Internally balanced 340 questions

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jason's duster

jason's duster

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I have a 72 340 I had built with a forged crank. The guy I purchased crank from sent harmonic balancer with it but not sure if its the correct one.
My flywheel will need to be changed for internally balanced crank as well?
Any input on these pics and what I need to do would be greatly appreciated.
I already changed timing cover and water pump to accommodate internal balancing.

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turn balancer over see the front face , if has no horse shoe, then its internal balanced, also external will have stamped on it 340 external only
 
The early 340 neutral harmonic balancer and the later 340 neutral harmonic balancer are balanced the same. The difference is the timing mark's are in different places so the timing covers are different to allow for this change. All cast crank 340s use the same external balanced harmonic balancers.
Do the 68 and the 71 use the same pulley bolt pattern? 72 bolt pattern is different from the 68. Easy fix with a rat tail file.

340 balancer lesson for the day.
 
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Jadaharabi said:
The early 340 neutral harmonic balancer and the later 340 neutral harmonic balancer are balanced the same. The difference is the timing mark's are in different places so the timing covers are different to allow for this change. All cast crank 340s use the same external balanced harmonic balancer.
340 balancer lesson for the day.
Click to expand...
Thank you for the lesson I love learning something new every chance I get. Still learning as I go.
I changed timing cover and water pump.
 
Did you change to an aluminum water pump or did you change to the early cast iron water pump.
 
A wheel balancer will tell you if the flywheel is neutral balanced.
You will find it was used on everything from a 318 to a 440. It just depends on how it was balanced which motor it was used on.
 
Yes, you will need a neutral balance flywheel. I cant tell you what you have in the picture.
Must have some light rods and/or pistons in that thing. Lots of weight removed from the crank.
 
MoparMike1974 said:
Yes, you will need a neutral balance flywheel. I cant tell you what you have in the picture.
Must have some light rods and/or pistons in that thing. Lots of weight removed from the crank.
Click to expand...
Eagle Rods Forged TRW flat tops
I’m not familiar enough with machining to know but I hope everything is right.
The builder has a good reputation so of course I put all my trust in him.
 
The water pump and timing cover have nothing to do with engine balance. Going by your photos, the engine has been rebalanced. The crank, balancer, and flywheel (looks correct for an internal balance engine) all look to have added fine balance holes drilled in them. Factory cast crank/external balance engines have different looking holes in the flywheel than what I see here. If all these parts came with the engine and from the machine shop who did the machine work, I would put it together and run it. If there is any question as to whether you have a matched set, I'd have the balance re-checked.
 
While the water pump and timing chain cover have nothing to do with the engine balance they have everything to do with the year of the car and which side of the harmonic balancer the timing mark is on and for the side that the bottom radiator hose hooks up. As I said earlier I'd check the flywheel for neutral balance.
 
Jadaharabi said:
While the water pump and timing chain cover have nothing to do with the engine balance they have everything to do with the year of the car and which side of the harmonic balancer the timing mark is on and for the side that the bottom radiator hose hooks up. As I said earlier I'd check the flywheel for neutral balance.
Click to expand...
The balancer can easily be re-marked if needed, and should be checked for accuracy anyway.
 
Jadaharabi said:
Same part number on your flywheel is on his flywheel. But that does not mean they are balanced the same. As I said Put it on a balancer see if it's neutral or not.
Click to expand...
Agreed, you can see the holes are drilled at different places on my old one vs his
 
Mine has the same casting number on it as yours but as you can tell it's balanced for a 360. It has 131 teeth.

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