Ignition Problems?

[bskier]

Hello... I'm running a 428FE in SPF 1001. Car is absolutely immaculate, not raced, just used for shows/cruising. Lately I've noticed that after the car warms up ~20min or so, it begins to stumble then surge. As you can imagine, there had better be about 1000 ft in front of me before I let out the clutch! This becomes more apparent if I stop the car to run errands, etc. get back in and start after 15 min or so. Car stumbles and flames out. I can restart, but it stumbles/surges until I make it back home. Usually, back road cruising is not a problem when the engine is under constant load. It seems to be a problem after it warms up and I'm in heavy traffic, or stop and then try to start it 10 - 15 min later.

Ignition coil issue perhaps? Any suggestions greatly appreciated.

Thanks,
Brian

[FWB]

Originally Posted by bskier

Hello... I'm running a 428FE in SPF 1001. Car is absolutely immaculate, not raced, just used for shows/cruising. Lately I've noticed that after the car warms up ~20min or so, it begins to stumble then surge. As you can imagine, there had better be about 1000 ft in front of me before I let out the clutch! This becomes more apparent if I stop the car to run errands, etc. get back in and start after 15 min or so. Car stumbles and flames out. I can restart, but it stumbles/surges until I make it back home. Usually, back road cruising is not a problem when the engine is under constant load. It seems to be a problem after it warms up and I'm in heavy traffic, or stop and then try to start it 10 - 15 min later.

Ignition coil issue perhaps? Any suggestions greatly appreciated.

Thanks,
Brian

Carb......

[Blas]

Agreed, check float levels first.

[patrickt]

Brian, first blow out your air bleeds. It's quick and it's easy. For instance, see this thread: This is new: stumbling/missing at idle/cruise speed

[Clois Harlan]

Patrick is spot on and check your floats as blast said. By the way what carb do you have? I ran a 428 for a long time and it is a great engine.

Clois

[STL Mark]

I've had that problem before.
Sounds like needle and seat.
Easy to replace.
While you're there, yes, check float levels, fuel filter, and fuel pressure.

[Gaz64]

Fuel in carb is percolating.

What carb? Do you have any heat shielding?

[patrickt]

Originally Posted by Gaz64

Fuel in carb is percolating.

What carb? Do you have any heat shielding?

Always a possibility. Brian, if cleaning the air bleeds doesn't fix it, and your floats are set right, use an infrared temp gauge to see how hot your bowls are -- if they're over 200 degrees, try fashioning a temporary Turkey Pan out of aluminum foil layered several times over itself and take her for a test drive. Try and do identical "before and after" test drives. See if your improvised TP improves it.

[bskier]

Originally Posted by patrickt

Always a possibility. Brian, if cleaning the air bleeds doesn't fix it, and your floats are set right, use an infrared temp gauge to see how hot your bowls are -- if they're over 200 degrees, try fashioning a temporary Turkey Pan out of aluminum foil layered several times over itself and take her for a test drive. Try and do identical "before and after" test drives. See if your improvised TP improves it.

Thanks to all for the replies!! I am running a Demon (will have to check size) The fuel percolation theory in an earlier reply may explain why it runs just fine as long as your are moving, or it is cold, but after a warm up period then getting into stop and go traffic, or parking for 20 minutes or so, the flame out, rough starting and surging begins.

I will definitely clean out the carb and try some heat shielding. Thanks to all for the help!

[gsharapa]

All great suggestions for you to try. One other is the fuel itself. This pump gas with enthanol is getting worse every year. It boils very quickly when hot outside or under the hood. If you let the fuel sit for some time with no stabalizer the enthanol will start eating up your carb seals etc. So if you have old gas get rid of it if not put a bottle of octaine booster in it like Lucas ($10.95) sold at most auto parts stores and see what that does. Couple guys at the Texas San Marco meet last year (late March) were having similar problems and the octaine booster cured it.

[jhv48]

If you want to reduce the fuel temp in your carb, a simple $20 phenolic spacer between the carb and manifold will work wonders and it's cheap and easy to do.

[vatdevil]

I would suggest a fresh tank of ethanol free pump gas or race gas. Similar issue with my car but only on very hot days.

[Blas]

Yes, winter blend gasoline can cause similar issues. This of course depends where you live.

[bskier]

I usually run with Lucas Octane boost + Chevron or Shell premium except for this last tank, but have noticed the problem in the past just that now it is much worse. Could be tied to the winter gas blend here in the SF Bay Area. Car has been spec'd to a "T" by Craig over at Top of the Hill and may have to take it back in for a check. Will try some of the quick fixes suggested herein and report back.

[vatdevil]

Its the RVP (Reid Vapor Pressure) number that matters. Lower is better, in the case of carbs and heat. Winter gas is around 13.5 Summer is either 9 or 7.8 in most areas. VP110 is 6.7 which is why blending some into pump gas helps. The EPA mandated numbers are on a sliding scale, dropping in the spring and rising in the fall.
If the supplier splash blends in ethanol, they are granted a 1 PSI waver. Winter limit is then 14.5 and summer 10 or 8.8. This is why ethanol free gas may help a bit.