340 Full throttle hesitation

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Liquidspine

Liquidspine

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Hi guys,

I did a search and didnt find what I was looking for.
This is a noob question im sure.
I have a 340 dart swinger. I dont know much about the engine other than its been bored 30 over, it has an edelbrock manifold, Aftermarket carb (carver I think?), and a flat tapped cam.
My question is if I give it throttle slowly its fine to redline. But if Im at.... lets say...2500 rpm and put it to the floor is almost dies or hesitates but just for a second then its fine and takes off.
Any help is appreciated. Thanks
 
Get your timing dialed in first, then tune the carb next.

Carter/Edelbrock carbs have two or three holes on the accelerator pump lever. Try using the different positions to see if it gets better or worse and adjust from there. That will lengthen or shorten the shot of gas from the carb.
 
Not sure. Im pretty new to all of this. I believe it is the stock ignition.
 
Liquidspine said:
Not sure. Im pretty new to all of this. I believe it is the stock ignition.
Click to expand...

Then take a picture of the engine compartment and post them so we can see what you have. Get everything from both inner fenders and the firewall. More than one picture is good, maybe one whole pan view, then some closer up views. Pull the cap off the distributor and take a picture of the insides under the rotor...
 
Ok I can do that tomorrow. I will post them then. Thanks Kuda I appreciate the help.
 
Look for a box like this with wires coming out of it. If you have one of these, then it's electronic. People usually mount them on the firewall or inner fender when they add electronic ign (sometimes they hide them).

Also, what year is your Swinger?

View attachment MP Ign Box.jpg
 
Its a 70 and Im about 99% sure I have that on the inner fender.
 
Do you know how to use a timing light? How about one with a dial to see the advance?
 
Ive never used one but Ive been reading a lot lately and it seems pretty straight forward. line the marks up and rotate the distributor to set.
 
Also, are you running vacuum advance on the distributor, or no vacuum advance.

Look for a vacuum hose coming from the carb to the vacuum pod on the distributor.

If you're not sure, get some close ups of the carb from all angles (front, left, right, and rear and make sure that they show the base and all vacuum line connections.

Also if you do have vacuum advance hooked up, where is it coming from on the carb? The base or higher vacuum port??? A common mistake is to use the wrong vacuum source, which could cause poor performance...

Pictures are worth a thousand words here... If we could see it, then we can let you know what you have and how to proceed.


Also do you know the difference between initial timing and total timing? You will need to know to get the timing dialed in...
 
You may want to consider getting one of these. It's a dead stop tool. It's used to find your true TDC. This will take out any variation error in the crank, and the vibration damper. (Sometimes the outer ring on the damper spins from the inner ring and will throw off the marks with it). It's a good idea to get a piston stop to find the true TDC. It's only $8...

http://www.summitracing.com/parts/sum-900189

Beware of the Mopar Performance and Comp Cams TDC tool. There was a batch of bad ones going around a few years ago, and there could still be some out there. The spark plug threads on the tool are off and they will not thread in. You can't correct them with a die because they are hardened.

The top dead center piston stop tool just threads in the #1 spark plug hole, then you screw the inner screw down and then turn the engine over BY HAND until it stops (removing all the spark plugs makes it easier to turn over with a wrench). Mark the vibration damper for where it is or take the reading. Then reverse the direction and spin the crank until it stops. then take that reading. Then take the difference between the two (find the middle) and then that will be your true TDC.

Finding true TDC is important to getting your timing set properly.
 
Liquidspine said:
Total timing you add throttle right?
Click to expand...


For total timing, you hold the engine at a steady 2500 - 3000 rpm to check the "total" timing with all of the vacuum advance and centrifical advance from the distributor kicked in.

Initial timing is the timing at idle.


340's usually like to run around 17° initial timing, and 34° - 36° total timing at 2500 - 3000 RPM.

You can use the idle screw to keep the engine speed steady while you check your readings and make your settings, then back it off when you are done.
 
Liquidspine said:
Kuda I will post pics tomorrow. Thanks for the help.
Click to expand...


Ok. When we see the pictures, we can help you out better.

I won't be on until late, as I have a few things to do tomorrow and won't be able to get to a computer for a while... I'll try to check in when I can.

There are also some other guys on here that can help.

Lets first start with the basics and go from there. Especially with an "unknown" engine...
 
Hope these help/ The last 3 are just to show off the car....Haha. Let me know what you think. Also I was reading about gas a little and there is a place near me with race gas 107 I believe. Could/should I use it mixed with 93? If so what mix half and half? The guy I got the car from said 10 to 1 if I remember correctly. Thanks
 
Here ya go!
 

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Dont ask me why he had different color plug wires. Im changing them and the plugs this weekend when I do the timing.
 
Ok, you have an electronic ignition with a mallory centrifical advance distributor. It does not have a vacuum advance pod, that is not a bad thing...


I'm not familiar with recurving the mallory dist. but there should be some others who can tell you how...

Carter carb, elelbrock dual plane intake, with headers and power brakes.

Is the brake pedal hard? What kind of vacuum do you have at idle?

Have you put a timing light on it to see where your timing is at idle and at 2500 and/or 3000 rpm?


To tune it, you will need a timing light, vacuum gauge, and an engine analyzer with a tachometer. The bigger the readout, the better for tuning...
 
t wouldn't hurt to do a compression test while you have all of the spark plugs out. Do you know how to do a compression test? You will need a compression gauge.

It's also good to do the compression test wet and dry. First do it dry and crank it until you get the maximum reading on the gauge (4-7 strokes usually). Then see if it will hold the pressure for about half a minute. Record the reading.

I like to do each cylinder 3-4 times at least to make sure that the results are repeatable and reasonable...

After you do the cylinder dry, then get an oil can and squirt 2-3 shots of oil in the cylinder and run the compression test again. Record the readings on paper.


After doing each cylinder wet and dry, then look at the numbers to see what they are telling you.

The cylinders should be within 20 psi of each other. What pressure are they at? Is there a higher reading wet than dry?

Are the wet readings higher than the dry, or pretty close. If the cylinder improves significantly wet, then there is a ring sealing problem. If there is a low cylinder and it doesn't get any better wet, then you should for a leaking valve...


If everything looks good, then you should then start to dial in your timing. 340's like to run near 17° initial timing and 34° - 36° total advance at 2500 - 3000 RPM. You should be able to get different tension springs from Mallory to change the curve of the timing in the distributor if you need to.

That should be a good start for you.

After you get the timing dialed in, then you move on to tuning the carb....
 
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