270HP Ignition

[Ray C.]

As recommended by John Hinckley, I just checked the points on my 270HP dual point distributor to find the points on the left side have burnt again. This is the third time this has happened with less than 200 miles driven. I have tried to locate the correct ballast resistor with no luck. The first resistor was a Delco reproduction (Paragon) that was incorrect for this engine. I am currently using an aftermarket .7-OHM resistor and .091 coil. What are other members with dual point set up using to prevent point burning? Would there be any other causes for these points to burn?

Thanks for any help!
Ray

[William C.]

Re: 270HP Ignition

Preferred resistance in the ballast resistor to prevent point burning is generally 1.8 ohms. Service bulletins were issued on tho old 409 engines that called for upgrading the ballast to 1.8 ohms to prevent point burning. Try a better resistance match in the ballast resistor and I think you problem will go away

[John H.]

Re: 270HP Ignition

Ray -

I had a reproduction ballast resistor on my '57 270 that measured 2.1 ohms, never touched the points for 5 years/5,000 miles after I rebuilt that 891 distributor and set up the dwell. Since only one set is burning (the primary set closes and the secondary set opens to trigger the coil), I'd replace the condenser and see how that works.

[Ray C.]

Re: 270HP Ignition

Thanks! John & Bill

I replaced the condenser after I burnt the original or first set of points after engine rebuild and during the thirty-minute cam break-in run. I was using a Paragon .2-OHM resistor. I replaced only the left set of points and tried the 2-OHM resistor again, the points burnt out after a very short engine run time. On the third try I replaced both set of points with Blue Streak points and a .5-OHM over the counter resistor. The voltage to the distributor with both resistors was in the 11V to 12V range, a drop from 14.? with the engine running. I just installed a new set of points with a new after market ballast resistor that has a resistance of 1.8-OHMs and with the engine running has a voltage of between 7.8V to 9.5V. I just took the car for a test run and it preformed better that it ever has. Now to see how long the points last before I call this a success.

John, another question; I called our local engine builder that preformed all the machining on the 270HP engine. He stated, "AC 46 spark plugs were too hot of a plug for this engine". What plugs were you running in your 57 270HP?

As always, Thanks for all the help!
Ray Carney #36314

What would we do with out all the experts!!

[John H.]

Re: 270HP Ignition

Ray, the primary carb on 2x4's was jetted on the rich side so the front cylinders wouldn't lean out during normal (primary carb-only) operation due to the poor single-carb mixture distribution characteristics of the 2x4 manifold. When they became a fouled-plug customer complaint field problem, Flint started building them with "46" plugs instead of the original 43's and 44's (although this production change never showed up in later owner's manuals, which continued to specify the colder plugs). The factory installed 46's, and I used 46's in my '57 270 until AC discontinued them; after that I used R45's, and they worked fine (44's fouled fairly quickly around town). Your machinist must be reading owner's manuals instead of Engineering changes