[convgto]

Well heres whats going on, I have a new rebuilt 455, 64 heads, comp 292ah cam, msd billet dist., 6al box, new elderbrock performer dual quad intake with 2 new elderbrock 500 cfm carbs.
Well heres whats going on, I set the idel at 1000 rpm in park (warm), put it in drive and idel goes down to 950 (thats ok) drive and stop at light or whatever stays at 950 in drive, then i stop and put it in park or neutral and it jumps to 1200 ideling and wont go down, put it back in drive or reverse (get the big trans clunck) drive it and it goes back to 950 in drive or reverse and then back to 1200 in park or neutral. I ve been trying to figure this out for 3 weeks. Help, Ken

[screamingchief]

That's a pretty big hydraulic cam (244* @ .050"),what kind of torque convertor are you using?

The clunk comment leads one to think you have a stock or near stock convertor,and that cam will need something closer to the 3000+ stall range to work well.

Have you had a vacuum gauge on it?

If not then you need to so you can see what's going on there first IMO.

Are you using any vacuum advance?

What springs in the distributor?

[berrygoat]

This might sound stupid, but did you adjust the idle with the car not just warmed up but hot ? I always make sure when I adjust timing, idle mixture, idle etc that the car is as hot as it's going to get.

[convgto]

Scremingchief, The converter is a b & m not sure of type, stall is 2800, springs are heavy silver/ light silver, timing is 10 ignitial, i will recheck vaccum.
Berygoat, i set it after the choke opened about 160-170 degrees, it runs 175-180 on the hiway and rises to 195 in traffic, thanks guys Ken

[berrygoat]

re-adjust once it hits 195. It's worth a shot.

[Hillard]

Hi Ken, wasn't there a vacuum leak. I can't remember for sure but I thought there was. If so, did you fix it?

[screamingchief]

Might also try bumping up the initial timing a bit (2-4 degrees or so) and back off the curb idle screw on the carb a little and see if that works better.

Then check the total timing and swap the limit bushings if needed to limit the total to what you want it to be.

And check the timing at idle (in park and in gear w/brakes applied) and make sure the advance is'nt kicking in early,it should'nt be with that spring combo,but check just to be sure.

A hydraulic like that will like a little more initial timing when it's run with an auto-trans.

Convertor should be OK.

[convgto]

hey 1050, i am pretty sure the vaccum leak is fixed, its doing alot better just this last issue, hows my 389 doing, no hurry, are you and your dad going to norwalk?
Screaming the bushing is the stock msd blue one, i am not sure i know what total i want. I had the ignitial up to 15 then to 12 and still pinged, i will try 12 since the vacuum leak is fixed. Thanks alot guys Ken

[convgto]

I have heard many different ways to tune my carbs- elderbrock tech#1 said 1 and half turns out on both carbs, elderbrock tech#2 front turned all the way in, back carb 2 and a half turns out, I bet they wont come on here and give tech like barry grant, Also you wait 25-30 minutes on the phone, then you tell they want you to go away, some others say open the idel screw front carb alittle, others say 1 and a half turn front, 2 and a half turns rear, does anybody know? ken

[Hillard]

[QUOTE=convgto]hey 1050, i am pretty sure the vaccum leak is fixed, its doing alot better just this last issue, hows my 389 doing, no hurry, are you and your dad going to norwalk?


Sorry I really haven't looked at the 389 yet. I'm trying to have the motor ready for the GTO to go to Norwalk. Getting close though, I just have to do the valve job, line hone the block, deck it, bore it, hone it, assemble it.....o.k., not that close.

Wish I could be of more help on your idling issues. Not sure how to adjust those carbs either. Good Luck and I'll talk to you later.

[8point]

If Your vac addvance is hooked to ported you are right on the edge and when it get up to temp it is pulling in some extra timing and causing the high idle.

[convgto]

My 8563 msd distributor doesnt have vaccum advance, Thanks Ken

[steve]

i am just guessing but it sounds like a trans thing not a carb thing.....the variable that causes the problem is the shifting of your trans. i am not an auto trans guy but is it possible to have a vacuum leak in the trans system ? with that clunking i would be looking at your trans not the carbs...just tryin to help......

[convgto]

Steve, i disconnected the vaccum to the trans and it still does it, thanks Ken

[kyle_blake]

I had that problem as well..drive around all night, put it in park and boom 1100 rpm.

WTF, I left my garage and it was tuned for a nice 850 RPM in park.

So what gives? [ I haven't driven car to that extent in ages ]

I guess that is the time to tune it down when the engine is really at it's peak heat.

Sometimes I see street cars at the race way .

They have their cars @ 1300 rpm in 1st gear or so..they stage ...

then go to stall speed and haul ass down the 1/4 mile.

If you asked them to make it streetable , turn it down.. make it idle what it can...there may be that gap of responsiveness that can't be obtained.

Or they'll see perhaps what you see now?

the only vacuum test I know of is spraying around the carb base.

I have no test to verify if one's intake is leaking.

make sure brake booster hose is good and not so secure that when the engine moves that it pulls on the booster housing, thus letting valuable vacuum out..thus a leak really..

little things.
That's my stab at this.

If I could I'd switch jobs to do engine building like some of the guys here.

[steve]

maybe it is time to take it to a shop with all the fancy diagnostic equip and see what they say......i know, its sacrilege.......

[Juliano]

On my edelbrock 750 it was the electric choke linkage screwing up my idle.

[convgto]

Thanks guys, juliano what was going on with your choke linkage, and how did you fix it. Ken

[theYman]

I had this happen to me as well...it ended up being the distributor weights were sticking and not fully returning to zero. Might be worth a look.
good luck,Trent

[LouisianaGuy]

My vote is for a dist problem....having same issue with buddies mustang and i have narrowed it down to either a bad/sticking vac advance or sticking weights.

Oh and dont bother with a Shop that has fancy diagnotic equip.....even if they have some one who knows how to operate it, more than likley they wont know crap about carburetors, and even less about pontiacs :P
Its all fuel injection and computers now :/ hehe
Mike