DaveP – Spring 2010

What is the difference between Tillotsons?

ChuckK – Spring 2010

DY9B is the early type. It has no fast idle step-up when you pull the choke, the choke is at an angle on the DY9B and it is horizontal on the DY9C. The DY9C has the step up feature. In some cars the choke cable comes out of the firewall high and you need the DY9B for the choke to operate smooth. Other than that not much. I make my DY9C's with larger jets because most are used on the newer engines with the better cranks and will take the higher RPM's. If you have a carb from a generator or something in that line, the carbs look the same but the jets aren't, you will have less power as they are meant to run at 2200-2500 RPM.

Pre-Wars used a DY1, the main difference from DY9 is the main nozzle, 2 holes must be closed, everything else remains the same inside the carb. The flow is adjustable & will be adjusted to a lesser fuel flow. - Chuck's Carbs

Chevy1943 – Fall 2009

I'm amazed that the Crosley never coughs on snapping the throttle open with no accelerator pump. How did Tillotson manage this? No other automobile carbs get away with it but vacuum motorcycle carbs don't have acc. pumps either.

Berard_M – Fall 2009

The Venturi is small, has a high velocity and they run rich to compensate for a simple design.

Chuckk – Fall 2009

Tillotson has what could be call a pump--it operates on engine vac.--that is why you're not to use the gas pedal when starting, it kills the choke system.

CrosWagon – Winter 2009

I just picked up a 49 HS. It was running fine and then wouldn't idle. There is gas coming out of the top of the Carter carb. I switched over to a Tillotson and got it started but again wont idle and then floods out. The gas keep coming into the carb.

PeteB – Winter 2009

There is some trash in the float valve (needle and seat) of both carbs. Not much doubt that there is no fuel filter installed and the tank might need to be flushed. The carbs will have to be disassembled and cleaned. When they're apart, check for fuel in the float itself. Insure that there is a filter as close to the fuel pump as possible so any trash in the lines will be captured before it gets to the pump or the carb. If you still have the original flex hose between the pump and carb get rid of it, because they rot on the inside. When you flex the hose these rubber bits ends up in the float valve.

rwms – Winter 2009

You may need to put a filter on to stop any drit, etc. from sticking the float. I had that same problem before installing a filter.

Chevy1943 – Fall 2009

The Crosley seems to have a problem with flooding after shutting it down when it is hot making it it hard to restart. What ways have been used to fix that? I was thinking maybe there is a way to relieve the fuel pump pressure after shutting down the engine. Maybe drill two tiny holes in the check valves of the fuel pump so the pressure would bleed off after shut down.... I don't like this idea though because the fuel would empty out of the line back to the tank. Maybe I need a new float valve or lower the float level? Thicker gasket to insulate the carb from manifold heat maybe? Ideas please?

Chuckk – Fall 2009

Most common cause is pump pressure---try an old pressure regulator.

Butch – Fall 2009

Check your float level, try a fuel pump heat shield to keep the exhaust manifold heat from the pump, check your fuel pump pressure & as Chuck said you might wish to install a pressure regulator if your pressure is much over 2 pounds.

DO NOT drill any holes in the fuel pump check valves! When we were rebuilding the fuel pumps, leaky check valves caused us more problems than you could ever imagine. I had to come up with some "unconventional" tools to recondition the seats to make them seal. ANY leakage at all, will keep the fuel pump from priming and operating properly. I've rebuilt a whole lot of pumps before we went with the new ones and check valves were the biggest problem I encountered.

Cutworm – Fall 2009

What is the advantage of two carb's instead of one on a stock engine, besides looks?

Crosley19 – Fall 2009

The advantage of 2 carburetors over one, is the engine can breathe easier, but unless you have a higher compression ratio, and a high performance camshaft the 2 carb setup is useless over the single carb, other than it looks neater.