Getting a crossram 426 Hemi to idle....HOW??
#448149
08/24/09 04:04 PM
08/24/09 04:04 PM
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Joined: May 2005
Posts: 1,130 Dayton, Ohio
wldtm
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I dont typically post alot of Race/tech questions, but I am not sure where I am going wrong. I am working on a 68 Hemi crossram with the correct Holleys on it for a 426 Hemi-Dart. I would rather figure this out for myself, but I am not experience with dual quads...so I need some help.
The problem is the car will not want to idle in gear. Will idle great in park (1400), but has to be two footed contantly when put in gear. Idling it up doesnt seem to help.
Details are..12.5 compression, 700 lift solid roller(R290 Cam), pretty much stock heads and valve train, stock crossram, auto car, with a dynamic conv, two holley blue pumps with dual regulators, jetting is close to stock per Direct Connection book. Carbs were rebuilt in past year. Timing is about 32 degrees. Old Mopar Per Dist. MSD 7al and coil. Taylor wires, Plug gap is about .045.
I used the Dvorack machine synchronizer, but the after checking the idle in neutral was pretty close to being right anyhow before using it.
I am sure this combination could be optimized, but I would like diag on the idle condition. Comment, questions would be appreciated...
Justin
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: 440FISH]
#448152
08/24/09 04:17 PM
08/24/09 04:17 PM
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Joined: May 2005
Posts: 1,130 Dayton, Ohio
wldtm
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Locked out at 32 degrees.. I thought about bumping it up to 34-35 range.
Thanks for the comments guys
Justin
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: 440FISH]
#448153
08/24/09 04:20 PM
08/24/09 04:20 PM
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Joined: Nov 2003
Posts: 6,293 Rock Springs
Bob_Coomer
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Well a vacuum leak will keep a engine from idling. I agree you need to check timing at idle. That big-ole cam would like lots of initial timing...Probably 20+ deg would be best. Recheck the timing, and for vacuum leaks and report your findings. Use some Brake Klean, or carb and choke cleaner and spray around the intake mating surfaces and carb base gaskets etc. But you say "it Wont idle in gear" Makes me think it will idle in Park? Stupid questions but how loose is the converter, and large cam like that and a stock converter WONT idle in gear.
[color:"red"]65 Hemi Belvedere coming soon [/color] [color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: 440FISH]
#448154
08/24/09 04:21 PM
08/24/09 04:21 PM
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Joined: Jan 2004
Posts: 4,866 North of Detroit
HemiDart68
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Just a little street driving advice for a crossram hemi, dont try to sit at a stop with the motor loping at idle in gear. If your not accelerating or moving, put the car in neutral. Your plugs will thank you for it.
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: HemiDart68]
#448155
08/24/09 04:26 PM
08/24/09 04:26 PM
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Posts: 1,130 Dayton, Ohio
wldtm
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timing idling in neutral is 32 and locked.
i agree a hemi doesnt want to just set in idle for an extended period of time in gear, but i think it should be idle for 10-20 seconds before it wants to load up that bad.
i thought about the vacuum leaks, but wouldnt that show up in neutral as well.
yes it idles well in neutral, but not in gear.
thanks again guys
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: wldtm]
#448156
08/24/09 04:27 PM
08/24/09 04:27 PM
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wldtm
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convertor about 4000 plus stall..
justin
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: wldtm]
#448157
08/24/09 05:04 PM
08/24/09 05:04 PM
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Anonymous
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Anonymous
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Quote:
timing idling in neutral is 32 and locked.
i agree a hemi doesnt want to just set in idle for an extended period of time in gear, but i think it should be idle for 10-20 seconds before it wants to load up that bad.
i thought about the vacuum leaks, but wouldnt that show up in neutral as well.
yes it idles well in neutral, but not in gear.
thanks again guys
its in your air mixture screws, turn them out evenly and watch your idle come up, problem solved. my hemi idles smoothly all day long in gear at any stop light or stop sign. if your plugs are rich, just jet it down a little at a time. carbs for street driving should be around 74 primary and 73 secondaries depending on your elevation.
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Re: Getting a crossram 426 Hemi to idle....HOW??
#448158
08/24/09 05:14 PM
08/24/09 05:14 PM
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Posts: 1,130 Dayton, Ohio
wldtm
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just checked for vacuum leaks and no change.
bumped up timing, and it seemed to like that.
as far as air mixture screws they are pretty dang close.
what makes you think its in the mixture scews out of curiousity?
thanks again justin
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: KD800X]
#448162
08/24/09 09:48 PM
08/24/09 09:48 PM
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Posts: 1,130 Dayton, Ohio
wldtm
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hemi-itis...i talked to another gentlemen and he mentioned some of the same stuff you did. but we were wanting to keep the carbs ss/ah legal, so we werent sure you could drill the holes.
jeff (MCH)..yes i thought about that, but i am hard headed and want to do it myself. i trust tony. i just dont learn much if i have someone else do it for me...hence the reason for not wanting to ask the question in the first place.
the power valves i believe are 3.5, but i dont think they are blown because it runs crisp in idle, and not real fat.
thanks for everyones comments..
justin
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: wldtm]
#448163
08/24/09 10:14 PM
08/24/09 10:14 PM
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Joined: Apr 2007
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thecarfarmer
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Quote:
timing idling in neutral is 32 and locked.
i agree a hemi doesnt want to just set in idle for an extended period of time in gear, but i think it should be idle for 10-20 seconds before it wants to load up that bad.
i thought about the vacuum leaks, but wouldnt that show up in neutral as well.
yes it idles well in neutral, but not in gear.
thanks again guys
If I had a buck for each car I've worked on that idled okay in neutral but not in gear due to bad gaskets/hoses/vac leak, etc... I might be able to buy both of us some lunch.
Sometimes these things won't show up w/o a load.
Also, with a big cam, the vacuum at idle is pretty low, and the idle's naturally pretty rough. This may mask a leaking manifold gasket.
IIRC, the manifold really obscures the gaskets' edges; a leak might not show up w/o a LOT of cleaner being sprayed at it (or may be leaking from underneath).
-Bill
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Re: Getting a crossram 426 Hemi to idle....HOW??
[Re: hemi-itis]
#448165
08/25/09 12:44 AM
08/25/09 12:44 AM
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Joined: May 2005
Posts: 1,130 Dayton, Ohio
wldtm
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I agree with the vacuum gauge being helpful. However I do not have a port on a crossram or these carbs. I will have to try to make an adapter tomorrow to get one hooked up. Yes the mixture screws will affect idle quality when i move them. I will try to hook up a gauge and see what the deal is tomorrow.
I guess I need to check for vacuum leaks more in depth...and if no prevail, try adjusting secondaries a little to see if the additional air helps.
Thanks
Justin
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