Differences between a 1970 and 1971 440 engine

Gary Masse

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I have a 440 in my 1971 GTX that the engine was casted 1-28-70 s/n 0G246189 and F 440 on the pad. The car and engine was rebuilt in 2010 and driven 600 miles over 10 years. I purchased the car unseen and had a prebuyers done on it. I have been working on the car over the last year and one thing it has is a vibration over 3500 rpm clutch pack forward. What are the differences between these two years of engines and could it be due to something as simple as the wrong year harmonic balancer.
 

early2drsedan

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is the 70 a hp block if i remember right the 70 hp 375hp had the six pack rods but the standard 440-350 hp did not it hell getting old
 

4speed68rt

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Its possible. There was different rods, cranks and balancers around that time. Not to mention flywheels and torque converters. Some are externally balanced. They don't really mix and match.
 

66Satellite47

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IIRC the '70 440's had either the LY rods and possibly the six pak rods. Don't think all the "HP" motors got six pak rods. The balancer is surely different. The difference between '70 & '71 is hard to say, these were transition years for many things. The other thing to check is the driveshaft.
 

1 Wild R/T

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IIRC the '70 440's had either the LY rods and possibly the six pak rods. Don't think all the "HP" motors got six pak rods. The balancer is surely different. The difference between '70 & '71 is hard to say, these were transition years for many things. The other thing to check is the driveshaft.k
Yes the 70 HP engines got the Sixpack rods... And the 350 HP engine did not get the big rods...
 

4speed68rt

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I guess the OP needs to say how bad the vibration is. I doubt it is a seriously bad out of balance problem with the rotating assembly if it doesn't appear until 3500 rpms, with a 4 speed. It would probably shake like heck when the clutch is released at less than 1500 rpms or so. (ask me how I know, haha) It sounds like its probably a driveshaft balance problem.
 

1 Wild R/T

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I guess the OP needs to say how bad the vibration is. I doubt it is a seriously bad out of balance problem with the rotating assembly if it doesn't appear until 3500 rpms, with a 4 speed. It would probably shake like heck when the clutch is released at less than 1500 rpms or so. (ask me how I know, haha) It sounds like its probably a driveshaft balance probelem

He states that it's clutch pack forward... I'm guessing that means it'll shake/vibrate in neutral...
 

Gary Masse

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It shakes above 3500, more noticeable in the higher gears but once I put the clutch in and engine rpm drops it goes away. It is not a violent shake but you sure know it is there. Just to note it has a Tremec 600 5 speed ( the good one). Yesterday I decide to see what it did at higher speeds. Above 115mph she still shakes with clutch in or out. All tires where balanced and the drive shaft was from Tremec new in 2010. Balance weights seam to be there.
 

66Satellite47

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I still suspect the driveshaft, but I am not a manual trans guy.
 

Gary Masse

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At high speeds it may be and I plan to get it balanced ( drive shaft) my thoughts are when they put the 1970 engine in they put some 1971 440 parts, ie hormonic balancer, fly wheel etc. They say in the paper work that it was balanced. I could be in the pressure plate or clutch pack, what do you guys think? I plan on pulling the engine this month to look it over.
 

1 Wild R/T

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If it's an engine balance problem you can duplicate it sitting in your driveway by slowly raising the engine RPM's till you hit the critical RPM.... If it won't vibrate in the driveway the problem is elsewhere...
 

Runcharger

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It could be the wrong balancer, only way to know what's in a 50 year old engine for sure is to tear it down. Lots of chances for swapped parts in 50 years. I put a 68 Cuda 340 together once that was a shaker. First thing I did was pull the flywheel out and my engine guys neutral balanced the flywheel and that along with throwing away the generic hardware store clutch bolts and replacing with proper shouldered clutch bolts cured it. My guess is if they balanced the engine that they did it without the flywheel that is in the car right now. All a person can do over the internet is guess though.
 

Rusty34

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70 and 71 440HP engines are pretty much the same. They both had the wide beam 6-Pak rods and were both externally balanced meaning extra balance weight was added to the front damper and the flywheel or torque converter. The 1968-69 engines were different, narrow beam rods and no external balance weight added.
 
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