DodgeTalk Forum banner
Status
Not open for further replies.

360 Tuning Issues

3K views 13 replies 4 participants last post by  Brian_RO 
#1 · (Edited)
Issue: In the cold weather (50 and below) the car was missing.

I figured it was running lean (due to glowing headers at idle) so a friend and I retuned it.

To start:

Idle in Neutral: 19 degrees
Idle RPM: 1080


This high idle was needed because of the old 904 trans and stock converter. Much less and it wouldn't stay alive in gear. Now I have my 518 AOD and the converter is much looser. Keep in mind I have not jacked with the cars tune in years and never had any issues because I never drove it in the cold before.

After our first tune, we had it set like this:

Warm idle: 940 rpms (800 in gear)
Timing @ idle: 22 degrees
Gauge shows good vacum at idle in neutral and in gear.


I felt the timing was way too high, but my friend is a dirt tracker and he thought it was fine as long as it started when hot. It runs OK, but still missed when engine was cold.

So I did some rework on the tuning:

Neutral Idle: 780rpms
Idle in Gear: 690rpms
Timing @ Idle: 17 degrees
Vacum: 15 inches @ idle
<- This is the best I can get out of it, but reading up on the web says that's normal with bigger cams and more overlap.

I adjusted the carb per the manual...I think it's reasonably close.
Fully warmed up I am reading 240-260 degrees at all of the header primary tubes (ceramic coated).

Now, with it set like this, and still not warmed up, it missed, as you can see in the first video below. After this I drove it for 15 minutes at all different speeds with no further problems, except that it is heat soaking. After sitting for 20 minutes with the engine OFF, it has the damnedest time starting.

This is my engine setup:
360 9:1 CR
625 Carter AFB - Electric Choke (new type)
Edelbrock Airgap intake
FBO Stage II Ignition (custom timing for my future 3.55 gears)
Cam: Herbert E3N 455/475

Video of it missing:
http://s289.photobucket.com/albums/ll236/cowtownmopars/Personal/?action=view&current=Dartmiss.flv
 
See less See more
#2 ·
Putting two video links in seemed to mess up the first post. Here is a link to it running only minutes later on the same drive. It ran fine, but heat soaked and would barely start once it was back in the garage.

http://videos.streetfire.net/video/Driving-the-Dart_641626.htm

Oh, and the first video auto-embedded. How do you get the streetfire one's to work right?
 
#4 ·
If the headers are glowing at idle you have 2 things possibly wrong here. Too much initial timing. Or too lean. I think you have too much timing advance at low rpms. What are the cam specs other than lift. Especially duaration at .050 on the intake? With an AirGap Intake, (I run an Eds Airgap on my 360 Magnum), it shouldn't cause heat soak due to the divorced plenum. I think you have a timing issue. Have you pulled a spark plug to see what the 'burn' is? What kind of dizzy are you using? www.4secondsflat.com
 
#5 ·
I'm about to go out and tinker with it some more. We'll see what happens when I back the timing down 1 or 2 degrees at a time.

I think any lean burn issues have already been addressed when we retuned the carb per the manual.

Cam is a Herbert E3N Hydraulic:

Intake duration 275 (215 @ .050)
Exhaust duration 285 (225 @ .050)

Lift: .450/.475
Lobe Separation: 112

My paperwork from Don (FBO) specifies 18 degrees initial timing and 34 degrees total at 3200 RPMs (again, based on the 3.55 gears that the car does not have yet). I bought the A688D kit a few years ago. It made a night and day difference on my car, and I was upgrading from a Mopar Orange box and Blaster II coil.
 
#6 ·
Sounds like a good idea! Keep us posted, you have a nice combo! It should run very nice once you get the timing and tune right. The Chet herbert cam is a nice street cam and should produce nice power over a wide RPM range and not be too 'choppy' at idle requiring a lot of lead or initial timing as some bigger cams need. I would also try a little less initial and see how this responds. You may have to turn the idle up a bit after backing the initial off. BTW, make sure that choke is opening up all the way when warmed up. I would try and adjust it so it opens as quickly as possible if thats possible. I dont use an electric on my Holley, it requires a few minutes during, only during the coldest months down here.
 
#7 ·
Well, got delayed on my start.

Gee, do you think I'm running a bit rich? :YO:

NOW I'm gonna go back the timing off and lean the carb out...as long as I don't get any more phone calls.
 

Attachments

#8 ·
#9 · (Edited)
It sounds very nice! As far as the plugs are concerned, what type and heat range are they? My 440 SixPack had the same carbon but dry build-up on a set that were only 50 miles old. It turns out I had too cold a plug in it. The Air/Fuel Ratio was 12.9/13.1 on my LM-1 meter,(this is even a bit lean). A replacment to a hotter plug one step cured the problem. But you know your combo better than anyone so I thought I would bring this up to possibly save some time and aggravation if it's a plug issue, but off hand yeah it's got either too much fuel or too cold a plug. If the plugs are the correct heat range, then it can only be too much fuel in the idle or primary circuit. I like NGK FR-5's for approx 9:0 to 10:1 comp. ratio 5/8 hex plugs. Another choice are Autolites but Ive never used those brand they are popular among the 5.2/5.9 crowd dare I say Champion RC12YC 5/8 hex (these 5/8 NGK's and Champions are projected tips as you are using) you're engine sounds very strong!!:rck:
 
#10 ·
They are Autolites plugs. Can't remember the heat range. I think I went +1 range over stock...didn't think to look while I had the plugs out. :banghead:

Car started fine after sitting 15 minutes.

I just got back form a drive, got it good and warm, and I'm letting it set another 15 and I'll see what happens. There was no stumbling when I had it out, other than the usual, gutless off idle acceleration (can't wait to get the friggin gears changed).
 
#11 ·
You might want to try the stock heat range. I have a pretty big stick for a street cam in my 440, I thought for sure it would need a colder plug. It didnt, and quickly 'gas fouled' I put the hotter,(1 step), plug in it and it runs great(Street use only). Does the exhaust smell 'bad' eyes watering at idle? You're real close on your tune. I woudl only change one thing at a time and you'll get it. The timing is real close if not perfect so I would leave that alone for now.
 
#14 ·
i agree try the stock heat range on the plugs or go +1 hotter. gas isn't what it used to be so a hotter plug may help.

as for a quick referance on the carb adjustments i always start the engine and let it get warm and then turn the idle screws in one at a time until it starts to stumble and back them out until it clears up. this will get you pretty close.
 
#12 ·
OK, thanks.

I'll need to recheck my plugs after a bit of driving. When I do, I'll check my plug range. I'd say those plugs have less than a thousand miles on them.

You can smell the exhaust at idle if you are behind the car, but I wouldn't define it as "bad". It just smells like an old car. :D

After sitting for 15 minutes after I got back, the car started right up, no problems. We have a Mopar dealer car show tomorrow, think I'll try to sneak it up there and see how it does (about 18 miles).

Here it is on my last drive. Excuse the background noise. The car has no interior other than seats and some broken A & C pillars, so you can hear EVERYTHING on the video. It doesn't help the camera mic amplifies hi frequency sound.

http://s289.photobucket.com/albums/ll236/cowtownmopars/Personal/?action=view&current=drive21.flv
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top