Car still stalling when put in gear?

[Clark]

Well I have found one of those problems that has me and alot of other people scratching there heads so any input would be great. We are dealing with a 393W with an auto trans that will idle a little rough at idle 1K, and will sing at 4K. The issue is when I put it in drive/ reverse the eng. wil make a couple of revs then dies. Will always start right back up. Now before you jump to any answers this is what has been done so far. Changed ignition system from pertronix to Accel, Carburetor stock to a Demon, Timing advanced/ retarded, fuel mixture rich/ lean, Eng. pulls 17 in. of solid vacuum, compression is 185 to 205, All vacuum lines plugged and no leaks, adjusted roller rockers three times, Changed trans. from FMX to AOD. After all these changes no difference.

The only thing I have noticed that is strange is some plugs are burning clean and some are sooting, and yes I have tried different plugs, I am leaning towards a cam issue, What do you think?

 

[Ozsum2]

I would be leaning towards a Fubar'd idle circuit on the carb. If it were the cam, I think you'd see some variation in the vac needle.

 

[stangman67]

What is your torque converter rated stall RPM? I had this problem with my 289 after I put in a big cam. At an 850 rpm, it would stall when going into gear. After I put in a TCI Break-a-way rated a 2500rpm stall, it worked like normal.

 

[mustangdave]

Are you using the correct firing order for a 351W?

 

[brianj5600]

What carb? What cam? It could be converter also. If you have not read a book on modifying carbs, it is worth the time and money.

 

[Clark]

Thanks for the responses and I will try to give you more details.

I would think Idle circuit might have been an issue but I tried two different carbs, the stock 4 barrell and now a 625 road demon.

The torque converter is basically stock but remember that I had the FMX in with a new converter and now I have the AOD in with a different converter. I also have the idle up to 1200 RPM.

The firing order is set for a 302 because the cam is set up for a 302 the cam is very mild at 292 duration/ [email protected] and .478 lift for intake/ exhaust 110 degrees lobe center.

The other reason I am thinking the cam because of the firing order change, my increased compression, and the plugs having some looking clean and some with sooting. Any other ideas or comments?

 

[pabear89]

Are the sooted plugs all on the same bank?
could be an internal leak from the intake not centered.
Have you checked the line to the trans and the mod valve?

PB

 

[Clark]

Good point Pabear,

The intake is coming off next to check for leakage but no the plugs were speratic did not follow the planes.

Yes all lines of vacuum have been capped, that was one benefit of having the AOD no vacuum needed for it.

Thanks again for the input, there are no stupid questions or ideas on this one it is great discussion to make me think as well.

Clark

 

[302 coupe]

interesting that it idles rough at 1K, but still pulls 17 vacuum. First thing I would do is crack open the rear throttle blades, that way it will draw more air at idle. You may need to richen up the idle mixture after doing this, and if the idle speed goes up you'll need to reset that. This should help your stalling problem, more air and fuel at idle means more idle power, maybe enough to overcome to your stalling problem.

 

[Clark]

Thanks 302 for the input,

The Secondary's getting cracked open is a little confusing, how would you do this on a vacuum secondary carb? Just to let you know I tried to enrich the mixture and just got tearing eyes from that.

 

[likesoldjunk]

I know it's to obvious , but it sure sound like
it's sucking air. Try spraying carb cleaner
around the base of the carb and the rear,
as well as anywhere you're vacum lines
go. Also check your PCV Valve.

 

[302 coupe]

If it were a vacuum leak it shouldn't have as much vacuum as it does.

Clark, the duration of that cam should make it idle kinda rough, and I wouldn't think it should have that much vacuum. I would expect 14 or 15 on vacuum, the 17 you're getting is a result of the engine starving for air, in my opinion. I'm running a Crane 284H which has a little less duration than yours, but more lift, and I can only get 13" vacuum.

I'm not real familiar with the demon carbs. If they don't have a linkage or screw you can adjust to crack the blades open a little, you'll have to drill a small hole in each of the rear throttle blades(be very conservative with your hole size!). It seems like some holleys have an adjustment and others don't. I've heard of people doing it both ways. I've been running manual trannies for the last few years so I'm getting rusty on my auto trans carb tuning.

There are some good carb guru's over on fordmuscle.com, so you may want to try doing a search over there, or signing up and making a post.

Good luck, let me know what fixes it.

 

[302 coupe]

Ok Clark, I did a little research to refresh my memory while at the same time hopefully help you solve your problem. I'll break it down in a step by step format.

1. Remove carb, drain gas
2. Flip it over upside down. Look at the primary and secondary blades, you'll see a narrow slot on the wall of each of the venturi. This is the transfer slot.
3. Go the side of the carb and back off the idle speed screw all the way. Put the throttle in the full closed postion. Now look at the transfer slot, there should be about a fingernails thickness of it showing(about .030") on the manifold side of the blade. If not, adjust the idle speed screw until there is. (I *think* the idle speed screw is the only way to adjust how open the front blades are at idle. I'd look around for maybe another means of adjustment just to be sure. I don't have a carb sitting beside me right now so its hard to say.)
4. If the primary transfer slot was out of adjustment, reinstall the carb, adjust idle mixture, see how it does. Normally they are adjusted right from the factory. If the adjustment is right, but you still have the problem...
5. Check the rear transfer slots. You can crack the blades open by adjusting the slotted screw on the bottomside of the baseplate. Be careful not to overtighten, the screw is tapered and only gets so tight before you start stripping threads. Open the blades to where about .030 of the transfer slot is showing.
6. Reinstall carb. For a base mixture setting, turn the screws in all the way, then back off 1 1/2 turns. Hook everything up. You may want to go ahead and hook up your vacuum gage to a full time vacuum source.
7. Start it up, it should only require some fine tuning of the mixture screws. Be careful to adjust the idle speed after you cracked the rear blades. If you set the idle too high it will put the rear two on the transition circuit, causing an erratic rich idle. Adjusting idle speed will be a balancing act, however with all four blades cracked open a little it should be about right to start with.

I pieced this info together from a compilation of about 10 others that had the same problem and have corrected it. Hopefully it will help you out some. If it helps but doesn't quite get it right, there are a few other things you can do if necessary. Let us know.

 

[pabear89]

Thanks 302 for the input,

The Secondary's getting cracked open is a little confusing, how would you do this on a vacuum secondary carb? Just to let you know I tried to enrich the mixture and just got tearing eyes from that.

Did moving the mix screws change anything else, other than the over rich smell?
If not then the rear throttle adjustment may be open too far,
drawing fuel at idle.
302coupe gave a good overall steps.


PB

 

[Clark]

Well here is the latest, and it just keeps getting better. I located another carb and installed it, started it up and the vacuum dropped to 15 in. and the idle was smoother and then I stuck it in reverse/drive and the engine stayed running with about 7 to 5 in. of vacuum bouncing back and forth, I thought I had found my problem the carb. Not so.

I started to look around at my carb and was trying to figure what was wrong with mine when I noticed that on my carb there was a PCV tap that I had plugged but did not see my friends carb capped there. Sure enough I found his un-capped and I then installed one. The car started doing the same thing put in gear and it would die. (the vacuum was about 7 before it dies).

Next I installed my carb, checked the primaries, opened the secondary's just a little, unplugged the PCV tap and then the car would idle in reverse or drive with about 10 in. of vacuum holding pretty steady.Put the cap back on and the engine was dying like before. I have tried to change the mixture but neither way helps.

What's going on here? My car obviously needs more air but what is causing this?

 

[pabear89]

You have too much fuel going in.
thats why when the plug is off it will idle but low vac.
The throttle plates are open too much, This will draw fuel past the idle stage and your mixture screws will make no change in the engine running.

Best start from the beginning and do a total recheck on ALL the settings.
Start with rear blades at about.003-.005 open.
unscrew the front till the screw no longer touches and turn it 11/2 to 2 turns.
start with the mixture screws about 1 1/2 turns out from closed position.

Start eng and if it will idle at speed the RECHECK Timing before proceeding further.

PB

 

[Clark]

I will try this and will close down the throttle plates by turning down the idle screw and making sure the secondary's are correct as well, but this does not explain the plugs burning good on some and not others. The other thing that doesn't make sense is that I have tried this when the problem first started, richening the mixture and turning the timing from 10 to 20 degrees.

Sorry but this is really starting to get me with no progress .

 

[Ozsum2]

I would be leaning towards a Fubar'd idle circuit on the carb. If it were the cam, I think you'd see some variation in the vac needle.

See my above post.

 

[Clark]

Ozsum,
It must be getting late for both of us, I already tried a different carburetor so I think the idle circuit was changed