Help me get my slant running right

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OldDart

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Here's my problem. I havn't had it that long. 70 swinger-slant.

It drove ok home but I remember some small backfires.

I moved the timing around because it was hard to start but the found out it was the coil- replaced it. Timed it by ear and sounded responsive and solid.

Drove it and when under load got lots of small backfires and would not accelerate. Tried moving the timing many times and always the same.

It has a new distributor, plugs, wires, rebuilt carb.

It seems like the PO was trying real hard to get it to run better.

My conclusion is probably the timing chain is sloppy. Any thoughts? How can I test for this. I don't have a timing light right now. May borrow one soon. Thanks! :munky2:
 
A good vacuum guage will help determine if your timing chain is jumping.Hook it up and if the reading jumps around on you it could be the timing chain!
 
i have a /6 in the old 82 pick up 550,000 no timing chain in it since the start of time . If it is old timer, older /6 they had mech valve adjustment newer one hdy ! points or electric ing ? compression test ?reman carb" my luck with these bad "...vac advance hold a vacuum .where here to help but got to give some info
 
You need to put a vacuum gauge on this engine to see what's going on. If your vacuum is steady, you may have an ignition issue. If your vacuum jumps around, you have a leaking intake valve(s). I would try a valve adjustment first to make sure none of the valves are too tight. But if the engine has been run too long in this condition, you are probably looking at a valve job.
 
Take your valve cover off. Put a socket and ratchet on the crankshaft pulley nut. Turn the engine over while watching the first valve. When it opens fully (a good guess is good enough), reverse direction. See how far you have to move the wrench before the valve starts to move.
 
thanks all for the input! i'm going to take a look at it in a couple days, hopefully. I forgot to mention, the compression is 120-130..... i'm pretty sure it's not the vac advance but will check it.... it's points. I'm pretty sure it's the original motor so it's mechanical lifters, right, 1970? i was told by the PO that the PPO had adjusted the valves.... maybe he got them too tight..... hopefully it's the valve adjustment and not the T-chain.... thanks again for the insight ...
 
Sounds like what was happening with my buddies 66 dart. We adjusted the valves (PO set them too tight) and set the timing and it runs great now. There is also a second adjustment for the timing bracket on the dist If you pull the dist and look underneith there is a bolt that holds it, that will give you a little more adjustment.
Makes sure that #1 is at top dead center and that the rotor is pointing at #1 onthe cap when you drop it back in.
 
360scamp said:
Sounds like what was happening with my buddies 66 dart. We adjusted the valves (PO set them too tight) and set the timing and it runs great now. There is also a second adjustment for the timing bracket on the carb. If you pull the dist and look underneith there is a bolt that holds it, that will give you a little more adjustment.
Makes sure that #1 is at top dead center and that the rotor is pointing at #1 onthe cap when you drop it back in.
Click to expand...

a second adjustment on the carb? that doesn't make sense to me-- the carb and the distributor are not even close to each other. Can anyone explain or confirm this.

Yea.... i'm feeling hopeful that is just a valve adjustment and tune. Timing chain means more money and time. Thanks.
 
You can forget the timing chain as the cause of an intake backfire. It is about as likely as your left-rear lugnuts to cause that problem.

The causes of such a malfunction are typically as follows:
1. Combustion pressure and gasses entering the intake due to a misadjusted or burned intake valve.
2. Crossfiring ignition due to crosswired or deteriorated ignition leads or distributor cap.

You need a vacuum gauge and a compression tester to diagnose this, starting with a vacuum gauge ($20 at your local parts store). Take a vacuum reading at idle if it is rock steady the problem is likely ignition related. However, if the vacuum reading is not steady, dipping rhythmically, you have #1 above. Sorry, but my money is on this.

Does the engine have a miss? Does it just spit back once, bog, and then accelerate smoothly or does it go pop-pop-pop and buck while accelerating, popping harder with more throttle?

Start with the obvious stuff like valve adjustment and ignition tune-up.

If you have a miss, you can isolate the missing cylinder by removing one spark plug lead at a time. The one which doesn't make the engine run rougher is your leaking cylinder. Remove the plug from that cylinder and test drive. If the pop is gone, pull the head, you need a valve job.
 
C130 Chief said:
You can forget the timing chain as the cause of an intake backfire. It is about as likely as your left-rear lugnuts to cause that problem.

The causes of such a malfunction are typically as follows:
1. Combustion pressure and gasses entering the intake due to a misadjusted or burned intake valve.
2. Crossfiring ignition due to crosswired or deteriorated ignition leads or distributor cap.

You need a vacuum gauge and a compression tester to diagnose this, starting with a vacuum gauge ($20 at your local parts store). Take a vacuum reading at idle if it is rock steady the problem is likely ignition related. However, if the vacuum reading is not steady, dipping rhythmically, you have #1 above. Sorry, but my money is on this.

Does the engine have a miss? Does it just spit back once, bog, and then accelerate smoothly or does it go pop-pop-pop and buck while accelerating, popping harder with more throttle?

Start with the obvious stuff like valve adjustment and ignition tune-up.

If you have a miss, you can isolate the missing cylinder by removing one spark plug lead at a time. The one which doesn't make the engine run rougher is your leaking cylinder. Remove the plug from that cylinder and test drive. If the pop is gone, pull the head, you need a valve job.
Click to expand...

it goes pop pop pop.... i don't think it has a miss and the distributor and cap/rotor are new..... I'm doing the valve adjustment tonight.... and checking the vacume before and after

UPDATE::banghead: I just got done adjusting the valves. It's still doing the same thing. Some of the valves seemed a little tight and it does seem to sound better, BUT it still backfires. pop pop pop, increasing if you try to accelerate (out the tail pipe and occasionally out the carb). I honestly think the valves are ok. I did .010 on the intakes and .020 on the exhaust while running and nice and warm. When you rev it in neutral it sounds GREAT, nice and smooth and idles fine too. Just coming off idle it is slightly rougher but then smooths out and sounds perfect. Unfortunately under load it runs like CRAPOLA. Oh, and I checked vacume before the adjusting the valves and it was bouncing a bit, after it was almost completely steady, just like a slight vibration of the needle.

Review:
Compression 120-130
Dwell: 35
 
I still can't figure this Fn thing out. Here is some more info:

I checked the vacume advance function with a pump and it worked fine.

The timing mark is not bouncing around a lot, though it is nowhere near the right position so it can't be correct.

The idle mixture screw seems to do nothing. If you turn it all the way in it stays running and turn it out and it doesn't seem to change anything.

It starts easy and idles fine and can turn the idle down very low.

It sounds real smooth at high RPM under no load.

Under load it backfires on acceleration, frequently and sometimes out the carb when you let off the gas after trying to run it.

If you push it past it's low RPM problems and open it up it stops backfiring and you can open it up and it sounds OK.

The fuel filter on the carb is not plugged.

It is not getting hot even after sitting running.

I think I have ruled the valve adjustment out.

The compression is good so I am doubting valve issues.

Lastly, it is pissing me OFF!

Conclusions:

Possibly carb or dist?

The dist. was remanufactured so I don't think it would be that. I need to check the bushing again. I am thinking carb at this point.

Any thoughts?
 
Here is a pic of the second adjustment on the slant dists. I would still try to adjust the valves, you may be surprised.

100_3375.jpg
 
i did adjust the valves... some could have been slightly tight......the problem didn't go away?
 
Does it look like fuel has been leaking around the throttle shaft and running down the side of the carb?
 
You usually don't see any gas. What you will see is a stain that runs from the bottom of the throttle shaft down the side of the carb. If that is there your throttle shaft is worn and sucking air when it is in the position where it spends most of its time. Usually just off idle. The only way to fix it is to rebush the throttle shaft bore and install a new shaft or get another carb.
 
Clean out your vacuum advance port on the carb and see if you have vacuum on the hose during acceleration. I'm betting you don't and that's your problem.
 
it's a 1bbl carb.... thats all i know..... i know it has vacume on the port but didn't check how it reacted to the throttle..... will check tomorrow.... will take a close look at the carb for leaks too..... thanks for the input... really... i know a guy who has a 73 with a slant close by... i think i will see if i can borrow his carb.... the swap wont take long..... why the hell is my timing mark 90 deg. apx. off? thanxxxx
 
grumpuscreature said:
You usually don't see any gas. What you will see is a stain that runs from the bottom of the throttle shaft down the side of the carb. If that is there your throttle shaft is worn and sucking air when it is in the position where it spends most of its time. Usually just off idle. The only way to fix it is to rebush the throttle shaft bore and install a new shaft or get another carb.
Click to expand...


i think you might have won the prize! ...... i looks like the throttle shaft is pretty sloppy ...... i think you might be right.... i hope so anyway.... what do you know about getting parts to fix this.?.. short of buying a rebuilt unit..... thanks...
 
A good carb shop can fix this. Or buy a few used carbs and take the best parts and rebuild or buy a NOS from SSDan over at slantsix.org. I have personally done this and was very happy, and for less money than a parts store rebuilt POS.
My 02.
Frank
 
does anyone know if a 73 1bbl is the same as a 70? or any problems running it...... advantages/disadvantages? thanks
 
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