I am thinking about purchasing a complete msd ignition system for my 1991 bbc502. If anyone out there has some feedback on his or her luck with the BBC msd ignition it would be appreciated. i wish i could figure out why my motor runs perfect at all rpm's until i put it in gear. (under load)help
There's a thread recently on the boards somewhere in which guys discussed this item. I would make sure your boat engine is relatively free of water on a regular basis (the non marine version dies if submerged or really splashed on). You get more power with more juice from it, but I'd stick with traditional stuff if the motor is exposed (open) and your boat is mostly a ski (non race) set up.
502-Do you have points in that 1991 BBC502? I had the same thing happen to me, after trying everything else I went to replace the points and found the old ones were fried. Check it out.
Kevnmcd
You need to figure out your problem before you spend the bucks on a new ign system. Running crappy under load could be caused by a couple of things, worn plugs or incorrect gap, bad plug wires, bad points & condenser if thats the type of dist being run. Once it runs right then spend the money, it will make a difference. Lots of people run MSD, I happen to run Mallory. Put a Mallory box on mine and it made a world of difference.
i do not have points. it is the standard thunderbolt V. i have replaced and gaped the plugs. it went from running great one day to this problem the next.
Check your wires. If they are the same ones that came on the boat they could be bad. Also read the plugs. The plugs will tell you alot about the combustion. You may also want to have some one do a leak down. These are just some things you may want to try. All can cause a motor to run like sh-- under a hard load.
Ronnie
ronnie, they are the wires that came on the boat. the problem is that it does this under any load, not just hard load. if i put it in grear at idle id does it, and if get it to not stall, it spits and sputters when i give it any more throttle than idle. it is really bazare.
First, the question in the topic...
If you go to the races in Texas, you will see 2 ignition systems; MSD and Jacobs. Both are the best of the bread, but a different in philosophy. Jacobs sells a full tilt boogie, and that is it. MSD sells a cheap model, but by the time you add all the parts, it is just as expensive.
Second, what the question became...
Running out of gear is easy. Once in gear, something is not enough... There are only 3 things to check; Fuel, sparc, and air. Air is unlikely. :-)
First, I would check sparc... Get a good timing light, and see if the sparc bounces around... (Bad distributer) Check the coil, points, wires and plugs.
For fuel, run it in stumble mode for a while, and kill it at high rev, and pull a plug. Look in the carb and see if a jet is dribbling.
Good luck!
502,
In your previous post, you were concerned that you may have knocked something loose when you removed the carb box. This is the most likely source of the problem. I would recommend that you inspect all the vacuum ports around the carb and associated area's. This would be the simplest source. Continue to inspect all areas that you disturbed during the installation/removal of the hardware. It could possibly be a vacuum leak causing this poor running condition. At no load idle, there is sufficient airflow for the carb to meter fuel for the demand,(most carbs are typically too rich at idle anyway) whereas when loaded, the fuel demands have changed to the point of a lean misfire.
BTW, the MSD is an excellent choice, you will notice gains in idle and low speed operation. I personally run Holley's new Annihilator system, and after some mods to the distributor to get the timing curve dialed, it has proven to be quite a good ignition system. Cost's a bit less than the MSD, mostly due to the built in rev limiter....
[This message has been edited by 1stepcloser (edited June 12, 2002).]
I think I'm going to get the Crane Hi-6 unit with the free LX92 coil in Jegs. Oh yea the Crane is fully potted and its Digital! The MSD 6A and 6AL are analog.
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