Hard starting 6 volt, positive ground - Electrical Grounds - 6 volt cars use 2x the current of a 12 volt car. You may notice that the wiring gauge is "large". In that the gauge large, the grounds are very significant. A poor connection can easily halve the current to the component. If you have dim headlights, this is a hint that your grounds are poor. You MUST have clean connections and good grounds. Adding a dab of electrolytic grease to connections assures the will not corrode from having dissimilar metals contact each other (cu vs. fe) Routing - Starter motors need all the current they can get on a 6 volt car. The standard factory wiring had the battery ground cable (+) attached to the water manifold. There are other ground straps attached from the motor to the chassis also. The BEST thing you can do, for grounding the starter, is to attach the battery ground cable to the lower bolt holding the starter motor onto the engine. Be sure to clean the terminals with steel wool, even to the point of removing any paint in the area. The battery cable gauge for a 6 volt car should be "0" or "00". ("00" is welders cable) Battery - You need a battery of at least 650 cranking amps (650 CA) The cold cranking amps are a lower number. Most 6 volt batteries manufactured these days are deep cycle and it's only a coincidence because of the way they're constructed.You can install an 8 volt battery but you also must adjust your voltage regulator or it won't be charged adequately. The condition of the starter motor is also a large factor. The more you crank at low speeds, the more current is trying to push that armature and roll the engine. This creates a lot of heat, which can toast the field coils. A rebuild is a pretty simple thing. New armature, bearings and brushes can be had for less than $100.00. Some opt to have their starter convertwed to a 4 field for heavier duty operation. It didn't come from the factory that way and worked fine then, so... Vapor lock or hot cranking- Vapor lock can be caused by a couple things.. The gas formulation these days in cars with carburetors, is MUCH more prone to vapor lock or fuel boiling out of the carb when turned off, or both, etc. (Cars with fuel injectors have no vent to let this happen) An early V8 setup is more at risk because the fuel pump is right on top of the engine and gets a lot of heat. Where the vapor lock occurs, either in the line (a) before the pump, (b) in the pump, (c) after the pump or (d) or in the carb is a factor here, but we don't know this, so... So, a few things to try are 1st) (Simple) Add a gallon of #2 fuel oil or Diesel fuel to the tank each fill up. You should add it BEFORE you do the gasoline fill up to get it mixed up well. This has the effect of raising the octane and changing the characteristics of the fuel, while not affecting the drive ability. This takes a, b, and c and d into consideration. 2nd) Install an electric fuel pump, near the tank, with a switch on the dash for manual operation AND/OR wire it to operate with the ignition. If wiring it directly to the ignition, there are safety issues, such as installing an oil pressure safety switch to prevent the pump from operating with the oil pressure below 5psi. This will shut the pump off in the event of an accident. The down side is, that it also prevents the pump from operating when you first start the car ( until the O.P. gets up from cranking). However, you can also use the dash switch to prime the carb. The dash switch also helps if, while on the road, you stop for a while and the gas boils out of the carb. The latter is the reason I installed an electric pump on my 55 Pres... If you install the pump,, also install another fuel filter right in front of the pump to keep the pump in good stead.. This method takes mostly (a) and (d) into consideration. If the vapor lock occurs while driving, you get a hint when the engine stumbles, so the electric pump can be easily brought online with the switch and can be useful here also. 3rd) You can install a return line from the existing fuel pump, but you need NOT go all the way to the tank. What is needed is a means to bleed off the 'vapor' and keep the fuel moving to prevent vaporization. Installing a 'tee' in the line, with a restrictor to prevent starvation can be run right back to another 'tee', somewhere ( at the the cooler) fuel line under the car. In the situation with an early V8, the tee has to be AFTER the pump/before the carb. However, if the problem is in the line before the pump, it won't have any effect, so an electric pump is the answer. 4th) there is a belief that if you bend/angle the lines so they are make the fuel continually travel upward, it will cause the vapor to rise in the line and end up venting into the carb, it wil help. On an early v8 this would be hard to accomplish. It can work on the later If the vapor lock occurs while driving, you get a hint when the engine stumbles, so the electric pum can be usefull here also.8's with the fuel pump on the timing cover. Happy motoring