I have a SB 727, and I I need to purchase a flexplate. Trouble is, I don't have the converter yet, and I don't know what bolts size is used, and the bolt circle diameter. I'm going to buy a PTC converter next week, and I wanted to find out ASAP what size converter bolts you use, 5/16 or 7/16? Also, there are two bolt circle sizes, 10" and 11.1". Is there a set standard for SB 727's? Lastly, can SB and BB 727 converters interchange?

Normally an aftermarket converter has 7/16 bolts and I know that the MP flexplate was already drilled for the bigger bolts, I am not sure about the bolt pattern but I would suspect the smallblock will use the smaller pattern because of a smaller bellhousing, if someone knows different then please correct me.

I have one it uses 7/16 bolts

Who's flex plate are you going with Dave?

I've had small blocks with both size flexplates. Depends on the stall and size of the converter itself. I just ordered a PTC converter for my BB and it cost an additional $20 for the 7/16 bolts. Almost all standard flexplates are the small size hole. All 727 converters are the same and will interchange, with the exception of the balance weights for a 360 or 400.

Dave,

Not sure if you knew Meziere made flexplates but I am going with one of thier's on my new build.

Needs to have custom hole pattern for the crank and 6 bolts for the NCR converter but I was told in the $500-550 range for one.

Here is link http://www.meziere.com/displaycategory.aspx?id=111,112,125

Like you said, buy once, cry once.... I like that. Going to have to use it when asked why parts are so expensive and buying the cheap ones...

I have 2 PTC converters for SB 727. They are 7" and 8". Both with 7/16 bolts. Flexplate is B&M SFI-approved and has 3 different bolt patterns, 2 for smaller and 1 for 7/16 bolts.