OMC 302 Ford Misfiring
 

Greetings!

I have a problem and need some advice. I am restoring a ’77 VIP, 190 hp, with an OMC 302 Ford. I have converted it to electronic ignition using an “Ignitor II” distributor conversion, an “Ignitor II” coil and “Ignitor” 8mm plug wires.

Problem – Without a load at the dock, obtaining and maintaining the book rpm of +/-4000 is no problem. However, on the water as the rpm is increased, the engine runs excellent all the way up to about 3500-4000 rpm. Once reaching this range, the engine runs very strong for several minutes, and then it begins to miss and fire back through the carburetor.

As power is reduced, the misfiring continues on down to around 1000-2000 rpm, and then once again the engine settles down. If the power is immediately taken back to idle, all indications of misfiring stop and power can then be applied. Extended running at or below 2000-2500 does not produce any problems.

Any ideas or recommendations will be appreciated.

check for possible fuel filter clog. The back firing through the carb is
indicative of a lean mixture. So check the float levels and the fuel
filter.

Jack

"Peaceful Pirate" wrote in
message ...

Greetings!

I have a problem and need some advice. I am restoring a '77 VIP, 190
hp, with an OMC 302 Ford. I have converted it to electronic ignition
using an "Ignitor II" distributor conversion, an "Ignitor II" coil and
"Ignitor" 8mm plug wires.

Problem - Without a load at the dock, obtaining and maintaining the
book rpm of +/-4000 is no problem. However, on the water as the rpm is
increased, the engine runs excellent all the way up to about 3500-4000
rpm. Once reaching this range, the engine runs very strong for several
minutes, and then it begins to miss and fire back through the
carburetor.

As power is reduced, the misfiring continues on down to around
1000-2000 rpm, and then once again the engine settles down. If the
power is immediately taken back to idle, all indications of misfiring
stop and power can then be applied. Extended running at or below
2000-2500 does not produce any problems.

Any ideas or recommendations will be appreciated.


--
Peaceful Pirate

Fords are real critical of timing. The static timing may be off, or the
advance weights inside the distributor are getting stuck.
Bill

"Peaceful Pirate" wrote in
message ...

Greetings!

I have a problem and need some advice. I am restoring a '77 VIP, 190
hp, with an OMC 302 Ford. I have converted it to electronic ignition
using an "Ignitor II" distributor conversion, an "Ignitor II" coil and
"Ignitor" 8mm plug wires.

Problem - Without a load at the dock, obtaining and maintaining the
book rpm of +/-4000 is no problem. However, on the water as the rpm is
increased, the engine runs excellent all the way up to about 3500-4000
rpm. Once reaching this range, the engine runs very strong for several
minutes, and then it begins to miss and fire back through the
carburetor.

As power is reduced, the misfiring continues on down to around
1000-2000 rpm, and then once again the engine settles down. If the
power is immediately taken back to idle, all indications of misfiring
stop and power can then be applied. Extended running at or below
2000-2500 does not produce any problems.

Any ideas or recommendations will be appreciated.


--
Peaceful Pirate

The problem is beginning to look like the power fuel system in the Holley carburetor, specifically the power valve itself. I have learned that the Holley uses the power valve to regulate the air/fuel mix at the upper end of the acceleration range and during high-end running. Since firing back through the carburetor can be a sign of a lean mix, it makes sense that a bad power valve that restricts fuel flow could be the source of this problem. Will post the outcome.