Carb Problems?

Brigand

Silver forum user
Messages
69
Ever since I have owned my Tiger the car has suffered with stuttering at high revs/load. It is fine below around 4000rpm/three quarters throttle.

I've changed most components on the ignition and fitted a new Holley 1850s carb. It has a 289 with a Torquer 289 inlet manifold.

Today the car started running very badly to say the least: it was barely drivable and wouldn't idle below 3000rpm. But, the running problems at high revs disappeared, I mean the car went like it has never gone before over 4000rpm. I was changing up at 5200rpm (an engine speed I've never managed to attain) for fear of damaging the engine, even though it was still pulling well.

When looked into why the car was running so badly at lower revs the cause was obvious. I had wired the manual choke mechanism on the Holley open and this had come loose, allowing the choke flap to cover the primary barrels so basically I was just running on the secondary barrels.

So I'd be very grateful if anyone could tell me why was the engine running so well at high revs on just the secondaries.

Thanks
 

hottigr

Gold forum user
CAT Member
Messages
816
wild guess

If it ran better with the choke covering, the carb might need to be leaned out...Kirk
 

Forrest39

Gold forum user
CAT Member
Messages
406
Putting and air fuel ratio sensor in would be very useful. Also, two often overlooked settings that can have a huge impact are fuel pressure and float level.

Have you changed main jet size? Pump cam? Pump nozzle?

There are a number of variables to consider once you have eliminated ignition settings as a potential problem.

Good luck! -Kevin
 

TAH_Tiger

Gold forum user
CAT Member
Messages
274
Holley 1850 carb

I had the same problem with this carb. Settings from factory are set way too rich and secondary jets had to be replaced to smallest possible. The carb is set up for the average 3500 lb vehicle which the Tiger is not.
 

Mark Adams

New forum user
Messages
1
I’ve heard this is a common problem for these cars and those carburetors. Like the poster above, I’d also suggest putting in an air fuel ratio sensor.
 
Last edited by a moderator:

TigerBlue

Gold forum user
Messages
827
Help

There is a lot of mistaken help on this thread.

1. Fuel air mixture is not affected by or changed in anyway by the weight of the car.

2. Choking makes the mixture very rich for cold starts. If it ran better when choked it was too lean.

Rick
 

hottigr

Gold forum user
CAT Member
Messages
816
Backwards thinking?

O.k., the car ran well with the primaries covered by the choke plate and the secondaries wide open. The primary side would still be squirting gas, even with the air restricted, and the car ran well at high rpm's. The venturi effect on the primary side would be limited or not in effect at all because of the lack of air. Yet, with the choke plate open on the primary side, the car would not rev, leading me to believe that the mixture was too rich when it was getting the proper amount of air. The venturi effect made the car run worse. Or, I could have it all backwards...
 
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