My problem is the following;
BBC with Mallory Comp 9000 dizzy andd promaster coil. Works great but decided to go with an new HEI and not have a coil laying around mounted in the engine bay. Took the comp 9000 out(I just had the engine running for 20 minutes) and installed the new dizzy. Would not start. Spins great and has a weak spark(new coil is supposed to have 50,000 volts?). New dizzy was dropped in the same placewithout a hitch. Imeasured voltage at dizzy batttery wire.
12.9 volts with key on
8.9 while cranking
Question is
Where do I look for a problem?
Is 8.9 volts at dizzy okay while cranking?
Any help would be appreciated.:bowtie:

That voltage drop sounds like a bad battery. It can not put out the cold cranking amps and then your voltage drops from the starter load.

The battery is fine. It spins the motor without a problem. Has a mini high torque starter and the cca is 650 and ca is 810. Battery is 4 months old. Before I removed the comp 9000, the motor started right up without a problem. So your saying that the voltage drop at the dizzy shouldn't be happening? Would running a wire straight from the battery to the dizzy for the moment be off any help? Thanks for the reply.

Where do I look for a problem?
Is 8.9 volts at dizzy okay while cranking?

That is about normal as voltage in the entire car drops because of the draw from the starter. Where are you getting power from for the HEI? You may also be a tooth off when you installed the dizzy, normally they just won't "drop back in", in the same place, you have to realign the oil pump with a long screwdriver. You could also have the plug wires one off on the cap. Start over in making sure dizzy is installed correctly. Do a search or post back if you don't know how.

Try putting a good charge on the battery. New batteries need to be charged if you did not already.

:bowtie: Well the problem is when I would let go of the key when the engine would start,it just quit. So I then ran a wire from an accessory hoook-up and everything was fine. Now I just have to go thru the wiring diagram and figure every thing from scratch(Wiring harness is not completely installed,car still disassembled). Thanks for the help fellas.:bowtie: