It might. It's a tic small, IMO, but you know how tuneable those are. I'm sure he could make it work. I think though if I was gonna out and out BUY something new, I'd try an AVS.
Help an old man tune a new to me 340
- Thread starter HS Duster
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DARTLARRY
Well-Known Member
Are you using a timing light? If not you cannot rotate the engine and tell where initial timing is set. You need to mark on the distributor body where number wire one the cap is. Then rotate the engine and watch the distributor. When the rotor points to the mark on the distributor body check the crank position, that will be your initial timing.
middleagecrisis
Well-Known Member
I have a 1405 and they are extremely easy to tune. There's a ton of video's on YouTube to show how to tune them. I think the biggest thing to do first is take the top off of the carb and verify there's no crud in the float bowls. I bought a cheap chinese tune kit off of Ebay and got mine zeroed in fairly easy. I think their great little carbs for fairly stock engines. You'll spend more money on a new carb than you would rebuilding and getting a tune kit for a 1405 carb. I see them on Facebook marketplace used for $50-$100. Just my .02 worth.
All sellers say it runs fine, never had an issue, has 500 hp at 1500 rpm and on and on.
In other words, the seller lies.
PRH
Well-Known Member
The later MP distributors used an adjustable mechanical advance, which makes limiting the amount of advance a piece of cake.
Yes, I am using a timing light. But I will verify with that method also. The confusion was the previous owner had marked the balancer with white paint pen. I thought that if was 0* but was actually 15*. Thats where he had been running it. My novice mistake.
Got a new AVS2 650CFM coming, be here 8am tomorrow. Hopefully it works better
Tried to borrow one, but he had sold it. You mean open it up and check float levels and for debris? Thought about trying to buy a used one but decided to go new. As stated before, they say it runs fine when it doesn't. Spending the children and grandchildren's inheritance.
PRH
Well-Known Member
FYI, The limiter plates don’t work with the newer style distributors.
NC Engine Builder
Grumpy Old Man
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Nobody goes through the trouble of finding TRUE top dead center and then marking the ballancer 15° away from that. You need a piston stop, and you need to mark the TRUE top dead before you do anything else. Otherwise your guessing
The balancer had marks on it. He had just highlighted the 15* mark as that is where he was running it. I used a crude method on #1 to verify as best as I could where TDC was. TDC, as best as I could tell, lined up with one of the long marks on the balancer, which I think is 0*. As you know, the long marks are 5* apart on the balancer with smaller indications between. His mark was on one of the marks 15* away. I should have caught this as his mark and not being 0*. I think this was done by the guy that built the engine, not the previous owner. I'm a novice and shade tree mechanic in my garage doing the best I can with what I have. I'm sure its not perfect as it would be with the proper tools.
Although I was a dealership line mechanic for may years, I can certainly relate to this now.
Before I bought a piston stop, I used wooden skewer(mmm shishkabob) to find TRUE tdc. Just as u did the 1st time, rotate engine clockwise until the skewer is at its highest point, make a mark on balancer, then rotate COUNTER clockwise until the skewer is at its highest, make another mark on balancer. The middle of those 2 marks is TRUE tdc.
At some point make sure the harmonic balancer hasn't "spun".
At some point make sure the harmonic balancer hasn't "spun".
Captainkirk
Old School Mopar Warrior
If you want to go this one better, you can take a compression tester air chuck fitting and use it to keep the shish-kabob stick centered. Lacking a compression tester, you can break off the porcelain (flush with top of plug) from an old spark plug, chuck it in a vise, and using a pin punch, drive the old center electrode out leaving a hole just the right size for a shish-kabob stick. You will also have to remove the ground electrode (duckbill pliers, bend it back and forth until it snaps off)
Great idea! I'll make one from an old spark plug.
I'll have to get one
Here's mine, spring loaded and has graduations on it.
HS.
[1] The only problem with the 750 Edel carbs [ only a few ] was pinched emulsion tubes on the secondaries. Your problem is occurring during operation of the primaries.
[2] It would be foolish to spend money on ANY carb until you have tried the simple tests in post #40....because the same fault may occur with a new carb....& you just paid hundreds of ### for a hesitation.....
[3] Is the PCV hooked up?????????? It adds air for idle. If not hooked up, air[ from somewhere ] will be needed to make up the short fall....& that is usually the pri blades cracked open further.
[4] The other possible extreme is that the PCV is hooked up but is blocked, or is not getting enough vacuum to work. Result is erratic idle & off idle performance...
[5] Correct T slot position is 0.020-0.040" above the blades at idle. See below.
[1] The only problem with the 750 Edel carbs [ only a few ] was pinched emulsion tubes on the secondaries. Your problem is occurring during operation of the primaries.
[2] It would be foolish to spend money on ANY carb until you have tried the simple tests in post #40....because the same fault may occur with a new carb....& you just paid hundreds of ### for a hesitation.....
[3] Is the PCV hooked up?????????? It adds air for idle. If not hooked up, air[ from somewhere ] will be needed to make up the short fall....& that is usually the pri blades cracked open further.
[4] The other possible extreme is that the PCV is hooked up but is blocked, or is not getting enough vacuum to work. Result is erratic idle & off idle performance...
[5] Correct T slot position is 0.020-0.040" above the blades at idle. See below.
At idle with high intake vacuum isn't the pcv blocked closed?
Swinger 340
Well-Known Member
If you have a vacuum leak, I think you would notice it mostly at idle. Before I would start spraying fluid all over the engine, I would do the old, block off the air horn trick and see if the ideal picks up (leak) or wants to stall out the engine (correct without leak). If you are sure, you have a leak after this simple test and checking all the common locations, check the distributor canister and brake booster diaphragm, by unhooking and blocking off the hoses. My 69' stock with the larger 4 speed purple DC came, timing is set at TDC. I would look at the Distributor. Make sure, if points, they are set correctly (I have dual points, and it takes me about an hour to get them right). As someone said, I would get another carb (Carter, AVS or Ellerbrock, AFB ), around 600-650 cfm. You say the problem starts around 1600 rpm, possible weak valve springs. Good luck.
Well, I did the carburetor swap and had a little improvement. Haven't tuned on the new carb any yet other than idle screw adjustments. Pulled the distributor and it is one of the newer styles where you can limit the advance. I moved it to the middle of the travel slot. Now the advance stops approximately before 30*. I'm going to pull it again and open it up just a little. I'm at about 16* initial. The advance seems to come in very quick also. What should my advance be at 1600? Should total advance be approximately 35*? I checked the vac advance on the dizzy while I had it out by blowing into and sucking on it and I couldn't move air through if either way. So, I think it is ok and not leaking. Putting in hotter plugs this afternoon as well as someone suggested. It's the best I have had it to this point, but still not right. I've checked for vac leaks and found none. I'll plug the brake booster line and see if makes a difference.
Plug the PCV while you're at it
PRH
Well-Known Member
If you’ve been using vac advance……..a very quick mechanical curve, along with vac advance, you could easily be over advanced in those lower rpm’s.
See it the symptoms improve/change with the vac adv disconnected.
See it the symptoms improve/change with the vac adv disconnected.
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