Surge when idling in 1st - Team Camaro Tech
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post #1 of 11 (permalink) Old Oct 9th, 02, 05:39 AM Thread Starter
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Marty
 
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Guys, I have a 350, TFS heads, Edelbrock RPM and 600cfm carb, headers, HEI, etc. I drive my car a bunch in traffic and it has always suffered a bit of "surge" when I'm creeping along at idle in first. The whole car starts to lurch forward continually when I'm at about 900rpms in fist. What do I need to look at?
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post #2 of 11 (permalink) Old Oct 9th, 02, 07:32 AM
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Matt Jones
 
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Check for any spark scatter than can be caused by the distributor shaft having too much endplay (or the cam has too much endplay).

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post #3 of 11 (permalink) Old Oct 9th, 02, 08:17 AM
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You could have too big of a cam for your converter, your floats could be adjusted wrong, you could be idling on the advance curve or even have the throttle bore open to much at idle to compensate for a rich idle mixture adjustment or not enough initial timing

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post #4 of 11 (permalink) Old Oct 9th, 02, 11:28 AM Thread Starter
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Forgot to mention that it's not an automatic tranny. Cam is a fairly tame Lunati grind.

For timing, I'm running 12 degrees initial connected to full manifold vacume and have adjusted the Crane vacume advance so that I end up with about 22 degrees at idle. My mechanical advance gets me to 36 degrees by 3500rpm.

Dennis, I'll check the throttle bore to see if it's "too" open. I think I am running a bit rich at idle as the exhaust fumes out the back are pretty strong.

Silver, How do you check for "spark scatter"? Not sure that I understand what this even is.

Marty
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post #5 of 11 (permalink) Old Oct 9th, 02, 12:02 PM
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Sounds like a big cam with low gears to me!

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post #6 of 11 (permalink) Old Oct 9th, 02, 01:50 PM Thread Starter
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Nope, pretty mild cam. Rear is 3.73 driving through a T5.
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post #7 of 11 (permalink) Old Oct 9th, 02, 02:12 PM
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I think what you're surging is a trate of every manual transmission car idling down the road in gear. Obviously the lighter the car and the smoother the cam the less lugging will be felt. Most V8's I ever drove with a stick would not pull the car on flat ground idling and would stall very quickly.
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post #8 of 11 (permalink) Old Oct 9th, 02, 09:27 PM
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Your timing sounds good, so I'd play with idle mixture. Maybe clean out the car with some spray carb cleaner and check the floats, then try different idle mixture settings. If it is too lean or has a vaccum leak, it will cough and spit. Just short of that lean it will get balky, stumble a little and act like it has more cam than it really has.

If it had points ignition, I'd check dwell.
Plug condition is important too. Maybe try a hotter plug. Make sure your wires are good, you need a lot of spark to fire a plug when pulling the car at idle.
David

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post #9 of 11 (permalink) Old Oct 10th, 02, 10:20 AM Thread Starter
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Thanks David, I'll check those things. I tried to watch the rpms this morning when the car does this and it doesn't seem to drop any rpms. I should probably not have described this as a surge as it is more of a jump or lurch ofthe entire car. It really starts to rocking if I don't give it some gas. I've been stuck in some serious Houston traffic this week with all the rain so I've noticed it more than usual. It also doesn't just happen in 1st. If I drop the rpms down to the 1000 range in 2nd, I start to get the same response.

[This message has been edited by 69CamaroSS (edited 10-10-2002).]

[This message has been edited by 69CamaroSS (edited 10-10-2002).]
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post #10 of 11 (permalink) Old Oct 10th, 02, 10:28 AM
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I really think you are reading more into this than it is... (not being able to drive with you in your car I can only go on what you say) Ever put the brakes on and forget to push in the clutch? What you are feeling is the car about to die but each chug pushes the car forward just a bit and keeps the engine moving. The second gear at 1000rpm doing the same thing just makes me think so all the more!
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post #11 of 11 (permalink) Old Oct 10th, 02, 01:46 PM Thread Starter
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Marty
 
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Ok Dennis, I hear ya.

But my left leg is going to be twice as big as my right one with all the stop and go traffic here lately. At least it's cool outside for a change (72 right now!) so I'm not sweatin my *** off.
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