fast idle when hot - 451ci
#1460007
06/29/13 07:51 PM
06/29/13 07:51 PM
|
Joined: Aug 2011
Posts: 13
MN
ebodykid
OP
member
|
OP
member
Joined: Aug 2011
Posts: 13
MN
|
ok guys, need a little help..
I have a 451 stroker (built by MM with plenty of power!), that i am having a little issue with when hot. I am trying to get everything dialed in for the Car Craft show in July..
My main issue, is that I have an issue when the car is hot, where it idles way up in park, and runs on if I turn it off with it in park (when the idle is up). I have a Quickfuel 830 on it, and everyone that has looked at the carb seem to think everything is setup properly with regards to idle and float positions. I had a bad vacuum leak in my power brake booster that has been resolved, an it doesnt appear to have any vacuum leak that I can see. I have read every post that i can find with these symptoms looking for a solution. I do have a new distributor(msd pro-billet RTR) that will arrive on Monday to replace the old chys electronic one i had, as well as replacing the old raggity spark plug cables to try to help rule anything from the ignition side.
I have read some people talk about a bad torque converter being a cause, and I might believe this for my car, as it currently likes to leak out the front of the transmission. It is a newer converter (5yrs) in a new trans (TCI SSFighter 727).
I also had some issues initially, as i didnt notice that the fuel pump that i was using, was a racing pump putting out 13psi. So it had initially run for the first couple hours of time on it, sending way too much PSI. I have put a regulator in it to take care of that, but wonder if it could have done something to the carb?
And lastly, timing could be an issue. My dad is set on the idea that it should be set at 8deg initial timing, as that is what the old 383 was supposed to be at. If i remember correctly it as at 12deg right now. What would you recommend to start at for initial timing for this combo?
Thx for your time!
|
|
|
Re: fast idle when hot - 451ci
[Re: coro500net]
#1460011
06/29/13 08:24 PM
06/29/13 08:24 PM
|
Joined: Aug 2011
Posts: 13
MN
ebodykid
OP
member
|
OP
member
Joined: Aug 2011
Posts: 13
MN
|
thanks for the responses so far.. I have the dizzy, and a new radiator (was up to 235deg last year at the show) set to arrive next week.. I will double-check the linkages, as I could see that maybe as an issue. We had to mess around with different springs to get it to feel right (has the taller edelbrock RPM intake) with the taller linkage bracket. If anyone else has any ideas / input, please chime in as well.. the more help the better! Getting the timing right, and figuring out this run-on issue will make me feel better. I am hoping that a lightbulb will come on and I will see that obvious issue. I will then just need to figure out my trans leak, and see if i can track down my little oil leak.. theres always something.. 
|
|
|
Re: fast idle when hot - 451ci
[Re: ebodykid]
#1460012
06/29/13 08:59 PM
06/29/13 08:59 PM
|
Joined: Oct 2007
Posts: 3,893
Oregon
hooziewhatsit
master
|
master
Joined: Oct 2007
Posts: 3,893
Oregon
|
Add more timing, while limiting the total amount.
More initial will let you close the throttle blades a bit more.
Also, you may be on the edge of when mechanical advance kicks in. When it's warm, it idles faster naturally, which then provides more advance, so it idles faster still... Does the timing change between neutral and drive?
If you ever find yourself in a fair fight, your tactics suck.
|
|
|
Re: fast idle when hot - 451ci
[Re: hooziewhatsit]
#1460013
06/29/13 09:14 PM
06/29/13 09:14 PM
|
Joined: Aug 2011
Posts: 13
MN
ebodykid
OP
member
|
OP
member
Joined: Aug 2011
Posts: 13
MN
|
Quote:
Add more timing, while limiting the total amount.
More initial will let you close the throttle blades a bit more.
Also, you may be on the edge of when mechanical advance kicks in. When it's warm, it idles faster naturally, which then provides more advance, so it idles faster still... Does the timing change between neutral and drive?
hmmm.. if i remember correctly, it did like to jump around when setting the timing on it, between n and d.. So you think upping the initial might help? The dizzy that had been in there had been recurved, but I have no idea what it was set to. I am going to start with the default curve on the new msd one that is coming to start.. I wish my parts were here so i could tinker with it.. with the weather and the new baby, i havent yet even fired my car up for the year 
|
|
|
Re: fast idle when hot - 451ci
[Re: hooziewhatsit]
#1460017
06/30/13 02:54 PM
06/30/13 02:54 PM
|
Joined: Aug 2011
Posts: 13
MN
ebodykid
OP
member
|
OP
member
Joined: Aug 2011
Posts: 13
MN
|
Quote:
More initial may help. If not, you'll need to put a slightly stronger spring in the distributor (assuming your timing does change between drive and N).
One thing that i have now just noticed (i had let my father do the distrubutor installation when it was first put in), is that the cap shows the rotation to be clockwise. This means that this was a smallblock Chy electronic distributor, correct? I havent yet found anything on the web to say what the curve is for this, but i'd imagine that the advance on this would be far different than what I'd want on a big block.. Would this make more sense to what you were saying about the spring weight?
I know that the only way to really find out is to play with it, so I am really anxious for my parts to arrive so i can put some of the suggestions to use..
|
|
|
Re: fast idle when hot - 451ci
[Re: ebodykid]
#1460018
06/30/13 03:52 PM
06/30/13 03:52 PM
|
Joined: Mar 2003
Posts: 4,848
Memphis
HemiRick
master
|
master
Joined: Mar 2003
Posts: 4,848
Memphis
|
The carb has an idle speed screw on the linkage side. You should be able to unscrew it and make the car stall....Can you?
Take care,
Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
|
|
|
Re: fast idle when hot - 451ci
[Re: ebodykid]
#1460019
06/30/13 05:48 PM
06/30/13 05:48 PM
|
Joined: Jan 2003
Posts: 75,043
U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,043
U.S.S.A.
|
Quote:
Quote:
More initial may help. If not, you'll need to put a slightly stronger spring in the distributor (assuming your timing does change between drive and N).
One thing that i have now just noticed (i had let my father do the distrubutor installation when it was first put in), is that the cap shows the rotation to be clockwise. This means that this was a smallblock Chy electronic distributor, correct? I havent yet found anything on the web to say what the curve is for this, but i'd imagine that the advance on this would be far different than what I'd want on a big block.. Would this make more sense to what you were saying about the spring weight?
I know that the only way to really find out is to play with it, so I am really anxious for my parts to arrive so i can put some of the suggestions to use..
if it were a smallblock distributor it would have no mechanical advance and a smallblock is CLOSE in size to a 440 distributor .
the cap markings do not matter because small and big block use the same cap , what side is the vac can on ?
|
|
|
Re: fast idle when hot - 451ci
[Re: coro500net]
#1460021
07/01/13 05:26 AM
07/01/13 05:26 AM
|
Joined: Jan 2003
Posts: 3,575
The Netherlands
BigBlockMopar
master
|
master
Joined: Jan 2003
Posts: 3,575
The Netherlands
|
Quote:
Had same problem on my Demon,took me a while to find it and it was just the throttle cable being to tight after the engine was hot.
This ^ is usually the problem.
Just disconnect the throttle cable at the carb with the engine hot and idling high. If the rpm's drop the cable was just a little too tight. Give it some more slack.
|
|
|
Re: fast idle when hot - 451ci
[Re: GTX MATT]
#1460023
07/05/13 05:20 PM
07/05/13 05:20 PM
|
Joined: Aug 2011
Posts: 13
MN
ebodykid
OP
member
|
OP
member
Joined: Aug 2011
Posts: 13
MN
|
I didnt disappear  I have my new distributor and radiator installed in the car, and now i have a bad fuel pump... So I get to wait a little longer until Mancini's gets me my new pump before I can pull all the recommendations to use.. Like I said before, if its not one thing, its another.. At least with the pump replacement, every single thing in my engine compartment will be new.. Hopefully that means i get to run it for a few years problem free... I will check back in once it is running again to either let you all know if your suggestions fixed my issues, or if there is any new info... thx guys!
|
|
|
Re: fast idle when hot - 451ci
[Re: ebodykid]
#1460024
07/05/13 05:42 PM
07/05/13 05:42 PM
|
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
StealthWedge67
master
|
master
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
|
"if its not one thing, its another." Get used to this concept. HotRod's test your patience, and the further from stock you get, the further your patience get tested. Not a good hobby for the guy that's "results oriented"; better for the "process oriented" type of fella. Gorgeous car, BTW! Good luck finding the issue. 
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
|
|
|
Re: fast idle when hot - 451ci
[Re: StealthWedge67]
#1460025
07/17/13 09:23 AM
07/17/13 09:23 AM
|
Joined: Aug 2011
Posts: 13
MN
ebodykid
OP
member
|
OP
member
Joined: Aug 2011
Posts: 13
MN
|
Ok - Just an update
With the new radiator, even with the hot days (90+) the cars hasnt had its temp climb above 190. It also hasnt yet idled up on me, nor run on. I have the timing set at 16 initial as suggested, with the stock 21 of advance in the the msd distr. Car Craft is this weekend, so sitting and idling while trying to get into the show will be the real test, but it seems that with just the timing recommendation, new distr and plug wires, and the fact that it doesnt get so damn hot with the new radiator, this might be all resolved. I also got my bad vibration at 60+ mph all figured out, (missing c-clips on back u-joint allowed it to shift in the cradle), and the trans seems to be happy and fluid level back to where it should be (air bubble caused me issues?), so i am feeling pretty good about things right now..
If you are at the car craft show stop and say hi! I will be near the Mr Norms 440 dart, and a bright red NSX.
|
|
|
|
|
)the travel in the mechanical advance slots so they have around 20 degrees total in the distributor so I can set the initial timing between 14 and 16 BTDC, which allows me to have between 34 and 36 degrees total timing revved up above 3000 RPM 
On the choke, if it doesn't have one you may need to set the idle speed in gear around 800 to 900 when hot so it will idle when cold 
All things are possible when it comes to tuning and peforamance 
It's just a matter of figuring out what to modify to get the results you want 
8 degrees is definitely not enough, and 12 most likely isn't either. 8 isn't even that good for the stock 383, which it isn't anymore.