seibertjd

After swapping motors and hitting just about every possible stumbling block, I am having trouble getting it to idle correctly.

Since last night, I have gotten it started up to where it stayed running twice. The first time, it had a lot more exhaust than usual it seemed like, and both times it ran very rough.

This is an 84 Z28, with a rebuilt late 80s 350, Edelbrock Performer 1407 750 CFM, T5 transmission... It still has a computer controlled dizzy, since I can't afford a new one right now, and I haven't put in smaller jets yet for the same reason.

I am not really a carburetor expert, and I am not sure how to tune it correctly. I read the owner's manual for the carb, and it didn't make much sense. As far as the timing goes, I don't have a timing tab, so I set it at TDC and then I advanced the timing at the distributor a little bit... but it seems like it has to be in exactly the right spot to run at all, so advancing or retarding the timing isn't helping.

85irocinjected

I would def. get the bracket setup for the timing. You can't just set it by listening. As with the carb. start by adjusting the floats and idle screws. Is it dumping to much fuel or not enough?

seibertjd

I assume it is dumping too much. The engine compartment will smell like fuel after cranking it, and when it runs the exhaust is very thick. I was really hoping to at least get it to where it would run at least somewhat decent for now, so I can buy all the other parts I need later on when I have more money.

I used 3 different methods to find TDC on the compression stroke, as I had outlined in another post. At TDC, the engine cranked very slowly and would not fire, so I turned the dizzy clockwise until it cranked faster and would fire. If it isn't in just the right spot, though, it will crank quickly and fire the cylinders while I hold the key, but it won't run on its own. If I turn it back too far counter clockwise, it just cranks slow again.

seibertjd

I thought I was close just a bit ago... I had it idling, and I was adjusting the mixture, and I was almost to the point where I had a relatively smooth idle, and then it started bogging down and died after a few seconds. I tried recovering while it was bogging down, but it didn't seem like adjustments did much good once that happened. Afterwards it went back to being hard to start--It spins and pops like it is firing, but doesn't run on its own. It seems like I am kinda stuck in this cycle. I charge the battery, crank at it for a bit, make little adjustments until I can get it started, then I try to make adjustments with it idling, it winds up dying, I try making little adjustments til I get it idling again but wind up draining the battery. Rinse and repeat. This is driving me crazy!

seibertjd

Still having problems--I really need some help on this. I got it to where the engine idled for about 3-4 minutes before it died, and it seems like I might be getting a little closer each time I get it to start to where it will idle correctly... but every time I get it to start, eventually it tapers off and the engine shuts off, and then it takes me forever to get it started again. I have retimed it to TDC about 6 times now, and that doesn't seem to help a whole lot.

I have checked all my vacuum lines. They are all hooked up, most of them are new. My fuel lines are properly run with no leaks, I have my A/F screws on my carb screwed about 1 1/2 turns out right now... This morning it seemed like I was the closest I have been, getting it to idle for several minutes and then shutting it off myself, and then I managed to get it to start up again after about 10 minutes of messing with it, only to have it die a couple minutes later.

When it is running, there are no knocks, no pings, no strange noises... it seems like I have gotten it fairly close to a normal idle... but no matter how close it sounds, it still tapers off and dies.

t-top havoc

iTrader: (3)

For the carb, go to the Edelbrock site. Good instructs on setting it.

seibertjd

I have read the manual that came with it, googled it, and watched their videos on youtube for installing it and setting it up. Doesn't help me too much if I sit out there for a half hour cranking on it trying to get it to run before I get it to idle, unfortunately. Once I go to adjust the mixture screws, by the time it starts sounding like a decent idle it tapers off and shuts off. It wouldn't be such a big deal if it shut off that way, if it didn't take so long to get it started again.

t-top havoc

iTrader: (3)

Makes sense!!!

If you open the throttle by hand at the carb, does it squirt gas?

seibertjd

With the engine off, or with it running?

t-top havoc

iTrader: (3)

Off.

seibertjd

No, not that I can tell.

t-top havoc

iTrader: (3)

Sounds to me there is a fuel delivery issue.

The carb should have fuel in it even when the motor is off.

Stock cam?
Stock manual fuel pump?

seibertjd

I don't know what cam is in it, because I bought the rebuilt motor off of craigslist and didn't remember to ask. It is a stock mechanical fuel pump, which is functioning correctly as far as I can tell. The line is pressurized and fuel is at least getting to the carb. It seems to be running rich when it does, and when I pulled a plug it appears some fouling has started to occur.

87 transam

when it dies are you sure you still have spark mybe your ICM is going out since you are still useing the stock dizzy and is the fuel pump new or is it the old one trying to time it with out the tab or light is like a broken pencil pointless you have all that money tied up in the motor and you skimp on the little stuff that just dont make no sense if the job is worth doing then it is worth doing right

SDTransAM

iTrader: (5)

accelerator pump working? But if it smells like gas I assume so.

Do you have the carb off your old engine? That 750 is HUGE for a stock 350.

seibertjd

I know it is... I don't have another option at the moment. Need money to buy parts, need car to get money... You get the idea.

I assume the accelerator pump is working alright, but I couldn't give you 100% sure answer on that. I am thinking I will buy a timing tab and redo my timing again, and see if that helps... Can't do anything about a timing light for right now, and unfortunately I have no options at the moment to step down the carburetor or even jet it down due to lack of funds. My old engine was also a stock 350, though--so even though the 750 is much too enormous, I know it can still make it work...