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4.3 chevy engine interchangeability

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17K views 7 replies 4 participants last post by  cobalt327  
#1 ·
I have a high mileage 1990 C-10 chevy with a non balance shaft 4.3 engine VIN Z . I would like to put a newer model (1993-1994) 4.3 with a balance shaft VIN Z out of an S-10. Is this possible ? Is it worth the trouble ? How much smoother is the balance shaft motor than the non balance shaft motor ? How bad could the non balance shaft motors have been since they used them for so many years ? Thanks
 
#2 ·
The non balance shaft engines will need to be balanced by a machine shop during the rebuild to 36%. The balance shaft engines have some things different than do non balance shafts, but will still interchange up to 1996 which was when the intake bolt pattern changed as did the cylinder heads. To be honest, the balance shaft engines aren`t much smoother than the non balance shafts.
 
#4 ·
Yep it was 36%. Machine Shop Tom was who told me to have it balanced to that spec. When I picked up the crank from the machine shop the guy told me 36% worked out excellant and that`s what he would balance the heavy 4.3 cranks to from that point on unless the customer asked for otherwise. I still have my spec card here.
Rod rotating: 484
Rod Bearing: 45
Oil Allowance: 4
Rotating total: 533
Piston and pin: 713
Locks: N/A
Rings: 58
Rod Riciprocating: 189
Reciprocating total: 960
Rotating total: 533
960 X .36 = 345.6
Bobweight total: 878.6
 
#5 ·
The reason I questioned it, is the info from the 04-2000 Automotive Rebuilder, Rebuilding the New Chevy 262 by Doug Anderson:

Any 90° V6 creates some strong, primary imbalance forces, especially in the vertical mode. The 262 is no exception. Chevy originally underbalanced these engines by putting about 46% on the bobweights instead of the usual 50%. This reduced the vertical imbalance that was trying to lift the engine up off the mounts, but created a strong horizontal imbalance that shook the engine from side-to-side instead. So, in order to eliminate a lot of the "noise, vibration and harshness" in the engine and make it into a world-class motor, Chevy added a balance shaft to the premium engines in ’92 and included it in all of them by ’95.
 
#8 ·
pemdj said:
If I don't have the crankshaft balanced on the rebuild on the original non balance shaft motor would it then run and vibrate like it came from the factory ?
That is correct. You will find differences between engines built at Romulus and Tonawanda. With these engines, don't mix and match parts randomly- there are specific parts that should be kept together. If you have an original unmolested engine, just reuse the parts it came with or replace w/like parts if necessary.

More HERE.