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Old 02-01-2012, 08:25 PM
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Sluggish top end kickdown

Have a 350 .60 over 288 crane cam 600 1406 eddy carb. Problem is I got the motor of a buddy and put it in 67 swb c10. The motor had a 750 Holley on it but I couldn't get it to idle. had plenty of power both top and bottom. I put the 600 on it idles like a dream and tones of power on stop to wot but at kickdown from cruise to wot it acts like its sluggish. Talked to eddelbrock and they said my timing was retarted to much but it's at 14 btdc and if I advance it I loose power on both ends. Haven't adjusted the pump actually thinking it needs bigger rods and jets in the carb. What's your all opinion. Any help would be greatly appreciated.

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Old 02-01-2012, 09:54 PM
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It could be what you mentioned and likely is. Also they were right, the timing is set too low. First of all start over with the spark timing. At idle, vacuum advance disconnected and plugged, set the timing to 12 degrees before top dead center, reconnect vacuum advance to a full time manifold vacuum source, one that pulls idle full time including at idle. Recheck the timing, it should be 18 to 24 degrees before top dead center. When you connect the vacuum advance it's right away going to idle up, so this is where you readjust the idle speed then set the idle mixture. With a cam that size and the holley you had on it, it likely wouldn't idle due to not enough base timing, when the base timing is too low the idle speed has to go up, which opens the butterflies to the point they are off the idle circuits and pulling from the boosters resulting in it being too rich. Another thing to check is fuel pressure and volume, when your trying to feed a hungry engine, especially on the top end the pressure and volume must be there. Also have you checked what the timing is at upper RPM? it should have 36 degrees total timing all in before 3000 RPM. The issue your having is just about always summed up as ignition or fuel problem and in many cases they diagnose the same. If the fuel pump can't keep up with the fuel demand it will act as you discribe, but it can also act this way if the jets aren't large enough. Also, a dirty fuel filter can cause this issue as well.
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Old 02-02-2012, 06:00 AM
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It's funny you said fuel filter. Cause when I had the Holley on I ran it without the fuel filter and when the edelbrock went on it had fuel filter attached to it. My base ignition timing is set at 14 with advance unhooked. So are you saying i should retard it down to 12.
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Old 02-02-2012, 11:00 AM
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I am saying this:
Engine at idle. Vacuum advance disconnected and plugged.

Set base spark timing at 12 degrees before top dead center. Lock down distributor.

Reconnect vacuum advance to a full time manifold source which on a Edelbrock carb is the port on the front drivers side.

Recheck base timing. It should be 18 to 24 degrees before top dead center.

When you connect the vac advance it's going to idle up. Lower the idle speed down to the given cams recommended speed.

Once idle speed is set, adjust the idle mixture.

After setting the idle mixture give the idle speed one final check.

Once you finish, you'll notice it sounds better with a lope at idle.

To check the mechanical timing disconnect the vacuum advance and plug it.
Have a assistant keep a eye on the tach to tell you where you are RPM wise and make sure your getting the full 36 degrees advance all in before the engine reaches 3000 RPM. You may have to change weights or springs in the mechanical advance to get it right. Check the mechanical advance for smoothness in operation, make sure it opens and closes smoothly with no rough spots. Once you get it right, reconnect vacuum advance and test drive.
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Old 02-02-2012, 11:43 AM
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Gonna check it after work. If my base doesn't go up that much will I need to change weights and springs in the dist. Also how do I know how munch to go up if needed.
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Old 02-02-2012, 05:18 PM
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Hooke up to direct and gained even more power on bottom but still sounds like its wanting more fuel from cruise to WOT.
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Old 02-02-2012, 06:13 PM
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THen more than likely it's still starving for gas. You'll have to figure out if the fuel pump is not keeping up with the demand or if the carb is jetted too lean.
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Old 02-05-2012, 06:21 PM
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Drove the truck to town today and it seems since I went to full manifold vacuum that it almost has a miss from take off to cruise kind of a small bump in the motor. It's timed on 12 ignition then about 30 when I plug vacuum advance back up.
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Old 02-05-2012, 09:06 PM
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Think I could have to much timing now???
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