Hello all, I was hoping someone has experienced a problem such as mine and had some advice as to what I may have missed. My 85 Capri has a Ford motorsport 302 engine with a Holley 4 barrel 580 cfm carb and Ford motorsport T-5 transmission. The distributor is original to the car and it recently started to miss or surge when I rev over 2000 rpm. Even when I rev it up stopped, it seems to be missing. The car idles fine and when I accelerate or go WOT, there are no problems. I have an O2 analyzer on the car and it runs at 12.5 to 13-1 in this condition. The car has 10000 km's since it was rebuilt and this is a new problem. To summarize what I have done so far is:
- Changed out to a Quick Fuel 580 carb. It ran worse and had a lean condition at cruising speed.
- Compression test of the engine and they were all within 10% of each other. (done cold to test head gasket)
- Checked plug condition-all were tan in appearance and none were found to be bad. Replaced with new ones as a precaution.
- Replace distributor cap and rotor. These had some slight fouling, grounding problem but no change after replacement.
- Replaced intake gaskets. Had to replace them when glycol entered #8 piston. Had to bring it in for repair and they did not find any other problems.
- Replaced coil. No change found.
- Disconnected vacuum advance while driving. No change found.
- Timing at 12 Deg BTDC. Not sure what final timing is but the timing light is steady from idle to 2500 rpm.
- I checked every wire with the timing light and all of them seemed to be firing with no intermittent missing. I did not test the resistance of each. These are Ford Motorsport wires if anyone cares.
- Tested intake with propane and did not find any sign of a leak.
- Vacuum at idle is steady at 14" HG. Ford motorsport said that was exactly what it should be with this engine combination.
To summarize, the car runs fine at ide. runs great while accelerating, and does not miss while driving WOT. It is only when the car is in high vacuum, cruising speed that is effected.
Any experience with this and any ideas what I can test?
Thanks for your help.
Patrick
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