VIPER EATER 425??

[Tom C.]

Gentlemen, My recently rebuilt (.60 over) 427/425 in my 66 coupe is not yet the "Viper Eater" many have told me it should be. To make a long story short, the motor stumbles and backfires at 5200 rpm (give or take 100 rpm). I know the trouble shooting list can be long, but if someone could start me down the most likely road, I would appreciate it. Facts: All parts used in the rebuild are top quality and the original specs were duplicated including solid cam and 11:1 compression. I am running a stock (non TI) single point distributor and coil (braided stainless shielded wires) correct 3247 Holley (new, with internal fuel filters).

Would the proper troubleshooting order be 1. ignition, 2. carburation, 3. valve train. Other ideas? And finally, I promise not to abuse this old car but I'd REALLY LIKE TO EAT A VIPER JUST ONE TIME (or I'd settle for a Mustang Cobra).

[Michael W.]

Re: VIPER EATER 425??

Sounds like a weak spark to me. You might want to swap out the easy to change components first, like coil, points and condenser.

Does it backfire just when you are accelerating or also with steady speed?

Mike


NCRS Quebec chapter

[Bill Braun]

Re: VIPER EATER 425??

I'd have to agree with the weak spark theory. Back in my earlier drag-racing days, we were often confronted with the limitations of the single point distributors. As long as originality is not a factor, why not go the TI route?

Bill Braun 33186

[Duke W.]

Re: VIPER EATER 425??

Did you inspect and/or rebuilt your Delco single point. Check for bushing wear and replace the bushings as required. Has the upper bushing grease well ever be relubricated? The proper lubriacant is a special siliconized formualtion part number 1960954 (13 oz.tube). Shim up the end play to .002-.008". Make sure the breaker plate sits dead level and does not wobble or replace it. Use the Standard "Blue Streak" DR-2371XP point set. These are the high breaker arm tension points equivalent to the Delco D-112P that were OEM in your big block, and set the dwell angle to 35 degrees. (Note: all hyper small blocks should use these points, too). It took me fifteen years to get the single point to work in my '63 340. Had the same problems you report, but now it provides a reliable spark to 7000 revs. One question: Does your ballast resistor have a black "dot" on it?

Duke

[John H.]

Heresy?

If peak performance is what you're after, why fight all the problems inherent with the original single-point distributor? You can have a really solid, accurate, reliable distributor by installing a Pertronix "Ignitor" kit in your existing distributor which will give you (invisible) electronic ignition. Using a single-point distributor in hopes of optimum performance is like going to a gunfight armed with a knife. Have used them for years - Summit has them. John

[Duke W.]

Re: Heresy?

Nah - it's not heresy. Following my post I thought that I should have mentioned the Pertronics. The only problem is that you have to run an extra wire for the 12v power to the unit, but it's probably easy to rig it so you can go back and forth for a dual purpose Viper killer/Flight (or Duntov) car - what a great combination! I guess I resist the Pertronix because it took me sooooo long to figure out how to make the single point work that I am bound and determined to stick with it. I suppose I'm getting as cantakerous and crotchety as my old SWC.

Duke

[Paul R Ouzts]

Re: TOM.............

You'll NEVER get the taste out of your mouth....ha ha ha ha ha Paul O.

[Tom C.]

Re: THANKS

Thanks guys for the help. I ordered the Pertronix unit (and the flame thrower coil) this morning. Does anyone suspect the braided stainless shielded wires of contributing to a igintion problem? (I know..I know..just fix one thing at a time and see what happens). Any suggestions on jetting at sea level, standard day for my secondaries?

[Bob Babcock]

Re: THANKS

I had the same problem with my 66 427ci/425hp roadster. I opted for putting the numbers matching distributor etc. in a box neatly stored away in my garage and installing a MSD ignition systemwith Mallory Unilight disributor. Problem solved.

I was also told that the shielded plug wires often get a cross fire from cyl 5 and 7 (I may be wrong on the cylinder numbers).

Fortunately, my mechanic has a dyno and we were able to get the performance dialed in nicely, but not with stock ignition.

Bob Babcock

[Jerry Clark]

Re: THANKS

I suspected the sheilded wires were a problem on my 68, 435, I had a set of solid core wires made and sheilded to appear stock, worked like a charm, looked great.

jerry