• From: Ontario, Canada
  • Registered: 2005-06-11
  • Posts: 266

Topic: Tuning questions - Electric Chokes, fuel pressure regulators, timing..

1)  I'm noticing that the chokes appear to do nothing on my carbs.  With the car off (no voltage), one doesnt want to stay open and the other doesn't want to close.  They naturally spring back to completely different positions.   With the car running (12volts), they don't appear to move at all and I'm having a hell of a time tuning the carbs with the choke's set at different places.  I'm having to hold them both open while adjusting each carb.. its turning into a nightmare.

Since they don't appear to be doing aNYTHING, is there a way to swap the electric chokes for a mechanical one? (a kit perhaps?)   I'm not opposed to the idea of disabling them completely and I understand that I'll just have to give it throttle to keep it running at idle (just to warm up)   Any concerns with that?  This is generally a warm-weather only car.


2)  Got a fuel pressure regulator and it did not come with any instructions about how to set it for a particular pressure.  I'd like about 2psi.  There is one large brass nut on top, and there appear to be two nuts on the bottom.  Loosening any of them appeared to just give me fuel leaks, so I'm wondering if its adjustable at all??? help!

3)  With dual carbs, SVDA dizzy, 1776cc, stock tranny, what is a good ballpark starting point to set my timing? 


Currently I'm getting a bit of backfiring out the muffler when downshifting so I'm going to adjust my mixture back down a bit but I want to set my timing properly to make sure that's not part of the issue.  I've adjusted the carbs following the procedure on lowbugget and they appear to perform quite well once the car is warmed up (with the exception of the backfiring during a downshift under load)

-biggie

thebignic's Website

  • Registered: 2009-06-25
  • Posts: 558

Re: Tuning questions - Electric Chokes, fuel pressure regulators, timing..

Hey Nic, tuning can be a bear, but that's not news to you. I'm new here, but used to be a racing mechanic.

1. Your choke plates should be in the same initial position as each other. Basically you are running 2 cylinders per carb with the same requirements, so settings should match from carb to carb. With the carbs dead cold, the choke on each should be closed or mostly closed depending on the model. After startup, the electric controls should gradually open on both both carbs, and at normal operating temp for the engine, both should be fully open. One is either severly mis-adjusted or defective, no way it should be wide open when cold unless it has a stepper motor controller, AND it's wired wrong or defective. Contact the carb manufacturer and explain JUST the choke problem. You can't tune the carbs with the chokes not functioning unless you just block the closed one open.

2.  Your fuel pressure regulator should be adjustable, but some may require loosening the top nut and tightning the others, or some other combination. Aparrently yours is meant to be adjusted while not running, but again you need to contact the manufacturer and ask for instructions or at least a link to their online documentation.

3. Different distributors require different timing. Post the dizzy model number and someone here can point you in the right direction, or you can look it up. I was given a great list at http://www.oldvolkshome.com/ignition.htm#A1974AFD that you can lookup your dizzy and the timing.

Paul

Last edited by Altema (2009-07-12 16:11:36)