Quote:
Originally Posted by budman k20
I have been tuning with the vacuum gauge to set the idle mixture. What I read was max out the vacuum at the correct idle speed and back off 1/8 turn.
I'm pretty sure the process you described is incorrect. You can download the tuning instructions for your carb from the edelbrock website. I remember the instructions saying adjust idle until max vac then adjust the other side go back a couple times and reset idle speed as needed. Just curious what your vacuum readings were? Sounds like you have a stock cam so it should have been over 18in. I would like to know how much your vacuum changed when you backed out the idle screw 1/8 turn. I have a 1407 so my instructons (and memory) may be off a little. If you have a stock fuel pump you should be OK... not for sure but the odds are in your favor that you dont need a fuel reg. What is your base timing set to? If its not around 12-14 btc you need to put it in that range and when you do it make sure the engine is not spinning fast enough to add mechanical advance <700 rpm to be sure. The other thing I found playing with my edelbrock is it needs a non metal spacer. This really helps out after hot shut down to keep the fuel from boiling. If you shafts are not worn you should be able to make your carb work. Finally what do you know about your dist timing... like the total advance it delivers and at what rpm? This has a big effect on how your engine runs and needs to be sorted out before you complete any carb fine tuning. Hopefully I gave you something to think about. Good luck I think you can make your carb work with a little research.
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29" of vacuum idling at 700-800. 12 degrees initial advance, I set that at about 600 rpm. No clue what cam is in this, I haven't had a reason to look inside the engine.
I rebuilt the distributor using an Accel kit I bought at the local speed shop. It had cap/rotor/springs/module/weights/etc. I haven't tried to see what the total advance is, as I have no way of reading past 15 where the timing tab ends.
I did the setting by idle RPM a couple of times, then found instructions from someone else saying how to do it with the vac gauge. Supposedly using the vac gauge is more accurate.
I just put in the special thick gasket from Edelbrock under the carb to help with hot starts. So far that seems to have helped.
Just driving around tonight starting and stopping the truck a few times, I saw it idle at 1400, 1200, 600, 900, 1000, etc. Every time I stop at a light or restart the engine I get a different idle speed. Otherwise it runs great. Only got it to hesitate once hitting the 4-barrels, after that they kicked in smoothly.