Carb popping fixed

[mdrburchette]

I haven't complained about it much, but my 71 with the dual IDFs had a unique way of popping through the carb and the exhaust practically at the same time. I was bored so I thought I'd install a working vacuum diaphragm to the 79 electonic distributor. When I pulled the rotor off, I found the metal band on the rotor had come loose on one end so I replaced the rotor and advanced the timing to 10 btdc. It's amazing that a $5 part has fixed the problem that's plagued this car since I bought it!

[msrmd]

Denise, I wish I understood what you just said, and maybe someday I will. I am delighted that you have solved your problem so elegantly and that you have persevered to acquire the expertise to make such an astute diagnosis.
You're my hero (or heroine)

[rlux4]

Popping throught the carburetors. Yeah, I used to have cars back in the day that had those. Worrisome little buggers they were. Good for you, Denise.
Ron

[kristoj]

Careful, Ron. If our FI cars backfire through the intake, it bends the door on the AFM, possibly resulting in a $600 bill -- in addition to the $5 part Denise is talking about!

[rlux4]

I hear ya John. But I've heard a few carbed models backfiring and have yet to hear an FI one do it. I'm sure the mechanics amongst us has, but I haven't. Mine was out of dist. timing and didn't run it's best and it still didn't pop. But if it ever does, I'd be interested in finding out if it would just take a little sheet metal work to straighten it out.
Ron

[mdrburchette]

Sorry, I didn't make my explanation clear. I did have to work on the Devil X too and that always messes with my mind. On the rotor (in the distributor) there's a metal strip that is attached by two rivets. It came loose from a rivet and was moving around in the cap. The new one I bought had the metal strip apoxied in. Now a question:
I had my timing set at 5 btdc but it would only advance to 26 degrees. Is this normal for the 79 elect. dist? I set it to 10. Should I go higher or should I go with weaker springs or heavier weights?

[racydave]

The 79 dizzy will need mods to achieve the proper range. This would be a good time to dust off that Sun distributor machine! Ive had a good chance to program a dist curve for my 2L with my MegaJolt. What you probably want is 10 D btdc at idle and a total advance of 34 btdc at approx 3,000 rpms.I had mine up to 37D total, but the headers got hot, and I didnt want to burn a piston, so I opted for 34 total advance.My new system starts the eng at 10 btdc, and idles at 18 btdc which runs great once its warmed up. When I had my dizzy, I modified some old GM cent weights and used some light springs. D, I still have my old " FrankenDizzy"... There is a fella who will set her up for ya also.

[mdrburchette]

I really do need to learn how to use that ole' Sun machine, don't I? Ron was looking for weaker springs in his toolbox, but things have a way of getting lost in that big old thing and with 3 or 4 people in the shop working on cars every night, there's no telling where stuff goes.
Now, this has me thinking about the 72. I changed it over to a 79 elect dist when we built the engine. I'll have to check the advance on it and see what I've got. Who's your contact for setting it up?
Here's another question: The original points distributor is supposed to be set at 5 btdc initially and advance to 31. Are the springs and weights interchangeable between the early dist and the later one?

[racydave]

Terry.zak@comcast.net I dont think replacing the weights and springs will add enough travel to obtain the full curve. Some more mods need to be done also!