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So where does your idle sit at?

Moparfiend

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Engine
Mods
Auto or manual
Carb type or
Fuel injection

1100 RPM in park and 650 RPM in gear.
340
High lift cam unknown, high rise manifold, unknown compression
Holly 4150 650CFM
 
My Charger has a cam that is relatively mild for the cubic inches.
440 based 493 10.07 to 1 CR. 284/528 Solid cam with 1.6 ratio rocker arms. DEmon 850 Vacuum secondary. 2" headers, Edelbrock 84 cc heads, RPM intake.
It idles at about 1000 in neutral and Park, about 700 in gear. It also makes about 17 hgs of idle vacuum in neutral, 11 in gear.
If my advice means anything, please consider using a vacuum secondary 4 barrel carburetor. The double pumper, mechanical secondary units run too rich for an automatic equipped street car with highway gears. A hot 340 would do well with a Basic Holley 750 vacuum secondary carb. I know, you'd think a "750" size would run richer but that is not the case.
 
440, .040" over, headers, .540" lift solid cam, 10.2 to 1 compression, ported heads, Dominator intake, 800cfm Eddy, 18°/37° timing.

Idle in park = 1000rpms
Idle in drive = 900rpms
 
My Charger has a cam that is relatively mild for the cubic inches.
440 based 493 10.07 to 1 CR. 284/528 Solid cam with 1.6 ratio rocker arms. DEmon 850 Vacuum secondary. 2" headers, Edelbrock 84 cc heads, RPM intake.
It idles at about 1000 in neutral and Park, about 700 in gear. It also makes about 17 hgs of idle vacuum in neutral, 11 in gear.
If my advice means anything, please consider using a vacuum secondary 4 barrel carburetor. The double pumper, mechanical secondary units run too rich for an automatic equipped street car with highway gears. A hot 340 would do well with a Basic Holley 750 vacuum secondary carb. I know, you'd think a "750" size would run richer but that is not the case.
I am planning on ditching the highway gears to something like a 373 or whatever is close to that in Mopar land. If I do you still think vacuum secondaries is much better?
 
440, .040" over, headers, .540" lift solid cam, 10.2 to 1 compression, ported heads, Dominator intake, 800cfm Eddy, 18°/37° timing.

Idle in park = 1000rpms
Idle in drive = 900rpms
Hey Threewood hows it going? That 440 motor of yours is a monster I remember you had some great pulls out in Phoenix a year ago! Looks like my idle is in sync with yours and KD’s. I am not used to automatics. All my cars in the past have been manuals..... What vacuum are you getting at idle?
 
Hey Threewood hows it going? That 440 motor of yours is a monster I remember you had some great pulls out in Phoenix a year ago! Looks like my idle is in sync with yours and KD’s. I am not used to automatics. All my cars in the past have been manuals..... What vacuum are you getting at idle?

Going good! Car is running better than ever, even at 100 degrees outside temp.

I'm at 14 in/hg at idle. If there is too big of a difference in idle and in gear you will get a nasty clunk into gear. The only way I know how to adjust it is with timing adjustments. I know you have been having spark knock issues so get it as good as you can.
 
I am planning on ditching the highway gears to something like a 373 or whatever is close to that in Mopar land. If I do you still think vacuum secondaries is much better?

3.55 gears is what I am using and at 65 it runs just north of 3k rpms. If you plan on doing any highway driving (especially in Phoenix where doing 75 will get you run off the road lol) I wouldn't go any higher.

I agree with Kern on the carb. Heavy automatic B body will do great with vacuum secondary carb on the street.
 
I have a 4 speed with a .539" lift and 244 duration @ .050 cam and it seems like to to idle around 800-850. Any lower and it sounds like crap and gets pissy. New motor and playing with stuff still, but that's where it seems to want to run the best. I seem to be pulling a constant 9" of vacuum at idle. I know I adjusted the carb to max vacuum at idle and it didn't like to start without assistance from the go pedal. I gave all the 4 corner idle screws between a 1/8-1/4 turn to fatten it up a bit and it seemed to help alot. I think alot goes out the window of "tuning to perfection" with a big cam and big cubes. Some of the gospel is a bit off the more you stray from stock. She likes to idle a bit fatter, sounds and is much crisper, and restarts alot better.

500" 440 based stroker
10.6:1 compression
4 speed
850 quick fuel mechanical secondary
.539 lift 244 duration @ .050
 
Going good! Car is running better than ever, even at 100 degrees outside temp.

I'm at 14 in/hg at idle. If there is too big of a difference in idle and in gear you will get a nasty clunk into gear. The only way I know how to adjust it is with timing adjustments. I know you have been having spark knock issues so get it as good as you can.

Threewood is that vacuum reading at idle taken in gear or in park?
 
Stick. Under 700. Want to hear the rumpity rump. When uncapping, I flip on the ac to pull it down a smidgeon. Perfect.
 
Threewood is that vacuum reading at idle taken in gear or in park?
That is in park. Verified when I dropped the new carb on and tuned it. I didn't see what it was in gear.
 
That is in park. Verified when I dropped the new carb on and tuned it. I didn't see what it was in gear.

OK it'll drop quite a bit in park.....you had me worried haha. I was like wtf man I am way off, but we are real close then because I have a stick. Bet you drop to 9-10 in park which is right where i am at. We have similar camshafts as well.
 
OK it'll drop quite a bit in park.....you had me worried haha. I was like wtf man I am way off, but we are real close then because I have a stick. Bet you drop to 9-10 in park which is right where i am at. We have similar camshafts as well.
I can get a reading in gear later today.
Here are my cams specs...I'm running 1.5:1 rockers.
STL3842BS.jpeg
 
Yea no biggie......we are close. You run a bit more lift and I have a bit more duration, and my cam is on a 110 lobe separation and yours a 109, so we should be in the same vicinity. You run the solid cam though right?
:thumbsup:
 
(Before the current freshen-up in progress)
440/+.040, 9-1 compression, RPM heads and intake, 850 demon mech. secondary carb, carter street fuel pump, 274/286 cam (230°/236°@.050), 1-7/8 headers to 3" exhaust, 2500 stall, 3.73 gears, 3650lbs with me in it. 800 rpm in neutral, 700 in gear@16 in. vacuum. Dropping 400+ rpm going into gear from a warm idle is too much for me.
I will say, I'm not a believer in the 'vacuum secondary only on the street', but that's only for my own experience, everybody's is different. I believe the reason that came about was from people slapping holley double pumpers on mostly stock cars back in the day, and there would be a bog when you floored it--too much too soon. With the adjustability of the carbs today it takes a little extra work but you can have a great running mechanical secondary carb on a street car if everything plays well together. Progressive linkage is a must. Mine doesn't bog, burp, fart or run too rich..but oh boy it's much easier to get your foot into it, thus a little worse on mileage if you're not careful (and who's got time for that lol!)
 
(Before the current freshen-up in progress)
440/+.040, 9-1 compression, RPM heads and intake, 850 demon mech. secondary carb, carter street fuel pump, 274/286 cam (230°/236°@.050), 1-7/8 headers to 3" exhaust, 2500 stall, 3.73 gears, 3650lbs with me in it. 800 rpm in neutral, 700 in gear@16 in. vacuum. Dropping 400+ rpm going into gear from a warm idle is too much for me.
I will say, I'm not a believer in the 'vacuum secondary only on the street', but that's only for my own experience, everybody's is different. I believe the reason that came about was from people slapping holley double pumpers on mostly stock cars back in the day, and there would be a bog when you floored it--too much too soon. With the adjustability of the carbs today it takes a little extra work but you can have a great running mechanical secondary carb on a street car if everything plays well together. Progressive linkage is a must. Mine doesn't bog, burp, fart or run too rich..but oh boy it's much easier to get your foot into it, thus a little worse on mileage if you're not careful (and who's got time for that lol!)
Wow thats a very low idle you achieved! What are or is progressive linkage? Is that a non linear throttle linkage? If so how?
 
Wow thats a very low idle you achieved! What are or is progressive linkage? Is that a non linear throttle linkage? If so how?
Progressive linkage is where the secondaries only begin to open as you move through about 1/2 throttle, give or take..there's a point where you can feel the linkage grab the secondaries and start to open them. It's very subtle, and it may depend on your throttle cable stiffness and such but in something like a big block that makes a lot of torque, you can cruise around town without ever really opening the secondaries(what fun is that though!).
The way they work is the carb throttle levers are slotted a certain way and the small arm that connects primary to secondary is bent in a certain way to allow some movement of the primaries before cracking open all four. On my particular carb, you can switch the rod around to run 1 to 1(all four barrels operate at the same time) or progressive style
 
Got it nice. Looks like they make one for the 4150

C687040A-950A-4391-88DC-0D8ABF75D9EB.png
 
1200 in park, 700 in gear, 7" at idle in park.

500cu.in stroker, 10-1 compression,
Comp cam 272/[email protected] 0.621/0.621 lift mechanical roller.
Little EZ 295 heads , Holley street dominator reworked to Max Wedge intake with a 850 Mighty Demon.
1 7/8 TTI's. MSD distributor locked @36°
3500 Stall.
 
1200 in park, 700 in gear, 7" at idle in park.

500cu.in stroker, 10-1 compression,
Comp cam 272/[email protected] 0.621/0.621 lift mechanical roller.
Little EZ 295 heads , Holley street dominator reworked to Max Wedge intake with a 850 Mighty Demon.
1 7/8 TTI's. MSD distributor locked @36°
3500 Stall.
I am just below you on idle but feel I need to boost it up 100RPM to where. Yours is at to maintain decent idle in gear. Seeing your numbers makes me feel better bumping it up. So you have your dizzy locked at 36 degrees....does that mean you are running at 36 everywhere no curve or does it mean your mechanical advance is maxed out at 36? I guess what I am asking is what does locked out mean??
 
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