[75400truck]

Here is the Info

75 400 SBC bored 40 over( Just bought afer rebuild)
750 CFm Carter AFB Carb ( Professionally rebuilt, and tested)
Polished Stock Heads
Med cam (Owner of Engine lost cam specs)
th400 trans (Convertor is unknown(assume Stock))
new Stock Mechanical Fuel Pump, with Regulator installed and set to 5 PSI
Have the Timing set at 10 BTDC with vac advanced disconnected,
Everything new and working properly Under distrubitor, Accel Hei, and Accel Rotor.
Dual exhaust with long tube headers, through 2 1/4 glasspacks and tail pipe
Hope this is enough.

Now my Question,
I was having an issue with carb (old one was a edelbrock 1405 ) replaced with Carter 750, after adjusting the carb truck cranks and idles good, but when I drop into reverse or park it drops idle to almost nothing then dies, unless feathering throttle. I addjusted the air screw and idle mixture, no change. I have checked for Vac leaks no that i can see or tell. good vacuum at idle in park (around 12 1/2 to 13 steady). Choking doesn't help either.
I am getting dizzy trying to figure this out anyhelp would be appreciated.
Thanks
Chris

 

[cuztomcarbuilder]

Stalling

Does the cam have a race like idle? If so then your engine needs more air at idle. Try drilling a 1/16" hole in the forward side of each butterfly. You may need to idle the engine down a little but this gives you more of the idle transfer slot to control idle. Also check your power valve/metering rod springs to make sure that they have the enrichment circuit closed at idle. And as a last resort...Check your timing at 3500/4500 rpm and set it at around 34 degrees for a 400 SBC. Also one thing I have found is that some people adjust the valves to 3/4 turn preload. I always talk to the people who make the cam and adjust it the way they tell you to. Usually it's 1/8 of a turn in after zero lash. Sometimes people OVER adjusted the valves and get them too tight. This can cause all kind of weird problems depending on the cam and how it is SUPPOSE to be adjusted. One last thing...You can install a corvette torque converter or an aftermarket one, to give you some slippage at idle. You might have gotten an RV/or diesel converter which will give you no stall except for your engine.
Hope these ideas help...

 

[11echo]

Just a thought ...check the modulator on the trans. I had a Nova once where after I rebuilt it the engine it idled fine, even revved up fine, but as soon as I put it in gear it wanted to die. Turned out to be a leaky modulator (cracked diaphram) ...worth a look. Good luck! ...Mark

 

[k-star]

stalling

There is alot of info that you are missing that we might need to solve the problem,,, like cam spec's, converter spec's etc. But lets see if we can fix it anyway......

You said that there was an issue with the 1405 eddy,,, Was it doing the same thing????? Have you tried anything at all to solve the problem??? If so what did you do so far???? What rpm is it ideling at right now in park???

Keith

 

[75400truck]

Unfortunately i dont know the cam specs, seller lost info, Converter i assume is stockdue to it coming from original trans with truck. The Idle circuit on the 1405 was unfixable at least that is what the Rebuilder told me, so upgraded and bought a 750 carter afb carb,
sorry about not knowing kills me too but when you get agood price on an engine i had to jump on it. On there dyno it rated around 380 horses with 600 cfm carb, and original exhaust manifolds,

Thanks
Chris

 

[GoneNova/406]

if you go to racing secrets.com,drop to the bottom right hand corner of the page and hit racing articles,then hit barry grant,about half way down you may find what you need.

 

[75400truck]

400sbc Stalling problem

The artivle was a good one, but i know a 750 cfm carb is not to big( maybe i read the wrong thing?) But my issue is a stalling issue. I will play around with the timing a bit maybe even replace the inards of distrib. i said they are all new but murphy's law always hits me pretty good, and the inards could be bad. Like i said just getting dizzy tryin to figure it out, rebuilt about 4 engines, 3 hi perfotmance 350s and 1 400 stock. I think part of my prblem might just be the mix of stock with performance parts.. I know compresssion is good, and no head warpage, block is good, intake is good, carb is good.

I will say that this is the firs time I have bought an engine already rebuilt....Murphy's law....lol....

Thanks guys I appreciate the help, if anyone else has a opinion all are welcome.
I will keep inform to let you know and will post progress.

Chris