• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

ZS Question for 76 1500 midget

Tipsy

Senior Member
Offline
Yesterday I topped off my Zenith Stromburg carb with 20w50 oil and it made it hesitate and chug a bit. So I got as much of it out and replaced it with some household oil which I'm thinking is too thin? Probably should switch to a straight 20 or 30 weight. But here's my question, It started and ran fine and I headed to the gas station to fill up my tank. Only a mile or two from home. After I filled it up it would not start for the longest time. This has not happened before. Is it because of the too thin oil? Or did I maybe just flood it?
Thanks!
Jeff
 

JPSmit

Moderator
Staff member
Silver
Country flag
Offline
Most likely you flooded it. Oil in the damper will affect acceleration but shouldn't impact starting. BTW, automatic transmission fluid seems to be a sweet spot for viscousity.
 

Morris

Yoda
Offline
I had a lot of issues with the float getting stuck on my ZS. This problem would typically manifest itself after a short drive.... which is probably just coincidental... but it's probably worth checking out.

Also... a worn or poorly seated float needle can make for very hard starts.

Annnnnd.... I think the ZS is not so easy to flood as it does not have an accelerator pump. But I am frequently wrong.

Regardless, probably has nothing to do with the damper oil.
 
OP
T

Tipsy

Senior Member
Offline
Found a large three part article about rebuilding ZS carbs that I researched when I rebuilt mine last year and it says "if there is no oil (in the damper)the engine will start with difficulty and will not accelerate quickly". I took this as possibly meaning that a very thin oil, which could act like no oil at all, might make it difficult to start. So this morning I replaced the very thin oil I had put in the day before and replaced it with 30w I had used in the past as I did not have any ATF handy. Seems ok for now but I'm gonna guess that I probably flooded it. Normally I don't need to touch the pedal when it's been started and warmed up in the summer but this time I accidentally hit the pedal before starting it. So it's possible I flooded it that way. yes, no acc. pump but still possible to over do it.
 

dklawson

Yoda
Offline
Everyone has their own preference for what weight oil to use in the damper. It is a discussion I cannot really add to. However, for future reference and spares to carry in the boot, 3-In-1 oil is convenient. The "blue" bottle is 20W, the "red" bottle is 30W.
 

nomad

Yoda
Offline
On SU's I seem to remember reading somewhere that if you are having a lean miss on acceleration that it may be helped by using heavier oil in the dash pots. Want quicker pickup use thinner.

Never did a comparison.

Kurt.
 

StarkM

Freshman Member
Offline
On the 1500 with water choke (automatic choke) it is very hard to flood. As Morris said, these do not have an accelerator pump. The starting procedure for these 1500's and MGB's with the auto choke is this: Depress the accelerator to the floor once, then crank engine. By doing so you are setting the choke (essentially pulling the choke cable out), as the engine warms up, the coolant flows through the choke body warming the spring that gradually reducing the amount of choke until it is completely off. Pumping the pedal causes the choke to be set and released, it does not spray gasoline into the carb.

As for the dashpot oil, the official weight is SAE 20W/50. We do sell dashpot oil, which is SAE 20, however, I too have used ATF with success.
 

reddsprite

Senior Member
Offline
I use motorcycle fork oil (20 wt) and it seems to work fine on my twin SU HS2's-I have never had any problems with this setup
 
OP
T

Tipsy

Senior Member
Offline
Thanks for all the input! Mine is a manual choke which I have not had since my first car back in the 70's hen I was a teen. But I only drive the midget in the summer as it has no heater. And I rarely choke the carb. It always starts cold with a pump of the pedal one time and usually no pedal needed after short warm up. So I believe I should not have pumped it at the gas station but maybe i'm wrong? If there is no accelerator pump then what introduces the gas to the carb? I'll have to go back and read the article again as it explains the science of the ZS carb.
 

bthompson

Jedi Warrior
Offline
If you have a manual choke, then pumping the pedal before cranking does jack-diddly-nothing. The gas is introduced purely by venturi under the cylinder and past the needle. The choke is nothing but a progressive air bleed in front of the butterfly, which reduces the vacuum over the piston. The piston sits lower, the orifice is smaller, the air flows faster past the needle and sucks more gas through. Voila. That's why with a ZS it's crucial to have a perfect vacuum...any leak will drive the system richer. You may have a combination of worn needle and manifold leak...it'll run rich enough to get ya started, but when the engine heats up and you try to restart, it's too much juice and floods out. Been there!
 
OP
T

Tipsy

Senior Member
Offline
Thanks Bill! It's beginning to make a bit more sense now. the needle is brand new recently with the carb rebuild. Manifold leak is another story. New exhaust/intake manifold gasket at carb rebuild time as well. But because of location of studs couldn't torque the nuts properly. Did my best but it's possible it could he a leak there. Have not checked head bolts if that's where you're talking about vacuum leak.
Jeff
 

JPSmit

Moderator
Staff member
Silver
Country flag
Offline
Tipsy said:
Thanks Bill! It's beginning to make a bit more sense now. the needle is brand new recently with the carb rebuild. Manifold leak is another story. New exhaust/intake manifold gasket at carb rebuild time as well. But because of location of studs couldn't torque the nuts properly. Did my best but it's possible it could he a leak there. Have not checked head bolts if that's where you're talking about vacuum leak.
Jeff

Jeff, I also had an issue where my manifold needed re-tightening - took awhile to figure that out.

Also, while you really can't torque the bottom studs, everyone I know with a 1500 has their special bent wrench to tighten it. Have you made yours yet? I can post a pic of mine though every shape is unique.
 
OP
T

Tipsy

Senior Member
Offline
JP! No I have not bent one. This is my first time with the manifold. Please show a pic!
Thanks!
Jeff
 

JPSmit

Moderator
Staff member
Silver
Country flag
Offline
Tipsy said:
JP! No I have not bent one. This is my first time with the manifold. Please show a pic!
Thanks!
Jeff

this is mine - Pic two is how I get torque on it.

2012-08-18131556640x480.jpg


2012-08-18131659640x480.jpg
 
OP
T

Tipsy

Senior Member
Offline
JP Thanks! I knew I needed something with a bend in it. Can I get enough heat with a MAPP gas torch or do I need something hotter? I'll have to experiment.
Thanks again everybody.
 

JPSmit

Moderator
Staff member
Silver
Country flag
Offline
Tipsy said:
JP Thanks! I knew I needed something with a bend in it. Can I get enough heat with a MAPP gas torch or do I need something hotter? I'll have to experiment.
Thanks again everybody.

I just bent that one in a vice. Otherwise bring it to a muffler shop, they'll be happy to help!
 
OP
T

Tipsy

Senior Member
Offline
OK So now I'm beginning to wonder if this issue could be the result of my fuel pump? Today I went to the hardware store and when I came back out 5 minutes later I had the no start problem again. It starts just fine the first time at home in my garage, then I go somewhere on a short trip and when I come back out to leave it wont start. I recently replaced my extremely noisy unknown name brand fuel pump with a Mr. Gasket import car pump. Much quieter and seems to handle everything fine except maybe this. I know some folks on this forum are saying the Mr. Gasket pump is junk and others say it's just fine. Everyone has their personal brand preference. This was what was available locally for me so I thought I would take a chance on it. Maybe I should change my filter that is down below the carb? There is another filter before the pump as well. The filter before the carb is a couple years old and I don't get much mileage on it. But it was all functioning well before the pump changeover. JUST NOISY! And the old pump is gone to the trash weeks ago so no chance of putting it back on. As I said before, the carb was just rebuilt last fall with a new needle too.
Anybody got any ideas?
 

Morris

Yoda
Offline
It could be your pump overdriving your float... but I still think you should double check the needle, the float and the float level. Lowering the float level could do the trick.

Next time it is difficult to sart, pull the air filter and stick your finger in the throttle body and see if it comes back wet with fuel. This won't sort out whether it's the pump or the float, but it will tell you that flooding is the problem. After all 90% of all carb problems are ignition problems. :wink:
 

JPSmit

Moderator
Staff member
Silver
Country flag
Offline
I think it unlikely to be the pump. Either pumps work or they don't. It could be a clog but they typically happen while driving and clear up while parked as things fall to the floor. Do change your filters as they are cheap! What colour are your plugs? Could you be running very rich and soaking them?
 
Similar threads
Thread starter Title Forum Replies Date
tosoutherncars Midget 1500 radiator question Spridgets 11
JPSmit Cooling System Question -1500 Midget Spridgets 3
G 1500 Midget Heater Valve Question Spridgets 21
R 78 1500 Midget Trans Question Spridgets 2
G Midget 1500 Water Pump / Fan Clutch Question Spridgets 6
77_MG_Midget Rack & Pinion Steering question, 1500 midget Spridgets 2
G 1500 Midget Clutch & Transmission Question Spridgets 7
77_MG_Midget Midget 1500 Brake Question Spridgets 14
R Spitfire 1500 gearbox question Triumph 1
R 1500 gearbox question Spridgets 0
JPSmit 1500 slave cylinder question Spridgets 0
S Spitfire 1973 Spitfire 1500 Dashboard question about warning light Triumph 3
frankenstang57 Sorta odd 1500 question... Spridgets 4
regularman another 1500 question Spridgets 10
F Spitfire Spitfire 1500 - Stromberg CD 150 Question Triumph 9
JPSmit 1500 Clutch hose question Spridgets 8
F Spitfire Spitfire 1500 Electrical Question?????? Triumph 4
G 1500 dual SU/ DCOE throttle cable question Spridgets 5
G 1500 euro carbs interference question Spridgets 5
Thor Reduction starter question for 1500 Spridgets 0
jvandyke noobie 1500 starting question Spridgets 4
M 1500 question. Spridgets 7
D Triumph 1500 Question... Triumph 3
JodyFKerr Spifire 1500 Carb teardown question Triumph 10
frankenstang57 Spitfire Spitfire 1500 fast road cam question Triumph 4
JPSmit 1500 Tranny Question Spridgets 8
JPSmit 1500 vacuum question Spridgets 21
JPSmit 1500 thrust bearing question Spridgets 10
tosoutherncars 1500 tuning question Spridgets 2
tosoutherncars Quick question - 1500 wiring for coil Spridgets 7
B New Memeber 1500 trans in question Spridgets 4
ahpook 1500 Weber/Pierce install question Spridgets 3
SilentUnicorn 1500 SU Conversion Question Spridgets 10
budk1953 1500 transmissiom Question Spridgets 8
S 1500 CLUTCH QUESTION. Spridgets 4
77_MG_Midget Triumph 1500 Motor Oil pressure question Triumph 8
ahpook 1500 ZS carb question Spridgets 4
G 1500 Oil Filter Question Spridgets 6
J question about a 1500 heater valve? Spridgets 13
J another 1500 engine question Spridgets 4
J 1500 engine question Spridgets 4
77_MG_Midget 1500 camshaft question Spridgets 6
DonC1948 TR6 A "CLASSIC" question. Triumph 6
71TR6 TR2/3/3A A TR3A wiring question Triumph 17
K TR2/3/3A Cylinder Head Bolt question.... Triumph 3
scottkilpatrick TR4/4A TR4 Rear Brake Drum Removal - Basic Question Triumph 16
scottkilpatrick TR4/4A Gear oil and choke question Triumph 4
B TR2/3/3A TR3A Gearbox fluid capacity question Triumph 7
D TR2/3/3A TR2 Flying Mile question Triumph 11
M New Member with an HD8 Carb Question Austin Healey 1

Similar threads

Top