Hey all, I posted a question on this a few weeks back, but I have some more info now.

A friend of mine has a 383 in his S10 with a pretty big cam, .630/.630, 274/284 on a 107 CL. The truck doesn't like to idle below 1500 and definitely not in gear. The converter is pretty loose, about a 5000 stall.

We tried the suggested mods, like opening the back barrels slightly and drilling 1/16" holes in the rear plates. The front ones already had 1/8" holes in them. We replaced a smaller solid roller that was the same lift, 264/274 duration on a 106 CL that idled fine.

We also replaced the center section of our 800 DP with one of the Proform pieces that has the 8 replaceable air bleeds. Anyone have any ideas if these would help, what they do and how to do it?

Any info would be appreciated as the truck runs great but just won't idle properly.

Tony, is the timing on that truck locked out?

I personally dont see how drilling holes in the plates will help to get the idle lower.

You cant lower the idle enough to get it under 1500rpms, or it will stall out?

Maybe there is a vacuum leak left undiscovered?

Brian,

The timing is not locked out and is set at 40 degrees. We've done alot of experimenting and this is what it seems to like best.

As far as the idle, I'm really not trying to get it under the 1500 rpms........I figure with the cam it's got it isn't going to get much lower. We would just like it to idle.........after running for about 30 seconds, the motor slowly looses rpm and then just dies. I had thought that the holes in the plates would give the motor sufficent air to have it idle.

If you have any ideas, let me know as I'm open to anything.

By the way, we went to Atco tonight for the Q8 shootout. Was hoping to see you there at the test and tune!!

Idling problems with a big cam can be initial advance related.

With a big azz cam like that the initial advance needs to be a minum of 20 degrees, the more the better with that big old stick.

Personally I would lock the distributor advance out and set the timing to 36-40.

i agree lock it out and see how it likes it.

I was wondering if you were planning to be there, but i dont get out of work early enough to get there in time to get some runs it, and my family wanted to go out to eat dinner.

I'll talk to my buddy and see what he thinks of doing the lockout.......what is the reason that this will fix the problem and are there any other advantages to doing this?

Also, how do I do it? Right now the truck has an MSD distributor. Is there some kind of kit I need to buy and with 40 degrees lockout, how do I start it? I assume I'll need some type of ignition retard also.

Also anyone have any ideas on those air bleeds? I'd still like to think playing with them will help the situation.

i'll call you later and explain it, easier to explain over the phone.

Had the same problem with the engine in my Nova......Car ran fine till I changed to a longer duration camshaft and then the fun started with Idle quality......(Barry Grant Race Demon).....I added Timing and that made the car at least driveable......but it was touchy in the transition off the Idle circuit......Anyhow....to make a very long story short.......I had a Nitrous explosion that bent the throttle plates into "U" shapes.......I bought a new BG Race Demon that has a new feature that is know as "Idle Eze" built in....basically the throttle plates stay in the proper position at Idle with about .020 of the transfer slot exposed and the Idle is set with a screwdriver thru the Aircleaner stud hole to a built in "Air Bleed" system.........WOW!!!!!!!!!!! What a difference, the car even with the long duration starts and Idles without any of the throttle finesse required in the past, the car now is fun to drive......check it out at the BG website
Ken
:cool:
http://www.chevelles.com/showroom/SS396Convert/nova.jpg
http://www.chevelles.com/showroom/SS396Convert/side4.JPG

ss 396convert, what is your idle rpm?

That big cam will make for a LEAN idle which will make the car die when you put it in gear.
How far open are the idle screws.
I would check how big the idle air bleeds are,with a Holley I change them to .070Ø or smaller when necessary.

Tony,did you ever get the boosters to stop leaking during idle? I read your first post and saw where you opened the throttle plates. Pat suggested closing them some and I agree, also with Ken around .020. I've seen this happend alot,you should mostly set idle from the primaries not the secondaries because, as soon as the plates start to open it transfers to the boosters.This can be to much for good idle, you should still be ok with four holes in the plates, this very common. I've done this several times ,I would hold off on tuning with the air bleeds for now,if it was mine I would put the timing light down for a bit and move the distributor around until it sounds the best.Then I would know it's not the ballancer giving false reading, maybe slipped a little.. It's all trial and error; have you tried plugging all vacuum lines temporary(if any)does it have a brake booster that can leak or moudulator valve, intake sealed good on each end,..I hope you get if figured out, sometimes all this fun wrenching turns into work.

ss 396convert, what is your idle rpm?

1000 in neutral......800 in drive....
Ken graemlins/thumbsup.gif

Ken,

That BG carb sounds like what we need.........only problem is we are trying to avoid buying a new carb because my friend is thinking about building another motor over the winter, something big enough where we will need a bigger carb, possibly a Dominator........lol

1968 Hot Rod,

I don't know how far the idle mixture screws are turned out.......I know we adjusted them with a vacuum guage and it didn't seem to make a whole bunch of difference. As far as the idle bleeds go, the new center has two bleeds for each barrel.......do I adjust them all to below .070 or just the primaries? Which one is considered the high and low speed airbleeds per barrel?

David,

We ended up fixing the leaking booster by changing out the center section with a Proform unit. With no other changes, it stopped leaking.

I think we are still going to lock out the timing........it seems easy to do after Brian explained it and it's only a race vehicle, so it shouldn't pose too many problems. Our balancer should be dead on as we corrected the marks when we degreed the new cam in. We also did the vacuum leak check on the intake and found out there was one and fixed it.......still same issue and it doen't have any other vacuum being strictly a race vehicle.

I think I just need some time to experiment......biggest problem is since it isn't mine I can only fool with it occasionally......I'll just have to see what I can accomplish on it this weekend.......

Thanks all for the suggestions, every little bit of knowledge helps!!

run through the valve lash again, maybe your clearances tightend up somehow and killed your vacume signal. What is the lash set at now?