Apparently I was given the wrong flexplate for my new engine
seen here: http://i14.photobucket.com/albums/a305/aallair/new.jpg

This is my old one: http://i14.photobucket.com/albums/a305/aallair/new.jpg

Why is the diameter different? Can i use a different starter or do I have to find a new flexplate?

 

Can't tell from the pictures but if it's an LT-1 and has 153 teeth and 12-3/4"dia it should work. The other small block wheel is 168 teeth and 14"dia.

 

SBCs since way back used 2 different diameters. 153 tooth and 168. And they each used a different starter. This applies even to the 87-up engines with one piece RMS, with some exceptions.

The smaller 153s used a starter designed for a 153. In the old days this was a "straight bolt patter" starter. Larger 168 tooth flexplates used a "staggered bolt pattern" starter. Most blocks (not all) were dual-bolt-pattern and could accept either type of starter.

Unfortunately, the LT-1s used a staggered bolt pattern starter but it's designed to work with a 153 tooth flexplate (I know because I used one on my older L-98 with 153 tooth flexplate). Basically, they messed up the old tried and true rules. I am not sure if anyone makes a starter for an LT-1 that uses the LT-1s staggered bolt pattern but works with a larger 168 tooth flexplate. Or even if the staggered bolt pattern on the LT-1 block is the same staggered bolt pattern as older blocks (allowing you to use an older staggered bolt pattern starter for a 168 tooth flexplate).

IF...... the staggered bolt pattern on the LT-1 block is the same as an older block then you can buy an older style staggered bolt pattern starter that is designed to work with a 168 tooth flexplate and bolt it right in. Here is the starter I often use in such applications which is very similar in size to an LT-1 starter and is gear reduction type:

http://www.gmgoodwrench.com/perfpart...ion=pp#9000852

Look half way down for part number 9000852. It says it's for big block 502s but staggered bolt pattern small block 168 tooth applications use the same one (I have one on the 383 in my Malibu- so this is not some "theory" I came up with off the top of my head).

There are also cheaper knock-offs of this same starter available on e-bay and other places.

A different flexplate is a lot cheaper than a new starter, but I understand the PITA of yanking the trans to change it might not be worth the cost savings.

 

Both links are to the same photo.

 

As I re-read my own post I realized something..... the staggered bolt pattern on an LT-1 block IS the same as older blocks. Like I said.... I have an LT-1 starter bolted to my old L-98 block right now. So, obviously, the bolt pattern must be the same as older blocks. Duh. Never claimed to be the sharpest knife in the drawer.

 

thanks for the reply. I ended up changing out the flexplate. I was told that the flexplate in the picture was for the 4l60E used in trucks. I don't know if there is any truth to that.
Here is what the old one looked like (the correct one)
http://i14.photobucket.com/albums/a305/aallair/old.jpg

 

Those 2 flexplates were probably the exact same diameter. The "new" one that you show just has the bolt holes for the torque converter in the furthest out position. On all the torque converters and flexplates, (stock and ATI and B&M) I have for my LT1 and 4L60E and TH400's there is an inner and and outer bolt hole and the flexplate will have an inner and an outer bolt hole to match. I betcha even that "new" one that you replaced had the inner holes too, (i.e. it has 3 holes somewhat further inward and 3 holes somewhat further ******d).
hth
Karl

 

No, the diameter isn't even close.

 

trying to run the larger flexplate in an f-body results in header to starter clearance problems.