Frustrated engine wants to die at idle

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68valiant500ci

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Just venting here cause I am not sure what to do. I have a 68 valiant. I rebuilt the motor with 500ci stroker kit from 440 source. Stock edelbrock closed heads with Harland sharp adj. rockers. 292 509 114 mopar cam. I think 9.5 pistons. M1 manifold 750 street dominator carb 72 jets front and rear 4500 elevation. Msd digital 6 box. Full aero motive fuel system with solid 6.5psi 3400 stall converter 323 rear.
So I start it up and seems to run rough. After a minute or so it seems to clear up after revving it up a bit. Get it warmed up then while idleling it seems to want to die if the idle is not up. If I give it gas it just kinda does nothing or feels like its barely running then will die.
If any of that makes sense and you have any ideas or suggestions please let me know.
Thanks, Rich.
:banghead:
 
I had 76 front 74back and my plugs were soaked so I brought the fronts down and the plugs seems to be good now.
 
Same as always for me, Initial timing?

Please don't say it's timed with xx total.

That's going to need a BUNCH of initial timing to run right.
 
oh no, this is a must must must. The major thing to get right, you must be able to tell what your initial timing is. AND, as cracked has preached to MANY on this site. Big ccams, big cubes and big carbs need more initial timing. Like, to start out, try 16 degrees just to get it to fire and you will most likely be twisting the dizzy to dial it up some more. Especially on a bigblock with a gargantuan sized bore. Gonna need lot of idle fuel also. Many threads on this thing here to help you with the initial timing deal so do some searches.
 
the dizzy's up front on a big block, jus start twisting it clockwise til it starts to die than twist it back til it smooths out. Who cares what the number is!! Its gonna need to be where it needs to be. If its too much, then it will be hard to start, the starter wont have enough umph, in that case, nudge it back (counterclockwise) a bit. Youll be getting close. Hey, you may be at 20 degrees probably. You may have to recurve the dizzy to get the total advance right. (this aint no stock motor, so this is what is necessary; oh well) You've gone this far, don't spend all this money and not have your timing right. Read the forum tips, buy some balancer timing decals. get a good timing light and a vacuum gauge. Learn how to do it and do it right, don't be lazy. Will you make mistakes? sure but just DO IT (GET"R DONE!!!)
 
omahamoparguy said:
oh no, this is a must must must. The major thing to get right, you must be able to tell what your initial timing is. AND, as cracked has preached to MANY on this site. Big ccams, big cubes and big carbs need more initial timing. Like, to start out, try 16 degrees just to get it to fire and you will most likely be twisting the dizzy to dial it up some more. Especially on a bigblock with a gargantuan sized bore. Gonna need lot of idle fuel also. Many threads on this thing here to help you with the initial timing deal so do some searches.
Click to expand...

This! Agreed initial timing is more than likely it...... Can't go by the book when using a bigger cam. Just have to play with it and find the sweet spot. Get a vacuum gauge and timing light. Then once you have it figured out add a note of the final settings in your repair book for future reference.
 
i had a similar problem on my stock 72 318 with holley 600. mine ended up being a bad needle and seat in the secondary's. the fuel was leaking badly. i replaced the carb and everything's fine again. check timing first but this could be the next place to look
 
Like everybody said, and few listen. Set it at it idla at highest vacuum. then limit dist advance.
 
68valiant500ci said:
I have a msd pro distributor without vacuum. Total at 34
Click to expand...

If the total is at 34* and you have not messed with the advance stop bushing. You probably got about 8* initial or so..... Way not enough to burn the fuel you are putting in the cylinders. Exhaust Smells like a fuel spill too right? Bump the initial to around 22-26* and see what it likes then pull the dizzy out and limit the stop for a total of say 34*. That will get you in the ball park.

THEN start messing with the carb after you get the timing right.

1) Timing
2) Carb tuning
 
68valiant500ci said:
I'm not sure how to get the initial timing set. I know... Sounds stupid.
Click to expand...

Get the car to idle around 1000 RPM by turning the idle stop on the carb.
Get timing light and turn the dizzy until you get 22-26* on the light. The idle may need to be turned down once you get it there. Check timing again. This is your initial timing snug up the dizzy.

After that.

with the timing light on rev the motor with your free hand until it does not advance any longer. That is your total. If you are over 34* you need to limit the stop bushing.

The above should get you pretty close and is a guide only........ Each engine is a lil different but I believe this will get you super close.
 
Yes it does have power valves in it. One other point of interest is... i dont have any vacuum ports. I think I am going to have to drill and tap the intake (how large of hole?) or maybe I can use a spacer. I do have a nitrous plate on but not hooked up yet. So could I go: manifold, nitrous plate, spacer plate with vacuum port then carb? Would that work? Probably look dumb but workable? I still have not had time to deal with the distributor but I will do that soon. I understand the process thanks to all your help here and really appreciate it! Thank you.
 
Ok well, i swapped the springs put a heavy and light silver spring in. I put the black little circle thing in. That was a royal pain in the ***! But its done. I also put a set of mufflers on the car as it has been open ever since i rebuilt the motor. So i proceed to fire it up hoping i got the rotor on correct cause i spun the engine over for that black doohicky. It fired... major exhaust leak at the head. Not happy at all with schumacher headers! But thats a different story. Timed it at 18 revved it up maybe 3500... brings it to 40. Felt pretty good but still cold and im sure the carb needs tuning. So isnt 40 too high? This is 92 pump gas 4500 elevation.
 
now you can jet the carb up. my 500 likes 88s square but its a dominator with a lot more cam.
 
If it loads up after a minute, or some time changes the idle, I would look at those fuel bowl float levels very closely. You wont get far with improper fuel float levels, you will be chasing your tail.
 
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