thermostat for a start, but remember an ignition system that gives a weak spark (i.e. old/dirty plugs, worn leads/points/cap/rotor etc), is less tolerant in less than ideal situations like weak mixture and cold start.
 

sdibbers

Well-Known Member
#8
If it walks like a duck (cold temp gauge), and quacks like a duck (choke fixes running) it’s probably a duck (bad themostat). Just be careful of the studs holding the themostat housing as they are thin and can seize then snap when removing the nuts.
 

sdibbers

Well-Known Member
#10
Do the themostat first. See how she does. Then do the coils and leads. That way if something improves and you’ve replaced everything you can’t be sure as to what the fix was.
 
#11
Indeed. I wanted to keep the old leads for originality! But the coil is probably overdue. Let’s see what differences I can observe. The car does VERY few miles, I can’t mention the exact amount as I might be banned for non usage.
 

mrtask

Well-Known Member
#12
Not to worry Adrian, being a committed custodian of a vehicle that doesn't see much use isn't a crime! That said, when you've fixed the present issue, drive it! ;)
 
#14
That's not something going wrong, that's you discovering what's already wrong. Without driving it, you'll never shake out gremlins like that so they'll just multiply, unseen, until...
 
#15
on your v8 perhaps one of the carbs if full + one not so much??
when you had did test it ,did you have a couple of colourtunes in adjacent plugs so you could see both carb were feeding ALL the cylinders equally? as they cross feed of course....perhaps thats why it seems to be running on half the cylinders?
used colour tune in EVERY cylinder . all were blue though couple had a slight touch of flickering yellow . can't find anything wrong as when she's warm she like a sewing machine and idles pretty well at around 650-700 rpms. any slower and she gets a bit lumpy and mild surging on revs.
 
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