I did a search, and some people say yes do it and some say no because it puts more stress and wears out the front cam bearing? What is everyones thoughts on this? I also read of some faulty Lt4 ED sets, with teeth wearing out? Should I just keep my stock cam and wp stock sprockets (excellent condition) and go with the new oversized crank gear with a new LT4 timing chain. Since I know they won't wear prematurely? Any info will be of great light in this dark situation. Thanks...John

 

I'm running an oversided crank sprocket. It really tightened up my extreme duty chain and my friend who is very experienced with motor building said that it was perfect. I would get the LT4 ED and oversized gear if you plan to keep the stock pump.

 

Z95m6 is right on. When I had my 396 built, my builder wasnt happy with the slack in the LT4 ED set. He called up Cloyes (who manufactures the set) and the guy new right away what he was talking about. From what the rep at Cloyes said, it seems that all of the ED timing sets have a bit of slack in them. He sent him a new chain and lower gear, and it solved the problem, no more slack. Give Cloyes a call direct, and they will send you what you need.


Nick

 

The sprocket supplied with complete assembly is undersized. Cloyes machined sprocket using GM supplied specs that were in error, thus the reason for an oversized, or rather a larger/correct/replacement sprocket.

There may be a few (in the minority) assemblies that will fit better with the original (smaller) sprocket, but most will be correct with the larger replacement.

 

anyone have a p/n on this oversized sprocket for the LT4 ED timing chain?

 

If you are running the stock water pump and stock cam brgs DON'T use the oversize sprocket. GM was trying to take a little load off of the front cam brg with the loose chain.It has enough load with the WP. If you have changed your valve springs this adds to the load.
The "oversize" crank sprocket puts the chain to early SB spect which didn't have to carry the gear driven WP and had better cam brgs from the factory.

 

Thunder racing carries them. $40 and its listed separately.

 

cool thanks. any truth to the above statement concerning stock cam bearings?

 

I don't know if i agree with the stock cam bearings. I see where you're coming from in that if the chain is super tight it would put a lot of load on one side of the bearing. I don't think you are getting the chain that tight. You are just getting it tight. If you really want to start hypothesising i think it would be better to have the cam pulled tight rather than to have the chain to loose and allow the cam to "slop" around in the bearings. Just my opinion. I rebuilt my motor when i put mine in. I think with the oversized gear it was just as tight, maybe a hair tighter than my buddies Cloyes double roller. He installed his 20k ago with his 224/230 on his 80k shortblock.

 

Larry, so you're stating GM spec'd the loose sprocket by design?
Would like to follow up on what was stated elsewhere, regarding the 'loose' spec'd sprocket as a GM error, but don't recall the source. Supposedly, source quoted contact at Cloyes, stating origin of 'small' sprocket issue.

Will not dispute oem bearing comparo, but aftermarket replacements for both, are same. If that is the case, for anything rebuilt, bearing quality issue should not be a concern.