Carb tuning help - Pontiac GTO Forum
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post #1 of 3 (permalink) Old 10-02-2007, 01:40 PM Thread Starter
 
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Carb tuning help

Hey goat people

I need some help tuning my 750 Eddlebrock carb. The carb sits on top of my 1970 455cid. I have a feeling that I'm running rich ( is that a bad thing?) and I'm scared of adjusting it to lean. Any info on how to set the mixture screw right would help.
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post #2 of 3 (permalink) Old 10-10-2007, 01:01 AM
 
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Vacuum gauge. Put one on the manifold vacuum and turn the screws till you get the most vacuum and Idle speed with a tachometer. Remember that the air cleaner will change things a bit when you put that on, so recheck it. Now you will need to have some one follow you and/ or check plugs at higher rpm runs, under load (aka driving the car). If some one follows, they will need to see if you get any smoke out the back when you shift to each gear and when you go full throttle (punch it). If there is, then you have a little to big of a jet or the secondaries are opening to fast. You can also tell if it bogs down when you accelerate. You will want to pull a plug and see if it is to clean or black. That will tell if it is jetted right, but do it right after a hard run with out letting it idle. The Eddlebrock carbs seem to be pretty good right out of the box, that I have worked on. A friend has the same one as you on a 1970 firebird 350 that I built for him with a 068 cam (ramair III) and 9:1 compression it runs very well. He has been using it as his only car for 4 years now. We never had to re-jet it but did have to fine tune the idle.
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post #3 of 3 (permalink) Old 10-10-2007, 03:27 PM Thread Starter
 
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Thanks for the info
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