Ok, its not the ED Lt4 timing set. I chose and bought the regular LT4 timing set due to the wp gear replacement issue for my 97 Z28 with 108,000. The stock chain has about 1/2 slack on the "loose" side, by that I mean the passenger side of the engine. The drivers side of the chain looks very tight, 1/4" at most. It appears the set has been on there about 30,000 to 50,000 miles which was before I bought the car. There was evidence of the oil pan being droped, RTV in the front corners of the pan plus the pan bolts were looose and the cam sprocket bolts we just barely more than finger tight.

I inspected my new LT4 set this morning, the cam gear is "pitted" on the front side with some evidence of rust showing, not to mention that a gear tooth is missing. The part numbers that I purchased are:
12555885 12555886 and 12555887 at just at $200 from a GM dealer, the gears on both sprokets are the size of a BICYCLE sproket, LESS than 1/8th inch wide. The chain looks just like a bicycle chain, it is labeled "12555887 MADE IN FRANCE" and is aprox 1 MM wide, the stock LT1 chain looks to be 1.5 MM wide. The stock gears have teeth that are 3 to 4 times wider than the LT4 teeth.

Can anybody explain why this LT4 set looks "DINKY" compared to a LT1 stock replacement. I have to speak to the dealer about this Monday at least to get the cam gear replaced, however my used stock set looks 4 times stronger than these bycycle looking parts. I was hoping to get the car running this weekend.

What is the recommended slack to replace a timing set and on which side. This repair started out as a water pump failure on May 20th, the repair from hell, now I have no idea how to proceed with this timing set. Thanks for your help, I need it!

 

Not to mention that today is my birthday, 52, thanks for your help or advise, Jim

 

I need a birthday present guys, help!

 

Happy Birthday!

The LT4 timing set is a roller and not a flat link chain so they do look drastically different. The LT4 chain looks small but I've never heard of a failure, not even on cam'd cars. I probably wouldn't run it on a healthy solid roller but is more than up to the task for most cars.

All of the ones I've seen show some slack. Unless the block has been align honed, I wouldn't worry about it.

Of course, I would return the cam gear for a new one. Missing teeth is NOT acceptable, but I'm sure you knew that

 

return it & buy an extreme duty set.

matt.

 

From the "LT1 vs. LT4" comparo that is available online:

http://www.malcams.com/legacy/misc/LT4.htm
According to the same article, the standard LT4 roller chain is made for GM by Cloyes.

 

I agree with trading it in for an extreme duty set. I will cost about $50 more
but it's a lot beefier. Just remember that you will have to press off the old
WP gear and press on the new one from the set. Also, getting the WP shaft
assy out is not too bad if the intake is off.

 

another vote for trading it in on the Extreme Duty...That's the one I went with and that sucka is tank proof....spend the extra $$$

 

Here's a pic that shows te Stock, HD, and Cloyes together:
http://z28.reanimator.org/pics/timing_chains.jpg

 

Hey Micky97Z, thanks for the pictures, you just made the whole deal worse!!
and took me right out of my newfound comfort zone with the stock LT4 set.

The LT4 timing chain part number 12555887 is about 2/3rds the size of the stock chain pictured on the left side. This is crazy, if your picture in the middle is the Cloyes, its a roller, its twice the size of this dinky LT4 timing chain. I am totally confused now. What is the part number of that chain in the middle if it is a Cloyes? I now have the replacement cam spocket on its way from Michigan. I would be stupid to put a chain on my car as small as what I have (paid $103.45 just for the chain) picture on its way!!!

 

Here is the picture link of the LT4 set I have:
http://f1.pg.photos.yahoo.com/ph/for...bum?.dir=/fac6

I think I just caught my folly on your pictures, the one you refer to as the Cloyes is the stock one on the left, the middle one is the Lt4ED set and the right one is the double roller. I guess I am straight now. Words of wisdom, if you decide not to pull the intake cause you got to sell the car to your son and get it running, buy the cloyes set, not the regular LT4 set. I have no confidence this LT4 set is any better than stock, its a roller, thats it, its very small.

 

The left is stock, the middle is GM LT4 HD, and the rigt is a Cloyes double-roller.
Sorry, I don't have any part numbers right now.

 

I had a the standard LT4 timing set and had no problems with it at all, ran it at least two racing seasons with it. I eventually switch to the Double Roller during the last engine tear down about two years ago.

What type of cam are you planning on running? If this is just a replacement with the stock cam or even with the LT4 Hotcam or equiv I would save the bucks and run the standard LT4 timing chain, my .023433 worth.

 

Correct Ken, stock cam, simply replacing a loose LT1 stock set while I was in there and trying to beef it up a bit since my son takes the car to the 1/8 mile track and likes to WOT. Thanks for the feedback!! I appreciate it.

 

As Injuneer's reference said, though smaller, it is supposed to be stronger than the LT1 set. If it was good enough for original equipment on the LT4, it should be ok.

A few oddities:

Your package says "France" on it. There is a Cloyes, France. However the Cloyes business was founded in the 1920's in Cleveland, Ohio. I guess they import some chains.

Most sets are made in Paris. No, not Paris, France, but Paris, Arkansas. Cloyes makes most or all of their timing sets in two plants in Arkansas (one in Paris and the other in Subiaco). They also have another plant in Billings, Oklahoma.