Hello from Switzerland
Our car is a 1966 Mustang Fastback, 289 4V, wide ratio toploader 4speed, standard 8 inch rear with 2.80:1 gear and pinion. Car was recently imported from the USA.
We have trouble and need help on dialing in carb, mixture and ignition. Therefore you will find below a) specs of the engine b) our checks and tests done so far, c) our problems.
Finding good advice on classic American V8s over here is difficult. Therefore your advice and help is highly appreciated. Thanks in advance.
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A) THE ENGINE
- 1966 289 Block C5AE casting and 1966 Heads (was original an standard 2V engine). Engine was rebuilt by former owner approx. 5000 miles ago. Unfortunately we do not have specs on the rebuilt. Pulling Intake manifold and oil pan showed a clean rebuilt with no debris or other un-normal signs whatsoever. We have not opend up the long block yet as there is no reason for it so far.
- New Pony Carburator Autolite 4100 4V Carb 1.12 "Spreadbore" 540 CFM, with Thermo-Choke, Vaccum Secondaries. No. 43 Primary Jets, No. 62 Secondary Jets. Pony Carburators Universal heater tube to fit on No 4 Cyl. header-tube as recommended. Coolant Hose from Heat-exchanger to Manifold is clamped to the Thermo-Choke Box as recommended.
- New Pony Carburator "Boss 302 Style" 1/4" spacer plate with pcv connector outlet
- New Blue Thunder COBRA dual-plane high rise alloy intake manifold
- Standard mechanical fuel pump with in-line fuel filter between pump and carb
- 1980 Duraspark Distributor, New Petronix Ignition Module instead of original 1980s electronics. New Coil, New MSD Street-Fire Ignition cables.
- Performance hydraulic cam with stamped steel roller rockers. Cam came installed with the engine / car and again no specs on manufacturer, duration and lift was given. Slightly "lumpy" idle at 800 - to 900 rpm with 12 inches hg vacuum.
- Standard Hedman Hedders with 2 1/4" dual exhaust, no X- or H-Pipe, Turbo Mufflers and large size "GT-Trumpet look-alikes" for unrestricted flow with the 2 1/4" exhaust
B) OUR CHECKS AND TESTS SO FAR
- Vaccuum tests performed on PCV Valve and tube, Power Brake Booster Tube, Distributor Vaccuum Advance Tube, Carb and Carb spacer installation. No Vaccum leaks found so far. Special Vaccuum test performed on COBRA intake manifold with Carb and Carb spacer removed, a special closed aloy plate with a vacuum outlet installed and all intake valves closed. Result: With a special vaccum pump equipment we where able to "draw" 20.67 inches hg vacuum with no loss, audible "hiss", whatsoever.
- Ignition is set at 12° advance at idle with vacuum hose disconnected and 36° total advance at high rpm with vaccuum hose connected. Test Equipment with Oscylographic Monitor showed normal equal ignition picture on all 8 Cylinders.
- A Bosch Lambda probe is installed in the R/H header in a 45° upward angle as recommended and connected to the Innovative LM1 AFR Box installed in the car.
- Two high temperature probes are installed on the R/H Header Cylinder No 1 and No 2 tubes and connected to the Temp Monitoring Box installed in the car.
- The carburator vaccum secondaries where checked. The secondaries diaphragm spring was misaligned. This was rectified and with a very small vaccum tube attached to the ventury air horn we where able to "draw" some vaccum and to perform a positiv static funtion test on the secondaries which opend accordingly.
C) OUR PROBLEMS
- On innitial start up engine went to a way to high idle at 2000 rpm. According to Pony Carburtors carb is factory-pre-set for 1200 rpm innital cold idle. Getting the carb of the innital step on the idler-cam reduced rpm only to about 1400 rpm. With engine warmed up and Choke butterfly fully opend we where still above 1000 rpm. We than adjusted the carb to 800-900 rpm hot idle.
- Temperature probes on cylinder No1 and No 2 showes a split (delta) of up to 122° F from No 1 (hot cylinder) to No 2 (cold cylinder) at idle and up to (delta) 392° F f rom No1 (hot cylinder) to No 2 (cold cylinder) on higher / high rpm under driving conditions
- The cylinders No 1, 4, 6 and 7 which are fed from the same corresponding half of the COBRA dual plane intake manifold are running hot with a lean white spark plug picture, the cylinders No. 2, 3, 5, 8 fed from the othe half of the intake manifold are running cold with a rich very dark spark plug picture.
- Even with the idler mixture screws on the "rich" side the LM1 read out is Lambda 1.10 / AFR 16.1 which is way to lean according recommandations.Lambda / AFR should be around 0.96 / 14.1 at idle.
- During driving tests the engine "flattens-out" around 5000 rpm and does not pull any more RPM. It once even misfired but as mentioned above innitial ignition timing and test showed no abnormalities.
- We have the impression that the secondaries are not opening up during driving / load conditions. There is not the slightest "surge" whatsoever as to be expected. More like running on the the two-barrels up front up to 5000 rpm and then running out of "steam".
We are still in the "test and tune" phase but running in the "cross-roads-decisson" problem. Which way to go? What to check next? Most intelligent sequence of tests to perform?
Your expert advice is highly recommended. Please do not hesitate to ask any question you may need to get a clarifying picture for better analysis.
Regards from Switzerland
Manuel and Frank Ring