Marc Greenleaf Jr

I have a 440 RR with the 1406 on it. It runs great under normal running conditions. However, when I put my foot into it at about 4500RMPs the carb is breaking up. It sounds as if it is running lean, almost like a back fire. I've gone through the entire fuel system from tank to carb replacing the hoses, filters, and even installing an electric fuel pump with 5.6lbs of pressure. Still have the same issue.

Any thoughts?

fivepoint

Has the carb been tuned to the motor? Has the ignition system been checked. You didn't say if this problem just started. If you are sure it may be running lean, maybe a stage or two richer on the metering rods will help.

440roadrunner

I would not assume this is the carb, could be ignition, or valve troubles. What do the plugs look like?

MercuryDon

If the carb is not giving enough fuel it will behaive like you are running ou of gas. Misfiring is most likely an ignition problem. Weak coil maybe. Stock 440s mount the coil on its side and quite frequently lose the oil that is a coolant. A loss of this oil will cause the coil to go bad.

Marc Greenleaf Jr

I just purchased the car and am in a learning curve. The engine was fully rebuilt about 2K mi ago. It has a slight competition cam, not sure exactly what, but recall being told it was light cam. I'll be checking with the builder tomorrow. Not certian if it has just started, as I had to replace all the hoses, filters and put an electic fuel pump in it. The old pump wouldn't continuosly pull fuel.
The car starts and drives perfect even when matting the throttle, until it reached high RPM's. Then it pukes and sounds almost like a backfire.
I'll pull the plugs and see if they are white, brown or black. That should help determine whether it running lean or rich. I've read elsewhere that this particular carb is actually an economy carb and think, that may be part of the problem. I have also read that it could be timing and the advance.... Looks like I have alot of reasearch to do.
I bought the car as a project to work on with my 15 and 16 year old son's, so it might not be bad that it doesn't pull at high R's, LOL.
Glad for all the advice and will let you all know what I find!

Marc Greenleaf Jr

BTW Five Point Nice CAR, hope to have ours looking that nice!

Mecury Don, I grew up riding in a 70' 351 Clevland Couger, nice!

Marc Greenleaf Jr

Okay, here is what I found and have done. I found that I also had an issue with the car starting after heating up and sitting for 5 to 10 minutes..... Got stuck at a gas station for 30 minutes waiting for it to cool down...Sucked!
Anyway, I checked the plugs and to my surprise the car is actually running rich. I changed the plugsand coil and set the timing to about 10* BTDC with the vacume advance disconnected. That took care of the break up issue and seemd to improve the starting when hot, although it's not firing as quickly as I would like. Thank you all so far for the advice! So now my next question is; Should I advance or retard the timing to improve hot restarts?

PK1

Here are some free things you can do to make sure you aren't wasting money on unnecessary items..

Insulate and or move the fuel line away from any source of heat. Vapor lock will cause the "no start" condition. But look at the coil and test the primary and secondary side of it to make sure if it's in spec. If out of normal ranges, replace it. And make sure it is away from heat. They are filled with oil to keep the coils cool.

As for high rpm break up, get the cam specs and make sure your springs are within manufacturers spec.

Make sure you have good plugs gapped correctly and they are correct heat range for your car.

distributor crack free with no corrosion, good rotor without corrosion making proper connection.

Clean unrestricted airflow.

Proper voltage and grounding of electrical.

Wires routed properly and not crossing or touching.

no vacuum leaks



Before you start purchasing items i would install a low cost wide band meter to see if the motor is going "lean" or "rich".

Good Luck!!

scotts74birds

Great advice PK! I was about to suggest an O2 till I saw your post. I'm not afraid of tech, and this could help. If you are running short of fuel, it would show up on the sensor as a lean condition. If ignition misfire, would look like a rich condition. As far as valves floating.....I'm not sure. How would that read PK1?

PK1

To read float you need to data log. Or you can take video with the tach in the back ground and your AF in front. I have the zeitronix and it logs to an old laptop and reads TPS, and RPM with air fuel. (you can also add 25 dollar sensors and log oil temp, trans temp, whatever... I am NOT a big tech guy but this was super easy to install. And it has an in cab digital readout that replaces a bunch of gauges if you don't have space.

Valve float ( at least in my experience) comes on around the same spot in the rpm curve regardless of the gear. And the motor starts to go fat. The graph looks like the back end of the bell curve with little jagged lines w / spikes.

Just did an old 5.0 Mustang and it's wot AF ratio was 12.8 - 13. Made good power for an old motor and this ratio worked the best for this motor. Float hit at 5500, the motor instantly started to fall of in power and the AF went to 12.1 and then in the 11.1 range. This cam should have peaked around 5700. A spring change extended the rpms to 6400 and then the cam was all done making power. Injector size, fuel trims, ignition, timing were all perfect.. So we turned to the valves..

I wont log a thing unless all the basics like fuel, spark, etc.. are all within spec.. Or i end up chasing my tail

I have seen some OBDII cars trip a 0300 MIL on float as the unburned gas goes into the pipe and trips a misfire..

scotts74birds

To the rest of us, I think he meant a code P0300 on the check-engine light. MIL means Malfunction Indicator Light. Good info PK1! Since I want to fuel inject the stroker for my BB Roadrunner, you seem like someone I'd like to talk more with!

PK1

A fuel injected 440? That's awesome!! Be happy to contribute in anyway i could. I'd love to see you do that.

scotts74birds

Dont wanna ***** the thread. Pm sent!