340 on the dyno

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Babyblue66

Babyblue66

Cool dude
Joined
Oct 29, 2007
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Location
In an apartment, MN
Bought a 74 dart in June with a 70 340 in it. Ran good but had a rear main leak and some bad vibes. So I pulled it to freshen it and I had a hunch it had a cast crank. Which it did with the wrong balancer and torque converter.
It has old TRW forged pistons ccing in at 9.2 to 1.
Balled honed it with new rings.
Resized 2 rods and got a reman trw rod off e-Bay. #6 was too egg shaped to fix.
Elgin E935p 230, 230 @.050 480 lift cam. Some nos Johnson lifters
Did a good Serdi valve job with just little pocket porting. Has 2.02 1.60
Has a D4B intake someone redrilled.
New main and rod bearings.
Got the correct weighted balancer and b&m flex plate.
Ran a 750 Holley hp and a 750 Carter. Lost just a handful with the Carter. Only about 6hp average. At this power level either carb works great. The holley was a bit richer on the left bank for some reason. It has done this before, when I ran it on a 360 and a 383. i should probably look into that. I'm running the holley on the car now and it really runs nice all around.

Made 359hp and 364 ft lbs. Ignore that little blip at the beginning. That's dyno load in. Dropped it back in the same day and it rips pretty good. I like the cam for $134.00. Good drivability, nice sound, quiet under the hood, and flat torque curve. Who needs all that new fangled extra super duper extreme stuff anyway.

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Couple more shots. Car is loaded with tons of good parts from the previous owner. TTI headers, 8 3/4, 3.55 New gears, posi, axles, rebuilt 727, $500.00 stall converter, suspension, brakes, tires, exhaust, gas tank, leafs, brake and fuel lines, modern radio that looks old, etc etc.. Probably 15k in receipts since 2009. Everything is new or rebuilt.

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A beautiful car. No too much of anything, including horsepower. To each his own, but I’m really big on balanced cars that are fun to drive. It all comes together for a nice well thought out ride. The top, color, and especially the wheels, just scream “class” to me. Nice job.
 
azaustin said:
A beautiful car. No too much of anything, including horsepower. To each his own, but I’m really big on balanced cars that are fun to drive. It all comes together for a nice well thought out ride. The top, color, and especially the wheels, just scream “class” to me. Nice job.
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Thanks, the previous owner had good taste. I just dialed it all in better. It's definitely a pleasure to drive.
 
For what you used it runs good.
Tuning now.
Dont rule out the intake for the slight lean condition...could leak on that side.
Maybe that head was ported more/ better .
Its a dual plane, so the carb wouldn't make the entire even bank run lean, just 2 of them would on each side, 2 & 8.
 
I'm just wondering about your average A/F ratio of 13.2 to 1. You don't think that's a little lean? I'd prefer to see some 12.5s there. Nice package though. Car looks great and I'm sure it'll be fun to rip around town in!
 
MOPAROFFICIAL said:
For what you used it runs good.
Tuning now.
Dont rule out the intake for the slight lean condition...could leak on that side.
Maybe that head was ported more/ better .
Its a dual plane, so the carb wouldn't make the entire even bank run lean, just 2 of them would on each side, 2 & 8.
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That's what I was thinking too. But the Carter was better. And this carb did the same thing on two different engines. One was a 383 and it evened out with the stock AVS on it. It's weird. The dyno operator said he often sees uneven ratios with dual planes.
 
66Valiant528 said:
I'm just wondering about your average A/F ratio of 13.2 to 1. You don't think that's a little lean? I'd prefer to see some 12.5s there. Nice package though. Car looks great and I'm sure it'll be fun to rip around town in!
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Once it's under the hood sucking in 180 degree air, It's probably rich.
 
Babyblue66 said:
That's what I was thinking too. But the Carter was better. And this carb did the same thing on two different engines. One was a 383 and it evened out with the stock AVS on it. It's weird. The dyno operator said he often sees uneven ratios with dual planes.
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Look how it almost doesn't change throughout the range. That's a vacuum leak somewhere. There are "builders" here and "mechanics"...
both put stuff together, one is more an order of nuts n bolts..while the other is more calculated.... after those two get done blaming eachother why it has a bug/glitch...in comes the diagnostic tech.
I'm qualified and experienced in all 3. The operator isn't being very helpful with his statement, or he himself doesn't really get it...which would be a scary scenario. With a dual plane there has been known a tendency for the 2 center cylinders to be leaner, not the ends. Each bank of a dual plane feeds 2 cylinders on each side, 4 total for each side of the plenum....like 2,8,3,5 one side...then 1,7,4,6 of the other. There is no way for one side of the carb to accomplish leaning out all 4 cyl on one side '2,4,6,8' because 2,8 are fed from the other side of the carb/plenum along with 3 & 5...while the others off the other side.
Imo Its leaking , be it some base plate leak or at the intake flange...or the bung the o2 is plugged into. One side is getting air after the carb...because it doesnt change af, not even half a point. Take it or leave it.
 
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MOPAROFFICIAL said:
Look how it almost doesn't change throughout the range. That's a vacuum leak somewhere. There are "builders" here and "mechanics"...
both put stuff together, one is more an order of nuts n bolts..while the other is more calculated.... after those two get done blaming eachother why it has a bug/glitch...in comes the diagnostic tech.
I'm qualified and experienced in all 3. The operator isn't being very helpful with his statement, or he himself doesn't really get it...which would be a scary scenario. With a dual plane there has been known a tendency for the 2 center cylinders to be leaner, not the ends. Each bank of a dual plane feeds 2 cylinders on each side, 4 total for each side of the plenum....like 2,8,3,5 one side...then 1,7,4,6 of the other. There is no way for one side of the carb to accomplish leaning out all 4 cyl on one side '2,4,6,8' because 2,8 are fed from the other side of the carb/plenum along with 3 & 5...while the others off the other side.
Imo Its leaking , be it some base plate leak or at the intake flange...or the bung the o2 is plugged into. One side is getting air after the carb...because it doesnt change af, not even half a point. Take it or leave it.
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OK I'll leave it.
 
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