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Discussion Starter #1
I recently got a new 670 Avenger carb for my cleveland. When we first put it on, it was obvious that it needed to be re-jetted. (would stall when put into gear or at stop lights) So, I spent the $$$ for a professional tuning/re-jetting. I got it today, bolted it on, and it still runs very bad. Idles way too high, and when I turn it down, it dies. The engine is already nice and warm. Anyway, we took it for aquick test drive. It feels like I have a 2bbl instead of the 4. Very little power. It is like the scondaries aer not opening, but they are. But with the 600 CFM edelbrock, it is very powerfull. I don't get it. Does any one have any ideas? I am getting tires of swaping carbs around.
Thanks!
Matt
 

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ok you took it off and send it to some one to be tuned, how would they know how your motor runs, only real way to tune it is on the car. I got a 770 avenger and bolted it on out of the box it worked great, maybe they forgot to put something in when they built it

they do have a warranty
 

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Discussion Starter #4
I took it to a guy how has a machine that can wet-test it, and you can program it with the engine specifications, so I don't see why it shouldn't work. I am taking it back 2 him today, and have him re-look at it. I think something on the inside might be broken or something, because it should work great.
Thanks for all of the help.
Matt
 

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you have to set the idle mixture right out of the box. That's why when you put it in gear it would stall. Every engine is different, with that being said, the only way a precise tune can be achieved by tuning the carb on the engine by trial and error, and educated guessing. If it's got no power, and is running poorly, first off, look for the basics. Make sure you have no vacuum leaks first and formost. Then turn each idle mixture screw in all the way, and back out exactly two turns. Start the car and adjust the idle rpms so that the engine says running. Then by going 1/4 of a turn adjust the idle mixture screws in first to see if the rpms rise, or out depending upon the engine. Do this 1/4 a turn at a time keeping each screw adjusted the same. The highest idle is what you want. You will have to then adjust the idle rpms down. To fine tune the mixture for driving you need to do this while having someone you trust put the car in gear and hold the breaks. But first do it while in park. Also one other question... Is the ignition timing correct?
 

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Discussion Starter #6
Matt-
I tried all of thoes things you suggested. That is why I took it to the profesional to get re-jetted, because I just figured I had way wrong jets in it. I can see that I would need to fine tune it once it is on the car, but that is not the case. I think there is something seriously wrong with it.
Yes, the timing is correct.
Thanks for the ideas.
Matt
 

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I have a 670 Avenger on my 351W engine with Performer RPM manifold and comp cam 268 extreme energy cam. My carb was way too lean. I installed an air/fuel gauge with oxygen sensor to figure out what was going on. I had to re-jet the primaries I believe 4 steps richer and the secondarie 5 steps. I went up to a 37 on the accelerator pump nozzle and put in a 50 cc pump. Works great now.
 

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The thing that get's me about this, is that it's not running right at idle. You could change to the fattest or leanest jet you could find and not have any change in the idle due to the idle circuit being controled by the idle adjustment screws. Methinks something else may be lurking, waiting to be discovered. Did you pull the distributor to change the intake? If so, then make sure all the wires are connected to the correct cylinder... now you've got me thinking.
 

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Discussion Starter #9
Matt-
We did a complete out of the car overhall/rebuild on this motor. So that excludes not putting something back when the intake was put on. The thing is, it works great with edelbrock, but not with this one. I would keed the edelbrock, but I was looking for some more power.
I took it back to the shop today. I will post if he finds anything out.
Thanks for the idea.
Matt
 

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Did anyone check the power valve? If it is not the right size it may act like this. What about the float levels are they OK? I know this sounds elementary but it's usually something simple .
 

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Discussion Starter #11
Power valves were re-placed, not sure of the float level. But I when I emptied it to take it in, the bowls seemed full.
Thanks for the idea.
 

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Wow this is a strange situation then. I've ran several holleys on my car, and they ran great. The one I have on now is a 650 dbbl that I bought for $100 from a guy at work. I rebuilt it and away I went, after I got the jets set, I haven't touched it since. I wonder if someplace, a vacuum port isn't plugged on they holley? Also how is the vacuum advanced hooked up on the car for the distributor? Is it hooked up the same way as was on the Ebrock? (ie full vacuum @ idle, or timed). Perhaps you did in deed get a bum carb
 

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you said they replace the power valves,
but they need to be specific to your
engine vacuum,
if the valve has a high number and your
cam is pretty big, it will cause the carb
to run rich and be non tunable at idle in gear


but this will not effect full throttle
operation
 
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