Sputtering/warmish Running BN1

[Gray_Cat]

Thought I had the rebuilt carbs on my 55 BN1 balanced, etc. but an extended drive told me different. Fires right up with full choke, cold and I get ok acceleration but when I level off at cruising speed (be it 5 mph or 50 mph) the car sputters constantly (no backfire). Plug inspection shows all gaps are right and the insulator is light gray in color. Sorry, I didn't write down the plug info, they are Champions - recommendations for plugs? It also runs warmer than I think it should as it was only in the high 70's this AM in LA and the temp showed 210 after a couple of miles of surface street driving. I installed a new 160 degree thermostat (sleeved type), have added water wetter and the coolant to water ratio is 50% and made certain the radiator was topped up before driving.
Haven't checked the timing yet, will do so after reviewing replies. As always, many thanks for your help! Then I gotta trouble shoot the OD and see why that doesn't work.... /ubbthreads/images/graemlins/cheers.gif

 

[Dave Russell]

Sorry you are having problems,
The plugs should be B6ES or equivalent & gapped at .025".
It sounds a if it may be running lean. This would possibly cause it to run hot also.

If it is a lean problem, pulling the choke all the way, when it is sputtering, should improve the situation. If it gets worse, the carbs are likely too rich.

Not sure what may be in the "rebuilt" carbs. If you have the standard H4 carbs with 1.5" bores, The float level should be 7/16" measured between float arm centers & carb lid, the metering needles should be "QW", & main jets .090". Make sure that the carb needle shoulders are seated flush with the bottom of the pistons/air valves.

Vacuum leaks at the manifolds or carbs could also cause a lean condition. The drain tubes on the bottom of the intake manifolds should be very small diameter & around 13" long. If the tubes are missing, make sure the manifold holes are plugged.

Timing that is way retarded could possibly cause the problem, as well as the overheating. Just for drill, check the point gap to be about .014"

One last question, maybe should have been first: How did it run before the rebuilt carbs & have you changed anything else?
D

 

[Gray_Cat]

Thanks Dave! I will check out the items you advised and make certain the gaps are right all around. Actually the car ran great before the carbs were rebuilt (they are the originals) and I didn't touch anything else at all (limits the diagnosis for me). The car ran a bit on the warmish side then too. The carbs were rebuilt because they leaked everywhere, I'm surprised the car didn't catch fire - that's how bad they were leaking. It does start easily, 1 push of the button and it goes. I will try enriching by choke and take my next step after that. It's so much fun driving this car - people stop in the crosswalk to ask about it. Some in cars have followed me until they can talk to me about it and in general brings a smile to everyone's face! Best Regards Roy /ubbthreads/images/graemlins/cheers.gif