Lunati Cam + Gear Drive issue

[Duckzunlimtd]

Its been a while since I have been on due to work. My truck progression had fallen behind as well. I recently started purchasing everything to finish my motor. Rocker arms, Cam, Gear drive, intake and Carb.

1997 350 Vortec block. Upon installing the cam and lifters (Lunati Hyd. Roller) http://www.lunatipower.com/Product.aspx?id=2011 .... We have ran into a problem with the gear drive bolting up to the cam. The gear drive says that the "INSIDE EDGE TO INSIDE EDGE" of the holes on the cam need to be .650 and "OUTSIDE EDGE TO OUTSIDE EDGE" of the holes should be 1.290 (The bolt holes for the cam gear)

The problem I am having is the holes on the end of the CAM are measuring roughly .740 inside to inside and 1.27 outside to outside. The gear drive says it is for 1990-2004 Hyd Roller 350, being what we have. We are searching for a STOCK 97 Roller timing set to measure the holes in it. We are trying to determine weather the cam is off, the gear drive is off, or if this application wont work for what it says it does.

Any help soon would be greatly appreciated

 

[Duckzunlimtd]

So I suppose my question would be.. Does anybody have a stock 97-99 vortec cam gear laying around they can measure the holes on?

 

[bucket]

I highly doubt Lunati made the came wrong. It's a "step nose" cam, correct? What brand is the timing set?

I have a '97 Vortec shortblock, I think it still has the timing set on it. I'll check it out.

 

[Green79Scottsdale]

According to your link, that cam is specified for the LT1/LT4 engine family. I would suspect that might be your issue.

 

[bucket]

According to your link, that cam is specified for the LT1/LT4 engine family. I would suspect that might be your issue.

They work in the '87 and later roller blocks. They may or may not have a lobe for a mechanical fuel pump.

 

[Green79Scottsdale]

I know they go in the block. I was thinking different pattern for the timing gears due to the crank position sensor. I wasn't sure how LT1's compared to Vortec's. The cam noses are different from early to late LT1's due to the OptiSpark fixes they did.

 

[bucket]

I know they go in the block. I was thinking different pattern for the timing gears due to the crank position sensor. I wasn't sure how LT1's compared to Vortec's. The cam noses are different from early to late LT1's due to the OptiSpark fixes they did.

I didn't know they were different at all. I just know of people running factory LT1 cams in TBI 305's and people using the LT4 "hot" cam in other TBI/TPI 350/383 builds. I don't remember a year ever being specified.

 

[Green79Scottsdale]

Well, Lunati themselves differentiate the 1955-1998 small block family from the LT1/LT4 family of cams. Theres gotta be a difference, or they wouldn't do that. I didn't know about the nose difference either until I looked up timing gears/chains on Summit's site. You get a whole 6 items when you search LT specifc, and this is in the description of half of them.... "Can be installed on Generation 1 LT1, if the OptiSpark is updated to the new, second design. This will require new ignition, new front cover, and cam change to second design cam, the nose is different."

I have read of a lot swaps also. Seems most are into LT1 Corvettes or Camaros, and the rest seem to be carb'd applications that don't need a crank position sensor. And a lot of those swaps seem to just say they swapped to a "hot cam", but never really go in to great detail about all the specific new parts they actually had to use to successfully accomplish the swap. Maybe they all did re-use the old stuff, IDK.

I am not trying to argue and say you are wrong and I am right bucket... I am just digging for information and looking at all possibilities to get to the bones of the issue.

OP, did you actually try to bolt the new timing gear onto the cam nose? I can't quite picture the dimensions all together that you listed, but it almost sounds like the standard clearance dimensions for screws and bolts.

 

[bucket]

I am not trying to argue and say you are wrong and I am right bucket... I am just digging for information and looking at all possibilities to get to the bones of the issue.

Oh I know, I'm not saying I'm right either I had just always been under the assumption that LT cams were always a direct swap into all the factory roller cam blocks, using a standard replacement timing set. And provided a mechanical fuel pump is being used. An assumption based on magazine articles over the years and peoples' build threads. I've personally never done an LT cam swap, never even pulled a timing cover on an LT motor for that matter.

I didn't have the time today to look at the vortec cam sprocket, I looked and realized I still need to remove the balancer and timing cover.

 

[Duckzunlimtd]

Sorry on the delay.. Got it straightened out. As far as the cam goes the 1955-1998 cams are retro rollers for any block, needing the special lifters.
We ended up talking to the head guy at our chevy dealership in town, and he himself said that the cam bolt pattern for the roller cams DID change, but he could not give us an exact year in which they changed the bolt patterns. He said that sometimes they have to order 3-4 timing sets to finally get one that fits. Says the LS motors have the same problem.

I did orber a performance timing set from Cloyes and it has fit.