Rough idle while in gear???? Almost stalls

[nacho55]

This 72 chevy truck I'm working on has a rough idle while it's In gear and almost stalls,But idles great while in park,and runs good while it's driving, I don't have a tac, but maybe I can hook one up for a min what should i set the rpms at?
here's the particulars on it:
Older hei distributor(could this cause erratic idle under load?)
New 350 crate motor
Rebuilt holley 600 carb w/electric choke ( seems to be functioning and open all the way)
Elderbrock performer manifold
Entire New fuel system
tank, pickup, fuel pump, new filter, rubber lines replaced and all hard lines cleaned out
Thanks for any ideas out there.
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[Boog]

Check your plug wires.

[Rufton]

Did you tune carb idle mix screws and RPM screw in drive?
Cam profile affects idle and low RPM performance.

[nacho55]

Wires are new, plugs are new, cap looks older, but runs good while driving down the road and doesnt miss, even when you stomp on it, just at lights or stop in gear runs like it's gonna die, I need one of my "assistants " to wake up and help hold the break and have it in gear if I try adjusting it in gear. I just did a couple turns out on the idle screws where it seemed to idle good in park. Also gonna hook up a old tac and see what it's actually iding at in park. I don't know what cam it has in it, but it doesnt seem to wild or lumpy.
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[Rufton]

May as well let your "assistant" get the beauty sleep so they will be prepared for a day of video games.

Maybe log chain axle to the oak tree so truck won't run you over.

[Coley]

Do you have a vacuum gauge? If not, procure one and find a reliable vacuum port on the intake manifold or tee into a vacuum line (not the vacuum advance tho') and then watch the gauges behavior.
Then compare that to the demo about half way down the page on this website.
http://www.secondchancegarage.com/public/186.cfm
After the vacuum 'test' post your results and we should be able to give you a bit more feedback.
(Initially it sounds like there is a problem in the carbs idle circuit OR a vacuum leak somewhere)
Keep us posted.
Coley

[truckster]

X2 for a possible vacuum leak.

[nacho55]

Im gonna go grab one and hook it up and have a look and see what the readings are, vacuum leaks are what I was thinking too and was out of carb cleaner to try to look for any, so another thing, I hooked up the timing light and noticed that it was way advanced, like way past the timing marker... So I put it back in range then it wouldn't start back up after I shut it off, and just poped and backfired when I tried starting, So I put it back where It was. And it Starts right up.. So more info, it was changed over to a single serpt belt and pulley setup. So now I'm thinking the timing tab may not be the right one for it.
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[domeier]

Originally Posted by nacho55

...So more info, it was changed over to a single serpt belt and pulley setup. So now I'm thinking the timing tab may not be the right one for it.
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That blows. You'll need to figure out and re-mark your tab. The problem you described above could be caused by retarded ignition, and if it's a vacuum leak, it should hesitate when you give it quick throttle. Some guys time "by ear." Maybe someone here can explain how to do that?

[domeier]

I mean, it doesn't blow to have the serpentine! I would love that.

[Rufton]

You can use existing timing tab. Rotate crank to #1 TDC. Put a pulley mark at #1 TDC. Timing tape would be nice but you can make your own and get it pretty close.

[Boog]

Originally Posted by nacho55

Im gonna go grab one and hook it up and have a look and see what the readings are, vacuum leaks are what I was thinking too and was out of carb cleaner to try to look for any, so another thing, I hooked up the timing light and noticed that it was way advanced, like way past the timing marker... So I put it back in range then it wouldn't start back up after I shut it off, and just poped and backfired when I tried starting, So I put it back where It was. And it Starts right up.. So more info, it was changed over to a single serpt belt and pulley setup. So now I'm thinking the timing tab may not be the right one for it.
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Did you disconnect the vacumn line to the distributor before checking the timing?

[nacho55]

Originally Posted by Boog

Did you disconnect the vacumn line to the distributor before checking the timing?

Yea and plugged the port on the carb during it, I didn't get a chance to check the vacuum yet, I got a gauge now I need to go hook it up and see what's happening, And Rufton I was thinking of that too, all good ideas, Thanks guys, I need to get out there and get checking,
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[nacho55]

Well finally got to hook up the vacuum gauge, and it was all irratic, so I started spraying some throttle cleaner around everywhere and no surprises big vacuum leaks around the passger side intake, couple bolts were not even tight.. (this was work done somewhere else) So I take it all off and replace the gaskets and torque them down in sequence and to spec, fire it up.... And the leaks are now worse!!! Glad nobody can hear me cussing out in the shop, Lol, so I guess I should have checked the intake for straightness looks like it's coming back off and more gaskets, has anyone else had trouble getting an eledebrock performer intake to seal to stock heads?
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[jc70chevy]

whats kind of carb could be a power valve. if a holley may be loading up at idle in gear. i nad a problem like this on my 1970 camaro just swapped out to a smaller power valve

[nacho55]

Yea its a Holley 600, but I for sure have some intake leaks to deal with, I used felpro gaskets and didn't have much luck getting it to seal when I redid it,
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[jc70chevy]

well start with your intakes leaks if it still presist then check power valve

[GASoline71]

Did you have a nasty backfire through the carb? Unless it's a Holley built before 1993... it has PV blowout protection already built in.

Gary

[nacho55]

Yes it did have a pretty good backfire, but the carb is only a couple years old so hopefully it didn't pop the power valve, but I can check it again, and after a little google searching I found that the eledebrock intakes don't work too well with the felpro permatorque gaskets....... And that's what I used so that will be coming back off and trying a set that they recomend and see how that goes, never had any problems with those on a big blocks that I've had, I'll keep you guys posted.
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[nacho55]

Well more trouble in paradise as I work on this beast... I changed out the intake gaskets with the recommended ones, torqued to 25#'s and in sequence used gaskasinch... And same dam leaks everywhere.. Could this intake be warped slightly, I'm stumped
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[geezer#99]

Maybe the block has been decked or the heads cut which would misalign the intake to the heads.
What torque sequence did you use to snug it down?

[nacho55]

It's supposed to be a gm crate motor so who knows if it was decked and it may not be from gm, the guy I got it from didn't know much and had a shop install the motor and intake originally and it never ran right, and i used the sequencing elelderbrock has on their site, I've never had this kinda trouble with any other motor, I'm tempted to get a different manifold and try it again.. and just keep throwing money at this problem child... Lol
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[geezer#99]

Here's a little trick for you!
Put the intake on dry. No gaskets.
Put a flashlight inside the lifter valley first. Make sure you turn it on!
Now you should be able to see any alignment issues. Look for any angle differences and clearance on the end rails.
A new intake might sit the same.

[nacho55]

Good idea, that's worth a shot for sure, intake has to come off anyways, gonna give that a try tonight, on a good note I'm getting really good and taking this intake on and off ... Not the skills I wanted to hone..
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[Rufton]

Is it possible head alignment dowels were left out?