B&M Converter is bad

[d55dave]

Have you verified that your timing marks are correct - is it actually on TDC when the marks are lined up? Is there a mis match in timing cover / damper? Also, is the distributor hooked up to manifold vacuum? If it is, sometimes what happens is when you put it in gear the idle slows enough that your vacuum drops enough to release the vacuum advance can and it dumps a bunch of timing.

 

[straightlinespeed]

Have you tried pulling off each plug wire at a time to make sure all 8 are firing?

No I have not, but I do have a new set of plug wires on the way and will be installing them soon. Oh its backfiring thru the carb not the tail pipes. I cant remember if I said that.

Make sure the engine is FULLY warm / up to temp when you adjust idle.
Yes it is fully warm
You MAY have a vacuum leak causing a lean condition. I agree--- sounds way lean.
I have sprayed carb cleaner all around the base of the carb and the intake itself and it did not change the RPM's so I believe that everything is sealed up good
Do NOT retard timing to "fix" chugging--the opposite. Set timing, adjust idle screws best you can for highest vacuum/ best idle, then diddle idle speed and adjust timing for now I'd LEAVE it at the 13/ 38 unless the engine seems to like more at idle. More idle speed/ more vacuum is an indicator. Keep backing the idle speed down as you improve idle.
Ok, thank you. I wasnt sure which way to move it and just wanted verification
Try pulling the idle screws clear out when running and stick your finger over the hole. This tends to pull out any dirt. If no effect, get some aerosol carb cleaner with a snorkel and blow some cleaner through the idle screw holes. Watch your eyes, it should come up out of the air bleeds int the throats.
I will do this tonight and give it a try.
The question is "have you improved it?" I dont know LOL

I'll throw out one crazy notion before I hit the sack...........Are you hooked up to a power brake booster?

No, I have manual brakes, but thanks for the thought

Have you verified that your timing marks are correct - is it actually on TDC when the marks are lined up? Is there a mis match in timing cover / damper? Also, is the distributor hooked up to manifold vacuum? If it is, sometimes what happens is when you put it in gear the idle slows enough that your vacuum drops enough to release the vacuum advance can and it dumps a bunch of timing.

Yes, I used a piston stop tool and checked it. Then remarked the balancer like Crackedback showed me. The balancer is 7.25" which from what I can find is the same as a stock factory balancer. So Im using the timing marks on the cover but the cover is from a 318, not a 360. Not sure if they changed them or not. I assume they are the same. The distributor is hooked up to the ported vacuum (higher port on carb)and not the manifold vacuum.

Im going to start from scratch again tonight after I clear out the idle mixture screws, I'll keep you all posted.

 

[fishy68]

No I have not, but I do have a new set of plug wires on the way and will be installing them soon. Oh its backfiring thru the carb not the tail pipes. I cant remember if I said that.

Im using the timing marks on the cover but the cover is from a 318, not a 360. Not sure if they changed them or not.

don't stop with just replacing the plug wires. Check and/or replace the spark plugs also. Most misfires are caused by the spark plugs themselves. In the last couple yrs. I've gotten a few plugs that for no reason at all didn't last good and when they start acting up the first thing I notice is a backfire out the exhaust when it's cold.

What year 318 timing cover do you have on it? They changed in 70 so 69 and back timing marks won't be right for a 360 cause they never made a 360 till 71. You can identify them easily because 69 and back has the timing indicator block on the pass side where-as 70 and up is on the drivers side.

 

[Snake]

back fireing through the carb is lean or timing right guys?

 

[straightlinespeed]

don't stop with just replacing the plug wires. Check and/or replace the spark plugs also. Most misfires are caused by the spark plugs themselves. In the last couple yrs. I've gotten a few plugs that for no reason at all didn't last good and when they start acting up the first thing I notice is a backfire out the exhaust when it's cold.

What year 318 timing cover do you have on it? They changed in 70 so 69 and back timing marks won't be right for a 360 cause they never made a 360 till 71. You can identify them easily because 69 and back has the timing indicator block on the pass side where-as 70 and up is on the drivers side.

Plugs are brand new, and I have a timing cover from a 71 318 with the marks on the drivers side so that sounds like its good.

 

[straightlinespeed]

back fireing through the carb is lean or timing right guys?

I was informed its a timing issue, I just have to figure out what way to go with the timing to fix it.

 

[d55dave]

Brand new plugs does not mean they are good. All it takes is for one of them to be dropped in shipping or by the parts guy, fracturing the porcelain and causing a missfire.

Keep at it, you will get it sorted out. Even though that vacuum port is higher I would suggest seeing if there is suction there at idle, there should be none.

 

[crackedback]

Quit worrying about total timing at this point and get the idle timing and carb settings right.

New carb? Are the floats set properly?

Timing FIRST, then adjust the carb mix screws. Get it warmed up. Advance idle timing 2* at a time, shut off, restart. Do this until you find point that starter drags like the battery is dead and back off timing 2*. Keep 800 idle RPM same when doing this, it should pick up RPM as you advance timing. Lock it down and see where the initial is at that point. Reset the idle speed 800rpm, then hit your mix screws, max idle vacuum with them in the most. See if the car still drops a bunch in gear. If it does, put a light on it and see if the number you saw when locking it down is different. If it is, then the distributor is tossing in mechanical advance and that MUST be corrected, stiffer spring(s).

How you end up with two different advance numbers when revving it up is beyond me. That should be consistent.

Is there a large port opening on the back of that carb that may be unplugged?

Do one thing at a time because it looks like you get overwhelmed by the big picture.

 

[Oldmanmopar]

There is nothing wrong with the converter. 2000 is good for a stock motor in a truck for puling a trailer. When you buy a converter always get a 3500 for the street.

A small block will brake stall a 3500 converter a@ 2800 which is perfect. Its what the 340's came with. I have two I kept for this reason.

With a 70 340 and a 474 purple shaft cam. A factory converter brake stalls @ 3000. Put the same converter in a big block and it brake stalls @ 3500.. Add 300-400 for flash stall.

I run a 5500 ATI on the street. It is what the cam shaft called for. Why build a motor and pick a cam you don't have the converter for.

The advance will also stall the engine when you put it in gear with a bigger cam. Disconnect the vacuum close up the mecanical travel to 20 Degrees. Set the initial at 15 this will put the total at 35. It won't stall then. But it still won't run well with that low stall converter.

 

[straightlinespeed]

Quit worrying about total timing at this point and get the idle timing and carb settings right.

New carb? Are the floats set properly?

Timing FIRST, then adjust the carb mix screws. Get it warmed up. Advance idle timing 2* at a time, shut off, restart. Do this until you find point that starter drags like the battery is dead and back off timing 2*. Keep 800 idle RPM same when doing this, it should pick up RPM as you advance timing. Lock it down and see where the initial is at that point. Reset the idle speed 800rpm, then hit your mix screws, max idle vacuum with them in the most. See if the car still drops a bunch in gear. If it does, put a light on it and see if the number you saw when locking it down is different. If it is, then the distributor is tossing in mechanical advance and that MUST be corrected, stiffer spring(s).

How you end up with two different advance numbers when revving it up is beyond me. That should be consistent.

Is there a large port opening on the back of that carb that may be unplugged?

Do one thing at a time because it looks like you get overwhelmed by the big picture.

Did exactly like you said. Seems right around the 15* area is where it likes it. I locked it down then made sure my idle was 800. Next went to the screws. As I adjusted them out. The idle kept increasing so I kept readjusting the idle to the 800 set point. Repeating until I did not gain anything else on the vacuum gauge which was about three different idle speed adjustments.

My question is, do I keep readjusting between idle speed and screws like I was doing? Or once I gain the max vacuum after the first time i leave it then adjust the idle back to 800?

 

[straightlinespeed]

I forgot to add that after that is all set I put it in gear and it drops to about 400 so I bumped the rpm up to about 900. So it roughly drops half the rpm when I gear. I also checked my mechanical and it ads about 20* so I'm sitting at 35* total. I'm going to take it for a drive now and see how it does

 

[straightlinespeed]

Definetly gaining in the right direction!!! I can actually sit at a stop light and not have the car want to drag me thru the intersection. I can coast at 10mph thru a parking lot and not at 25.

I still can not get it to break loose doing a brake stand and if i punch it from a dead stop it bogs down and grumbles all the way up to speed. It will however once on a good 20+ mph roll and punch it, go like a bat out of hell!

So with that info what do you think? To much initial still?

 

[Dusterdude72]

The way I have always adjusted carburetor a nd had good luck at it. Is setting the idle around 800rpm or so (don't want to set idle to high or it will not be running off idle circuit and the adjuster screws won't work correctly).

Then I start on the right side and turn the screw in until it starts to stumble the idle and then I back it off a 1/4 of a turn. Then repeat on left side. Then I repeat the process again just because. Then once that's done I set my idle where I want it.

 

[67Dart273]

Definetly gaining in the right direction!!! I can actually sit at a stop light and not have the car want to drag me thru the intersection. I can coast at 10mph thru a parking lot and not at 25.

I still can not get it to break loose doing a brake stand and if i punch it from a dead stop it bogs down and grumbles all the way up to speed. It will however once on a good 20+ mph roll and punch it, go like a bat out of hell!

So with that info what do you think? To much initial still?

!!!NO!!!

Maybe even not enough. As we've said, adjust initial for a combination of..........

best (fastest) idle, and highest vacuum,

without bumping back on the starter

or without pinging at low RPM heavy loads

 

[straightlinespeed]

Then I start on the right side and turn the screw in until it starts to stumble the idle and then I back it off a 1/4 of a turn. Then repeat on left side. Then I repeat the process again just because. Then once that's done I set my idle where I want it.

I did that to start with back before I got a vacuum gauge. I started at 1.5 turns out and did exactly what you said, but the engine would jump all over, and not really want to stay running.

Once I got the vacuum gauge, and started turning them out as described. Watching the vacuum come up from 10 to almost 15. Then readjust my idle. Then adjusted them again until almost 15, readjusted my idle. I did this 3 times total until I no longer got any increase off of the 14-15 at 800rpm. The engine smoothed out big time and no longer jumped and actually just purred.

Although. Im not sure if I was suppose to keep readjusting the screws.

 

[67Dart273]

You will reach a point where you don't gain more. There should be a sort of "flat" spot on "top" of the maximum vacuum reading, where it does not increase. "Just touch" the screws CW (lean) until you JUST DETECT either an RPM or vacuum drop. In other words you want the pretty much "peaked" but on the "lean side" of the peak.

You want the last adjustments made with the idle close to where you want it speedwise.

 

[straightlinespeed]

!!!NO!!!

Maybe even not enough. As we've said, adjust initial for a combination of..........

best (fastest) idle, and highest vacuum,

without bumping back on the starter

or without pinging at low RPM heavy loads

Hmmm, here I thought I would have to take some out.

If I adjust closer to 20* btdc the starter sounds like its being dragged along after the engine fires. Is that what you mean?

 

[straightlinespeed]

You will reach a point where you don't gain more. There should be a sort of "flat" spot on "top" of the maximum vacuum reading, where it does not increase. "Just touch" the screws CW (lean) until you JUST DETECT either an RPM or vacuum drop. In other words you want the pretty much "peaked" but on the "lean side" of the peak.

You want the last adjustments made with the idle close to where you want it speedwise.

Ok I was turning them out (CCW) until I hit that flat spot and that is where I left it.. I did not turn them back in (CW) until the idle dropped and then back out a 1/4 turn. I should do this correct?

Will that make a big difference in the way the car just drove?

 

[67Dart273]

Hmmm, here I thought I would have to take some out.

If I adjust closer to 20* btdc the starter sounds like its being dragged along after the engine fires. Is that what you mean?

Yes. You can check that it is "kick back" by cranking it with the coil wire pulled out and grounded. If it cranks good when hot, with the wire out, you know it's "kicking"

So where is it, 15?

Idle screws. Many guys use a fixed amount like 1/4. I don't I peak them as described, turn them in until I get the SLIGHTEST drop and then back out the tiniest amount. You will get various opinions. Main thing is that it's warmed up.

 

[straightlinespeed]

Yes. You can check that it is "kick back" by cranking it with the coil wire pulled out and grounded. If it cranks good when hot, with the wire out, you know it's "kicking"

So where is it, 15?

Idle screws. Many guys use a fixed amount like 1/4. I don't I peak them as described, turn them in until I get the SLIGHTEST drop and then back out the tiniest amount. You will get various opinions. Main thing is that it's warmed up.

Your talking the coil wire that goes to the distributor correct? Whats the best way to ground it?

Yes Im at roughly 15.

Ok, I will go and turn them screw in until I get a idle drop then back out somewhere up to a quarter turn. I have to ask again, will that make a big difference in the way it drives or not really noticable

 

[fishy68]

back fireing through the carb is lean or timing right guys?

Timing has to be pretty far off to backfire through the carb, but yes it can. A lean condition (accelerator pump not working, lean main circuit) is far more likely to cause a backfire through the carb.

I was informed its a timing issue, I just have to figure out what way to go with the timing to fix it.

Snake's question does not pertain to you. He was simply jumping in and asking a question. Ignore it

 

[fishy68]

Your talking the coil wire that goes to the distributor correct? Whats the best way to ground it?

Yes Im at roughly 15.

Ok, I will go and turn them screw in until I get a idle drop then back out somewhere up to a quarter turn. I have to ask again, will that make a big difference in the way it drives or not really noticeable

It'll make more of a difference in how it idles and drives at low speeds less than 25-30 mph. It won't affect wide open throttle, that's the carb's main circuit, which by your earlier description in post #87 may also be running quite lean, but go by Crackedback and 67Dart273 because their getting you there. Like mentioned earlier get the timing right first, then the idle circuit in the carb. Sounds like your getting the hang of it, Keep at it and you'll get it.

 

[EL5DEMON340]

Sounds like you have it idling good, 15 initial should be ok for that cam. at any rate the weak take off may be the sqirter/pump shot now. With the engine idling and in park take the throttle by hand and just barely move it off idle you should see gas squirting out of the squirters at the same moment you move the throttle (not a 1/4 sec after you move it) RIGHT AS YOU MOVE IT.

 

[EL5DEMON340]

also champion plugs never seemed to work good on my engines, if you have any resone to suspect the plugs try NGK Vpower gap at .035

 

[Snake]

Timing has to be pretty far off to backfire through the carb, but yes it can. A lean condition (accelerator pump not working, lean main circuit) is far more likely to cause a backfire through the carb.



Snake's question does not pertain to you. He was simply jumping in and asking a question. Ignore it

IGNORE it,unreal ,well thatsssssssssss just about it for me here.:wack: