03-25-2014, 09:27 AM
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CC Member
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Join Date: May 2006
Location: Denia / SPAIN,
ESP
Cobra Make, Engine: NAF 289 Blue/White strips
Posts: 188
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Not Ranked
AFR and VACUUM values
After several works and test drives I try to solve some carburator problems regarding the engine.
SPF 306
ALU Heads Ford J302
Intakes to heads portet
Comp Cam 288R @050 246/246. Dur. 288/288
Holly 600 vacuum
CR 10.5:1
Idling at 900 +/-:
Vacuum idling 7.0 - 7.5 hg
AFR idling 13+ / 14+.
Between these values the AFR leaps up to 20 and then back to 13/14.
Sometimes there are longer, sometimes shorter intervals between the leaps.
The engine sound on idle is like a hard working truck. Once it reaches the 1500/2000 RPMs, AFR is at 12+/13+ and vacuum +/-10, engine sounds very smooth.
Ignition timing is 12° at idling, 32° at 2700 RPM and 34° at 3000 RPM.
Is there probably a spark missing, which causes the leaps regarding the AFR figures?
Or what ...........?
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Rico, NAF 289
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