Im trying to get this thing running right, and I think I just messed it up some more. I seated the mixture screws lightly and brought them out 2.5 turns each and she started up good,, but ran pretty rough.. So I brought up the idle a little and then put her in drive and she ran rough again.. Soo.. I retarded the timing just a little and now when I kill it the engine tries to keep turning for a second and then kills out..

Give me some pointers.. Please..

Is it better to run rich with the timing advanced a little or should I back it off a little?? I wish I knew what I was doing with this thing..

 

From your description, it sounds like you retarded the timing at idle too much, forcing you to screw the idle speed screw in more, which in turn keeps the throttle plates open enough at idle to keep enough air flowing into the engine after you shut it off to make it want to keep running. Ever try to kill the engine with your right foot keeping it at 1500rpm? Same effect.

First of all, what'd you set your timing at? I'd have to guestimate 10-12* BTDC at idle (with the vacuum advance disconnected and plugged) would be proper for that cam, with a total of 30* or so in by 2800-3000. Set your idle, set your timing, then reset your idle if it changes and check the timing again.

Once you've got the idle speed and timing right, go back to the idle mixture screws. Seat, back out 2.5 turns, then fire up the engine and turn one screw in half a turn at a time until the rpm's drop, then back out half a turn and do the same to the other screw. Then go back and turn each screw 1/4 turn until the rpm's drop, then back off 1/4 turn. That should get it pretty close. Then go back and adjust the idle again.

Keep in mind, the screws only affect the mixture of the idle circuit. Once you get above 1500rpm or so, they don't make any difference.

 

So your saying that my pinging from before must have been due to timing being too far advanced? I havent timed it with a light,, got it by ear when I put the motor together.. I guess I will have to do that tomorrow during lunch.. I will follow your instructions tonight in the garage and see what happens.. When we say 2.5 turns, is that actually a full 360 or 180? I just have to be sure..

 

You definitely need to pick up a light. One of the nice adjustable dial types would be awesome, but even a cheap $20 unit will do the trick (that's what I have). Set the initialadvance to 12* and see if it pings like that. If it does, back it off to 10* and try again. If you're still getting pinging at 10* initial, you need higher octane gas, or your mechanical advance isn't functioning properly. A lean mix will increase the likelihood of pinging, but not that much, and you'll get hesitation and misfires to go with it.

Yes, by one turn I mean a full 360 degrees. Half turn = 180, quarter turn = 90.

What kind of carb are you running? Has it ever been tuned for that engine? It's rare for a carb to be perfectly tuned out of the box for the engine you slap it on. You may very well need to tune it once you get the timing situation fixed. At the very least you should pull a plug after a drive to see how it's running.

 

Its an Autolite 2100D put on the engine in 03 (found the receipt) then it sat for about 2 years 05-07.. I rebuilt the motor with a performer plus cam and just slapped it back on and now it pings and I allways smell like a can of gas when I run the car..So I tried tuning it.. I will get in to the auto hobby shop tomorrow and check out the timing..

 

the biggest problem is you added a cam, headers and exhaust and your trying to run a 2bbl carb that is jetted and designed for a stock cam and exhaust......you need a 4bbl intake and carb or at least a holley 2bbl carb. What distributor are you running? 10-12 degrees initial timing should be a good starting point......

 

I got it... After I posted this, I went back to work (yea, I was actually tuning the carb in the parking lot at work).. Well I drove it home as it was,, Idle very hight,, and I didnt have any pinging, hesitation or anything,, just that high 1400rpm Idle.. So when I pulled into the garage i turned off the ignition and the damn thing kept plunking along running really crappy... So i hit the gas and turned the key back on,, and she revved back up.. Got out and adjusted my idle back down and then killed it, and now she runs great again.. Soooo.. thanks for all the help guys.. I still need to hit it with a timing light and fine tune the carb but its alot better now..

Now I just need to fix the oil leak..

 

Good luck with that. Mine has been marking its territory for years...

 

hiya ...
first of all: ya. you need a strobe (timing light). pinging means to far advanced. If you have to go without strobe. keep advancing until it pings under high load (full throtte uphill 4th gear).
when iot pings retard until it stops. that's your timing set.
for the autolite 2100 carbs (dont know the D version):
- the idle mixture screws are around one and a half turns out.
stop engine, tunr them in fully seated (careful. when you feel it seating stop immediately, otherwise you destry the pointy front of the screw). then 360+180 degrees out. both of them. for finetuning the post above is great (start at 2.5 turns ....)

- the screw which which determines idle speed (the one on the throttle linkage):
best not mess with this one. but when it happened. make sure that engine is warm. the choke plate must be fully opened. adjust the screw so it just touches the plate and turn it, so that it justr moves that throttle plate slightly. so basically that the screw just opens the plate a bit.

- with your ignition advance disconnected (hose disconnected at distributor side and hose plugged tight with a screw) the idle should be below 1000rpm (600? 800?) . if you reconnect the hose back to the ignition advance and the idle goes up a lot (1200+), then you have
- either connected the vacuum advance at manifold vacuum instead oftimed vacuum (above throttle plate in carb)
- or the screw at throttle linkage isscrewed in too far(increased vacuumover throttle plate).

Ashtwhels67 mentions above:
2bbl carb is no good when you have a 302 with hotter cam. at least I would guess the same. you're reducingthe amount of air the engine can intake.

autolite 4100 or some holley carb might help here. Pony carb have a nice cfm calculator, or someone here on the boards might now what cfm rating to go for
my blind guess is 600cfm. but that's not based on knowledge, just from guessing.

PS: if you have a vacuum tester (a gauge with a hose that shows how much vacuum is on the hose), let us know. I might be able to pull exact details on how to set the idle sped screw.

Most important:
when the engine is warm the choke plate has to be fully open (when removing the airfilter, the plate on top of carb that you can see). otherwise:
- too rich
- if properly connected idle to high (fast idle screws)

so check on that as well


Kalli

 

Thanks,, Its doing more than marking now,, it seems to be leaking worse.. so im stuck and need to fix it.. I will drain it, fix it and then put the oil back in I guess..