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I purchased a numbers matching project 69 convertible 300 hp base engine. The engine was out of the car and rebuilt when I picked everything up. Upon inspection I couldn't install the engine with a 55 year old balancer. It was cracked and dry. To me it didn't make sense to install a old balancer. Well the lower pulley's don't line up with the water pump pulley. The water pump pulley is in front of the crankshaft pulley by maybe 1/4". When I pressed in the balancer you usually keep going until it stops. The balancer typically presses against the crank gear. So I'm not sure which way to go because my problem is the exact opposite of what normally people encounter when they don't press it in enough. Any help would be appreciated. When I had the old and new balancers together they looked identical even the snout. Any help would be appreciated.
malicatasr
Did you get an exact replacement balancer? Did you compare it to the old one? If so then we can save some time if you post all the pulley numbers.
Let me get a chart I made for my 68..... should pretty much help you get the correct pulleys.
Gimme a sec... meanwhile look at your 1969 AIM for pulley numbers..... so you can compare them with the list I'm going to go get....
My crank pulley is 3850838
PS pulley is 3751232BB
I'm not 100% on the water pump pulley, will check after work today.
I do not have A/C and the air pump is long gone.
Looks like the correct pulleys, my car is a 69 early (September 68)
Should I have a concern reinstalling a 55 year old balancer. There are no hammer marks on it. It just looks old. (Like me). When I get home I'm going to pull the new balance and visually compare to the new. Which I did but not with calipers.
My crank pulley is 3850838
PS pulley is 3751232BB
I'm not 100% on the water pump pulley, will check after work today.
I do not have A/C and the air pump is long gone.
Looks like the correct pulleys, my car is a 69 early (September 68)
Should I have a concern reinstalling a 55 year old balancer. There are no hammer marks on it. It just looks old. (Like me). When I get home I'm going to pull the new balance and visually compare to the new. Which I did but not with calipers.
What manufacturer and part number is the new balancer?
The water pump pulley is in front of the crankshaft pulley by maybe 1/4".
Do you know if the water pump is the short-design* for your '69? What is the pilot shaft diameter (the nub the fan clutch mounts to)? How much space is there between the rear plate of the water pump and the timing cover? If you can fit your hand in between, then it's not a Corvette pump and will push your WP pulley outward and out of alignment.
*All Corvettes used a "short" leg pump but there were two of them – a 5/8" pilot shaft up to 1970 and a 3/4" pilot shaft from '70 up.
Last edited by barkingrats; Nov 4, 2024 at 09:57 PM.
malicatasr
See this post. Hayes69 posted an image of an AIM page and I think it is a 1969.
Should have some relevant pulley numbers needed. You can then use that gm wiki webpage to cross reference with alternate pulleys.
So I checked last night compared the old and new balancers and they are almost identical. The new one is .001 shorter in the snout. That's nothing in my eyes. They are both 8 inch, the machined face to a flat surface are the same. My .
My pulley's are: Crank pulley: 3850838 PS pulley: 3751232BB
Water pump pulley is 3890419 - according to the AIM my base 300 HP should be 3876846. The 419 is for the 327.??
I also have a short water pump.
Balancer is 7704H
I haven't even gotten to the alternator yet. I want to clean up the exhaust manifolds before I put them on. So who know what joy that's going to bring.
So I pulled the new one and checked and reinstalled and once again when it bottomed out it was still offset. So I measured the distance to the front of the timing tab as a reference. I then pulled the new balancer out a little bit and aligned everything and re took the same measurement. It's 3/16 of .1875 difference. I saw crank pully shims online and was going to try them. I really don't want the balancer not seated properly.
Last edited by malicatasr; Nov 5, 2024 at 09:05 AM.
malicatasr
I previously forwarded this table-- it is within a link above....anyway, you have this info available to make your decision for pulleys that will align. Take a look at this table... and you might want to read the whole post anyway. The link and table lets you know what will align and mate (as far as the forwardmost pulley).
Since you now know which pulleys to get I suggest checking ebay. Pulleys last forever and you'll find the best prices there.
So I checked last night compared the old and new balancers and they are almost identical. The new one is .001 shorter in the snout. That's nothing in my eyes. They are both 8 inch, the machined face to a flat surface are the same. My .
My pulley's are: Crank pulley: 3850838 PS pulley: 3751232BB
Water pump pulley is 3890419 - according to the AIM my base 300 HP should be 3876846. The 419 is for the 327.??
I also have a short water pump.
Balancer is 7704H
I haven't even gotten to the alternator yet. I want to clean up the exhaust manifolds before I put them on. So who know what joy that's going to bring.
So I pulled the new one and checked and reinstalled and once again when it bottomed out it was still offset. So I measured the distance to the front of the timing tab as a reference. I then pulled the new balancer out a little bit and aligned everything and re took the same measurement. It's 3/16 of .1875 difference. I saw crank pully shims online and was going to try them. I really don't want the balancer not seated properly.
Hello. We would recommend bringing this concern to a Chevrolet dealership who can provide expertise guidance and answer your questions in greater detail. Should you need help connecting with one in your area, please email us at socialmedia@gm.com.
Hello. We would recommend bringing this concern to a Chevrolet dealership who can provide expertise guidance and answer your questions in greater detail. Should you need help connecting with one in your area, please email us at socialmedia@gm.com.
malicatasr
I previously forwarded this table-- it is within a link above....anyway, you have this info available to make your decision for pulleys that will align. Take a look at this table... and you might want to read the whole post anyway. The link and table lets you know what will align and mate (as far as the forwardmost pulley).
Since you now know which pulleys to get I suggest checking ebay. Pulleys last forever and you'll find the best prices there.
69 Pulley Alignment issues
