ezstriper

ok, have a almost new(100 hrs) gen VI 454 that I bought a pair from a marine engine warehouse, the reverse rotation engine developed a knock recently that would come and go, also noticed the balancer had some wobble to it, checked the bolt was tight. we felt the balance and felt loose, took apart, bolt was tight and was able to simply pull the balancer off by hand !! thats dead wrong...after checking it all out found that the balancer slides down on the crank about 1/8" past the end of the crank !! so bolt tightens on the crank not the balancer....now the balancer is worn from moving around crank looks fine, but many years of working on big blocks never seen anything like this..now this a factory stock engine that never see's 4k...seem I have no problems coming up with weird issues...thanks for any input....Rob

BillK

EZ,
You need to take the damper to your machine shop and have them measure the id to see if it is worn, or if the crankshaft is the problem. You cant tell by looking. The crankshaft might "look" fine but be worn too much. The interference fit is less than two thousanths ( .002" ) If you have a good micrometer, measure the front of the crank and lock the micrometer. Take it with you to the machine shop so they can set up thier bore guage to your micrometer, that way they will be able to tell you what is worn.

What has probably happened is the builder used the incorrect timing chain set. There are several different ones for the GenVI engines. The one you have is probably the one that is meant to be used on an engine that has a crankshaft trigger wheel on the front. The trigger wheel goes between the damper and the crankshaft sprocket so it requires a thinner sprocket to leep everything in the correct position. If you use the thin sprocket without the trigger wheel, you end up with the situation you have with the bolt not tightening on the damper

However ..... I am not too sure if this really would have caused the damper to move and come loose ? Big Blocks are usually so tight that its rediculous. Unfortunately, you need to pull the front cover off the engine and take a good look to see what you have.

If you need some help, I am only about an hour away and will gladly measure the parts for you if you want to wander up to Maryland You are also welcome to call 301-843-5700

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

ezstriper

Bill, my machine shop guy was the one with me when we took it apart, yes we miked the crank and balancer, crank is ok the balancer is not, we can only figure that with the bolt bottomed out and the balancer finally shook loose...he also thinks the timing gear was possibly made wrong....we did not know about the different gears...but the problem would have come fron GM as those peices have not been changed....will give you a call this week....thanks Rob

Ghostrider

Was the magnetic trigger wheel still on the crankk inside the timing cover when you took it off? Apparently they need to be on there whether you run the crank trigger ignition or not as they act like a spacer. My motor has never had crank trigger ignition but the wheel is on there. If it's not there, it may cause play and allow the crank bolt to bottom out?

Just guessing, but that's my thoughts.

BillK

That is correct, but they also make a timing set with the correct, thicker lower gear. I think there are actually 3 different sets for the GenVI

EZ,
You can either get a trigger wheel to take up the space, or replace the bottom sprocket with the correct one. They are all listed in the Cloyes catalog. The trigger wheel is probably only available from GM.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Raylar

I think if he is talking about the reverse rotation engine here the camshaft is driven by a gear setup that turns the camshaft backwards for reverse rotation firing order and running. It does not have a timing chain setup.
I don't think these setups ever had a crankshaft reluctor gear on them . I suspect he just has a balancer with the crankshaft snout bore to far oversize. a new balancer should solve the problem I believe.

Best Regards,
Ray @ Raylar

ezstriper

the old way of reversing the engine was to run a gear to gear and reverse the cam, but the newer gen VI engines use a reverse cut dist gear and special dist and the stock timing chain set up....I'm sure from you guys are saying they left the wheel off when they swapped out the cam....from the issues I had with them right after I got the engines would not surprise me...thanks Rob

ezstriper

we have not pulled the cover off yet, can't see in there not much room as this is a V-Drive boat and the ft of the engine is about 12" from the transom.....will look into it...