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Timing and Idle Adjustment
Procedures For Thunderbolt V Ignition Setting Base Ignition Timing 1. Connect timing light to number 1 spark plug. Connect timing light power supply leads (if applicable) to 12 volt source. 2. Connect a shop tachometer to engine. 3. Using a jumper wire, connect the ignition system timing lead “13” (PUR/WHT wire) to a good en- gine ground (–). This locks the ignition module into the “Base Timing Mode”. 4. Start engine and run at normal idle speed. Allow engine to reach normal operating temperature. 5. Aim timing light at timing tab, located on the tim- ing gear cover and crankshaft torsional damper. 6. Adjust timing using the conventional method. IMPORTANT: Be sure to disconnect the jumper wire from the ignition system test terminal before attempting to resume normal operations. If the jumper wire is left in place, the ignition module will operate in the “Base Timing Mode”. This means that the additional timing advance fea- tures would not function. 7. Make sure that the distributor has been tight- ened. Remove the jumper wire from the timing terminal. 1. Using a jumper wire, connect the ignition system timing lead “13” (PUR/WHT wire) to a good en- gine ground (–). This locks the ignition module into the “Base Timing Mode”. 2. Adjust idle mixture following the procedure in the appropriate engine service manual. 3. Remove the jumper wire from the timing terminal. Adjusting Engine Idle Speed This procedure should be done with boat in the water, drive unit in neutral and engine at normal operating temperature. Refer to the Operation and Mainte- nance Manual for the correct idle speed. 1. Disconnect the throttle cable from carburetor. IMPORTANT: In order to properly set idle speed, the ignition module MUST BE locked in the “Base Timing Mode”. This is necessary because of the “Idle Speed Control” feature that exists in the ignition module. See information on the previous pages about this feature. 2. Connect a shop tachometer to engine. 3. Using a jumper wire, connect the ignition system timing lead “13” (PUR/WHT wire) to a good en- gine ground (–). This locks the ignition module into the “Base Timing Mode”. 4. Start engine and allow it to reach normal operat- ing temperature. 5. Adjust idle speed to recommended RPM. 6. Stop engine. Readjust cable barrel and reinstall |
wow
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http://www.cpperformance.com/c-161-distributors.aspx here wt i did i got a msd with the box and set mine up .idles 650 in gear and timing at 34 she runs great tops at 5600rpm i took all merc stuff off . but that me . i got one more thing for you to check the is the float level . make shore it not to high that will make you run bad at a idle !!good luck
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Fixx
Originally Posted by ballon78
(Post 3103103)
Here is the TB V info as it different than the TB IV by alot. Its always changing advance so i dont think you can check the advance at at 3500 as depending on load it will chang itself. Thats why they want you to set base timing with wire grounded at 8 degrees....The knock sensor pulls and adds advance.
I have gotten alot of great ideas and info that i need to look into all of these ideas. See they tell u in the manual to set idle and mixture screw adjustments with the ECM in base timing mode with the wire grounded, is this rally necessary? in gear what should rpms be. General Description The Thunderbolt V ignition system has several spark control features that will be described following: D Idle Speed Spark Control D Acceleration Spark Advance D Mean-Best-Timing Spark Advance D Over-Speed Control (Rev-Limiter) D Knock Retard Spark Control NOTE: The Ski models do not have the Mean Best Timing feature. Idle Speed Spark Control The ignition module will control ignition timing to maintain a calibrated idle speed. This is accom- plished by making small spark advance adjustments. This feature is only active within a certain RPM range. This range may be slightly different from one engine model to another. The approximate range is 400-700 RPM. Acceleration Spark Advance This feature is active during acceleration only. When accelerating, the ignition module may add more spark advance to the “Base Spark Timing Curve”. The amount of spark advance added, is totally de- pendant on how fast RPM increases (how fast the throttle is moved). This feature is also active within a certain RPM range. This range may be slightly differ- ent from one engine model to another. The approxi- mate RPM range for this feature is 1200-4000 RPM. Within this range, the module can add approximately 10 degrees of spark advance to the base spark timing curve. Mean-Best-Timing (MBT) Spark Advance During light load cruising, the ignition module searches for the optimal ignition timing. This is also accomplished by small changes to the spark ad- vance. At a given RPM, the module will try to add a small amount of advance and wait to see if there is an RPM change. If RPM increases, it will try to in- crease timing more. The module will continue to ad- vance timing until it no longer gets an increase in RPM. Conversely, if it senses an RPM drop, it will start to retard some of the spark timing. The approxi- mate RPM range for this feature is 1200-4000 RPM. Within this range, the ignition module can add approximately 10-15 degrees of spark advance to the base spark timing curve. NOTE: The Audio Warning System is also connected into the ignition module circuit. If the audio warning system becomes activated by the closing of one of the audio warning system switches, the MBT feature is deactivated. Over-Speed Control The ignition module will prevent the engine speed from exceeding a preset limit by stopping the spark. This feature has an RPM range that varies from mod- el to model. The over-speed limit for a particular en- gine is set slightly higher than the top end of the RPM range for that model. For example, if the recom- mended range is 4600-5000 RPM, the over-speed limit would be set at 5100 RPM. When RPM reaches this limit, spark is turned-off until engine RPM drops down to a “Reset RPM”, which would be approxi- mately 4750 RPM for this example. At this point, spark comes back on. Knock Retard Spark Control The knock control feature helps provide protection from harmful detonation. Knock control is handled by the Knock Control Module. This module receives a signal from a sensor that is mounted on the engine block. The knock control module works in conjunc- tion with the ignition module to retard the timing if spark knock is present. so you installed a Holley on your boat now all that info is useless, set your timing procedure and go from their on the carburetor issues...you will need to do this by touch and feel of how the engine performs..i can go on and on about accelerator pump sizes,air bleeds,metering block modifications,accelerator pump cams,accelerator pump squatters but with out seeing it or hearing it run i would be here for hours trying to explain to you what to do. you may want to buy a Holley tuning book and read up on your carburetor to get the feel for what your trying to accomplish :) |
Originally Posted by getrdunn
(Post 3103163)
wow
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Originally Posted by bajabob
(Post 3103164)
http://www.cpperformance.com/c-161-distributors.aspx here wt i did i got a msd with the box and set mine up .idles 650 in gear and timing at 34 she runs great tops at 5600rpm i took all merc stuff off . but that me . i got one more thing for you to check the is the float level . make shore it not to high that will make you run bad at a idle !!good luck
I want reliababilty and won't run the msd stuff, everyone i know on here and around be carry an extra msd box, because its not if it will fail, but when. having a single engine i cant put, put home like twins can. |
Float levels are good, just below threads and only spill out when i rock boat with caps off...Im going to spend some time this weekend and try to dial it in better and look at a few thing that you folks have mentioned, I have lots of ideas now.
The thunderbolt V system was one my boat from new and so was a AFB carb, which wasnt ecm controlled.....basicly all i did was swap blocks and new carb. everything else is same. When i recheck timing and fuel screws, and idle should i do it all with the boat in gear? |
ok thats good floats fine. 1990 i install a msd box and it still works good for me i have msd install in my two cars gto and camaro. ok you wt to use the old stuff . you have to do the timing at a idle . i would set it at 14 not 8 let it warm up then put it gear and adjust your carb . good luck:drink::drink:
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with the flame arrester off, not running, ck to see if you a good accel pump shot when you open the throttle, you may have to change the cam position or the cam itself..also may have to up the shooter to get a better shot..Rob
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