Folks:
I have been following with interest the discussion on ignition. The advice I
have read has been first rate. I would like to add a question into the mix.
I have a MKII. The 289 engine is near stock. Modifications include:
Edlebrock Performer RPM aluminum heads
Slightly hotter than stock cam
TIGER aluminum intake manifold
Holly 600 cfm carb
Tubular headers
I completely rebuilt the engine which now has about 500 miles on it.
Lately, after driving in summer heat for say about 30 minutes and the engine
is thoroughly heat soaked, the engine tends to miss when accelerating.
Typically, the miss happens around 2500-3000 rpm and is particularly
noticeable in 3rd gear. Occasionally, the engine will backfire at lower rpm
- again when thoroughly heat soaked.
As best I can tell the timing is dead on. Plugs and wires look good. I have
measured the temperature in the engine bay and observe the following while
the engine is running after thorough heat soak:
Radiator input temp: 205-215 F
Radiator output temp: 175-185 F
Intake manifold temp at base of carb: same as radiator input temp
Carb fuel bowl temp: 175-180 F
There is insufficient hood clearance room to fit any additional carb
spacers.
Anyone have some helpful hints on what may be going on and how to diagnose
the problem? Anyone have a recommendation on which sparkplugs to use (note
stock plugs will not fit this head)?
Wayne
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