Okay,
Back to basics before I give up on this engine completely. I've had the SVDA dizzy on my car off and on throughout the year, and I recently re-installed it. As per my other thread, the car runs but simply falls on it's face and backfires like crazy at 4,000 rpm.
I'm beginning to wonder if I've had my wires installed 180 degrees out the whole time. I understand the process of finding TDC on #1, and that the rotor should be pointing toward the #1 spark plug wire when everything is hunky-dory. I've used multiple resources, but the process is explained here:

http://www.hot-spark.eu/docs/Installing-SVDA-034.pdf

The problem that no one ever seems to acknowledge is that the distributor turns. So when I have the engine at TDC, how do I know the rotor is pointing at the true #1 spark plug wire? If I turn the dizzy 90 degrees to the left or the right, I'm at a different plug wire.

What would really help me is if someone who has an SVDA installed would post a picture and point out where #1 is on their setup. Sorry, but I have a habit of making the really simple things far too complicated. But I thank you for your help.

"Sorry, but I have a habit of making the really simple things far too complicated." You got that right.
If you can turn the distributor so the rotor lines up with No 1 on the cap at TDC, set the timing and you're good to go as long as the wires are on the cap in the proper firing order. Sorry I don't have a picture but when looking from the rear of my car forward the No 1 wire is approx 1 o'clock on the cap and the vacuum advance unit is approx 9 o'clock.

Thanks Michael. I went back out and reset everything as you described. I'll try to start it tomorrow and re-time it and report back.

well, it's tomorrow what happened?

I believe that my SVDA has #1 at about 7 o'clock (12 o'clock being towards the front of the car). Putting it at 11 o'clock, like on my old dizzy didn't give me the freedom to turn the dizzy as the vacuum can got hung up on the tin.

Spoke with McMark before I tried setting this thing up again and it all made perfect sense. Started right up after I set TDC and all the plug wires right. Timed it once again, this time at around 30 degrees total advance, since I don't have vacuum advance hooked up. Runs great at low and mid range RPMs, with a nice smooth transition through the idle-main circuit. Unfortunately the backfire is still there, strong as ever.

But thank you guys for helping me ensure the dizzy was right at least (I think it was all along).

I wish you lived closer so I could fix this.

Can you post a video?

Did you rebuild the motor?

Rich

this is an "old" motor?


the valve springs could be about done or broken, or a slightly bent valve that is hanging up at high rpm.

Hehe, I wish we all lived closer! I'd like to meet all of you guys someday, and knowing that's probably not going to every happen really depresses me sometimes Oh well.


This is indeed an old motor. The numbers I have for compression indicate it *may* have some life left (110 PSI on all 4) but I'm not holding out hope. I have no idea if, or when it has been rebuilt, but certainly not by me. Everything I know makes me believe it is the original, with over 100,000 miles and probably not rebuilt - there were no rebuild tags or markings on the engine when I got the car.

Rich - I'll post a video sometime this weekend. I've got a GoPro, and as long as I keep the windows up, it should get pretty good sound.

Please list the carb specs for venturis and jets again.

Rich

And please post a few pics of the carbs on the car, with linkage attached.

Good thought. Have you confirmed sync of the carb both at idle and off-idle?

Backfire when? On decel thru exhaust? Rich. Thru carbs? lean.

Do you have access to an LM1 or LM2? Seeing your A/F ratio will help you a lot.

Glad you got the dizzy running!

does SVA HAVE a vac canister on it? what did you plug the ports on the carbs with?

At this point I'd be looking to yank the motor and do a tear down. You have swapped induction and ignition and neither has solved your problem.

I'm beginning to wonder if your heads aren't shot. Have you performed a leakdown test on this motor?